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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> | |
630d9c47 | 32 | #include <linux/export.h> |
1da177e4 LT |
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 | ||
a3f3c29c | 49 | void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) |
1da177e4 LT |
50 | { |
51 | bh->b_end_io = handler; | |
52 | bh->b_private = private; | |
53 | } | |
1fe72eaa | 54 | EXPORT_SYMBOL(init_buffer); |
1da177e4 | 55 | |
7eaceacc | 56 | static int sleep_on_buffer(void *word) |
1da177e4 | 57 | { |
1da177e4 LT |
58 | io_schedule(); |
59 | return 0; | |
60 | } | |
61 | ||
fc9b52cd | 62 | void __lock_buffer(struct buffer_head *bh) |
1da177e4 | 63 | { |
7eaceacc | 64 | wait_on_bit_lock(&bh->b_state, BH_Lock, sleep_on_buffer, |
1da177e4 LT |
65 | TASK_UNINTERRUPTIBLE); |
66 | } | |
67 | EXPORT_SYMBOL(__lock_buffer); | |
68 | ||
fc9b52cd | 69 | void unlock_buffer(struct buffer_head *bh) |
1da177e4 | 70 | { |
51b07fc3 | 71 | clear_bit_unlock(BH_Lock, &bh->b_state); |
1da177e4 LT |
72 | smp_mb__after_clear_bit(); |
73 | wake_up_bit(&bh->b_state, BH_Lock); | |
74 | } | |
1fe72eaa | 75 | EXPORT_SYMBOL(unlock_buffer); |
1da177e4 LT |
76 | |
77 | /* | |
78 | * Block until a buffer comes unlocked. This doesn't stop it | |
79 | * from becoming locked again - you have to lock it yourself | |
80 | * if you want to preserve its state. | |
81 | */ | |
82 | void __wait_on_buffer(struct buffer_head * bh) | |
83 | { | |
7eaceacc | 84 | wait_on_bit(&bh->b_state, BH_Lock, sleep_on_buffer, TASK_UNINTERRUPTIBLE); |
1da177e4 | 85 | } |
1fe72eaa | 86 | EXPORT_SYMBOL(__wait_on_buffer); |
1da177e4 LT |
87 | |
88 | static void | |
89 | __clear_page_buffers(struct page *page) | |
90 | { | |
91 | ClearPagePrivate(page); | |
4c21e2f2 | 92 | set_page_private(page, 0); |
1da177e4 LT |
93 | page_cache_release(page); |
94 | } | |
95 | ||
08bafc03 KM |
96 | |
97 | static int quiet_error(struct buffer_head *bh) | |
98 | { | |
99 | if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit()) | |
100 | return 0; | |
101 | return 1; | |
102 | } | |
103 | ||
104 | ||
1da177e4 LT |
105 | static void buffer_io_error(struct buffer_head *bh) |
106 | { | |
107 | char b[BDEVNAME_SIZE]; | |
1da177e4 LT |
108 | printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", |
109 | bdevname(bh->b_bdev, b), | |
110 | (unsigned long long)bh->b_blocknr); | |
111 | } | |
112 | ||
113 | /* | |
68671f35 DM |
114 | * End-of-IO handler helper function which does not touch the bh after |
115 | * unlocking it. | |
116 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but | |
117 | * a race there is benign: unlock_buffer() only use the bh's address for | |
118 | * hashing after unlocking the buffer, so it doesn't actually touch the bh | |
119 | * itself. | |
1da177e4 | 120 | */ |
68671f35 | 121 | static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
122 | { |
123 | if (uptodate) { | |
124 | set_buffer_uptodate(bh); | |
125 | } else { | |
126 | /* This happens, due to failed READA attempts. */ | |
127 | clear_buffer_uptodate(bh); | |
128 | } | |
129 | unlock_buffer(bh); | |
68671f35 DM |
130 | } |
131 | ||
132 | /* | |
133 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and | |
134 | * unlock the buffer. This is what ll_rw_block uses too. | |
135 | */ | |
136 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) | |
137 | { | |
138 | __end_buffer_read_notouch(bh, uptodate); | |
1da177e4 LT |
139 | put_bh(bh); |
140 | } | |
1fe72eaa | 141 | EXPORT_SYMBOL(end_buffer_read_sync); |
1da177e4 LT |
142 | |
143 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) | |
144 | { | |
145 | char b[BDEVNAME_SIZE]; | |
146 | ||
147 | if (uptodate) { | |
148 | set_buffer_uptodate(bh); | |
149 | } else { | |
0edd55fa | 150 | if (!quiet_error(bh)) { |
1da177e4 LT |
151 | buffer_io_error(bh); |
152 | printk(KERN_WARNING "lost page write due to " | |
153 | "I/O error on %s\n", | |
154 | bdevname(bh->b_bdev, b)); | |
155 | } | |
156 | set_buffer_write_io_error(bh); | |
157 | clear_buffer_uptodate(bh); | |
158 | } | |
159 | unlock_buffer(bh); | |
160 | put_bh(bh); | |
161 | } | |
1fe72eaa | 162 | EXPORT_SYMBOL(end_buffer_write_sync); |
1da177e4 | 163 | |
1da177e4 LT |
164 | /* |
165 | * Various filesystems appear to want __find_get_block to be non-blocking. | |
166 | * But it's the page lock which protects the buffers. To get around this, | |
167 | * we get exclusion from try_to_free_buffers with the blockdev mapping's | |
168 | * private_lock. | |
169 | * | |
170 | * Hack idea: for the blockdev mapping, i_bufferlist_lock contention | |
171 | * may be quite high. This code could TryLock the page, and if that | |
172 | * succeeds, there is no need to take private_lock. (But if | |
173 | * private_lock is contended then so is mapping->tree_lock). | |
174 | */ | |
175 | static struct buffer_head * | |
385fd4c5 | 176 | __find_get_block_slow(struct block_device *bdev, sector_t block) |
1da177e4 LT |
177 | { |
178 | struct inode *bd_inode = bdev->bd_inode; | |
179 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
180 | struct buffer_head *ret = NULL; | |
181 | pgoff_t index; | |
182 | struct buffer_head *bh; | |
183 | struct buffer_head *head; | |
184 | struct page *page; | |
185 | int all_mapped = 1; | |
186 | ||
187 | index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); | |
188 | page = find_get_page(bd_mapping, index); | |
189 | if (!page) | |
190 | goto out; | |
191 | ||
192 | spin_lock(&bd_mapping->private_lock); | |
193 | if (!page_has_buffers(page)) | |
194 | goto out_unlock; | |
195 | head = page_buffers(page); | |
196 | bh = head; | |
197 | do { | |
97f76d3d NK |
198 | if (!buffer_mapped(bh)) |
199 | all_mapped = 0; | |
200 | else if (bh->b_blocknr == block) { | |
1da177e4 LT |
201 | ret = bh; |
202 | get_bh(bh); | |
203 | goto out_unlock; | |
204 | } | |
1da177e4 LT |
205 | bh = bh->b_this_page; |
206 | } while (bh != head); | |
207 | ||
208 | /* we might be here because some of the buffers on this page are | |
209 | * not mapped. This is due to various races between | |
210 | * file io on the block device and getblk. It gets dealt with | |
211 | * elsewhere, don't buffer_error if we had some unmapped buffers | |
212 | */ | |
213 | if (all_mapped) { | |
72a2ebd8 TM |
214 | char b[BDEVNAME_SIZE]; |
215 | ||
1da177e4 LT |
216 | printk("__find_get_block_slow() failed. " |
217 | "block=%llu, b_blocknr=%llu\n", | |
205f87f6 BP |
218 | (unsigned long long)block, |
219 | (unsigned long long)bh->b_blocknr); | |
220 | printk("b_state=0x%08lx, b_size=%zu\n", | |
221 | bh->b_state, bh->b_size); | |
72a2ebd8 TM |
222 | printk("device %s blocksize: %d\n", bdevname(bdev, b), |
223 | 1 << bd_inode->i_blkbits); | |
1da177e4 LT |
224 | } |
225 | out_unlock: | |
226 | spin_unlock(&bd_mapping->private_lock); | |
227 | page_cache_release(page); | |
228 | out: | |
229 | return ret; | |
230 | } | |
231 | ||
1da177e4 | 232 | /* |
5b0830cb | 233 | * Kick the writeback threads then try to free up some ZONE_NORMAL memory. |
1da177e4 LT |
234 | */ |
235 | static void free_more_memory(void) | |
236 | { | |
19770b32 | 237 | struct zone *zone; |
0e88460d | 238 | int nid; |
1da177e4 | 239 | |
0e175a18 | 240 | wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM); |
1da177e4 LT |
241 | yield(); |
242 | ||
0e88460d | 243 | for_each_online_node(nid) { |
19770b32 MG |
244 | (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS), |
245 | gfp_zone(GFP_NOFS), NULL, | |
246 | &zone); | |
247 | if (zone) | |
54a6eb5c | 248 | try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, |
327c0e96 | 249 | GFP_NOFS, NULL); |
1da177e4 LT |
250 | } |
251 | } | |
252 | ||
253 | /* | |
254 | * I/O completion handler for block_read_full_page() - pages | |
255 | * which come unlocked at the end of I/O. | |
256 | */ | |
257 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) | |
258 | { | |
1da177e4 | 259 | unsigned long flags; |
a3972203 | 260 | struct buffer_head *first; |
1da177e4 LT |
261 | struct buffer_head *tmp; |
262 | struct page *page; | |
263 | int page_uptodate = 1; | |
264 | ||
265 | BUG_ON(!buffer_async_read(bh)); | |
266 | ||
267 | page = bh->b_page; | |
268 | if (uptodate) { | |
269 | set_buffer_uptodate(bh); | |
270 | } else { | |
271 | clear_buffer_uptodate(bh); | |
08bafc03 | 272 | if (!quiet_error(bh)) |
1da177e4 LT |
273 | buffer_io_error(bh); |
274 | SetPageError(page); | |
275 | } | |
276 | ||
277 | /* | |
278 | * Be _very_ careful from here on. Bad things can happen if | |
279 | * two buffer heads end IO at almost the same time and both | |
280 | * decide that the page is now completely done. | |
281 | */ | |
a3972203 NP |
282 | first = page_buffers(page); |
283 | local_irq_save(flags); | |
284 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
1da177e4 LT |
285 | clear_buffer_async_read(bh); |
286 | unlock_buffer(bh); | |
287 | tmp = bh; | |
288 | do { | |
289 | if (!buffer_uptodate(tmp)) | |
290 | page_uptodate = 0; | |
291 | if (buffer_async_read(tmp)) { | |
292 | BUG_ON(!buffer_locked(tmp)); | |
293 | goto still_busy; | |
294 | } | |
295 | tmp = tmp->b_this_page; | |
296 | } while (tmp != bh); | |
a3972203 NP |
297 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
298 | local_irq_restore(flags); | |
1da177e4 LT |
299 | |
300 | /* | |
301 | * If none of the buffers had errors and they are all | |
302 | * uptodate then we can set the page uptodate. | |
303 | */ | |
304 | if (page_uptodate && !PageError(page)) | |
305 | SetPageUptodate(page); | |
306 | unlock_page(page); | |
307 | return; | |
308 | ||
309 | still_busy: | |
a3972203 NP |
310 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
311 | local_irq_restore(flags); | |
1da177e4 LT |
312 | return; |
313 | } | |
314 | ||
315 | /* | |
316 | * Completion handler for block_write_full_page() - pages which are unlocked | |
317 | * during I/O, and which have PageWriteback cleared upon I/O completion. | |
318 | */ | |
35c80d5f | 319 | void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
320 | { |
321 | char b[BDEVNAME_SIZE]; | |
1da177e4 | 322 | unsigned long flags; |
a3972203 | 323 | struct buffer_head *first; |
1da177e4 LT |
324 | struct buffer_head *tmp; |
325 | struct page *page; | |
326 | ||
327 | BUG_ON(!buffer_async_write(bh)); | |
328 | ||
329 | page = bh->b_page; | |
330 | if (uptodate) { | |
331 | set_buffer_uptodate(bh); | |
332 | } else { | |
08bafc03 | 333 | if (!quiet_error(bh)) { |
1da177e4 LT |
334 | buffer_io_error(bh); |
335 | printk(KERN_WARNING "lost page write due to " | |
336 | "I/O error on %s\n", | |
337 | bdevname(bh->b_bdev, b)); | |
338 | } | |
339 | set_bit(AS_EIO, &page->mapping->flags); | |
58ff407b | 340 | set_buffer_write_io_error(bh); |
1da177e4 LT |
341 | clear_buffer_uptodate(bh); |
342 | SetPageError(page); | |
343 | } | |
344 | ||
a3972203 NP |
345 | first = page_buffers(page); |
346 | local_irq_save(flags); | |
347 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
348 | ||
1da177e4 LT |
349 | clear_buffer_async_write(bh); |
350 | unlock_buffer(bh); | |
351 | tmp = bh->b_this_page; | |
352 | while (tmp != bh) { | |
353 | if (buffer_async_write(tmp)) { | |
354 | BUG_ON(!buffer_locked(tmp)); | |
355 | goto still_busy; | |
356 | } | |
357 | tmp = tmp->b_this_page; | |
358 | } | |
a3972203 NP |
359 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
360 | local_irq_restore(flags); | |
1da177e4 LT |
361 | end_page_writeback(page); |
362 | return; | |
363 | ||
364 | still_busy: | |
a3972203 NP |
365 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
366 | local_irq_restore(flags); | |
1da177e4 LT |
367 | return; |
368 | } | |
1fe72eaa | 369 | EXPORT_SYMBOL(end_buffer_async_write); |
1da177e4 LT |
370 | |
371 | /* | |
372 | * If a page's buffers are under async readin (end_buffer_async_read | |
373 | * completion) then there is a possibility that another thread of | |
374 | * control could lock one of the buffers after it has completed | |
375 | * but while some of the other buffers have not completed. This | |
376 | * locked buffer would confuse end_buffer_async_read() into not unlocking | |
377 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() | |
378 | * that this buffer is not under async I/O. | |
379 | * | |
380 | * The page comes unlocked when it has no locked buffer_async buffers | |
381 | * left. | |
382 | * | |
383 | * PageLocked prevents anyone starting new async I/O reads any of | |
384 | * the buffers. | |
385 | * | |
386 | * PageWriteback is used to prevent simultaneous writeout of the same | |
387 | * page. | |
388 | * | |
389 | * PageLocked prevents anyone from starting writeback of a page which is | |
390 | * under read I/O (PageWriteback is only ever set against a locked page). | |
391 | */ | |
392 | static void mark_buffer_async_read(struct buffer_head *bh) | |
393 | { | |
394 | bh->b_end_io = end_buffer_async_read; | |
395 | set_buffer_async_read(bh); | |
396 | } | |
397 | ||
1fe72eaa HS |
398 | static void mark_buffer_async_write_endio(struct buffer_head *bh, |
399 | bh_end_io_t *handler) | |
1da177e4 | 400 | { |
35c80d5f | 401 | bh->b_end_io = handler; |
1da177e4 LT |
402 | set_buffer_async_write(bh); |
403 | } | |
35c80d5f CM |
404 | |
405 | void mark_buffer_async_write(struct buffer_head *bh) | |
406 | { | |
407 | mark_buffer_async_write_endio(bh, end_buffer_async_write); | |
408 | } | |
1da177e4 LT |
409 | EXPORT_SYMBOL(mark_buffer_async_write); |
410 | ||
411 | ||
412 | /* | |
413 | * fs/buffer.c contains helper functions for buffer-backed address space's | |
414 | * fsync functions. A common requirement for buffer-based filesystems is | |
415 | * that certain data from the backing blockdev needs to be written out for | |
416 | * a successful fsync(). For example, ext2 indirect blocks need to be | |
417 | * written back and waited upon before fsync() returns. | |
418 | * | |
419 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), | |
420 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the | |
421 | * management of a list of dependent buffers at ->i_mapping->private_list. | |
422 | * | |
423 | * Locking is a little subtle: try_to_free_buffers() will remove buffers | |
424 | * from their controlling inode's queue when they are being freed. But | |
425 | * try_to_free_buffers() will be operating against the *blockdev* mapping | |
426 | * at the time, not against the S_ISREG file which depends on those buffers. | |
427 | * So the locking for private_list is via the private_lock in the address_space | |
428 | * which backs the buffers. Which is different from the address_space | |
429 | * against which the buffers are listed. So for a particular address_space, | |
430 | * mapping->private_lock does *not* protect mapping->private_list! In fact, | |
431 | * mapping->private_list will always be protected by the backing blockdev's | |
432 | * ->private_lock. | |
433 | * | |
434 | * Which introduces a requirement: all buffers on an address_space's | |
435 | * ->private_list must be from the same address_space: the blockdev's. | |
436 | * | |
437 | * address_spaces which do not place buffers at ->private_list via these | |
438 | * utility functions are free to use private_lock and private_list for | |
439 | * whatever they want. The only requirement is that list_empty(private_list) | |
440 | * be true at clear_inode() time. | |
441 | * | |
442 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The | |
443 | * filesystems should do that. invalidate_inode_buffers() should just go | |
444 | * BUG_ON(!list_empty). | |
445 | * | |
446 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should | |
447 | * take an address_space, not an inode. And it should be called | |
448 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being | |
449 | * queued up. | |
450 | * | |
451 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the | |
452 | * list if it is already on a list. Because if the buffer is on a list, | |
453 | * it *must* already be on the right one. If not, the filesystem is being | |
454 | * silly. This will save a ton of locking. But first we have to ensure | |
455 | * that buffers are taken *off* the old inode's list when they are freed | |
456 | * (presumably in truncate). That requires careful auditing of all | |
457 | * filesystems (do it inside bforget()). It could also be done by bringing | |
458 | * b_inode back. | |
459 | */ | |
460 | ||
461 | /* | |
462 | * The buffer's backing address_space's private_lock must be held | |
463 | */ | |
dbacefc9 | 464 | static void __remove_assoc_queue(struct buffer_head *bh) |
1da177e4 LT |
465 | { |
466 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b JK |
467 | WARN_ON(!bh->b_assoc_map); |
468 | if (buffer_write_io_error(bh)) | |
469 | set_bit(AS_EIO, &bh->b_assoc_map->flags); | |
470 | bh->b_assoc_map = NULL; | |
1da177e4 LT |
471 | } |
472 | ||
473 | int inode_has_buffers(struct inode *inode) | |
474 | { | |
475 | return !list_empty(&inode->i_data.private_list); | |
476 | } | |
477 | ||
478 | /* | |
479 | * osync is designed to support O_SYNC io. It waits synchronously for | |
480 | * all already-submitted IO to complete, but does not queue any new | |
481 | * writes to the disk. | |
482 | * | |
483 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as | |
484 | * you dirty the buffers, and then use osync_inode_buffers to wait for | |
485 | * completion. Any other dirty buffers which are not yet queued for | |
486 | * write will not be flushed to disk by the osync. | |
487 | */ | |
488 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) | |
489 | { | |
490 | struct buffer_head *bh; | |
491 | struct list_head *p; | |
492 | int err = 0; | |
493 | ||
494 | spin_lock(lock); | |
495 | repeat: | |
496 | list_for_each_prev(p, list) { | |
497 | bh = BH_ENTRY(p); | |
498 | if (buffer_locked(bh)) { | |
499 | get_bh(bh); | |
500 | spin_unlock(lock); | |
501 | wait_on_buffer(bh); | |
502 | if (!buffer_uptodate(bh)) | |
503 | err = -EIO; | |
504 | brelse(bh); | |
505 | spin_lock(lock); | |
506 | goto repeat; | |
507 | } | |
508 | } | |
509 | spin_unlock(lock); | |
510 | return err; | |
511 | } | |
512 | ||
01a05b33 | 513 | static void do_thaw_one(struct super_block *sb, void *unused) |
c2d75438 | 514 | { |
c2d75438 | 515 | char b[BDEVNAME_SIZE]; |
01a05b33 AV |
516 | while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) |
517 | printk(KERN_WARNING "Emergency Thaw on %s\n", | |
518 | bdevname(sb->s_bdev, b)); | |
519 | } | |
c2d75438 | 520 | |
01a05b33 AV |
521 | static void do_thaw_all(struct work_struct *work) |
522 | { | |
523 | iterate_supers(do_thaw_one, NULL); | |
053c525f | 524 | kfree(work); |
c2d75438 ES |
525 | printk(KERN_WARNING "Emergency Thaw complete\n"); |
526 | } | |
527 | ||
528 | /** | |
529 | * emergency_thaw_all -- forcibly thaw every frozen filesystem | |
530 | * | |
531 | * Used for emergency unfreeze of all filesystems via SysRq | |
532 | */ | |
533 | void emergency_thaw_all(void) | |
534 | { | |
053c525f JA |
535 | struct work_struct *work; |
536 | ||
537 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
538 | if (work) { | |
539 | INIT_WORK(work, do_thaw_all); | |
540 | schedule_work(work); | |
541 | } | |
c2d75438 ES |
542 | } |
543 | ||
1da177e4 | 544 | /** |
78a4a50a | 545 | * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers |
67be2dd1 | 546 | * @mapping: the mapping which wants those buffers written |
1da177e4 LT |
547 | * |
548 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
549 | * that I/O. | |
550 | * | |
67be2dd1 MW |
551 | * Basically, this is a convenience function for fsync(). |
552 | * @mapping is a file or directory which needs those buffers to be written for | |
553 | * a successful fsync(). | |
1da177e4 LT |
554 | */ |
555 | int sync_mapping_buffers(struct address_space *mapping) | |
556 | { | |
252aa6f5 | 557 | struct address_space *buffer_mapping = mapping->private_data; |
1da177e4 LT |
558 | |
559 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) | |
560 | return 0; | |
561 | ||
562 | return fsync_buffers_list(&buffer_mapping->private_lock, | |
563 | &mapping->private_list); | |
564 | } | |
565 | EXPORT_SYMBOL(sync_mapping_buffers); | |
566 | ||
567 | /* | |
568 | * Called when we've recently written block `bblock', and it is known that | |
569 | * `bblock' was for a buffer_boundary() buffer. This means that the block at | |
570 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's | |
571 | * dirty, schedule it for IO. So that indirects merge nicely with their data. | |
572 | */ | |
573 | void write_boundary_block(struct block_device *bdev, | |
574 | sector_t bblock, unsigned blocksize) | |
575 | { | |
576 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); | |
577 | if (bh) { | |
578 | if (buffer_dirty(bh)) | |
579 | ll_rw_block(WRITE, 1, &bh); | |
580 | put_bh(bh); | |
581 | } | |
582 | } | |
583 | ||
584 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) | |
585 | { | |
586 | struct address_space *mapping = inode->i_mapping; | |
587 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
588 | ||
589 | mark_buffer_dirty(bh); | |
252aa6f5 RA |
590 | if (!mapping->private_data) { |
591 | mapping->private_data = buffer_mapping; | |
1da177e4 | 592 | } else { |
252aa6f5 | 593 | BUG_ON(mapping->private_data != buffer_mapping); |
1da177e4 | 594 | } |
535ee2fb | 595 | if (!bh->b_assoc_map) { |
1da177e4 LT |
596 | spin_lock(&buffer_mapping->private_lock); |
597 | list_move_tail(&bh->b_assoc_buffers, | |
598 | &mapping->private_list); | |
58ff407b | 599 | bh->b_assoc_map = mapping; |
1da177e4 LT |
600 | spin_unlock(&buffer_mapping->private_lock); |
601 | } | |
602 | } | |
603 | EXPORT_SYMBOL(mark_buffer_dirty_inode); | |
604 | ||
787d2214 NP |
605 | /* |
606 | * Mark the page dirty, and set it dirty in the radix tree, and mark the inode | |
607 | * dirty. | |
608 | * | |
609 | * If warn is true, then emit a warning if the page is not uptodate and has | |
610 | * not been truncated. | |
611 | */ | |
a8e7d49a | 612 | static void __set_page_dirty(struct page *page, |
787d2214 NP |
613 | struct address_space *mapping, int warn) |
614 | { | |
19fd6231 | 615 | spin_lock_irq(&mapping->tree_lock); |
787d2214 NP |
616 | if (page->mapping) { /* Race with truncate? */ |
617 | WARN_ON_ONCE(warn && !PageUptodate(page)); | |
e3a7cca1 | 618 | account_page_dirtied(page, mapping); |
787d2214 NP |
619 | radix_tree_tag_set(&mapping->page_tree, |
620 | page_index(page), PAGECACHE_TAG_DIRTY); | |
621 | } | |
19fd6231 | 622 | spin_unlock_irq(&mapping->tree_lock); |
787d2214 | 623 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
787d2214 NP |
624 | } |
625 | ||
1da177e4 LT |
626 | /* |
627 | * Add a page to the dirty page list. | |
628 | * | |
629 | * It is a sad fact of life that this function is called from several places | |
630 | * deeply under spinlocking. It may not sleep. | |
631 | * | |
632 | * If the page has buffers, the uptodate buffers are set dirty, to preserve | |
633 | * dirty-state coherency between the page and the buffers. It the page does | |
634 | * not have buffers then when they are later attached they will all be set | |
635 | * dirty. | |
636 | * | |
637 | * The buffers are dirtied before the page is dirtied. There's a small race | |
638 | * window in which a writepage caller may see the page cleanness but not the | |
639 | * buffer dirtiness. That's fine. If this code were to set the page dirty | |
640 | * before the buffers, a concurrent writepage caller could clear the page dirty | |
641 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean | |
642 | * page on the dirty page list. | |
643 | * | |
644 | * We use private_lock to lock against try_to_free_buffers while using the | |
645 | * page's buffer list. Also use this to protect against clean buffers being | |
646 | * added to the page after it was set dirty. | |
647 | * | |
648 | * FIXME: may need to call ->reservepage here as well. That's rather up to the | |
649 | * address_space though. | |
650 | */ | |
651 | int __set_page_dirty_buffers(struct page *page) | |
652 | { | |
a8e7d49a | 653 | int newly_dirty; |
787d2214 | 654 | struct address_space *mapping = page_mapping(page); |
ebf7a227 NP |
655 | |
656 | if (unlikely(!mapping)) | |
657 | return !TestSetPageDirty(page); | |
1da177e4 LT |
658 | |
659 | spin_lock(&mapping->private_lock); | |
660 | if (page_has_buffers(page)) { | |
661 | struct buffer_head *head = page_buffers(page); | |
662 | struct buffer_head *bh = head; | |
663 | ||
664 | do { | |
665 | set_buffer_dirty(bh); | |
666 | bh = bh->b_this_page; | |
667 | } while (bh != head); | |
668 | } | |
a8e7d49a | 669 | newly_dirty = !TestSetPageDirty(page); |
1da177e4 LT |
670 | spin_unlock(&mapping->private_lock); |
671 | ||
a8e7d49a LT |
672 | if (newly_dirty) |
673 | __set_page_dirty(page, mapping, 1); | |
674 | return newly_dirty; | |
1da177e4 LT |
675 | } |
676 | EXPORT_SYMBOL(__set_page_dirty_buffers); | |
677 | ||
678 | /* | |
679 | * Write out and wait upon a list of buffers. | |
680 | * | |
681 | * We have conflicting pressures: we want to make sure that all | |
682 | * initially dirty buffers get waited on, but that any subsequently | |
683 | * dirtied buffers don't. After all, we don't want fsync to last | |
684 | * forever if somebody is actively writing to the file. | |
685 | * | |
686 | * Do this in two main stages: first we copy dirty buffers to a | |
687 | * temporary inode list, queueing the writes as we go. Then we clean | |
688 | * up, waiting for those writes to complete. | |
689 | * | |
690 | * During this second stage, any subsequent updates to the file may end | |
691 | * up refiling the buffer on the original inode's dirty list again, so | |
692 | * there is a chance we will end up with a buffer queued for write but | |
693 | * not yet completed on that list. So, as a final cleanup we go through | |
694 | * the osync code to catch these locked, dirty buffers without requeuing | |
695 | * any newly dirty buffers for write. | |
696 | */ | |
697 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) | |
698 | { | |
699 | struct buffer_head *bh; | |
700 | struct list_head tmp; | |
7eaceacc | 701 | struct address_space *mapping; |
1da177e4 | 702 | int err = 0, err2; |
4ee2491e | 703 | struct blk_plug plug; |
1da177e4 LT |
704 | |
705 | INIT_LIST_HEAD(&tmp); | |
4ee2491e | 706 | blk_start_plug(&plug); |
1da177e4 LT |
707 | |
708 | spin_lock(lock); | |
709 | while (!list_empty(list)) { | |
710 | bh = BH_ENTRY(list->next); | |
535ee2fb | 711 | mapping = bh->b_assoc_map; |
58ff407b | 712 | __remove_assoc_queue(bh); |
535ee2fb JK |
713 | /* Avoid race with mark_buffer_dirty_inode() which does |
714 | * a lockless check and we rely on seeing the dirty bit */ | |
715 | smp_mb(); | |
1da177e4 LT |
716 | if (buffer_dirty(bh) || buffer_locked(bh)) { |
717 | list_add(&bh->b_assoc_buffers, &tmp); | |
535ee2fb | 718 | bh->b_assoc_map = mapping; |
1da177e4 LT |
719 | if (buffer_dirty(bh)) { |
720 | get_bh(bh); | |
721 | spin_unlock(lock); | |
722 | /* | |
723 | * Ensure any pending I/O completes so that | |
9cb569d6 CH |
724 | * write_dirty_buffer() actually writes the |
725 | * current contents - it is a noop if I/O is | |
726 | * still in flight on potentially older | |
727 | * contents. | |
1da177e4 | 728 | */ |
721a9602 | 729 | write_dirty_buffer(bh, WRITE_SYNC); |
9cf6b720 JA |
730 | |
731 | /* | |
732 | * Kick off IO for the previous mapping. Note | |
733 | * that we will not run the very last mapping, | |
734 | * wait_on_buffer() will do that for us | |
735 | * through sync_buffer(). | |
736 | */ | |
1da177e4 LT |
737 | brelse(bh); |
738 | spin_lock(lock); | |
739 | } | |
740 | } | |
741 | } | |
742 | ||
4ee2491e JA |
743 | spin_unlock(lock); |
744 | blk_finish_plug(&plug); | |
745 | spin_lock(lock); | |
746 | ||
1da177e4 LT |
747 | while (!list_empty(&tmp)) { |
748 | bh = BH_ENTRY(tmp.prev); | |
1da177e4 | 749 | get_bh(bh); |
535ee2fb JK |
750 | mapping = bh->b_assoc_map; |
751 | __remove_assoc_queue(bh); | |
752 | /* Avoid race with mark_buffer_dirty_inode() which does | |
753 | * a lockless check and we rely on seeing the dirty bit */ | |
754 | smp_mb(); | |
755 | if (buffer_dirty(bh)) { | |
756 | list_add(&bh->b_assoc_buffers, | |
e3892296 | 757 | &mapping->private_list); |
535ee2fb JK |
758 | bh->b_assoc_map = mapping; |
759 | } | |
1da177e4 LT |
760 | spin_unlock(lock); |
761 | wait_on_buffer(bh); | |
762 | if (!buffer_uptodate(bh)) | |
763 | err = -EIO; | |
764 | brelse(bh); | |
765 | spin_lock(lock); | |
766 | } | |
767 | ||
768 | spin_unlock(lock); | |
769 | err2 = osync_buffers_list(lock, list); | |
770 | if (err) | |
771 | return err; | |
772 | else | |
773 | return err2; | |
774 | } | |
775 | ||
776 | /* | |
777 | * Invalidate any and all dirty buffers on a given inode. We are | |
778 | * probably unmounting the fs, but that doesn't mean we have already | |
779 | * done a sync(). Just drop the buffers from the inode list. | |
780 | * | |
781 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which | |
782 | * assumes that all the buffers are against the blockdev. Not true | |
783 | * for reiserfs. | |
784 | */ | |
785 | void invalidate_inode_buffers(struct inode *inode) | |
786 | { | |
787 | if (inode_has_buffers(inode)) { | |
788 | struct address_space *mapping = &inode->i_data; | |
789 | struct list_head *list = &mapping->private_list; | |
252aa6f5 | 790 | struct address_space *buffer_mapping = mapping->private_data; |
1da177e4 LT |
791 | |
792 | spin_lock(&buffer_mapping->private_lock); | |
793 | while (!list_empty(list)) | |
794 | __remove_assoc_queue(BH_ENTRY(list->next)); | |
795 | spin_unlock(&buffer_mapping->private_lock); | |
796 | } | |
797 | } | |
52b19ac9 | 798 | EXPORT_SYMBOL(invalidate_inode_buffers); |
1da177e4 LT |
799 | |
800 | /* | |
801 | * Remove any clean buffers from the inode's buffer list. This is called | |
802 | * when we're trying to free the inode itself. Those buffers can pin it. | |
803 | * | |
804 | * Returns true if all buffers were removed. | |
805 | */ | |
806 | int remove_inode_buffers(struct inode *inode) | |
807 | { | |
808 | int ret = 1; | |
809 | ||
810 | if (inode_has_buffers(inode)) { | |
811 | struct address_space *mapping = &inode->i_data; | |
812 | struct list_head *list = &mapping->private_list; | |
252aa6f5 | 813 | struct address_space *buffer_mapping = mapping->private_data; |
1da177e4 LT |
814 | |
815 | spin_lock(&buffer_mapping->private_lock); | |
816 | while (!list_empty(list)) { | |
817 | struct buffer_head *bh = BH_ENTRY(list->next); | |
818 | if (buffer_dirty(bh)) { | |
819 | ret = 0; | |
820 | break; | |
821 | } | |
822 | __remove_assoc_queue(bh); | |
823 | } | |
824 | spin_unlock(&buffer_mapping->private_lock); | |
825 | } | |
826 | return ret; | |
827 | } | |
828 | ||
829 | /* | |
830 | * Create the appropriate buffers when given a page for data area and | |
831 | * the size of each buffer.. Use the bh->b_this_page linked list to | |
832 | * follow the buffers created. Return NULL if unable to create more | |
833 | * buffers. | |
834 | * | |
835 | * The retry flag is used to differentiate async IO (paging, swapping) | |
836 | * which may not fail from ordinary buffer allocations. | |
837 | */ | |
838 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
839 | int retry) | |
840 | { | |
841 | struct buffer_head *bh, *head; | |
842 | long offset; | |
843 | ||
844 | try_again: | |
845 | head = NULL; | |
846 | offset = PAGE_SIZE; | |
847 | while ((offset -= size) >= 0) { | |
848 | bh = alloc_buffer_head(GFP_NOFS); | |
849 | if (!bh) | |
850 | goto no_grow; | |
851 | ||
852 | bh->b_bdev = NULL; | |
853 | bh->b_this_page = head; | |
854 | bh->b_blocknr = -1; | |
855 | head = bh; | |
856 | ||
857 | bh->b_state = 0; | |
858 | atomic_set(&bh->b_count, 0); | |
859 | bh->b_size = size; | |
860 | ||
861 | /* Link the buffer to its page */ | |
862 | set_bh_page(bh, page, offset); | |
863 | ||
01ffe339 | 864 | init_buffer(bh, NULL, NULL); |
1da177e4 LT |
865 | } |
866 | return head; | |
867 | /* | |
868 | * In case anything failed, we just free everything we got. | |
869 | */ | |
870 | no_grow: | |
871 | if (head) { | |
872 | do { | |
873 | bh = head; | |
874 | head = head->b_this_page; | |
875 | free_buffer_head(bh); | |
876 | } while (head); | |
877 | } | |
878 | ||
879 | /* | |
880 | * Return failure for non-async IO requests. Async IO requests | |
881 | * are not allowed to fail, so we have to wait until buffer heads | |
882 | * become available. But we don't want tasks sleeping with | |
883 | * partially complete buffers, so all were released above. | |
884 | */ | |
885 | if (!retry) | |
886 | return NULL; | |
887 | ||
888 | /* We're _really_ low on memory. Now we just | |
889 | * wait for old buffer heads to become free due to | |
890 | * finishing IO. Since this is an async request and | |
891 | * the reserve list is empty, we're sure there are | |
892 | * async buffer heads in use. | |
893 | */ | |
894 | free_more_memory(); | |
895 | goto try_again; | |
896 | } | |
897 | EXPORT_SYMBOL_GPL(alloc_page_buffers); | |
898 | ||
899 | static inline void | |
900 | link_dev_buffers(struct page *page, struct buffer_head *head) | |
901 | { | |
902 | struct buffer_head *bh, *tail; | |
903 | ||
904 | bh = head; | |
905 | do { | |
906 | tail = bh; | |
907 | bh = bh->b_this_page; | |
908 | } while (bh); | |
909 | tail->b_this_page = head; | |
910 | attach_page_buffers(page, head); | |
911 | } | |
912 | ||
bbec0270 LT |
913 | static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) |
914 | { | |
915 | sector_t retval = ~((sector_t)0); | |
916 | loff_t sz = i_size_read(bdev->bd_inode); | |
917 | ||
918 | if (sz) { | |
919 | unsigned int sizebits = blksize_bits(size); | |
920 | retval = (sz >> sizebits); | |
921 | } | |
922 | return retval; | |
923 | } | |
924 | ||
1da177e4 LT |
925 | /* |
926 | * Initialise the state of a blockdev page's buffers. | |
927 | */ | |
676ce6d5 | 928 | static sector_t |
1da177e4 LT |
929 | init_page_buffers(struct page *page, struct block_device *bdev, |
930 | sector_t block, int size) | |
931 | { | |
932 | struct buffer_head *head = page_buffers(page); | |
933 | struct buffer_head *bh = head; | |
934 | int uptodate = PageUptodate(page); | |
bbec0270 | 935 | sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); |
1da177e4 LT |
936 | |
937 | do { | |
938 | if (!buffer_mapped(bh)) { | |
939 | init_buffer(bh, NULL, NULL); | |
940 | bh->b_bdev = bdev; | |
941 | bh->b_blocknr = block; | |
942 | if (uptodate) | |
943 | set_buffer_uptodate(bh); | |
080399aa JM |
944 | if (block < end_block) |
945 | set_buffer_mapped(bh); | |
1da177e4 LT |
946 | } |
947 | block++; | |
948 | bh = bh->b_this_page; | |
949 | } while (bh != head); | |
676ce6d5 HD |
950 | |
951 | /* | |
952 | * Caller needs to validate requested block against end of device. | |
953 | */ | |
954 | return end_block; | |
1da177e4 LT |
955 | } |
956 | ||
957 | /* | |
958 | * Create the page-cache page that contains the requested block. | |
959 | * | |
676ce6d5 | 960 | * This is used purely for blockdev mappings. |
1da177e4 | 961 | */ |
676ce6d5 | 962 | static int |
1da177e4 | 963 | grow_dev_page(struct block_device *bdev, sector_t block, |
676ce6d5 | 964 | pgoff_t index, int size, int sizebits) |
1da177e4 LT |
965 | { |
966 | struct inode *inode = bdev->bd_inode; | |
967 | struct page *page; | |
968 | struct buffer_head *bh; | |
676ce6d5 HD |
969 | sector_t end_block; |
970 | int ret = 0; /* Will call free_more_memory() */ | |
1da177e4 | 971 | |
ea125892 | 972 | page = find_or_create_page(inode->i_mapping, index, |
769848c0 | 973 | (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE); |
1da177e4 | 974 | if (!page) |
676ce6d5 | 975 | return ret; |
1da177e4 | 976 | |
e827f923 | 977 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
978 | |
979 | if (page_has_buffers(page)) { | |
980 | bh = page_buffers(page); | |
981 | if (bh->b_size == size) { | |
676ce6d5 HD |
982 | end_block = init_page_buffers(page, bdev, |
983 | index << sizebits, size); | |
984 | goto done; | |
1da177e4 LT |
985 | } |
986 | if (!try_to_free_buffers(page)) | |
987 | goto failed; | |
988 | } | |
989 | ||
990 | /* | |
991 | * Allocate some buffers for this page | |
992 | */ | |
993 | bh = alloc_page_buffers(page, size, 0); | |
994 | if (!bh) | |
995 | goto failed; | |
996 | ||
997 | /* | |
998 | * Link the page to the buffers and initialise them. Take the | |
999 | * lock to be atomic wrt __find_get_block(), which does not | |
1000 | * run under the page lock. | |
1001 | */ | |
1002 | spin_lock(&inode->i_mapping->private_lock); | |
1003 | link_dev_buffers(page, bh); | |
676ce6d5 | 1004 | end_block = init_page_buffers(page, bdev, index << sizebits, size); |
1da177e4 | 1005 | spin_unlock(&inode->i_mapping->private_lock); |
676ce6d5 HD |
1006 | done: |
1007 | ret = (block < end_block) ? 1 : -ENXIO; | |
1da177e4 | 1008 | failed: |
1da177e4 LT |
1009 | unlock_page(page); |
1010 | page_cache_release(page); | |
676ce6d5 | 1011 | return ret; |
1da177e4 LT |
1012 | } |
1013 | ||
1014 | /* | |
1015 | * Create buffers for the specified block device block's page. If | |
1016 | * that page was dirty, the buffers are set dirty also. | |
1da177e4 | 1017 | */ |
858119e1 | 1018 | static int |
1da177e4 LT |
1019 | grow_buffers(struct block_device *bdev, sector_t block, int size) |
1020 | { | |
1da177e4 LT |
1021 | pgoff_t index; |
1022 | int sizebits; | |
1023 | ||
1024 | sizebits = -1; | |
1025 | do { | |
1026 | sizebits++; | |
1027 | } while ((size << sizebits) < PAGE_SIZE); | |
1028 | ||
1029 | index = block >> sizebits; | |
1da177e4 | 1030 | |
e5657933 AM |
1031 | /* |
1032 | * Check for a block which wants to lie outside our maximum possible | |
1033 | * pagecache index. (this comparison is done using sector_t types). | |
1034 | */ | |
1035 | if (unlikely(index != block >> sizebits)) { | |
1036 | char b[BDEVNAME_SIZE]; | |
1037 | ||
1038 | printk(KERN_ERR "%s: requested out-of-range block %llu for " | |
1039 | "device %s\n", | |
8e24eea7 | 1040 | __func__, (unsigned long long)block, |
e5657933 AM |
1041 | bdevname(bdev, b)); |
1042 | return -EIO; | |
1043 | } | |
676ce6d5 | 1044 | |
1da177e4 | 1045 | /* Create a page with the proper size buffers.. */ |
676ce6d5 | 1046 | return grow_dev_page(bdev, block, index, size, sizebits); |
1da177e4 LT |
1047 | } |
1048 | ||
75c96f85 | 1049 | static struct buffer_head * |
1da177e4 LT |
1050 | __getblk_slow(struct block_device *bdev, sector_t block, int size) |
1051 | { | |
1052 | /* Size must be multiple of hard sectorsize */ | |
e1defc4f | 1053 | if (unlikely(size & (bdev_logical_block_size(bdev)-1) || |
1da177e4 LT |
1054 | (size < 512 || size > PAGE_SIZE))) { |
1055 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", | |
1056 | size); | |
e1defc4f MP |
1057 | printk(KERN_ERR "logical block size: %d\n", |
1058 | bdev_logical_block_size(bdev)); | |
1da177e4 LT |
1059 | |
1060 | dump_stack(); | |
1061 | return NULL; | |
1062 | } | |
1063 | ||
676ce6d5 HD |
1064 | for (;;) { |
1065 | struct buffer_head *bh; | |
1066 | int ret; | |
1da177e4 LT |
1067 | |
1068 | bh = __find_get_block(bdev, block, size); | |
1069 | if (bh) | |
1070 | return bh; | |
676ce6d5 HD |
1071 | |
1072 | ret = grow_buffers(bdev, block, size); | |
1073 | if (ret < 0) | |
1074 | return NULL; | |
1075 | if (ret == 0) | |
1076 | free_more_memory(); | |
1da177e4 LT |
1077 | } |
1078 | } | |
1079 | ||
1080 | /* | |
1081 | * The relationship between dirty buffers and dirty pages: | |
1082 | * | |
1083 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and | |
1084 | * the page is tagged dirty in its radix tree. | |
1085 | * | |
1086 | * At all times, the dirtiness of the buffers represents the dirtiness of | |
1087 | * subsections of the page. If the page has buffers, the page dirty bit is | |
1088 | * merely a hint about the true dirty state. | |
1089 | * | |
1090 | * When a page is set dirty in its entirety, all its buffers are marked dirty | |
1091 | * (if the page has buffers). | |
1092 | * | |
1093 | * When a buffer is marked dirty, its page is dirtied, but the page's other | |
1094 | * buffers are not. | |
1095 | * | |
1096 | * Also. When blockdev buffers are explicitly read with bread(), they | |
1097 | * individually become uptodate. But their backing page remains not | |
1098 | * uptodate - even if all of its buffers are uptodate. A subsequent | |
1099 | * block_read_full_page() against that page will discover all the uptodate | |
1100 | * buffers, will set the page uptodate and will perform no I/O. | |
1101 | */ | |
1102 | ||
1103 | /** | |
1104 | * mark_buffer_dirty - mark a buffer_head as needing writeout | |
67be2dd1 | 1105 | * @bh: the buffer_head to mark dirty |
1da177e4 LT |
1106 | * |
1107 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set its | |
1108 | * backing page dirty, then tag the page as dirty in its address_space's radix | |
1109 | * tree and then attach the address_space's inode to its superblock's dirty | |
1110 | * inode list. | |
1111 | * | |
1112 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, | |
250df6ed | 1113 | * mapping->tree_lock and mapping->host->i_lock. |
1da177e4 | 1114 | */ |
fc9b52cd | 1115 | void mark_buffer_dirty(struct buffer_head *bh) |
1da177e4 | 1116 | { |
787d2214 | 1117 | WARN_ON_ONCE(!buffer_uptodate(bh)); |
1be62dc1 LT |
1118 | |
1119 | /* | |
1120 | * Very *carefully* optimize the it-is-already-dirty case. | |
1121 | * | |
1122 | * Don't let the final "is it dirty" escape to before we | |
1123 | * perhaps modified the buffer. | |
1124 | */ | |
1125 | if (buffer_dirty(bh)) { | |
1126 | smp_mb(); | |
1127 | if (buffer_dirty(bh)) | |
1128 | return; | |
1129 | } | |
1130 | ||
a8e7d49a LT |
1131 | if (!test_set_buffer_dirty(bh)) { |
1132 | struct page *page = bh->b_page; | |
8e9d78ed LT |
1133 | if (!TestSetPageDirty(page)) { |
1134 | struct address_space *mapping = page_mapping(page); | |
1135 | if (mapping) | |
1136 | __set_page_dirty(page, mapping, 0); | |
1137 | } | |
a8e7d49a | 1138 | } |
1da177e4 | 1139 | } |
1fe72eaa | 1140 | EXPORT_SYMBOL(mark_buffer_dirty); |
1da177e4 LT |
1141 | |
1142 | /* | |
1143 | * Decrement a buffer_head's reference count. If all buffers against a page | |
1144 | * have zero reference count, are clean and unlocked, and if the page is clean | |
1145 | * and unlocked then try_to_free_buffers() may strip the buffers from the page | |
1146 | * in preparation for freeing it (sometimes, rarely, buffers are removed from | |
1147 | * a page but it ends up not being freed, and buffers may later be reattached). | |
1148 | */ | |
1149 | void __brelse(struct buffer_head * buf) | |
1150 | { | |
1151 | if (atomic_read(&buf->b_count)) { | |
1152 | put_bh(buf); | |
1153 | return; | |
1154 | } | |
5c752ad9 | 1155 | WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); |
1da177e4 | 1156 | } |
1fe72eaa | 1157 | EXPORT_SYMBOL(__brelse); |
1da177e4 LT |
1158 | |
1159 | /* | |
1160 | * bforget() is like brelse(), except it discards any | |
1161 | * potentially dirty data. | |
1162 | */ | |
1163 | void __bforget(struct buffer_head *bh) | |
1164 | { | |
1165 | clear_buffer_dirty(bh); | |
535ee2fb | 1166 | if (bh->b_assoc_map) { |
1da177e4 LT |
1167 | struct address_space *buffer_mapping = bh->b_page->mapping; |
1168 | ||
1169 | spin_lock(&buffer_mapping->private_lock); | |
1170 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b | 1171 | bh->b_assoc_map = NULL; |
1da177e4 LT |
1172 | spin_unlock(&buffer_mapping->private_lock); |
1173 | } | |
1174 | __brelse(bh); | |
1175 | } | |
1fe72eaa | 1176 | EXPORT_SYMBOL(__bforget); |
1da177e4 LT |
1177 | |
1178 | static struct buffer_head *__bread_slow(struct buffer_head *bh) | |
1179 | { | |
1180 | lock_buffer(bh); | |
1181 | if (buffer_uptodate(bh)) { | |
1182 | unlock_buffer(bh); | |
1183 | return bh; | |
1184 | } else { | |
1185 | get_bh(bh); | |
1186 | bh->b_end_io = end_buffer_read_sync; | |
1187 | submit_bh(READ, bh); | |
1188 | wait_on_buffer(bh); | |
1189 | if (buffer_uptodate(bh)) | |
1190 | return bh; | |
1191 | } | |
1192 | brelse(bh); | |
1193 | return NULL; | |
1194 | } | |
1195 | ||
1196 | /* | |
1197 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). | |
1198 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their | |
1199 | * refcount elevated by one when they're in an LRU. A buffer can only appear | |
1200 | * once in a particular CPU's LRU. A single buffer can be present in multiple | |
1201 | * CPU's LRUs at the same time. | |
1202 | * | |
1203 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and | |
1204 | * sb_find_get_block(). | |
1205 | * | |
1206 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use | |
1207 | * a local interrupt disable for that. | |
1208 | */ | |
1209 | ||
1210 | #define BH_LRU_SIZE 8 | |
1211 | ||
1212 | struct bh_lru { | |
1213 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1214 | }; | |
1215 | ||
1216 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; | |
1217 | ||
1218 | #ifdef CONFIG_SMP | |
1219 | #define bh_lru_lock() local_irq_disable() | |
1220 | #define bh_lru_unlock() local_irq_enable() | |
1221 | #else | |
1222 | #define bh_lru_lock() preempt_disable() | |
1223 | #define bh_lru_unlock() preempt_enable() | |
1224 | #endif | |
1225 | ||
1226 | static inline void check_irqs_on(void) | |
1227 | { | |
1228 | #ifdef irqs_disabled | |
1229 | BUG_ON(irqs_disabled()); | |
1230 | #endif | |
1231 | } | |
1232 | ||
1233 | /* | |
1234 | * The LRU management algorithm is dopey-but-simple. Sorry. | |
1235 | */ | |
1236 | static void bh_lru_install(struct buffer_head *bh) | |
1237 | { | |
1238 | struct buffer_head *evictee = NULL; | |
1da177e4 LT |
1239 | |
1240 | check_irqs_on(); | |
1241 | bh_lru_lock(); | |
c7b92516 | 1242 | if (__this_cpu_read(bh_lrus.bhs[0]) != bh) { |
1da177e4 LT |
1243 | struct buffer_head *bhs[BH_LRU_SIZE]; |
1244 | int in; | |
1245 | int out = 0; | |
1246 | ||
1247 | get_bh(bh); | |
1248 | bhs[out++] = bh; | |
1249 | for (in = 0; in < BH_LRU_SIZE; in++) { | |
c7b92516 CL |
1250 | struct buffer_head *bh2 = |
1251 | __this_cpu_read(bh_lrus.bhs[in]); | |
1da177e4 LT |
1252 | |
1253 | if (bh2 == bh) { | |
1254 | __brelse(bh2); | |
1255 | } else { | |
1256 | if (out >= BH_LRU_SIZE) { | |
1257 | BUG_ON(evictee != NULL); | |
1258 | evictee = bh2; | |
1259 | } else { | |
1260 | bhs[out++] = bh2; | |
1261 | } | |
1262 | } | |
1263 | } | |
1264 | while (out < BH_LRU_SIZE) | |
1265 | bhs[out++] = NULL; | |
c7b92516 | 1266 | memcpy(__this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs)); |
1da177e4 LT |
1267 | } |
1268 | bh_lru_unlock(); | |
1269 | ||
1270 | if (evictee) | |
1271 | __brelse(evictee); | |
1272 | } | |
1273 | ||
1274 | /* | |
1275 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. | |
1276 | */ | |
858119e1 | 1277 | static struct buffer_head * |
3991d3bd | 1278 | lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1279 | { |
1280 | struct buffer_head *ret = NULL; | |
3991d3bd | 1281 | unsigned int i; |
1da177e4 LT |
1282 | |
1283 | check_irqs_on(); | |
1284 | bh_lru_lock(); | |
1da177e4 | 1285 | for (i = 0; i < BH_LRU_SIZE; i++) { |
c7b92516 | 1286 | struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); |
1da177e4 LT |
1287 | |
1288 | if (bh && bh->b_bdev == bdev && | |
1289 | bh->b_blocknr == block && bh->b_size == size) { | |
1290 | if (i) { | |
1291 | while (i) { | |
c7b92516 CL |
1292 | __this_cpu_write(bh_lrus.bhs[i], |
1293 | __this_cpu_read(bh_lrus.bhs[i - 1])); | |
1da177e4 LT |
1294 | i--; |
1295 | } | |
c7b92516 | 1296 | __this_cpu_write(bh_lrus.bhs[0], bh); |
1da177e4 LT |
1297 | } |
1298 | get_bh(bh); | |
1299 | ret = bh; | |
1300 | break; | |
1301 | } | |
1302 | } | |
1303 | bh_lru_unlock(); | |
1304 | return ret; | |
1305 | } | |
1306 | ||
1307 | /* | |
1308 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh | |
1309 | * it in the LRU and mark it as accessed. If it is not present then return | |
1310 | * NULL | |
1311 | */ | |
1312 | struct buffer_head * | |
3991d3bd | 1313 | __find_get_block(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1314 | { |
1315 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); | |
1316 | ||
1317 | if (bh == NULL) { | |
385fd4c5 | 1318 | bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1319 | if (bh) |
1320 | bh_lru_install(bh); | |
1321 | } | |
1322 | if (bh) | |
1323 | touch_buffer(bh); | |
1324 | return bh; | |
1325 | } | |
1326 | EXPORT_SYMBOL(__find_get_block); | |
1327 | ||
1328 | /* | |
1329 | * __getblk will locate (and, if necessary, create) the buffer_head | |
1330 | * which corresponds to the passed block_device, block and size. The | |
1331 | * returned buffer has its reference count incremented. | |
1332 | * | |
1da177e4 LT |
1333 | * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() |
1334 | * attempt is failing. FIXME, perhaps? | |
1335 | */ | |
1336 | struct buffer_head * | |
3991d3bd | 1337 | __getblk(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1338 | { |
1339 | struct buffer_head *bh = __find_get_block(bdev, block, size); | |
1340 | ||
1341 | might_sleep(); | |
1342 | if (bh == NULL) | |
1343 | bh = __getblk_slow(bdev, block, size); | |
1344 | return bh; | |
1345 | } | |
1346 | EXPORT_SYMBOL(__getblk); | |
1347 | ||
1348 | /* | |
1349 | * Do async read-ahead on a buffer.. | |
1350 | */ | |
3991d3bd | 1351 | void __breadahead(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1352 | { |
1353 | struct buffer_head *bh = __getblk(bdev, block, size); | |
a3e713b5 AM |
1354 | if (likely(bh)) { |
1355 | ll_rw_block(READA, 1, &bh); | |
1356 | brelse(bh); | |
1357 | } | |
1da177e4 LT |
1358 | } |
1359 | EXPORT_SYMBOL(__breadahead); | |
1360 | ||
1361 | /** | |
1362 | * __bread() - reads a specified block and returns the bh | |
67be2dd1 | 1363 | * @bdev: the block_device to read from |
1da177e4 LT |
1364 | * @block: number of block |
1365 | * @size: size (in bytes) to read | |
1366 | * | |
1367 | * Reads a specified block, and returns buffer head that contains it. | |
1368 | * It returns NULL if the block was unreadable. | |
1369 | */ | |
1370 | struct buffer_head * | |
3991d3bd | 1371 | __bread(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1372 | { |
1373 | struct buffer_head *bh = __getblk(bdev, block, size); | |
1374 | ||
a3e713b5 | 1375 | if (likely(bh) && !buffer_uptodate(bh)) |
1da177e4 LT |
1376 | bh = __bread_slow(bh); |
1377 | return bh; | |
1378 | } | |
1379 | EXPORT_SYMBOL(__bread); | |
1380 | ||
1381 | /* | |
1382 | * invalidate_bh_lrus() is called rarely - but not only at unmount. | |
1383 | * This doesn't race because it runs in each cpu either in irq | |
1384 | * or with preempt disabled. | |
1385 | */ | |
1386 | static void invalidate_bh_lru(void *arg) | |
1387 | { | |
1388 | struct bh_lru *b = &get_cpu_var(bh_lrus); | |
1389 | int i; | |
1390 | ||
1391 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1392 | brelse(b->bhs[i]); | |
1393 | b->bhs[i] = NULL; | |
1394 | } | |
1395 | put_cpu_var(bh_lrus); | |
1396 | } | |
42be35d0 GBY |
1397 | |
1398 | static bool has_bh_in_lru(int cpu, void *dummy) | |
1399 | { | |
1400 | struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); | |
1401 | int i; | |
1da177e4 | 1402 | |
42be35d0 GBY |
1403 | for (i = 0; i < BH_LRU_SIZE; i++) { |
1404 | if (b->bhs[i]) | |
1405 | return 1; | |
1406 | } | |
1407 | ||
1408 | return 0; | |
1409 | } | |
1410 | ||
f9a14399 | 1411 | void invalidate_bh_lrus(void) |
1da177e4 | 1412 | { |
42be35d0 | 1413 | on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); |
1da177e4 | 1414 | } |
9db5579b | 1415 | EXPORT_SYMBOL_GPL(invalidate_bh_lrus); |
1da177e4 LT |
1416 | |
1417 | void set_bh_page(struct buffer_head *bh, | |
1418 | struct page *page, unsigned long offset) | |
1419 | { | |
1420 | bh->b_page = page; | |
e827f923 | 1421 | BUG_ON(offset >= PAGE_SIZE); |
1da177e4 LT |
1422 | if (PageHighMem(page)) |
1423 | /* | |
1424 | * This catches illegal uses and preserves the offset: | |
1425 | */ | |
1426 | bh->b_data = (char *)(0 + offset); | |
1427 | else | |
1428 | bh->b_data = page_address(page) + offset; | |
1429 | } | |
1430 | EXPORT_SYMBOL(set_bh_page); | |
1431 | ||
1432 | /* | |
1433 | * Called when truncating a buffer on a page completely. | |
1434 | */ | |
858119e1 | 1435 | static void discard_buffer(struct buffer_head * bh) |
1da177e4 LT |
1436 | { |
1437 | lock_buffer(bh); | |
1438 | clear_buffer_dirty(bh); | |
1439 | bh->b_bdev = NULL; | |
1440 | clear_buffer_mapped(bh); | |
1441 | clear_buffer_req(bh); | |
1442 | clear_buffer_new(bh); | |
1443 | clear_buffer_delay(bh); | |
33a266dd | 1444 | clear_buffer_unwritten(bh); |
1da177e4 LT |
1445 | unlock_buffer(bh); |
1446 | } | |
1447 | ||
1da177e4 | 1448 | /** |
814e1d25 | 1449 | * block_invalidatepage - invalidate part or all of a buffer-backed page |
1da177e4 LT |
1450 | * |
1451 | * @page: the page which is affected | |
1452 | * @offset: the index of the truncation point | |
1453 | * | |
1454 | * block_invalidatepage() is called when all or part of the page has become | |
814e1d25 | 1455 | * invalidated by a truncate operation. |
1da177e4 LT |
1456 | * |
1457 | * block_invalidatepage() does not have to release all buffers, but it must | |
1458 | * ensure that no dirty buffer is left outside @offset and that no I/O | |
1459 | * is underway against any of the blocks which are outside the truncation | |
1460 | * point. Because the caller is about to free (and possibly reuse) those | |
1461 | * blocks on-disk. | |
1462 | */ | |
2ff28e22 | 1463 | void block_invalidatepage(struct page *page, unsigned long offset) |
1da177e4 LT |
1464 | { |
1465 | struct buffer_head *head, *bh, *next; | |
1466 | unsigned int curr_off = 0; | |
1da177e4 LT |
1467 | |
1468 | BUG_ON(!PageLocked(page)); | |
1469 | if (!page_has_buffers(page)) | |
1470 | goto out; | |
1471 | ||
1472 | head = page_buffers(page); | |
1473 | bh = head; | |
1474 | do { | |
1475 | unsigned int next_off = curr_off + bh->b_size; | |
1476 | next = bh->b_this_page; | |
1477 | ||
1478 | /* | |
1479 | * is this block fully invalidated? | |
1480 | */ | |
1481 | if (offset <= curr_off) | |
1482 | discard_buffer(bh); | |
1483 | curr_off = next_off; | |
1484 | bh = next; | |
1485 | } while (bh != head); | |
1486 | ||
1487 | /* | |
1488 | * We release buffers only if the entire page is being invalidated. | |
1489 | * The get_block cached value has been unconditionally invalidated, | |
1490 | * so real IO is not possible anymore. | |
1491 | */ | |
1492 | if (offset == 0) | |
2ff28e22 | 1493 | try_to_release_page(page, 0); |
1da177e4 | 1494 | out: |
2ff28e22 | 1495 | return; |
1da177e4 LT |
1496 | } |
1497 | EXPORT_SYMBOL(block_invalidatepage); | |
1498 | ||
1499 | /* | |
1500 | * We attach and possibly dirty the buffers atomically wrt | |
1501 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers | |
1502 | * is already excluded via the page lock. | |
1503 | */ | |
1504 | void create_empty_buffers(struct page *page, | |
1505 | unsigned long blocksize, unsigned long b_state) | |
1506 | { | |
1507 | struct buffer_head *bh, *head, *tail; | |
1508 | ||
1509 | head = alloc_page_buffers(page, blocksize, 1); | |
1510 | bh = head; | |
1511 | do { | |
1512 | bh->b_state |= b_state; | |
1513 | tail = bh; | |
1514 | bh = bh->b_this_page; | |
1515 | } while (bh); | |
1516 | tail->b_this_page = head; | |
1517 | ||
1518 | spin_lock(&page->mapping->private_lock); | |
1519 | if (PageUptodate(page) || PageDirty(page)) { | |
1520 | bh = head; | |
1521 | do { | |
1522 | if (PageDirty(page)) | |
1523 | set_buffer_dirty(bh); | |
1524 | if (PageUptodate(page)) | |
1525 | set_buffer_uptodate(bh); | |
1526 | bh = bh->b_this_page; | |
1527 | } while (bh != head); | |
1528 | } | |
1529 | attach_page_buffers(page, head); | |
1530 | spin_unlock(&page->mapping->private_lock); | |
1531 | } | |
1532 | EXPORT_SYMBOL(create_empty_buffers); | |
1533 | ||
1534 | /* | |
1535 | * We are taking a block for data and we don't want any output from any | |
1536 | * buffer-cache aliases starting from return from that function and | |
1537 | * until the moment when something will explicitly mark the buffer | |
1538 | * dirty (hopefully that will not happen until we will free that block ;-) | |
1539 | * We don't even need to mark it not-uptodate - nobody can expect | |
1540 | * anything from a newly allocated buffer anyway. We used to used | |
1541 | * unmap_buffer() for such invalidation, but that was wrong. We definitely | |
1542 | * don't want to mark the alias unmapped, for example - it would confuse | |
1543 | * anyone who might pick it with bread() afterwards... | |
1544 | * | |
1545 | * Also.. Note that bforget() doesn't lock the buffer. So there can | |
1546 | * be writeout I/O going on against recently-freed buffers. We don't | |
1547 | * wait on that I/O in bforget() - it's more efficient to wait on the I/O | |
1548 | * only if we really need to. That happens here. | |
1549 | */ | |
1550 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block) | |
1551 | { | |
1552 | struct buffer_head *old_bh; | |
1553 | ||
1554 | might_sleep(); | |
1555 | ||
385fd4c5 | 1556 | old_bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1557 | if (old_bh) { |
1558 | clear_buffer_dirty(old_bh); | |
1559 | wait_on_buffer(old_bh); | |
1560 | clear_buffer_req(old_bh); | |
1561 | __brelse(old_bh); | |
1562 | } | |
1563 | } | |
1564 | EXPORT_SYMBOL(unmap_underlying_metadata); | |
1565 | ||
45bce8f3 LT |
1566 | /* |
1567 | * Size is a power-of-two in the range 512..PAGE_SIZE, | |
1568 | * and the case we care about most is PAGE_SIZE. | |
1569 | * | |
1570 | * So this *could* possibly be written with those | |
1571 | * constraints in mind (relevant mostly if some | |
1572 | * architecture has a slow bit-scan instruction) | |
1573 | */ | |
1574 | static inline int block_size_bits(unsigned int blocksize) | |
1575 | { | |
1576 | return ilog2(blocksize); | |
1577 | } | |
1578 | ||
1579 | static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) | |
1580 | { | |
1581 | BUG_ON(!PageLocked(page)); | |
1582 | ||
1583 | if (!page_has_buffers(page)) | |
1584 | create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state); | |
1585 | return page_buffers(page); | |
1586 | } | |
1587 | ||
1da177e4 LT |
1588 | /* |
1589 | * NOTE! All mapped/uptodate combinations are valid: | |
1590 | * | |
1591 | * Mapped Uptodate Meaning | |
1592 | * | |
1593 | * No No "unknown" - must do get_block() | |
1594 | * No Yes "hole" - zero-filled | |
1595 | * Yes No "allocated" - allocated on disk, not read in | |
1596 | * Yes Yes "valid" - allocated and up-to-date in memory. | |
1597 | * | |
1598 | * "Dirty" is valid only with the last case (mapped+uptodate). | |
1599 | */ | |
1600 | ||
1601 | /* | |
1602 | * While block_write_full_page is writing back the dirty buffers under | |
1603 | * the page lock, whoever dirtied the buffers may decide to clean them | |
1604 | * again at any time. We handle that by only looking at the buffer | |
1605 | * state inside lock_buffer(). | |
1606 | * | |
1607 | * If block_write_full_page() is called for regular writeback | |
1608 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a | |
1609 | * locked buffer. This only can happen if someone has written the buffer | |
1610 | * directly, with submit_bh(). At the address_space level PageWriteback | |
1611 | * prevents this contention from occurring. | |
6e34eedd TT |
1612 | * |
1613 | * If block_write_full_page() is called with wbc->sync_mode == | |
721a9602 JA |
1614 | * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this |
1615 | * causes the writes to be flagged as synchronous writes. | |
1da177e4 LT |
1616 | */ |
1617 | static int __block_write_full_page(struct inode *inode, struct page *page, | |
35c80d5f CM |
1618 | get_block_t *get_block, struct writeback_control *wbc, |
1619 | bh_end_io_t *handler) | |
1da177e4 LT |
1620 | { |
1621 | int err; | |
1622 | sector_t block; | |
1623 | sector_t last_block; | |
f0fbd5fc | 1624 | struct buffer_head *bh, *head; |
45bce8f3 | 1625 | unsigned int blocksize, bbits; |
1da177e4 | 1626 | int nr_underway = 0; |
6e34eedd | 1627 | int write_op = (wbc->sync_mode == WB_SYNC_ALL ? |
721a9602 | 1628 | WRITE_SYNC : WRITE); |
1da177e4 | 1629 | |
45bce8f3 | 1630 | head = create_page_buffers(page, inode, |
1da177e4 | 1631 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
1da177e4 LT |
1632 | |
1633 | /* | |
1634 | * Be very careful. We have no exclusion from __set_page_dirty_buffers | |
1635 | * here, and the (potentially unmapped) buffers may become dirty at | |
1636 | * any time. If a buffer becomes dirty here after we've inspected it | |
1637 | * then we just miss that fact, and the page stays dirty. | |
1638 | * | |
1639 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; | |
1640 | * handle that here by just cleaning them. | |
1641 | */ | |
1642 | ||
1da177e4 | 1643 | bh = head; |
45bce8f3 LT |
1644 | blocksize = bh->b_size; |
1645 | bbits = block_size_bits(blocksize); | |
1646 | ||
1647 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); | |
1648 | last_block = (i_size_read(inode) - 1) >> bbits; | |
1da177e4 LT |
1649 | |
1650 | /* | |
1651 | * Get all the dirty buffers mapped to disk addresses and | |
1652 | * handle any aliases from the underlying blockdev's mapping. | |
1653 | */ | |
1654 | do { | |
1655 | if (block > last_block) { | |
1656 | /* | |
1657 | * mapped buffers outside i_size will occur, because | |
1658 | * this page can be outside i_size when there is a | |
1659 | * truncate in progress. | |
1660 | */ | |
1661 | /* | |
1662 | * The buffer was zeroed by block_write_full_page() | |
1663 | */ | |
1664 | clear_buffer_dirty(bh); | |
1665 | set_buffer_uptodate(bh); | |
29a814d2 AT |
1666 | } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && |
1667 | buffer_dirty(bh)) { | |
b0cf2321 | 1668 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1669 | err = get_block(inode, block, bh, 1); |
1670 | if (err) | |
1671 | goto recover; | |
29a814d2 | 1672 | clear_buffer_delay(bh); |
1da177e4 LT |
1673 | if (buffer_new(bh)) { |
1674 | /* blockdev mappings never come here */ | |
1675 | clear_buffer_new(bh); | |
1676 | unmap_underlying_metadata(bh->b_bdev, | |
1677 | bh->b_blocknr); | |
1678 | } | |
1679 | } | |
1680 | bh = bh->b_this_page; | |
1681 | block++; | |
1682 | } while (bh != head); | |
1683 | ||
1684 | do { | |
1da177e4 LT |
1685 | if (!buffer_mapped(bh)) |
1686 | continue; | |
1687 | /* | |
1688 | * If it's a fully non-blocking write attempt and we cannot | |
1689 | * lock the buffer then redirty the page. Note that this can | |
5b0830cb JA |
1690 | * potentially cause a busy-wait loop from writeback threads |
1691 | * and kswapd activity, but those code paths have their own | |
1692 | * higher-level throttling. | |
1da177e4 | 1693 | */ |
1b430bee | 1694 | if (wbc->sync_mode != WB_SYNC_NONE) { |
1da177e4 | 1695 | lock_buffer(bh); |
ca5de404 | 1696 | } else if (!trylock_buffer(bh)) { |
1da177e4 LT |
1697 | redirty_page_for_writepage(wbc, page); |
1698 | continue; | |
1699 | } | |
1700 | if (test_clear_buffer_dirty(bh)) { | |
35c80d5f | 1701 | mark_buffer_async_write_endio(bh, handler); |
1da177e4 LT |
1702 | } else { |
1703 | unlock_buffer(bh); | |
1704 | } | |
1705 | } while ((bh = bh->b_this_page) != head); | |
1706 | ||
1707 | /* | |
1708 | * The page and its buffers are protected by PageWriteback(), so we can | |
1709 | * drop the bh refcounts early. | |
1710 | */ | |
1711 | BUG_ON(PageWriteback(page)); | |
1712 | set_page_writeback(page); | |
1da177e4 LT |
1713 | |
1714 | do { | |
1715 | struct buffer_head *next = bh->b_this_page; | |
1716 | if (buffer_async_write(bh)) { | |
a64c8610 | 1717 | submit_bh(write_op, bh); |
1da177e4 LT |
1718 | nr_underway++; |
1719 | } | |
1da177e4 LT |
1720 | bh = next; |
1721 | } while (bh != head); | |
05937baa | 1722 | unlock_page(page); |
1da177e4 LT |
1723 | |
1724 | err = 0; | |
1725 | done: | |
1726 | if (nr_underway == 0) { | |
1727 | /* | |
1728 | * The page was marked dirty, but the buffers were | |
1729 | * clean. Someone wrote them back by hand with | |
1730 | * ll_rw_block/submit_bh. A rare case. | |
1731 | */ | |
1da177e4 | 1732 | end_page_writeback(page); |
3d67f2d7 | 1733 | |
1da177e4 LT |
1734 | /* |
1735 | * The page and buffer_heads can be released at any time from | |
1736 | * here on. | |
1737 | */ | |
1da177e4 LT |
1738 | } |
1739 | return err; | |
1740 | ||
1741 | recover: | |
1742 | /* | |
1743 | * ENOSPC, or some other error. We may already have added some | |
1744 | * blocks to the file, so we need to write these out to avoid | |
1745 | * exposing stale data. | |
1746 | * The page is currently locked and not marked for writeback | |
1747 | */ | |
1748 | bh = head; | |
1749 | /* Recovery: lock and submit the mapped buffers */ | |
1750 | do { | |
29a814d2 AT |
1751 | if (buffer_mapped(bh) && buffer_dirty(bh) && |
1752 | !buffer_delay(bh)) { | |
1da177e4 | 1753 | lock_buffer(bh); |
35c80d5f | 1754 | mark_buffer_async_write_endio(bh, handler); |
1da177e4 LT |
1755 | } else { |
1756 | /* | |
1757 | * The buffer may have been set dirty during | |
1758 | * attachment to a dirty page. | |
1759 | */ | |
1760 | clear_buffer_dirty(bh); | |
1761 | } | |
1762 | } while ((bh = bh->b_this_page) != head); | |
1763 | SetPageError(page); | |
1764 | BUG_ON(PageWriteback(page)); | |
7e4c3690 | 1765 | mapping_set_error(page->mapping, err); |
1da177e4 | 1766 | set_page_writeback(page); |
1da177e4 LT |
1767 | do { |
1768 | struct buffer_head *next = bh->b_this_page; | |
1769 | if (buffer_async_write(bh)) { | |
1770 | clear_buffer_dirty(bh); | |
a64c8610 | 1771 | submit_bh(write_op, bh); |
1da177e4 LT |
1772 | nr_underway++; |
1773 | } | |
1da177e4 LT |
1774 | bh = next; |
1775 | } while (bh != head); | |
ffda9d30 | 1776 | unlock_page(page); |
1da177e4 LT |
1777 | goto done; |
1778 | } | |
1779 | ||
afddba49 NP |
1780 | /* |
1781 | * If a page has any new buffers, zero them out here, and mark them uptodate | |
1782 | * and dirty so they'll be written out (in order to prevent uninitialised | |
1783 | * block data from leaking). And clear the new bit. | |
1784 | */ | |
1785 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) | |
1786 | { | |
1787 | unsigned int block_start, block_end; | |
1788 | struct buffer_head *head, *bh; | |
1789 | ||
1790 | BUG_ON(!PageLocked(page)); | |
1791 | if (!page_has_buffers(page)) | |
1792 | return; | |
1793 | ||
1794 | bh = head = page_buffers(page); | |
1795 | block_start = 0; | |
1796 | do { | |
1797 | block_end = block_start + bh->b_size; | |
1798 | ||
1799 | if (buffer_new(bh)) { | |
1800 | if (block_end > from && block_start < to) { | |
1801 | if (!PageUptodate(page)) { | |
1802 | unsigned start, size; | |
1803 | ||
1804 | start = max(from, block_start); | |
1805 | size = min(to, block_end) - start; | |
1806 | ||
eebd2aa3 | 1807 | zero_user(page, start, size); |
afddba49 NP |
1808 | set_buffer_uptodate(bh); |
1809 | } | |
1810 | ||
1811 | clear_buffer_new(bh); | |
1812 | mark_buffer_dirty(bh); | |
1813 | } | |
1814 | } | |
1815 | ||
1816 | block_start = block_end; | |
1817 | bh = bh->b_this_page; | |
1818 | } while (bh != head); | |
1819 | } | |
1820 | EXPORT_SYMBOL(page_zero_new_buffers); | |
1821 | ||
ebdec241 | 1822 | int __block_write_begin(struct page *page, loff_t pos, unsigned len, |
6e1db88d | 1823 | get_block_t *get_block) |
1da177e4 | 1824 | { |
ebdec241 CH |
1825 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
1826 | unsigned to = from + len; | |
6e1db88d | 1827 | struct inode *inode = page->mapping->host; |
1da177e4 LT |
1828 | unsigned block_start, block_end; |
1829 | sector_t block; | |
1830 | int err = 0; | |
1831 | unsigned blocksize, bbits; | |
1832 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1833 | ||
1834 | BUG_ON(!PageLocked(page)); | |
1835 | BUG_ON(from > PAGE_CACHE_SIZE); | |
1836 | BUG_ON(to > PAGE_CACHE_SIZE); | |
1837 | BUG_ON(from > to); | |
1838 | ||
45bce8f3 LT |
1839 | head = create_page_buffers(page, inode, 0); |
1840 | blocksize = head->b_size; | |
1841 | bbits = block_size_bits(blocksize); | |
1da177e4 | 1842 | |
1da177e4 LT |
1843 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); |
1844 | ||
1845 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1846 | block++, block_start=block_end, bh = bh->b_this_page) { | |
1847 | block_end = block_start + blocksize; | |
1848 | if (block_end <= from || block_start >= to) { | |
1849 | if (PageUptodate(page)) { | |
1850 | if (!buffer_uptodate(bh)) | |
1851 | set_buffer_uptodate(bh); | |
1852 | } | |
1853 | continue; | |
1854 | } | |
1855 | if (buffer_new(bh)) | |
1856 | clear_buffer_new(bh); | |
1857 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 1858 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1859 | err = get_block(inode, block, bh, 1); |
1860 | if (err) | |
f3ddbdc6 | 1861 | break; |
1da177e4 | 1862 | if (buffer_new(bh)) { |
1da177e4 LT |
1863 | unmap_underlying_metadata(bh->b_bdev, |
1864 | bh->b_blocknr); | |
1865 | if (PageUptodate(page)) { | |
637aff46 | 1866 | clear_buffer_new(bh); |
1da177e4 | 1867 | set_buffer_uptodate(bh); |
637aff46 | 1868 | mark_buffer_dirty(bh); |
1da177e4 LT |
1869 | continue; |
1870 | } | |
eebd2aa3 CL |
1871 | if (block_end > to || block_start < from) |
1872 | zero_user_segments(page, | |
1873 | to, block_end, | |
1874 | block_start, from); | |
1da177e4 LT |
1875 | continue; |
1876 | } | |
1877 | } | |
1878 | if (PageUptodate(page)) { | |
1879 | if (!buffer_uptodate(bh)) | |
1880 | set_buffer_uptodate(bh); | |
1881 | continue; | |
1882 | } | |
1883 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
33a266dd | 1884 | !buffer_unwritten(bh) && |
1da177e4 LT |
1885 | (block_start < from || block_end > to)) { |
1886 | ll_rw_block(READ, 1, &bh); | |
1887 | *wait_bh++=bh; | |
1888 | } | |
1889 | } | |
1890 | /* | |
1891 | * If we issued read requests - let them complete. | |
1892 | */ | |
1893 | while(wait_bh > wait) { | |
1894 | wait_on_buffer(*--wait_bh); | |
1895 | if (!buffer_uptodate(*wait_bh)) | |
f3ddbdc6 | 1896 | err = -EIO; |
1da177e4 | 1897 | } |
f9f07b6c | 1898 | if (unlikely(err)) |
afddba49 | 1899 | page_zero_new_buffers(page, from, to); |
1da177e4 LT |
1900 | return err; |
1901 | } | |
ebdec241 | 1902 | EXPORT_SYMBOL(__block_write_begin); |
1da177e4 LT |
1903 | |
1904 | static int __block_commit_write(struct inode *inode, struct page *page, | |
1905 | unsigned from, unsigned to) | |
1906 | { | |
1907 | unsigned block_start, block_end; | |
1908 | int partial = 0; | |
1909 | unsigned blocksize; | |
1910 | struct buffer_head *bh, *head; | |
1911 | ||
45bce8f3 LT |
1912 | bh = head = page_buffers(page); |
1913 | blocksize = bh->b_size; | |
1da177e4 | 1914 | |
45bce8f3 LT |
1915 | block_start = 0; |
1916 | do { | |
1da177e4 LT |
1917 | block_end = block_start + blocksize; |
1918 | if (block_end <= from || block_start >= to) { | |
1919 | if (!buffer_uptodate(bh)) | |
1920 | partial = 1; | |
1921 | } else { | |
1922 | set_buffer_uptodate(bh); | |
1923 | mark_buffer_dirty(bh); | |
1924 | } | |
afddba49 | 1925 | clear_buffer_new(bh); |
45bce8f3 LT |
1926 | |
1927 | block_start = block_end; | |
1928 | bh = bh->b_this_page; | |
1929 | } while (bh != head); | |
1da177e4 LT |
1930 | |
1931 | /* | |
1932 | * If this is a partial write which happened to make all buffers | |
1933 | * uptodate then we can optimize away a bogus readpage() for | |
1934 | * the next read(). Here we 'discover' whether the page went | |
1935 | * uptodate as a result of this (potentially partial) write. | |
1936 | */ | |
1937 | if (!partial) | |
1938 | SetPageUptodate(page); | |
1939 | return 0; | |
1940 | } | |
1941 | ||
afddba49 | 1942 | /* |
155130a4 CH |
1943 | * block_write_begin takes care of the basic task of block allocation and |
1944 | * bringing partial write blocks uptodate first. | |
1945 | * | |
7bb46a67 | 1946 | * The filesystem needs to handle block truncation upon failure. |
afddba49 | 1947 | */ |
155130a4 CH |
1948 | int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, |
1949 | unsigned flags, struct page **pagep, get_block_t *get_block) | |
afddba49 | 1950 | { |
6e1db88d | 1951 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
afddba49 | 1952 | struct page *page; |
6e1db88d | 1953 | int status; |
afddba49 | 1954 | |
6e1db88d CH |
1955 | page = grab_cache_page_write_begin(mapping, index, flags); |
1956 | if (!page) | |
1957 | return -ENOMEM; | |
afddba49 | 1958 | |
6e1db88d | 1959 | status = __block_write_begin(page, pos, len, get_block); |
afddba49 | 1960 | if (unlikely(status)) { |
6e1db88d CH |
1961 | unlock_page(page); |
1962 | page_cache_release(page); | |
1963 | page = NULL; | |
afddba49 NP |
1964 | } |
1965 | ||
6e1db88d | 1966 | *pagep = page; |
afddba49 NP |
1967 | return status; |
1968 | } | |
1969 | EXPORT_SYMBOL(block_write_begin); | |
1970 | ||
1971 | int block_write_end(struct file *file, struct address_space *mapping, | |
1972 | loff_t pos, unsigned len, unsigned copied, | |
1973 | struct page *page, void *fsdata) | |
1974 | { | |
1975 | struct inode *inode = mapping->host; | |
1976 | unsigned start; | |
1977 | ||
1978 | start = pos & (PAGE_CACHE_SIZE - 1); | |
1979 | ||
1980 | if (unlikely(copied < len)) { | |
1981 | /* | |
1982 | * The buffers that were written will now be uptodate, so we | |
1983 | * don't have to worry about a readpage reading them and | |
1984 | * overwriting a partial write. However if we have encountered | |
1985 | * a short write and only partially written into a buffer, it | |
1986 | * will not be marked uptodate, so a readpage might come in and | |
1987 | * destroy our partial write. | |
1988 | * | |
1989 | * Do the simplest thing, and just treat any short write to a | |
1990 | * non uptodate page as a zero-length write, and force the | |
1991 | * caller to redo the whole thing. | |
1992 | */ | |
1993 | if (!PageUptodate(page)) | |
1994 | copied = 0; | |
1995 | ||
1996 | page_zero_new_buffers(page, start+copied, start+len); | |
1997 | } | |
1998 | flush_dcache_page(page); | |
1999 | ||
2000 | /* This could be a short (even 0-length) commit */ | |
2001 | __block_commit_write(inode, page, start, start+copied); | |
2002 | ||
2003 | return copied; | |
2004 | } | |
2005 | EXPORT_SYMBOL(block_write_end); | |
2006 | ||
2007 | int generic_write_end(struct file *file, struct address_space *mapping, | |
2008 | loff_t pos, unsigned len, unsigned copied, | |
2009 | struct page *page, void *fsdata) | |
2010 | { | |
2011 | struct inode *inode = mapping->host; | |
c7d206b3 | 2012 | int i_size_changed = 0; |
afddba49 NP |
2013 | |
2014 | copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); | |
2015 | ||
2016 | /* | |
2017 | * No need to use i_size_read() here, the i_size | |
2018 | * cannot change under us because we hold i_mutex. | |
2019 | * | |
2020 | * But it's important to update i_size while still holding page lock: | |
2021 | * page writeout could otherwise come in and zero beyond i_size. | |
2022 | */ | |
2023 | if (pos+copied > inode->i_size) { | |
2024 | i_size_write(inode, pos+copied); | |
c7d206b3 | 2025 | i_size_changed = 1; |
afddba49 NP |
2026 | } |
2027 | ||
2028 | unlock_page(page); | |
2029 | page_cache_release(page); | |
2030 | ||
c7d206b3 JK |
2031 | /* |
2032 | * Don't mark the inode dirty under page lock. First, it unnecessarily | |
2033 | * makes the holding time of page lock longer. Second, it forces lock | |
2034 | * ordering of page lock and transaction start for journaling | |
2035 | * filesystems. | |
2036 | */ | |
2037 | if (i_size_changed) | |
2038 | mark_inode_dirty(inode); | |
2039 | ||
afddba49 NP |
2040 | return copied; |
2041 | } | |
2042 | EXPORT_SYMBOL(generic_write_end); | |
2043 | ||
8ab22b9a HH |
2044 | /* |
2045 | * block_is_partially_uptodate checks whether buffers within a page are | |
2046 | * uptodate or not. | |
2047 | * | |
2048 | * Returns true if all buffers which correspond to a file portion | |
2049 | * we want to read are uptodate. | |
2050 | */ | |
2051 | int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, | |
2052 | unsigned long from) | |
2053 | { | |
8ab22b9a HH |
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 | ||
45bce8f3 LT |
2062 | head = page_buffers(page); |
2063 | blocksize = head->b_size; | |
8ab22b9a HH |
2064 | to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count); |
2065 | to = from + to; | |
2066 | if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize) | |
2067 | return 0; | |
2068 | ||
8ab22b9a HH |
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]; | |
45bce8f3 | 2101 | unsigned int blocksize, bbits; |
1da177e4 LT |
2102 | int nr, i; |
2103 | int fully_mapped = 1; | |
2104 | ||
45bce8f3 LT |
2105 | head = create_page_buffers(page, inode, 0); |
2106 | blocksize = head->b_size; | |
2107 | bbits = block_size_bits(blocksize); | |
1da177e4 | 2108 | |
45bce8f3 LT |
2109 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); |
2110 | lblock = (i_size_read(inode)+blocksize-1) >> bbits; | |
1da177e4 LT |
2111 | bh = head; |
2112 | nr = 0; | |
2113 | i = 0; | |
2114 | ||
2115 | do { | |
2116 | if (buffer_uptodate(bh)) | |
2117 | continue; | |
2118 | ||
2119 | if (!buffer_mapped(bh)) { | |
c64610ba AM |
2120 | int err = 0; |
2121 | ||
1da177e4 LT |
2122 | fully_mapped = 0; |
2123 | if (iblock < lblock) { | |
b0cf2321 | 2124 | WARN_ON(bh->b_size != blocksize); |
c64610ba AM |
2125 | err = get_block(inode, iblock, bh, 0); |
2126 | if (err) | |
1da177e4 LT |
2127 | SetPageError(page); |
2128 | } | |
2129 | if (!buffer_mapped(bh)) { | |
eebd2aa3 | 2130 | zero_user(page, i * blocksize, blocksize); |
c64610ba AM |
2131 | if (!err) |
2132 | set_buffer_uptodate(bh); | |
1da177e4 LT |
2133 | continue; |
2134 | } | |
2135 | /* | |
2136 | * get_block() might have updated the buffer | |
2137 | * synchronously | |
2138 | */ | |
2139 | if (buffer_uptodate(bh)) | |
2140 | continue; | |
2141 | } | |
2142 | arr[nr++] = bh; | |
2143 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
2144 | ||
2145 | if (fully_mapped) | |
2146 | SetPageMappedToDisk(page); | |
2147 | ||
2148 | if (!nr) { | |
2149 | /* | |
2150 | * All buffers are uptodate - we can set the page uptodate | |
2151 | * as well. But not if get_block() returned an error. | |
2152 | */ | |
2153 | if (!PageError(page)) | |
2154 | SetPageUptodate(page); | |
2155 | unlock_page(page); | |
2156 | return 0; | |
2157 | } | |
2158 | ||
2159 | /* Stage two: lock the buffers */ | |
2160 | for (i = 0; i < nr; i++) { | |
2161 | bh = arr[i]; | |
2162 | lock_buffer(bh); | |
2163 | mark_buffer_async_read(bh); | |
2164 | } | |
2165 | ||
2166 | /* | |
2167 | * Stage 3: start the IO. Check for uptodateness | |
2168 | * inside the buffer lock in case another process reading | |
2169 | * the underlying blockdev brought it uptodate (the sct fix). | |
2170 | */ | |
2171 | for (i = 0; i < nr; i++) { | |
2172 | bh = arr[i]; | |
2173 | if (buffer_uptodate(bh)) | |
2174 | end_buffer_async_read(bh, 1); | |
2175 | else | |
2176 | submit_bh(READ, bh); | |
2177 | } | |
2178 | return 0; | |
2179 | } | |
1fe72eaa | 2180 | EXPORT_SYMBOL(block_read_full_page); |
1da177e4 LT |
2181 | |
2182 | /* utility function for filesystems that need to do work on expanding | |
89e10787 | 2183 | * truncates. Uses filesystem pagecache writes to allow the filesystem to |
1da177e4 LT |
2184 | * deal with the hole. |
2185 | */ | |
89e10787 | 2186 | int generic_cont_expand_simple(struct inode *inode, loff_t size) |
1da177e4 LT |
2187 | { |
2188 | struct address_space *mapping = inode->i_mapping; | |
2189 | struct page *page; | |
89e10787 | 2190 | void *fsdata; |
1da177e4 LT |
2191 | int err; |
2192 | ||
c08d3b0e | 2193 | err = inode_newsize_ok(inode, size); |
2194 | if (err) | |
1da177e4 LT |
2195 | goto out; |
2196 | ||
89e10787 NP |
2197 | err = pagecache_write_begin(NULL, mapping, size, 0, |
2198 | AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, | |
2199 | &page, &fsdata); | |
2200 | if (err) | |
05eb0b51 | 2201 | goto out; |
05eb0b51 | 2202 | |
89e10787 NP |
2203 | err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); |
2204 | BUG_ON(err > 0); | |
05eb0b51 | 2205 | |
1da177e4 LT |
2206 | out: |
2207 | return err; | |
2208 | } | |
1fe72eaa | 2209 | EXPORT_SYMBOL(generic_cont_expand_simple); |
1da177e4 | 2210 | |
f1e3af72 AB |
2211 | static int cont_expand_zero(struct file *file, struct address_space *mapping, |
2212 | loff_t pos, loff_t *bytes) | |
1da177e4 | 2213 | { |
1da177e4 | 2214 | struct inode *inode = mapping->host; |
1da177e4 | 2215 | unsigned blocksize = 1 << inode->i_blkbits; |
89e10787 NP |
2216 | struct page *page; |
2217 | void *fsdata; | |
2218 | pgoff_t index, curidx; | |
2219 | loff_t curpos; | |
2220 | unsigned zerofrom, offset, len; | |
2221 | int err = 0; | |
1da177e4 | 2222 | |
89e10787 NP |
2223 | index = pos >> PAGE_CACHE_SHIFT; |
2224 | offset = pos & ~PAGE_CACHE_MASK; | |
2225 | ||
2226 | while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { | |
2227 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 LT |
2228 | if (zerofrom & (blocksize-1)) { |
2229 | *bytes |= (blocksize-1); | |
2230 | (*bytes)++; | |
2231 | } | |
89e10787 | 2232 | len = PAGE_CACHE_SIZE - zerofrom; |
1da177e4 | 2233 | |
89e10787 NP |
2234 | err = pagecache_write_begin(file, mapping, curpos, len, |
2235 | AOP_FLAG_UNINTERRUPTIBLE, | |
2236 | &page, &fsdata); | |
2237 | if (err) | |
2238 | goto out; | |
eebd2aa3 | 2239 | zero_user(page, zerofrom, len); |
89e10787 NP |
2240 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2241 | page, fsdata); | |
2242 | if (err < 0) | |
2243 | goto out; | |
2244 | BUG_ON(err != len); | |
2245 | err = 0; | |
061e9746 OH |
2246 | |
2247 | balance_dirty_pages_ratelimited(mapping); | |
89e10787 | 2248 | } |
1da177e4 | 2249 | |
89e10787 NP |
2250 | /* page covers the boundary, find the boundary offset */ |
2251 | if (index == curidx) { | |
2252 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 | 2253 | /* if we will expand the thing last block will be filled */ |
89e10787 NP |
2254 | if (offset <= zerofrom) { |
2255 | goto out; | |
2256 | } | |
2257 | if (zerofrom & (blocksize-1)) { | |
1da177e4 LT |
2258 | *bytes |= (blocksize-1); |
2259 | (*bytes)++; | |
2260 | } | |
89e10787 | 2261 | len = offset - zerofrom; |
1da177e4 | 2262 | |
89e10787 NP |
2263 | err = pagecache_write_begin(file, mapping, curpos, len, |
2264 | AOP_FLAG_UNINTERRUPTIBLE, | |
2265 | &page, &fsdata); | |
2266 | if (err) | |
2267 | goto out; | |
eebd2aa3 | 2268 | zero_user(page, zerofrom, len); |
89e10787 NP |
2269 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2270 | page, fsdata); | |
2271 | if (err < 0) | |
2272 | goto out; | |
2273 | BUG_ON(err != len); | |
2274 | err = 0; | |
1da177e4 | 2275 | } |
89e10787 NP |
2276 | out: |
2277 | return err; | |
2278 | } | |
2279 | ||
2280 | /* | |
2281 | * For moronic filesystems that do not allow holes in file. | |
2282 | * We may have to extend the file. | |
2283 | */ | |
282dc178 | 2284 | int cont_write_begin(struct file *file, struct address_space *mapping, |
89e10787 NP |
2285 | loff_t pos, unsigned len, unsigned flags, |
2286 | struct page **pagep, void **fsdata, | |
2287 | get_block_t *get_block, loff_t *bytes) | |
2288 | { | |
2289 | struct inode *inode = mapping->host; | |
2290 | unsigned blocksize = 1 << inode->i_blkbits; | |
2291 | unsigned zerofrom; | |
2292 | int err; | |
2293 | ||
2294 | err = cont_expand_zero(file, mapping, pos, bytes); | |
2295 | if (err) | |
155130a4 | 2296 | return err; |
89e10787 NP |
2297 | |
2298 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2299 | if (pos+len > *bytes && zerofrom & (blocksize-1)) { | |
2300 | *bytes |= (blocksize-1); | |
2301 | (*bytes)++; | |
1da177e4 | 2302 | } |
1da177e4 | 2303 | |
155130a4 | 2304 | return block_write_begin(mapping, pos, len, flags, pagep, get_block); |
1da177e4 | 2305 | } |
1fe72eaa | 2306 | EXPORT_SYMBOL(cont_write_begin); |
1da177e4 | 2307 | |
1da177e4 LT |
2308 | int block_commit_write(struct page *page, unsigned from, unsigned to) |
2309 | { | |
2310 | struct inode *inode = page->mapping->host; | |
2311 | __block_commit_write(inode,page,from,to); | |
2312 | return 0; | |
2313 | } | |
1fe72eaa | 2314 | EXPORT_SYMBOL(block_commit_write); |
1da177e4 | 2315 | |
54171690 DC |
2316 | /* |
2317 | * block_page_mkwrite() is not allowed to change the file size as it gets | |
2318 | * called from a page fault handler when a page is first dirtied. Hence we must | |
2319 | * be careful to check for EOF conditions here. We set the page up correctly | |
2320 | * for a written page which means we get ENOSPC checking when writing into | |
2321 | * holes and correct delalloc and unwritten extent mapping on filesystems that | |
2322 | * support these features. | |
2323 | * | |
2324 | * We are not allowed to take the i_mutex here so we have to play games to | |
2325 | * protect against truncate races as the page could now be beyond EOF. Because | |
7bb46a67 | 2326 | * truncate writes the inode size before removing pages, once we have the |
54171690 DC |
2327 | * page lock we can determine safely if the page is beyond EOF. If it is not |
2328 | * beyond EOF, then the page is guaranteed safe against truncation until we | |
2329 | * unlock the page. | |
ea13a864 | 2330 | * |
14da9200 JK |
2331 | * Direct callers of this function should protect against filesystem freezing |
2332 | * using sb_start_write() - sb_end_write() functions. | |
54171690 | 2333 | */ |
24da4fab JK |
2334 | int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
2335 | get_block_t get_block) | |
54171690 | 2336 | { |
c2ec175c | 2337 | struct page *page = vmf->page; |
54171690 DC |
2338 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; |
2339 | unsigned long end; | |
2340 | loff_t size; | |
24da4fab | 2341 | int ret; |
54171690 DC |
2342 | |
2343 | lock_page(page); | |
2344 | size = i_size_read(inode); | |
2345 | if ((page->mapping != inode->i_mapping) || | |
18336338 | 2346 | (page_offset(page) > size)) { |
24da4fab JK |
2347 | /* We overload EFAULT to mean page got truncated */ |
2348 | ret = -EFAULT; | |
2349 | goto out_unlock; | |
54171690 DC |
2350 | } |
2351 | ||
2352 | /* page is wholly or partially inside EOF */ | |
2353 | if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) | |
2354 | end = size & ~PAGE_CACHE_MASK; | |
2355 | else | |
2356 | end = PAGE_CACHE_SIZE; | |
2357 | ||
ebdec241 | 2358 | ret = __block_write_begin(page, 0, end, get_block); |
54171690 DC |
2359 | if (!ret) |
2360 | ret = block_commit_write(page, 0, end); | |
2361 | ||
24da4fab JK |
2362 | if (unlikely(ret < 0)) |
2363 | goto out_unlock; | |
ea13a864 | 2364 | set_page_dirty(page); |
d76ee18a | 2365 | wait_on_page_writeback(page); |
24da4fab JK |
2366 | return 0; |
2367 | out_unlock: | |
2368 | unlock_page(page); | |
54171690 | 2369 | return ret; |
24da4fab JK |
2370 | } |
2371 | EXPORT_SYMBOL(__block_page_mkwrite); | |
2372 | ||
2373 | int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, | |
2374 | get_block_t get_block) | |
2375 | { | |
ea13a864 JK |
2376 | int ret; |
2377 | struct super_block *sb = vma->vm_file->f_path.dentry->d_inode->i_sb; | |
24da4fab | 2378 | |
14da9200 | 2379 | sb_start_pagefault(sb); |
041bbb6d TT |
2380 | |
2381 | /* | |
2382 | * Update file times before taking page lock. We may end up failing the | |
2383 | * fault so this update may be superfluous but who really cares... | |
2384 | */ | |
2385 | file_update_time(vma->vm_file); | |
2386 | ||
ea13a864 | 2387 | ret = __block_page_mkwrite(vma, vmf, get_block); |
14da9200 | 2388 | sb_end_pagefault(sb); |
24da4fab | 2389 | return block_page_mkwrite_return(ret); |
54171690 | 2390 | } |
1fe72eaa | 2391 | EXPORT_SYMBOL(block_page_mkwrite); |
1da177e4 LT |
2392 | |
2393 | /* | |
03158cd7 | 2394 | * nobh_write_begin()'s prereads are special: the buffer_heads are freed |
1da177e4 LT |
2395 | * immediately, while under the page lock. So it needs a special end_io |
2396 | * handler which does not touch the bh after unlocking it. | |
1da177e4 LT |
2397 | */ |
2398 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2399 | { | |
68671f35 | 2400 | __end_buffer_read_notouch(bh, uptodate); |
1da177e4 LT |
2401 | } |
2402 | ||
03158cd7 NP |
2403 | /* |
2404 | * Attach the singly-linked list of buffers created by nobh_write_begin, to | |
2405 | * the page (converting it to circular linked list and taking care of page | |
2406 | * dirty races). | |
2407 | */ | |
2408 | static void attach_nobh_buffers(struct page *page, struct buffer_head *head) | |
2409 | { | |
2410 | struct buffer_head *bh; | |
2411 | ||
2412 | BUG_ON(!PageLocked(page)); | |
2413 | ||
2414 | spin_lock(&page->mapping->private_lock); | |
2415 | bh = head; | |
2416 | do { | |
2417 | if (PageDirty(page)) | |
2418 | set_buffer_dirty(bh); | |
2419 | if (!bh->b_this_page) | |
2420 | bh->b_this_page = head; | |
2421 | bh = bh->b_this_page; | |
2422 | } while (bh != head); | |
2423 | attach_page_buffers(page, head); | |
2424 | spin_unlock(&page->mapping->private_lock); | |
2425 | } | |
2426 | ||
1da177e4 | 2427 | /* |
ea0f04e5 CH |
2428 | * On entry, the page is fully not uptodate. |
2429 | * On exit the page is fully uptodate in the areas outside (from,to) | |
7bb46a67 | 2430 | * The filesystem needs to handle block truncation upon failure. |
1da177e4 | 2431 | */ |
ea0f04e5 | 2432 | int nobh_write_begin(struct address_space *mapping, |
03158cd7 NP |
2433 | loff_t pos, unsigned len, unsigned flags, |
2434 | struct page **pagep, void **fsdata, | |
1da177e4 LT |
2435 | get_block_t *get_block) |
2436 | { | |
03158cd7 | 2437 | struct inode *inode = mapping->host; |
1da177e4 LT |
2438 | const unsigned blkbits = inode->i_blkbits; |
2439 | const unsigned blocksize = 1 << blkbits; | |
a4b0672d | 2440 | struct buffer_head *head, *bh; |
03158cd7 NP |
2441 | struct page *page; |
2442 | pgoff_t index; | |
2443 | unsigned from, to; | |
1da177e4 | 2444 | unsigned block_in_page; |
a4b0672d | 2445 | unsigned block_start, block_end; |
1da177e4 | 2446 | sector_t block_in_file; |
1da177e4 | 2447 | int nr_reads = 0; |
1da177e4 LT |
2448 | int ret = 0; |
2449 | int is_mapped_to_disk = 1; | |
1da177e4 | 2450 | |
03158cd7 NP |
2451 | index = pos >> PAGE_CACHE_SHIFT; |
2452 | from = pos & (PAGE_CACHE_SIZE - 1); | |
2453 | to = from + len; | |
2454 | ||
54566b2c | 2455 | page = grab_cache_page_write_begin(mapping, index, flags); |
03158cd7 NP |
2456 | if (!page) |
2457 | return -ENOMEM; | |
2458 | *pagep = page; | |
2459 | *fsdata = NULL; | |
2460 | ||
2461 | if (page_has_buffers(page)) { | |
309f77ad NK |
2462 | ret = __block_write_begin(page, pos, len, get_block); |
2463 | if (unlikely(ret)) | |
2464 | goto out_release; | |
2465 | return ret; | |
03158cd7 | 2466 | } |
a4b0672d | 2467 | |
1da177e4 LT |
2468 | if (PageMappedToDisk(page)) |
2469 | return 0; | |
2470 | ||
a4b0672d NP |
2471 | /* |
2472 | * Allocate buffers so that we can keep track of state, and potentially | |
2473 | * attach them to the page if an error occurs. In the common case of | |
2474 | * no error, they will just be freed again without ever being attached | |
2475 | * to the page (which is all OK, because we're under the page lock). | |
2476 | * | |
2477 | * Be careful: the buffer linked list is a NULL terminated one, rather | |
2478 | * than the circular one we're used to. | |
2479 | */ | |
2480 | head = alloc_page_buffers(page, blocksize, 0); | |
03158cd7 NP |
2481 | if (!head) { |
2482 | ret = -ENOMEM; | |
2483 | goto out_release; | |
2484 | } | |
a4b0672d | 2485 | |
1da177e4 | 2486 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); |
1da177e4 LT |
2487 | |
2488 | /* | |
2489 | * We loop across all blocks in the page, whether or not they are | |
2490 | * part of the affected region. This is so we can discover if the | |
2491 | * page is fully mapped-to-disk. | |
2492 | */ | |
a4b0672d | 2493 | for (block_start = 0, block_in_page = 0, bh = head; |
1da177e4 | 2494 | block_start < PAGE_CACHE_SIZE; |
a4b0672d | 2495 | block_in_page++, block_start += blocksize, bh = bh->b_this_page) { |
1da177e4 LT |
2496 | int create; |
2497 | ||
a4b0672d NP |
2498 | block_end = block_start + blocksize; |
2499 | bh->b_state = 0; | |
1da177e4 LT |
2500 | create = 1; |
2501 | if (block_start >= to) | |
2502 | create = 0; | |
2503 | ret = get_block(inode, block_in_file + block_in_page, | |
a4b0672d | 2504 | bh, create); |
1da177e4 LT |
2505 | if (ret) |
2506 | goto failed; | |
a4b0672d | 2507 | if (!buffer_mapped(bh)) |
1da177e4 | 2508 | is_mapped_to_disk = 0; |
a4b0672d NP |
2509 | if (buffer_new(bh)) |
2510 | unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); | |
2511 | if (PageUptodate(page)) { | |
2512 | set_buffer_uptodate(bh); | |
1da177e4 | 2513 | continue; |
a4b0672d NP |
2514 | } |
2515 | if (buffer_new(bh) || !buffer_mapped(bh)) { | |
eebd2aa3 CL |
2516 | zero_user_segments(page, block_start, from, |
2517 | to, block_end); | |
1da177e4 LT |
2518 | continue; |
2519 | } | |
a4b0672d | 2520 | if (buffer_uptodate(bh)) |
1da177e4 LT |
2521 | continue; /* reiserfs does this */ |
2522 | if (block_start < from || block_end > to) { | |
a4b0672d NP |
2523 | lock_buffer(bh); |
2524 | bh->b_end_io = end_buffer_read_nobh; | |
2525 | submit_bh(READ, bh); | |
2526 | nr_reads++; | |
1da177e4 LT |
2527 | } |
2528 | } | |
2529 | ||
2530 | if (nr_reads) { | |
1da177e4 LT |
2531 | /* |
2532 | * The page is locked, so these buffers are protected from | |
2533 | * any VM or truncate activity. Hence we don't need to care | |
2534 | * for the buffer_head refcounts. | |
2535 | */ | |
a4b0672d | 2536 | for (bh = head; bh; bh = bh->b_this_page) { |
1da177e4 LT |
2537 | wait_on_buffer(bh); |
2538 | if (!buffer_uptodate(bh)) | |
2539 | ret = -EIO; | |
1da177e4 LT |
2540 | } |
2541 | if (ret) | |
2542 | goto failed; | |
2543 | } | |
2544 | ||
2545 | if (is_mapped_to_disk) | |
2546 | SetPageMappedToDisk(page); | |
1da177e4 | 2547 | |
03158cd7 | 2548 | *fsdata = head; /* to be released by nobh_write_end */ |
a4b0672d | 2549 | |
1da177e4 LT |
2550 | return 0; |
2551 | ||
2552 | failed: | |
03158cd7 | 2553 | BUG_ON(!ret); |
1da177e4 | 2554 | /* |
a4b0672d NP |
2555 | * Error recovery is a bit difficult. We need to zero out blocks that |
2556 | * were newly allocated, and dirty them to ensure they get written out. | |
2557 | * Buffers need to be attached to the page at this point, otherwise | |
2558 | * the handling of potential IO errors during writeout would be hard | |
2559 | * (could try doing synchronous writeout, but what if that fails too?) | |
1da177e4 | 2560 | */ |
03158cd7 NP |
2561 | attach_nobh_buffers(page, head); |
2562 | page_zero_new_buffers(page, from, to); | |
a4b0672d | 2563 | |
03158cd7 NP |
2564 | out_release: |
2565 | unlock_page(page); | |
2566 | page_cache_release(page); | |
2567 | *pagep = NULL; | |
a4b0672d | 2568 | |
7bb46a67 | 2569 | return ret; |
2570 | } | |
03158cd7 | 2571 | EXPORT_SYMBOL(nobh_write_begin); |
1da177e4 | 2572 | |
03158cd7 NP |
2573 | int nobh_write_end(struct file *file, struct address_space *mapping, |
2574 | loff_t pos, unsigned len, unsigned copied, | |
2575 | struct page *page, void *fsdata) | |
1da177e4 LT |
2576 | { |
2577 | struct inode *inode = page->mapping->host; | |
efdc3131 | 2578 | struct buffer_head *head = fsdata; |
03158cd7 | 2579 | struct buffer_head *bh; |
5b41e74a | 2580 | BUG_ON(fsdata != NULL && page_has_buffers(page)); |
1da177e4 | 2581 | |
d4cf109f | 2582 | if (unlikely(copied < len) && head) |
5b41e74a DM |
2583 | attach_nobh_buffers(page, head); |
2584 | if (page_has_buffers(page)) | |
2585 | return generic_write_end(file, mapping, pos, len, | |
2586 | copied, page, fsdata); | |
a4b0672d | 2587 | |
22c8ca78 | 2588 | SetPageUptodate(page); |
1da177e4 | 2589 | set_page_dirty(page); |
03158cd7 NP |
2590 | if (pos+copied > inode->i_size) { |
2591 | i_size_write(inode, pos+copied); | |
1da177e4 LT |
2592 | mark_inode_dirty(inode); |
2593 | } | |
03158cd7 NP |
2594 | |
2595 | unlock_page(page); | |
2596 | page_cache_release(page); | |
2597 | ||
03158cd7 NP |
2598 | while (head) { |
2599 | bh = head; | |
2600 | head = head->b_this_page; | |
2601 | free_buffer_head(bh); | |
2602 | } | |
2603 | ||
2604 | return copied; | |
1da177e4 | 2605 | } |
03158cd7 | 2606 | EXPORT_SYMBOL(nobh_write_end); |
1da177e4 LT |
2607 | |
2608 | /* | |
2609 | * nobh_writepage() - based on block_full_write_page() except | |
2610 | * that it tries to operate without attaching bufferheads to | |
2611 | * the page. | |
2612 | */ | |
2613 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2614 | struct writeback_control *wbc) | |
2615 | { | |
2616 | struct inode * const inode = page->mapping->host; | |
2617 | loff_t i_size = i_size_read(inode); | |
2618 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2619 | unsigned offset; | |
1da177e4 LT |
2620 | int ret; |
2621 | ||
2622 | /* Is the page fully inside i_size? */ | |
2623 | if (page->index < end_index) | |
2624 | goto out; | |
2625 | ||
2626 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2627 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2628 | if (page->index >= end_index+1 || !offset) { | |
2629 | /* | |
2630 | * The page may have dirty, unmapped buffers. For example, | |
2631 | * they may have been added in ext3_writepage(). Make them | |
2632 | * freeable here, so the page does not leak. | |
2633 | */ | |
2634 | #if 0 | |
2635 | /* Not really sure about this - do we need this ? */ | |
2636 | if (page->mapping->a_ops->invalidatepage) | |
2637 | page->mapping->a_ops->invalidatepage(page, offset); | |
2638 | #endif | |
2639 | unlock_page(page); | |
2640 | return 0; /* don't care */ | |
2641 | } | |
2642 | ||
2643 | /* | |
2644 | * The page straddles i_size. It must be zeroed out on each and every | |
2645 | * writepage invocation because it may be mmapped. "A file is mapped | |
2646 | * in multiples of the page size. For a file that is not a multiple of | |
2647 | * the page size, the remaining memory is zeroed when mapped, and | |
2648 | * writes to that region are not written out to the file." | |
2649 | */ | |
eebd2aa3 | 2650 | zero_user_segment(page, offset, PAGE_CACHE_SIZE); |
1da177e4 LT |
2651 | out: |
2652 | ret = mpage_writepage(page, get_block, wbc); | |
2653 | if (ret == -EAGAIN) | |
35c80d5f CM |
2654 | ret = __block_write_full_page(inode, page, get_block, wbc, |
2655 | end_buffer_async_write); | |
1da177e4 LT |
2656 | return ret; |
2657 | } | |
2658 | EXPORT_SYMBOL(nobh_writepage); | |
2659 | ||
03158cd7 NP |
2660 | int nobh_truncate_page(struct address_space *mapping, |
2661 | loff_t from, get_block_t *get_block) | |
1da177e4 | 2662 | { |
1da177e4 LT |
2663 | pgoff_t index = from >> PAGE_CACHE_SHIFT; |
2664 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
03158cd7 NP |
2665 | unsigned blocksize; |
2666 | sector_t iblock; | |
2667 | unsigned length, pos; | |
2668 | struct inode *inode = mapping->host; | |
1da177e4 | 2669 | struct page *page; |
03158cd7 NP |
2670 | struct buffer_head map_bh; |
2671 | int err; | |
1da177e4 | 2672 | |
03158cd7 NP |
2673 | blocksize = 1 << inode->i_blkbits; |
2674 | length = offset & (blocksize - 1); | |
2675 | ||
2676 | /* Block boundary? Nothing to do */ | |
2677 | if (!length) | |
2678 | return 0; | |
2679 | ||
2680 | length = blocksize - length; | |
2681 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
1da177e4 | 2682 | |
1da177e4 | 2683 | page = grab_cache_page(mapping, index); |
03158cd7 | 2684 | err = -ENOMEM; |
1da177e4 LT |
2685 | if (!page) |
2686 | goto out; | |
2687 | ||
03158cd7 NP |
2688 | if (page_has_buffers(page)) { |
2689 | has_buffers: | |
2690 | unlock_page(page); | |
2691 | page_cache_release(page); | |
2692 | return block_truncate_page(mapping, from, get_block); | |
2693 | } | |
2694 | ||
2695 | /* Find the buffer that contains "offset" */ | |
2696 | pos = blocksize; | |
2697 | while (offset >= pos) { | |
2698 | iblock++; | |
2699 | pos += blocksize; | |
2700 | } | |
2701 | ||
460bcf57 TT |
2702 | map_bh.b_size = blocksize; |
2703 | map_bh.b_state = 0; | |
03158cd7 NP |
2704 | err = get_block(inode, iblock, &map_bh, 0); |
2705 | if (err) | |
2706 | goto unlock; | |
2707 | /* unmapped? It's a hole - nothing to do */ | |
2708 | if (!buffer_mapped(&map_bh)) | |
2709 | goto unlock; | |
2710 | ||
2711 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2712 | if (!PageUptodate(page)) { | |
2713 | err = mapping->a_ops->readpage(NULL, page); | |
2714 | if (err) { | |
2715 | page_cache_release(page); | |
2716 | goto out; | |
2717 | } | |
2718 | lock_page(page); | |
2719 | if (!PageUptodate(page)) { | |
2720 | err = -EIO; | |
2721 | goto unlock; | |
2722 | } | |
2723 | if (page_has_buffers(page)) | |
2724 | goto has_buffers; | |
1da177e4 | 2725 | } |
eebd2aa3 | 2726 | zero_user(page, offset, length); |
03158cd7 NP |
2727 | set_page_dirty(page); |
2728 | err = 0; | |
2729 | ||
2730 | unlock: | |
1da177e4 LT |
2731 | unlock_page(page); |
2732 | page_cache_release(page); | |
2733 | out: | |
03158cd7 | 2734 | return err; |
1da177e4 LT |
2735 | } |
2736 | EXPORT_SYMBOL(nobh_truncate_page); | |
2737 | ||
2738 | int block_truncate_page(struct address_space *mapping, | |
2739 | loff_t from, get_block_t *get_block) | |
2740 | { | |
2741 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2742 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2743 | unsigned blocksize; | |
54b21a79 | 2744 | sector_t iblock; |
1da177e4 LT |
2745 | unsigned length, pos; |
2746 | struct inode *inode = mapping->host; | |
2747 | struct page *page; | |
2748 | struct buffer_head *bh; | |
1da177e4 LT |
2749 | int err; |
2750 | ||
2751 | blocksize = 1 << inode->i_blkbits; | |
2752 | length = offset & (blocksize - 1); | |
2753 | ||
2754 | /* Block boundary? Nothing to do */ | |
2755 | if (!length) | |
2756 | return 0; | |
2757 | ||
2758 | length = blocksize - length; | |
54b21a79 | 2759 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
2760 | |
2761 | page = grab_cache_page(mapping, index); | |
2762 | err = -ENOMEM; | |
2763 | if (!page) | |
2764 | goto out; | |
2765 | ||
2766 | if (!page_has_buffers(page)) | |
2767 | create_empty_buffers(page, blocksize, 0); | |
2768 | ||
2769 | /* Find the buffer that contains "offset" */ | |
2770 | bh = page_buffers(page); | |
2771 | pos = blocksize; | |
2772 | while (offset >= pos) { | |
2773 | bh = bh->b_this_page; | |
2774 | iblock++; | |
2775 | pos += blocksize; | |
2776 | } | |
2777 | ||
2778 | err = 0; | |
2779 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 2780 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
2781 | err = get_block(inode, iblock, bh, 0); |
2782 | if (err) | |
2783 | goto unlock; | |
2784 | /* unmapped? It's a hole - nothing to do */ | |
2785 | if (!buffer_mapped(bh)) | |
2786 | goto unlock; | |
2787 | } | |
2788 | ||
2789 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2790 | if (PageUptodate(page)) | |
2791 | set_buffer_uptodate(bh); | |
2792 | ||
33a266dd | 2793 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { |
1da177e4 LT |
2794 | err = -EIO; |
2795 | ll_rw_block(READ, 1, &bh); | |
2796 | wait_on_buffer(bh); | |
2797 | /* Uhhuh. Read error. Complain and punt. */ | |
2798 | if (!buffer_uptodate(bh)) | |
2799 | goto unlock; | |
2800 | } | |
2801 | ||
eebd2aa3 | 2802 | zero_user(page, offset, length); |
1da177e4 LT |
2803 | mark_buffer_dirty(bh); |
2804 | err = 0; | |
2805 | ||
2806 | unlock: | |
2807 | unlock_page(page); | |
2808 | page_cache_release(page); | |
2809 | out: | |
2810 | return err; | |
2811 | } | |
1fe72eaa | 2812 | EXPORT_SYMBOL(block_truncate_page); |
1da177e4 LT |
2813 | |
2814 | /* | |
2815 | * The generic ->writepage function for buffer-backed address_spaces | |
35c80d5f | 2816 | * this form passes in the end_io handler used to finish the IO. |
1da177e4 | 2817 | */ |
35c80d5f CM |
2818 | int block_write_full_page_endio(struct page *page, get_block_t *get_block, |
2819 | struct writeback_control *wbc, bh_end_io_t *handler) | |
1da177e4 LT |
2820 | { |
2821 | struct inode * const inode = page->mapping->host; | |
2822 | loff_t i_size = i_size_read(inode); | |
2823 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2824 | unsigned offset; | |
1da177e4 LT |
2825 | |
2826 | /* Is the page fully inside i_size? */ | |
2827 | if (page->index < end_index) | |
35c80d5f CM |
2828 | return __block_write_full_page(inode, page, get_block, wbc, |
2829 | handler); | |
1da177e4 LT |
2830 | |
2831 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2832 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2833 | if (page->index >= end_index+1 || !offset) { | |
2834 | /* | |
2835 | * The page may have dirty, unmapped buffers. For example, | |
2836 | * they may have been added in ext3_writepage(). Make them | |
2837 | * freeable here, so the page does not leak. | |
2838 | */ | |
aaa4059b | 2839 | do_invalidatepage(page, 0); |
1da177e4 LT |
2840 | unlock_page(page); |
2841 | return 0; /* don't care */ | |
2842 | } | |
2843 | ||
2844 | /* | |
2845 | * The page straddles i_size. It must be zeroed out on each and every | |
2a61aa40 | 2846 | * writepage invocation because it may be mmapped. "A file is mapped |
1da177e4 LT |
2847 | * in multiples of the page size. For a file that is not a multiple of |
2848 | * the page size, the remaining memory is zeroed when mapped, and | |
2849 | * writes to that region are not written out to the file." | |
2850 | */ | |
eebd2aa3 | 2851 | zero_user_segment(page, offset, PAGE_CACHE_SIZE); |
35c80d5f | 2852 | return __block_write_full_page(inode, page, get_block, wbc, handler); |
1da177e4 | 2853 | } |
1fe72eaa | 2854 | EXPORT_SYMBOL(block_write_full_page_endio); |
1da177e4 | 2855 | |
35c80d5f CM |
2856 | /* |
2857 | * The generic ->writepage function for buffer-backed address_spaces | |
2858 | */ | |
2859 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
2860 | struct writeback_control *wbc) | |
2861 | { | |
2862 | return block_write_full_page_endio(page, get_block, wbc, | |
2863 | end_buffer_async_write); | |
2864 | } | |
1fe72eaa | 2865 | EXPORT_SYMBOL(block_write_full_page); |
35c80d5f | 2866 | |
1da177e4 LT |
2867 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, |
2868 | get_block_t *get_block) | |
2869 | { | |
2870 | struct buffer_head tmp; | |
2871 | struct inode *inode = mapping->host; | |
2872 | tmp.b_state = 0; | |
2873 | tmp.b_blocknr = 0; | |
b0cf2321 | 2874 | tmp.b_size = 1 << inode->i_blkbits; |
1da177e4 LT |
2875 | get_block(inode, block, &tmp, 0); |
2876 | return tmp.b_blocknr; | |
2877 | } | |
1fe72eaa | 2878 | EXPORT_SYMBOL(generic_block_bmap); |
1da177e4 | 2879 | |
6712ecf8 | 2880 | static void end_bio_bh_io_sync(struct bio *bio, int err) |
1da177e4 LT |
2881 | { |
2882 | struct buffer_head *bh = bio->bi_private; | |
2883 | ||
1da177e4 LT |
2884 | if (err == -EOPNOTSUPP) { |
2885 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
1da177e4 LT |
2886 | } |
2887 | ||
08bafc03 KM |
2888 | if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags))) |
2889 | set_bit(BH_Quiet, &bh->b_state); | |
2890 | ||
1da177e4 LT |
2891 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); |
2892 | bio_put(bio); | |
1da177e4 LT |
2893 | } |
2894 | ||
57302e0d LT |
2895 | /* |
2896 | * This allows us to do IO even on the odd last sectors | |
2897 | * of a device, even if the bh block size is some multiple | |
2898 | * of the physical sector size. | |
2899 | * | |
2900 | * We'll just truncate the bio to the size of the device, | |
2901 | * and clear the end of the buffer head manually. | |
2902 | * | |
2903 | * Truly out-of-range accesses will turn into actual IO | |
2904 | * errors, this only handles the "we need to be able to | |
2905 | * do IO at the final sector" case. | |
2906 | */ | |
2907 | static void guard_bh_eod(int rw, struct bio *bio, struct buffer_head *bh) | |
2908 | { | |
2909 | sector_t maxsector; | |
2910 | unsigned bytes; | |
2911 | ||
2912 | maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; | |
2913 | if (!maxsector) | |
2914 | return; | |
2915 | ||
2916 | /* | |
2917 | * If the *whole* IO is past the end of the device, | |
2918 | * let it through, and the IO layer will turn it into | |
2919 | * an EIO. | |
2920 | */ | |
2921 | if (unlikely(bio->bi_sector >= maxsector)) | |
2922 | return; | |
2923 | ||
2924 | maxsector -= bio->bi_sector; | |
2925 | bytes = bio->bi_size; | |
2926 | if (likely((bytes >> 9) <= maxsector)) | |
2927 | return; | |
2928 | ||
2929 | /* Uhhuh. We've got a bh that straddles the device size! */ | |
2930 | bytes = maxsector << 9; | |
2931 | ||
2932 | /* Truncate the bio.. */ | |
2933 | bio->bi_size = bytes; | |
2934 | bio->bi_io_vec[0].bv_len = bytes; | |
2935 | ||
2936 | /* ..and clear the end of the buffer for reads */ | |
27d7c2a0 | 2937 | if ((rw & RW_MASK) == READ) { |
57302e0d LT |
2938 | void *kaddr = kmap_atomic(bh->b_page); |
2939 | memset(kaddr + bh_offset(bh) + bytes, 0, bh->b_size - bytes); | |
2940 | kunmap_atomic(kaddr); | |
2941 | } | |
2942 | } | |
2943 | ||
1da177e4 LT |
2944 | int submit_bh(int rw, struct buffer_head * bh) |
2945 | { | |
2946 | struct bio *bio; | |
2947 | int ret = 0; | |
2948 | ||
2949 | BUG_ON(!buffer_locked(bh)); | |
2950 | BUG_ON(!buffer_mapped(bh)); | |
2951 | BUG_ON(!bh->b_end_io); | |
8fb0e342 AK |
2952 | BUG_ON(buffer_delay(bh)); |
2953 | BUG_ON(buffer_unwritten(bh)); | |
1da177e4 | 2954 | |
1da177e4 | 2955 | /* |
48fd4f93 | 2956 | * Only clear out a write error when rewriting |
1da177e4 | 2957 | */ |
48fd4f93 | 2958 | if (test_set_buffer_req(bh) && (rw & WRITE)) |
1da177e4 LT |
2959 | clear_buffer_write_io_error(bh); |
2960 | ||
2961 | /* | |
2962 | * from here on down, it's all bio -- do the initial mapping, | |
2963 | * submit_bio -> generic_make_request may further map this bio around | |
2964 | */ | |
2965 | bio = bio_alloc(GFP_NOIO, 1); | |
2966 | ||
2967 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); | |
2968 | bio->bi_bdev = bh->b_bdev; | |
2969 | bio->bi_io_vec[0].bv_page = bh->b_page; | |
2970 | bio->bi_io_vec[0].bv_len = bh->b_size; | |
2971 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); | |
2972 | ||
2973 | bio->bi_vcnt = 1; | |
2974 | bio->bi_idx = 0; | |
2975 | bio->bi_size = bh->b_size; | |
2976 | ||
2977 | bio->bi_end_io = end_bio_bh_io_sync; | |
2978 | bio->bi_private = bh; | |
2979 | ||
57302e0d LT |
2980 | /* Take care of bh's that straddle the end of the device */ |
2981 | guard_bh_eod(rw, bio, bh); | |
2982 | ||
1da177e4 LT |
2983 | bio_get(bio); |
2984 | submit_bio(rw, bio); | |
2985 | ||
2986 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) | |
2987 | ret = -EOPNOTSUPP; | |
2988 | ||
2989 | bio_put(bio); | |
2990 | return ret; | |
2991 | } | |
1fe72eaa | 2992 | EXPORT_SYMBOL(submit_bh); |
1da177e4 LT |
2993 | |
2994 | /** | |
2995 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
9cb569d6 | 2996 | * @rw: whether to %READ or %WRITE or maybe %READA (readahead) |
1da177e4 LT |
2997 | * @nr: number of &struct buffer_heads in the array |
2998 | * @bhs: array of pointers to &struct buffer_head | |
2999 | * | |
a7662236 JK |
3000 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
3001 | * requests an I/O operation on them, either a %READ or a %WRITE. The third | |
9cb569d6 CH |
3002 | * %READA option is described in the documentation for generic_make_request() |
3003 | * which ll_rw_block() calls. | |
1da177e4 LT |
3004 | * |
3005 | * This function drops any buffer that it cannot get a lock on (with the | |
9cb569d6 CH |
3006 | * BH_Lock state bit), any buffer that appears to be clean when doing a write |
3007 | * request, and any buffer that appears to be up-to-date when doing read | |
3008 | * request. Further it marks as clean buffers that are processed for | |
3009 | * writing (the buffer cache won't assume that they are actually clean | |
3010 | * until the buffer gets unlocked). | |
1da177e4 LT |
3011 | * |
3012 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
3013 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes | |
3014 | * any waiters. | |
3015 | * | |
3016 | * All of the buffers must be for the same device, and must also be a | |
3017 | * multiple of the current approved size for the device. | |
3018 | */ | |
3019 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) | |
3020 | { | |
3021 | int i; | |
3022 | ||
3023 | for (i = 0; i < nr; i++) { | |
3024 | struct buffer_head *bh = bhs[i]; | |
3025 | ||
9cb569d6 | 3026 | if (!trylock_buffer(bh)) |
1da177e4 | 3027 | continue; |
9cb569d6 | 3028 | if (rw == WRITE) { |
1da177e4 | 3029 | if (test_clear_buffer_dirty(bh)) { |
76c3073a | 3030 | bh->b_end_io = end_buffer_write_sync; |
e60e5c50 | 3031 | get_bh(bh); |
9cb569d6 | 3032 | submit_bh(WRITE, bh); |
1da177e4 LT |
3033 | continue; |
3034 | } | |
3035 | } else { | |
1da177e4 | 3036 | if (!buffer_uptodate(bh)) { |
76c3073a | 3037 | bh->b_end_io = end_buffer_read_sync; |
e60e5c50 | 3038 | get_bh(bh); |
1da177e4 LT |
3039 | submit_bh(rw, bh); |
3040 | continue; | |
3041 | } | |
3042 | } | |
3043 | unlock_buffer(bh); | |
1da177e4 LT |
3044 | } |
3045 | } | |
1fe72eaa | 3046 | EXPORT_SYMBOL(ll_rw_block); |
1da177e4 | 3047 | |
9cb569d6 CH |
3048 | void write_dirty_buffer(struct buffer_head *bh, int rw) |
3049 | { | |
3050 | lock_buffer(bh); | |
3051 | if (!test_clear_buffer_dirty(bh)) { | |
3052 | unlock_buffer(bh); | |
3053 | return; | |
3054 | } | |
3055 | bh->b_end_io = end_buffer_write_sync; | |
3056 | get_bh(bh); | |
3057 | submit_bh(rw, bh); | |
3058 | } | |
3059 | EXPORT_SYMBOL(write_dirty_buffer); | |
3060 | ||
1da177e4 LT |
3061 | /* |
3062 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
3063 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
3064 | * the buffer_head. | |
3065 | */ | |
87e99511 | 3066 | int __sync_dirty_buffer(struct buffer_head *bh, int rw) |
1da177e4 LT |
3067 | { |
3068 | int ret = 0; | |
3069 | ||
3070 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
3071 | lock_buffer(bh); | |
3072 | if (test_clear_buffer_dirty(bh)) { | |
3073 | get_bh(bh); | |
3074 | bh->b_end_io = end_buffer_write_sync; | |
87e99511 | 3075 | ret = submit_bh(rw, bh); |
1da177e4 | 3076 | wait_on_buffer(bh); |
1da177e4 LT |
3077 | if (!ret && !buffer_uptodate(bh)) |
3078 | ret = -EIO; | |
3079 | } else { | |
3080 | unlock_buffer(bh); | |
3081 | } | |
3082 | return ret; | |
3083 | } | |
87e99511 CH |
3084 | EXPORT_SYMBOL(__sync_dirty_buffer); |
3085 | ||
3086 | int sync_dirty_buffer(struct buffer_head *bh) | |
3087 | { | |
3088 | return __sync_dirty_buffer(bh, WRITE_SYNC); | |
3089 | } | |
1fe72eaa | 3090 | EXPORT_SYMBOL(sync_dirty_buffer); |
1da177e4 LT |
3091 | |
3092 | /* | |
3093 | * try_to_free_buffers() checks if all the buffers on this particular page | |
3094 | * are unused, and releases them if so. | |
3095 | * | |
3096 | * Exclusion against try_to_free_buffers may be obtained by either | |
3097 | * locking the page or by holding its mapping's private_lock. | |
3098 | * | |
3099 | * If the page is dirty but all the buffers are clean then we need to | |
3100 | * be sure to mark the page clean as well. This is because the page | |
3101 | * may be against a block device, and a later reattachment of buffers | |
3102 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
3103 | * filesystem data on the same device. | |
3104 | * | |
3105 | * The same applies to regular filesystem pages: if all the buffers are | |
3106 | * clean then we set the page clean and proceed. To do that, we require | |
3107 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
3108 | * private_lock. | |
3109 | * | |
3110 | * try_to_free_buffers() is non-blocking. | |
3111 | */ | |
3112 | static inline int buffer_busy(struct buffer_head *bh) | |
3113 | { | |
3114 | return atomic_read(&bh->b_count) | | |
3115 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
3116 | } | |
3117 | ||
3118 | static int | |
3119 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
3120 | { | |
3121 | struct buffer_head *head = page_buffers(page); | |
3122 | struct buffer_head *bh; | |
3123 | ||
3124 | bh = head; | |
3125 | do { | |
de7d5a3b | 3126 | if (buffer_write_io_error(bh) && page->mapping) |
1da177e4 LT |
3127 | set_bit(AS_EIO, &page->mapping->flags); |
3128 | if (buffer_busy(bh)) | |
3129 | goto failed; | |
3130 | bh = bh->b_this_page; | |
3131 | } while (bh != head); | |
3132 | ||
3133 | do { | |
3134 | struct buffer_head *next = bh->b_this_page; | |
3135 | ||
535ee2fb | 3136 | if (bh->b_assoc_map) |
1da177e4 LT |
3137 | __remove_assoc_queue(bh); |
3138 | bh = next; | |
3139 | } while (bh != head); | |
3140 | *buffers_to_free = head; | |
3141 | __clear_page_buffers(page); | |
3142 | return 1; | |
3143 | failed: | |
3144 | return 0; | |
3145 | } | |
3146 | ||
3147 | int try_to_free_buffers(struct page *page) | |
3148 | { | |
3149 | struct address_space * const mapping = page->mapping; | |
3150 | struct buffer_head *buffers_to_free = NULL; | |
3151 | int ret = 0; | |
3152 | ||
3153 | BUG_ON(!PageLocked(page)); | |
ecdfc978 | 3154 | if (PageWriteback(page)) |
1da177e4 LT |
3155 | return 0; |
3156 | ||
3157 | if (mapping == NULL) { /* can this still happen? */ | |
3158 | ret = drop_buffers(page, &buffers_to_free); | |
3159 | goto out; | |
3160 | } | |
3161 | ||
3162 | spin_lock(&mapping->private_lock); | |
3163 | ret = drop_buffers(page, &buffers_to_free); | |
ecdfc978 LT |
3164 | |
3165 | /* | |
3166 | * If the filesystem writes its buffers by hand (eg ext3) | |
3167 | * then we can have clean buffers against a dirty page. We | |
3168 | * clean the page here; otherwise the VM will never notice | |
3169 | * that the filesystem did any IO at all. | |
3170 | * | |
3171 | * Also, during truncate, discard_buffer will have marked all | |
3172 | * the page's buffers clean. We discover that here and clean | |
3173 | * the page also. | |
87df7241 NP |
3174 | * |
3175 | * private_lock must be held over this entire operation in order | |
3176 | * to synchronise against __set_page_dirty_buffers and prevent the | |
3177 | * dirty bit from being lost. | |
ecdfc978 LT |
3178 | */ |
3179 | if (ret) | |
3180 | cancel_dirty_page(page, PAGE_CACHE_SIZE); | |
87df7241 | 3181 | spin_unlock(&mapping->private_lock); |
1da177e4 LT |
3182 | out: |
3183 | if (buffers_to_free) { | |
3184 | struct buffer_head *bh = buffers_to_free; | |
3185 | ||
3186 | do { | |
3187 | struct buffer_head *next = bh->b_this_page; | |
3188 | free_buffer_head(bh); | |
3189 | bh = next; | |
3190 | } while (bh != buffers_to_free); | |
3191 | } | |
3192 | return ret; | |
3193 | } | |
3194 | EXPORT_SYMBOL(try_to_free_buffers); | |
3195 | ||
1da177e4 LT |
3196 | /* |
3197 | * There are no bdflush tunables left. But distributions are | |
3198 | * still running obsolete flush daemons, so we terminate them here. | |
3199 | * | |
3200 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
5b0830cb | 3201 | * The `flush-X' kernel threads fully replace bdflush daemons and this call. |
1da177e4 | 3202 | */ |
bdc480e3 | 3203 | SYSCALL_DEFINE2(bdflush, int, func, long, data) |
1da177e4 LT |
3204 | { |
3205 | static int msg_count; | |
3206 | ||
3207 | if (!capable(CAP_SYS_ADMIN)) | |
3208 | return -EPERM; | |
3209 | ||
3210 | if (msg_count < 5) { | |
3211 | msg_count++; | |
3212 | printk(KERN_INFO | |
3213 | "warning: process `%s' used the obsolete bdflush" | |
3214 | " system call\n", current->comm); | |
3215 | printk(KERN_INFO "Fix your initscripts?\n"); | |
3216 | } | |
3217 | ||
3218 | if (func == 1) | |
3219 | do_exit(0); | |
3220 | return 0; | |
3221 | } | |
3222 | ||
3223 | /* | |
3224 | * Buffer-head allocation | |
3225 | */ | |
a0a9b043 | 3226 | static struct kmem_cache *bh_cachep __read_mostly; |
1da177e4 LT |
3227 | |
3228 | /* | |
3229 | * Once the number of bh's in the machine exceeds this level, we start | |
3230 | * stripping them in writeback. | |
3231 | */ | |
3232 | static int max_buffer_heads; | |
3233 | ||
3234 | int buffer_heads_over_limit; | |
3235 | ||
3236 | struct bh_accounting { | |
3237 | int nr; /* Number of live bh's */ | |
3238 | int ratelimit; /* Limit cacheline bouncing */ | |
3239 | }; | |
3240 | ||
3241 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
3242 | ||
3243 | static void recalc_bh_state(void) | |
3244 | { | |
3245 | int i; | |
3246 | int tot = 0; | |
3247 | ||
ee1be862 | 3248 | if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) |
1da177e4 | 3249 | return; |
c7b92516 | 3250 | __this_cpu_write(bh_accounting.ratelimit, 0); |
8a143426 | 3251 | for_each_online_cpu(i) |
1da177e4 LT |
3252 | tot += per_cpu(bh_accounting, i).nr; |
3253 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
3254 | } | |
c7b92516 | 3255 | |
dd0fc66f | 3256 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
1da177e4 | 3257 | { |
019b4d12 | 3258 | struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); |
1da177e4 | 3259 | if (ret) { |
a35afb83 | 3260 | INIT_LIST_HEAD(&ret->b_assoc_buffers); |
c7b92516 CL |
3261 | preempt_disable(); |
3262 | __this_cpu_inc(bh_accounting.nr); | |
1da177e4 | 3263 | recalc_bh_state(); |
c7b92516 | 3264 | preempt_enable(); |
1da177e4 LT |
3265 | } |
3266 | return ret; | |
3267 | } | |
3268 | EXPORT_SYMBOL(alloc_buffer_head); | |
3269 | ||
3270 | void free_buffer_head(struct buffer_head *bh) | |
3271 | { | |
3272 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
3273 | kmem_cache_free(bh_cachep, bh); | |
c7b92516 CL |
3274 | preempt_disable(); |
3275 | __this_cpu_dec(bh_accounting.nr); | |
1da177e4 | 3276 | recalc_bh_state(); |
c7b92516 | 3277 | preempt_enable(); |
1da177e4 LT |
3278 | } |
3279 | EXPORT_SYMBOL(free_buffer_head); | |
3280 | ||
1da177e4 LT |
3281 | static void buffer_exit_cpu(int cpu) |
3282 | { | |
3283 | int i; | |
3284 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
3285 | ||
3286 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
3287 | brelse(b->bhs[i]); | |
3288 | b->bhs[i] = NULL; | |
3289 | } | |
c7b92516 | 3290 | this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); |
8a143426 | 3291 | per_cpu(bh_accounting, cpu).nr = 0; |
1da177e4 LT |
3292 | } |
3293 | ||
3294 | static int buffer_cpu_notify(struct notifier_block *self, | |
3295 | unsigned long action, void *hcpu) | |
3296 | { | |
8bb78442 | 3297 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) |
1da177e4 LT |
3298 | buffer_exit_cpu((unsigned long)hcpu); |
3299 | return NOTIFY_OK; | |
3300 | } | |
1da177e4 | 3301 | |
389d1b08 | 3302 | /** |
a6b91919 | 3303 | * bh_uptodate_or_lock - Test whether the buffer is uptodate |
389d1b08 AK |
3304 | * @bh: struct buffer_head |
3305 | * | |
3306 | * Return true if the buffer is up-to-date and false, | |
3307 | * with the buffer locked, if not. | |
3308 | */ | |
3309 | int bh_uptodate_or_lock(struct buffer_head *bh) | |
3310 | { | |
3311 | if (!buffer_uptodate(bh)) { | |
3312 | lock_buffer(bh); | |
3313 | if (!buffer_uptodate(bh)) | |
3314 | return 0; | |
3315 | unlock_buffer(bh); | |
3316 | } | |
3317 | return 1; | |
3318 | } | |
3319 | EXPORT_SYMBOL(bh_uptodate_or_lock); | |
3320 | ||
3321 | /** | |
a6b91919 | 3322 | * bh_submit_read - Submit a locked buffer for reading |
389d1b08 AK |
3323 | * @bh: struct buffer_head |
3324 | * | |
3325 | * Returns zero on success and -EIO on error. | |
3326 | */ | |
3327 | int bh_submit_read(struct buffer_head *bh) | |
3328 | { | |
3329 | BUG_ON(!buffer_locked(bh)); | |
3330 | ||
3331 | if (buffer_uptodate(bh)) { | |
3332 | unlock_buffer(bh); | |
3333 | return 0; | |
3334 | } | |
3335 | ||
3336 | get_bh(bh); | |
3337 | bh->b_end_io = end_buffer_read_sync; | |
3338 | submit_bh(READ, bh); | |
3339 | wait_on_buffer(bh); | |
3340 | if (buffer_uptodate(bh)) | |
3341 | return 0; | |
3342 | return -EIO; | |
3343 | } | |
3344 | EXPORT_SYMBOL(bh_submit_read); | |
3345 | ||
1da177e4 LT |
3346 | void __init buffer_init(void) |
3347 | { | |
3348 | int nrpages; | |
3349 | ||
b98938c3 CL |
3350 | bh_cachep = kmem_cache_create("buffer_head", |
3351 | sizeof(struct buffer_head), 0, | |
3352 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| | |
3353 | SLAB_MEM_SPREAD), | |
019b4d12 | 3354 | NULL); |
1da177e4 LT |
3355 | |
3356 | /* | |
3357 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3358 | */ | |
3359 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3360 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
3361 | hotcpu_notifier(buffer_cpu_notify, 0); | |
3362 | } |