Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/fs/buffer.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 2002 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95 | |
9 | * | |
10 | * Removed a lot of unnecessary code and simplified things now that | |
11 | * the buffer cache isn't our primary cache - Andrew Tridgell 12/96 | |
12 | * | |
13 | * Speed up hash, lru, and free list operations. Use gfp() for allocating | |
14 | * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM | |
15 | * | |
16 | * Added 32k buffer block sizes - these are required older ARM systems. - RMK | |
17 | * | |
18 | * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de> | |
19 | */ | |
20 | ||
1da177e4 LT |
21 | #include <linux/kernel.h> |
22 | #include <linux/syscalls.h> | |
23 | #include <linux/fs.h> | |
24 | #include <linux/mm.h> | |
25 | #include <linux/percpu.h> | |
26 | #include <linux/slab.h> | |
16f7e0fe | 27 | #include <linux/capability.h> |
1da177e4 LT |
28 | #include <linux/blkdev.h> |
29 | #include <linux/file.h> | |
30 | #include <linux/quotaops.h> | |
31 | #include <linux/highmem.h> | |
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> |
5305cb83 | 44 | #include <trace/events/block.h> |
1da177e4 LT |
45 | |
46 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); | |
1da177e4 LT |
47 | |
48 | #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) | |
49 | ||
a3f3c29c | 50 | void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) |
1da177e4 LT |
51 | { |
52 | bh->b_end_io = handler; | |
53 | bh->b_private = private; | |
54 | } | |
1fe72eaa | 55 | EXPORT_SYMBOL(init_buffer); |
1da177e4 | 56 | |
f0059afd TH |
57 | inline void touch_buffer(struct buffer_head *bh) |
58 | { | |
5305cb83 | 59 | trace_block_touch_buffer(bh); |
f0059afd TH |
60 | mark_page_accessed(bh->b_page); |
61 | } | |
62 | EXPORT_SYMBOL(touch_buffer); | |
63 | ||
7eaceacc | 64 | static int sleep_on_buffer(void *word) |
1da177e4 | 65 | { |
1da177e4 LT |
66 | io_schedule(); |
67 | return 0; | |
68 | } | |
69 | ||
fc9b52cd | 70 | void __lock_buffer(struct buffer_head *bh) |
1da177e4 | 71 | { |
7eaceacc | 72 | wait_on_bit_lock(&bh->b_state, BH_Lock, sleep_on_buffer, |
1da177e4 LT |
73 | TASK_UNINTERRUPTIBLE); |
74 | } | |
75 | EXPORT_SYMBOL(__lock_buffer); | |
76 | ||
fc9b52cd | 77 | void unlock_buffer(struct buffer_head *bh) |
1da177e4 | 78 | { |
51b07fc3 | 79 | clear_bit_unlock(BH_Lock, &bh->b_state); |
1da177e4 LT |
80 | smp_mb__after_clear_bit(); |
81 | wake_up_bit(&bh->b_state, BH_Lock); | |
82 | } | |
1fe72eaa | 83 | EXPORT_SYMBOL(unlock_buffer); |
1da177e4 | 84 | |
b4597226 MG |
85 | /* |
86 | * Returns if the page has dirty or writeback buffers. If all the buffers | |
87 | * are unlocked and clean then the PageDirty information is stale. If | |
88 | * any of the pages are locked, it is assumed they are locked for IO. | |
89 | */ | |
90 | void buffer_check_dirty_writeback(struct page *page, | |
91 | bool *dirty, bool *writeback) | |
92 | { | |
93 | struct buffer_head *head, *bh; | |
94 | *dirty = false; | |
95 | *writeback = false; | |
96 | ||
97 | BUG_ON(!PageLocked(page)); | |
98 | ||
99 | if (!page_has_buffers(page)) | |
100 | return; | |
101 | ||
102 | if (PageWriteback(page)) | |
103 | *writeback = true; | |
104 | ||
105 | head = page_buffers(page); | |
106 | bh = head; | |
107 | do { | |
108 | if (buffer_locked(bh)) | |
109 | *writeback = true; | |
110 | ||
111 | if (buffer_dirty(bh)) | |
112 | *dirty = true; | |
113 | ||
114 | bh = bh->b_this_page; | |
115 | } while (bh != head); | |
116 | } | |
117 | EXPORT_SYMBOL(buffer_check_dirty_writeback); | |
118 | ||
1da177e4 LT |
119 | /* |
120 | * Block until a buffer comes unlocked. This doesn't stop it | |
121 | * from becoming locked again - you have to lock it yourself | |
122 | * if you want to preserve its state. | |
123 | */ | |
124 | void __wait_on_buffer(struct buffer_head * bh) | |
125 | { | |
7eaceacc | 126 | wait_on_bit(&bh->b_state, BH_Lock, sleep_on_buffer, TASK_UNINTERRUPTIBLE); |
1da177e4 | 127 | } |
1fe72eaa | 128 | EXPORT_SYMBOL(__wait_on_buffer); |
1da177e4 LT |
129 | |
130 | static void | |
131 | __clear_page_buffers(struct page *page) | |
132 | { | |
133 | ClearPagePrivate(page); | |
4c21e2f2 | 134 | set_page_private(page, 0); |
1da177e4 LT |
135 | page_cache_release(page); |
136 | } | |
137 | ||
08bafc03 KM |
138 | |
139 | static int quiet_error(struct buffer_head *bh) | |
140 | { | |
141 | if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit()) | |
142 | return 0; | |
143 | return 1; | |
144 | } | |
145 | ||
146 | ||
1da177e4 LT |
147 | static void buffer_io_error(struct buffer_head *bh) |
148 | { | |
149 | char b[BDEVNAME_SIZE]; | |
1da177e4 LT |
150 | printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", |
151 | bdevname(bh->b_bdev, b), | |
152 | (unsigned long long)bh->b_blocknr); | |
153 | } | |
154 | ||
155 | /* | |
68671f35 DM |
156 | * End-of-IO handler helper function which does not touch the bh after |
157 | * unlocking it. | |
158 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but | |
159 | * a race there is benign: unlock_buffer() only use the bh's address for | |
160 | * hashing after unlocking the buffer, so it doesn't actually touch the bh | |
161 | * itself. | |
1da177e4 | 162 | */ |
68671f35 | 163 | static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
164 | { |
165 | if (uptodate) { | |
166 | set_buffer_uptodate(bh); | |
167 | } else { | |
168 | /* This happens, due to failed READA attempts. */ | |
169 | clear_buffer_uptodate(bh); | |
170 | } | |
171 | unlock_buffer(bh); | |
68671f35 DM |
172 | } |
173 | ||
174 | /* | |
175 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and | |
176 | * unlock the buffer. This is what ll_rw_block uses too. | |
177 | */ | |
178 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) | |
179 | { | |
180 | __end_buffer_read_notouch(bh, uptodate); | |
1da177e4 LT |
181 | put_bh(bh); |
182 | } | |
1fe72eaa | 183 | EXPORT_SYMBOL(end_buffer_read_sync); |
1da177e4 LT |
184 | |
185 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) | |
186 | { | |
187 | char b[BDEVNAME_SIZE]; | |
188 | ||
189 | if (uptodate) { | |
190 | set_buffer_uptodate(bh); | |
191 | } else { | |
0edd55fa | 192 | if (!quiet_error(bh)) { |
1da177e4 LT |
193 | buffer_io_error(bh); |
194 | printk(KERN_WARNING "lost page write due to " | |
195 | "I/O error on %s\n", | |
196 | bdevname(bh->b_bdev, b)); | |
197 | } | |
198 | set_buffer_write_io_error(bh); | |
199 | clear_buffer_uptodate(bh); | |
200 | } | |
201 | unlock_buffer(bh); | |
202 | put_bh(bh); | |
203 | } | |
1fe72eaa | 204 | EXPORT_SYMBOL(end_buffer_write_sync); |
1da177e4 | 205 | |
1da177e4 LT |
206 | /* |
207 | * Various filesystems appear to want __find_get_block to be non-blocking. | |
208 | * But it's the page lock which protects the buffers. To get around this, | |
209 | * we get exclusion from try_to_free_buffers with the blockdev mapping's | |
210 | * private_lock. | |
211 | * | |
212 | * Hack idea: for the blockdev mapping, i_bufferlist_lock contention | |
213 | * may be quite high. This code could TryLock the page, and if that | |
214 | * succeeds, there is no need to take private_lock. (But if | |
215 | * private_lock is contended then so is mapping->tree_lock). | |
216 | */ | |
217 | static struct buffer_head * | |
385fd4c5 | 218 | __find_get_block_slow(struct block_device *bdev, sector_t block) |
1da177e4 LT |
219 | { |
220 | struct inode *bd_inode = bdev->bd_inode; | |
221 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
222 | struct buffer_head *ret = NULL; | |
223 | pgoff_t index; | |
224 | struct buffer_head *bh; | |
225 | struct buffer_head *head; | |
226 | struct page *page; | |
227 | int all_mapped = 1; | |
228 | ||
229 | index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); | |
230 | page = find_get_page(bd_mapping, index); | |
231 | if (!page) | |
232 | goto out; | |
233 | ||
234 | spin_lock(&bd_mapping->private_lock); | |
235 | if (!page_has_buffers(page)) | |
236 | goto out_unlock; | |
237 | head = page_buffers(page); | |
238 | bh = head; | |
239 | do { | |
97f76d3d NK |
240 | if (!buffer_mapped(bh)) |
241 | all_mapped = 0; | |
242 | else if (bh->b_blocknr == block) { | |
1da177e4 LT |
243 | ret = bh; |
244 | get_bh(bh); | |
245 | goto out_unlock; | |
246 | } | |
1da177e4 LT |
247 | bh = bh->b_this_page; |
248 | } while (bh != head); | |
249 | ||
250 | /* we might be here because some of the buffers on this page are | |
251 | * not mapped. This is due to various races between | |
252 | * file io on the block device and getblk. It gets dealt with | |
253 | * elsewhere, don't buffer_error if we had some unmapped buffers | |
254 | */ | |
255 | if (all_mapped) { | |
72a2ebd8 TM |
256 | char b[BDEVNAME_SIZE]; |
257 | ||
1da177e4 LT |
258 | printk("__find_get_block_slow() failed. " |
259 | "block=%llu, b_blocknr=%llu\n", | |
205f87f6 BP |
260 | (unsigned long long)block, |
261 | (unsigned long long)bh->b_blocknr); | |
262 | printk("b_state=0x%08lx, b_size=%zu\n", | |
263 | bh->b_state, bh->b_size); | |
72a2ebd8 TM |
264 | printk("device %s blocksize: %d\n", bdevname(bdev, b), |
265 | 1 << bd_inode->i_blkbits); | |
1da177e4 LT |
266 | } |
267 | out_unlock: | |
268 | spin_unlock(&bd_mapping->private_lock); | |
269 | page_cache_release(page); | |
270 | out: | |
271 | return ret; | |
272 | } | |
273 | ||
1da177e4 | 274 | /* |
5b0830cb | 275 | * Kick the writeback threads then try to free up some ZONE_NORMAL memory. |
1da177e4 LT |
276 | */ |
277 | static void free_more_memory(void) | |
278 | { | |
19770b32 | 279 | struct zone *zone; |
0e88460d | 280 | int nid; |
1da177e4 | 281 | |
0e175a18 | 282 | wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM); |
1da177e4 LT |
283 | yield(); |
284 | ||
0e88460d | 285 | for_each_online_node(nid) { |
19770b32 MG |
286 | (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS), |
287 | gfp_zone(GFP_NOFS), NULL, | |
288 | &zone); | |
289 | if (zone) | |
54a6eb5c | 290 | try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, |
327c0e96 | 291 | GFP_NOFS, NULL); |
1da177e4 LT |
292 | } |
293 | } | |
294 | ||
295 | /* | |
296 | * I/O completion handler for block_read_full_page() - pages | |
297 | * which come unlocked at the end of I/O. | |
298 | */ | |
299 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) | |
300 | { | |
1da177e4 | 301 | unsigned long flags; |
a3972203 | 302 | struct buffer_head *first; |
1da177e4 LT |
303 | struct buffer_head *tmp; |
304 | struct page *page; | |
305 | int page_uptodate = 1; | |
306 | ||
307 | BUG_ON(!buffer_async_read(bh)); | |
308 | ||
309 | page = bh->b_page; | |
310 | if (uptodate) { | |
311 | set_buffer_uptodate(bh); | |
312 | } else { | |
313 | clear_buffer_uptodate(bh); | |
08bafc03 | 314 | if (!quiet_error(bh)) |
1da177e4 LT |
315 | buffer_io_error(bh); |
316 | SetPageError(page); | |
317 | } | |
318 | ||
319 | /* | |
320 | * Be _very_ careful from here on. Bad things can happen if | |
321 | * two buffer heads end IO at almost the same time and both | |
322 | * decide that the page is now completely done. | |
323 | */ | |
a3972203 NP |
324 | first = page_buffers(page); |
325 | local_irq_save(flags); | |
326 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
1da177e4 LT |
327 | clear_buffer_async_read(bh); |
328 | unlock_buffer(bh); | |
329 | tmp = bh; | |
330 | do { | |
331 | if (!buffer_uptodate(tmp)) | |
332 | page_uptodate = 0; | |
333 | if (buffer_async_read(tmp)) { | |
334 | BUG_ON(!buffer_locked(tmp)); | |
335 | goto still_busy; | |
336 | } | |
337 | tmp = tmp->b_this_page; | |
338 | } while (tmp != bh); | |
a3972203 NP |
339 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
340 | local_irq_restore(flags); | |
1da177e4 LT |
341 | |
342 | /* | |
343 | * If none of the buffers had errors and they are all | |
344 | * uptodate then we can set the page uptodate. | |
345 | */ | |
346 | if (page_uptodate && !PageError(page)) | |
347 | SetPageUptodate(page); | |
348 | unlock_page(page); | |
349 | return; | |
350 | ||
351 | still_busy: | |
a3972203 NP |
352 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
353 | local_irq_restore(flags); | |
1da177e4 LT |
354 | return; |
355 | } | |
356 | ||
357 | /* | |
358 | * Completion handler for block_write_full_page() - pages which are unlocked | |
359 | * during I/O, and which have PageWriteback cleared upon I/O completion. | |
360 | */ | |
35c80d5f | 361 | void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
362 | { |
363 | char b[BDEVNAME_SIZE]; | |
1da177e4 | 364 | unsigned long flags; |
a3972203 | 365 | struct buffer_head *first; |
1da177e4 LT |
366 | struct buffer_head *tmp; |
367 | struct page *page; | |
368 | ||
369 | BUG_ON(!buffer_async_write(bh)); | |
370 | ||
371 | page = bh->b_page; | |
372 | if (uptodate) { | |
373 | set_buffer_uptodate(bh); | |
374 | } else { | |
08bafc03 | 375 | if (!quiet_error(bh)) { |
1da177e4 LT |
376 | buffer_io_error(bh); |
377 | printk(KERN_WARNING "lost page write due to " | |
378 | "I/O error on %s\n", | |
379 | bdevname(bh->b_bdev, b)); | |
380 | } | |
381 | set_bit(AS_EIO, &page->mapping->flags); | |
58ff407b | 382 | set_buffer_write_io_error(bh); |
1da177e4 LT |
383 | clear_buffer_uptodate(bh); |
384 | SetPageError(page); | |
385 | } | |
386 | ||
a3972203 NP |
387 | first = page_buffers(page); |
388 | local_irq_save(flags); | |
389 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
390 | ||
1da177e4 LT |
391 | clear_buffer_async_write(bh); |
392 | unlock_buffer(bh); | |
393 | tmp = bh->b_this_page; | |
394 | while (tmp != bh) { | |
395 | if (buffer_async_write(tmp)) { | |
396 | BUG_ON(!buffer_locked(tmp)); | |
397 | goto still_busy; | |
398 | } | |
399 | tmp = tmp->b_this_page; | |
400 | } | |
a3972203 NP |
401 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
402 | local_irq_restore(flags); | |
1da177e4 LT |
403 | end_page_writeback(page); |
404 | return; | |
405 | ||
406 | still_busy: | |
a3972203 NP |
407 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
408 | local_irq_restore(flags); | |
1da177e4 LT |
409 | return; |
410 | } | |
1fe72eaa | 411 | EXPORT_SYMBOL(end_buffer_async_write); |
1da177e4 LT |
412 | |
413 | /* | |
414 | * If a page's buffers are under async readin (end_buffer_async_read | |
415 | * completion) then there is a possibility that another thread of | |
416 | * control could lock one of the buffers after it has completed | |
417 | * but while some of the other buffers have not completed. This | |
418 | * locked buffer would confuse end_buffer_async_read() into not unlocking | |
419 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() | |
420 | * that this buffer is not under async I/O. | |
421 | * | |
422 | * The page comes unlocked when it has no locked buffer_async buffers | |
423 | * left. | |
424 | * | |
425 | * PageLocked prevents anyone starting new async I/O reads any of | |
426 | * the buffers. | |
427 | * | |
428 | * PageWriteback is used to prevent simultaneous writeout of the same | |
429 | * page. | |
430 | * | |
431 | * PageLocked prevents anyone from starting writeback of a page which is | |
432 | * under read I/O (PageWriteback is only ever set against a locked page). | |
433 | */ | |
434 | static void mark_buffer_async_read(struct buffer_head *bh) | |
435 | { | |
436 | bh->b_end_io = end_buffer_async_read; | |
437 | set_buffer_async_read(bh); | |
438 | } | |
439 | ||
1fe72eaa HS |
440 | static void mark_buffer_async_write_endio(struct buffer_head *bh, |
441 | bh_end_io_t *handler) | |
1da177e4 | 442 | { |
35c80d5f | 443 | bh->b_end_io = handler; |
1da177e4 LT |
444 | set_buffer_async_write(bh); |
445 | } | |
35c80d5f CM |
446 | |
447 | void mark_buffer_async_write(struct buffer_head *bh) | |
448 | { | |
449 | mark_buffer_async_write_endio(bh, end_buffer_async_write); | |
450 | } | |
1da177e4 LT |
451 | EXPORT_SYMBOL(mark_buffer_async_write); |
452 | ||
453 | ||
454 | /* | |
455 | * fs/buffer.c contains helper functions for buffer-backed address space's | |
456 | * fsync functions. A common requirement for buffer-based filesystems is | |
457 | * that certain data from the backing blockdev needs to be written out for | |
458 | * a successful fsync(). For example, ext2 indirect blocks need to be | |
459 | * written back and waited upon before fsync() returns. | |
460 | * | |
461 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), | |
462 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the | |
463 | * management of a list of dependent buffers at ->i_mapping->private_list. | |
464 | * | |
465 | * Locking is a little subtle: try_to_free_buffers() will remove buffers | |
466 | * from their controlling inode's queue when they are being freed. But | |
467 | * try_to_free_buffers() will be operating against the *blockdev* mapping | |
468 | * at the time, not against the S_ISREG file which depends on those buffers. | |
469 | * So the locking for private_list is via the private_lock in the address_space | |
470 | * which backs the buffers. Which is different from the address_space | |
471 | * against which the buffers are listed. So for a particular address_space, | |
472 | * mapping->private_lock does *not* protect mapping->private_list! In fact, | |
473 | * mapping->private_list will always be protected by the backing blockdev's | |
474 | * ->private_lock. | |
475 | * | |
476 | * Which introduces a requirement: all buffers on an address_space's | |
477 | * ->private_list must be from the same address_space: the blockdev's. | |
478 | * | |
479 | * address_spaces which do not place buffers at ->private_list via these | |
480 | * utility functions are free to use private_lock and private_list for | |
481 | * whatever they want. The only requirement is that list_empty(private_list) | |
482 | * be true at clear_inode() time. | |
483 | * | |
484 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The | |
485 | * filesystems should do that. invalidate_inode_buffers() should just go | |
486 | * BUG_ON(!list_empty). | |
487 | * | |
488 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should | |
489 | * take an address_space, not an inode. And it should be called | |
490 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being | |
491 | * queued up. | |
492 | * | |
493 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the | |
494 | * list if it is already on a list. Because if the buffer is on a list, | |
495 | * it *must* already be on the right one. If not, the filesystem is being | |
496 | * silly. This will save a ton of locking. But first we have to ensure | |
497 | * that buffers are taken *off* the old inode's list when they are freed | |
498 | * (presumably in truncate). That requires careful auditing of all | |
499 | * filesystems (do it inside bforget()). It could also be done by bringing | |
500 | * b_inode back. | |
501 | */ | |
502 | ||
503 | /* | |
504 | * The buffer's backing address_space's private_lock must be held | |
505 | */ | |
dbacefc9 | 506 | static void __remove_assoc_queue(struct buffer_head *bh) |
1da177e4 LT |
507 | { |
508 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b JK |
509 | WARN_ON(!bh->b_assoc_map); |
510 | if (buffer_write_io_error(bh)) | |
511 | set_bit(AS_EIO, &bh->b_assoc_map->flags); | |
512 | bh->b_assoc_map = NULL; | |
1da177e4 LT |
513 | } |
514 | ||
515 | int inode_has_buffers(struct inode *inode) | |
516 | { | |
517 | return !list_empty(&inode->i_data.private_list); | |
518 | } | |
519 | ||
520 | /* | |
521 | * osync is designed to support O_SYNC io. It waits synchronously for | |
522 | * all already-submitted IO to complete, but does not queue any new | |
523 | * writes to the disk. | |
524 | * | |
525 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as | |
526 | * you dirty the buffers, and then use osync_inode_buffers to wait for | |
527 | * completion. Any other dirty buffers which are not yet queued for | |
528 | * write will not be flushed to disk by the osync. | |
529 | */ | |
530 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) | |
531 | { | |
532 | struct buffer_head *bh; | |
533 | struct list_head *p; | |
534 | int err = 0; | |
535 | ||
536 | spin_lock(lock); | |
537 | repeat: | |
538 | list_for_each_prev(p, list) { | |
539 | bh = BH_ENTRY(p); | |
540 | if (buffer_locked(bh)) { | |
541 | get_bh(bh); | |
542 | spin_unlock(lock); | |
543 | wait_on_buffer(bh); | |
544 | if (!buffer_uptodate(bh)) | |
545 | err = -EIO; | |
546 | brelse(bh); | |
547 | spin_lock(lock); | |
548 | goto repeat; | |
549 | } | |
550 | } | |
551 | spin_unlock(lock); | |
552 | return err; | |
553 | } | |
554 | ||
01a05b33 | 555 | static void do_thaw_one(struct super_block *sb, void *unused) |
c2d75438 | 556 | { |
c2d75438 | 557 | char b[BDEVNAME_SIZE]; |
01a05b33 AV |
558 | while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) |
559 | printk(KERN_WARNING "Emergency Thaw on %s\n", | |
560 | bdevname(sb->s_bdev, b)); | |
561 | } | |
c2d75438 | 562 | |
01a05b33 AV |
563 | static void do_thaw_all(struct work_struct *work) |
564 | { | |
565 | iterate_supers(do_thaw_one, NULL); | |
053c525f | 566 | kfree(work); |
c2d75438 ES |
567 | printk(KERN_WARNING "Emergency Thaw complete\n"); |
568 | } | |
569 | ||
570 | /** | |
571 | * emergency_thaw_all -- forcibly thaw every frozen filesystem | |
572 | * | |
573 | * Used for emergency unfreeze of all filesystems via SysRq | |
574 | */ | |
575 | void emergency_thaw_all(void) | |
576 | { | |
053c525f JA |
577 | struct work_struct *work; |
578 | ||
579 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
580 | if (work) { | |
581 | INIT_WORK(work, do_thaw_all); | |
582 | schedule_work(work); | |
583 | } | |
c2d75438 ES |
584 | } |
585 | ||
1da177e4 | 586 | /** |
78a4a50a | 587 | * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers |
67be2dd1 | 588 | * @mapping: the mapping which wants those buffers written |
1da177e4 LT |
589 | * |
590 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
591 | * that I/O. | |
592 | * | |
67be2dd1 MW |
593 | * Basically, this is a convenience function for fsync(). |
594 | * @mapping is a file or directory which needs those buffers to be written for | |
595 | * a successful fsync(). | |
1da177e4 LT |
596 | */ |
597 | int sync_mapping_buffers(struct address_space *mapping) | |
598 | { | |
252aa6f5 | 599 | struct address_space *buffer_mapping = mapping->private_data; |
1da177e4 LT |
600 | |
601 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) | |
602 | return 0; | |
603 | ||
604 | return fsync_buffers_list(&buffer_mapping->private_lock, | |
605 | &mapping->private_list); | |
606 | } | |
607 | EXPORT_SYMBOL(sync_mapping_buffers); | |
608 | ||
609 | /* | |
610 | * Called when we've recently written block `bblock', and it is known that | |
611 | * `bblock' was for a buffer_boundary() buffer. This means that the block at | |
612 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's | |
613 | * dirty, schedule it for IO. So that indirects merge nicely with their data. | |
614 | */ | |
615 | void write_boundary_block(struct block_device *bdev, | |
616 | sector_t bblock, unsigned blocksize) | |
617 | { | |
618 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); | |
619 | if (bh) { | |
620 | if (buffer_dirty(bh)) | |
621 | ll_rw_block(WRITE, 1, &bh); | |
622 | put_bh(bh); | |
623 | } | |
624 | } | |
625 | ||
626 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) | |
627 | { | |
628 | struct address_space *mapping = inode->i_mapping; | |
629 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
630 | ||
631 | mark_buffer_dirty(bh); | |
252aa6f5 RA |
632 | if (!mapping->private_data) { |
633 | mapping->private_data = buffer_mapping; | |
1da177e4 | 634 | } else { |
252aa6f5 | 635 | BUG_ON(mapping->private_data != buffer_mapping); |
1da177e4 | 636 | } |
535ee2fb | 637 | if (!bh->b_assoc_map) { |
1da177e4 LT |
638 | spin_lock(&buffer_mapping->private_lock); |
639 | list_move_tail(&bh->b_assoc_buffers, | |
640 | &mapping->private_list); | |
58ff407b | 641 | bh->b_assoc_map = mapping; |
1da177e4 LT |
642 | spin_unlock(&buffer_mapping->private_lock); |
643 | } | |
644 | } | |
645 | EXPORT_SYMBOL(mark_buffer_dirty_inode); | |
646 | ||
787d2214 NP |
647 | /* |
648 | * Mark the page dirty, and set it dirty in the radix tree, and mark the inode | |
649 | * dirty. | |
650 | * | |
651 | * If warn is true, then emit a warning if the page is not uptodate and has | |
652 | * not been truncated. | |
653 | */ | |
a8e7d49a | 654 | static void __set_page_dirty(struct page *page, |
787d2214 NP |
655 | struct address_space *mapping, int warn) |
656 | { | |
19fd6231 | 657 | spin_lock_irq(&mapping->tree_lock); |
787d2214 NP |
658 | if (page->mapping) { /* Race with truncate? */ |
659 | WARN_ON_ONCE(warn && !PageUptodate(page)); | |
e3a7cca1 | 660 | account_page_dirtied(page, mapping); |
787d2214 NP |
661 | radix_tree_tag_set(&mapping->page_tree, |
662 | page_index(page), PAGECACHE_TAG_DIRTY); | |
663 | } | |
19fd6231 | 664 | spin_unlock_irq(&mapping->tree_lock); |
787d2214 | 665 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
787d2214 NP |
666 | } |
667 | ||
1da177e4 LT |
668 | /* |
669 | * Add a page to the dirty page list. | |
670 | * | |
671 | * It is a sad fact of life that this function is called from several places | |
672 | * deeply under spinlocking. It may not sleep. | |
673 | * | |
674 | * If the page has buffers, the uptodate buffers are set dirty, to preserve | |
675 | * dirty-state coherency between the page and the buffers. It the page does | |
676 | * not have buffers then when they are later attached they will all be set | |
677 | * dirty. | |
678 | * | |
679 | * The buffers are dirtied before the page is dirtied. There's a small race | |
680 | * window in which a writepage caller may see the page cleanness but not the | |
681 | * buffer dirtiness. That's fine. If this code were to set the page dirty | |
682 | * before the buffers, a concurrent writepage caller could clear the page dirty | |
683 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean | |
684 | * page on the dirty page list. | |
685 | * | |
686 | * We use private_lock to lock against try_to_free_buffers while using the | |
687 | * page's buffer list. Also use this to protect against clean buffers being | |
688 | * added to the page after it was set dirty. | |
689 | * | |
690 | * FIXME: may need to call ->reservepage here as well. That's rather up to the | |
691 | * address_space though. | |
692 | */ | |
693 | int __set_page_dirty_buffers(struct page *page) | |
694 | { | |
a8e7d49a | 695 | int newly_dirty; |
787d2214 | 696 | struct address_space *mapping = page_mapping(page); |
ebf7a227 NP |
697 | |
698 | if (unlikely(!mapping)) | |
699 | return !TestSetPageDirty(page); | |
1da177e4 LT |
700 | |
701 | spin_lock(&mapping->private_lock); | |
702 | if (page_has_buffers(page)) { | |
703 | struct buffer_head *head = page_buffers(page); | |
704 | struct buffer_head *bh = head; | |
705 | ||
706 | do { | |
707 | set_buffer_dirty(bh); | |
708 | bh = bh->b_this_page; | |
709 | } while (bh != head); | |
710 | } | |
a8e7d49a | 711 | newly_dirty = !TestSetPageDirty(page); |
1da177e4 LT |
712 | spin_unlock(&mapping->private_lock); |
713 | ||
a8e7d49a LT |
714 | if (newly_dirty) |
715 | __set_page_dirty(page, mapping, 1); | |
716 | return newly_dirty; | |
1da177e4 LT |
717 | } |
718 | EXPORT_SYMBOL(__set_page_dirty_buffers); | |
719 | ||
720 | /* | |
721 | * Write out and wait upon a list of buffers. | |
722 | * | |
723 | * We have conflicting pressures: we want to make sure that all | |
724 | * initially dirty buffers get waited on, but that any subsequently | |
725 | * dirtied buffers don't. After all, we don't want fsync to last | |
726 | * forever if somebody is actively writing to the file. | |
727 | * | |
728 | * Do this in two main stages: first we copy dirty buffers to a | |
729 | * temporary inode list, queueing the writes as we go. Then we clean | |
730 | * up, waiting for those writes to complete. | |
731 | * | |
732 | * During this second stage, any subsequent updates to the file may end | |
733 | * up refiling the buffer on the original inode's dirty list again, so | |
734 | * there is a chance we will end up with a buffer queued for write but | |
735 | * not yet completed on that list. So, as a final cleanup we go through | |
736 | * the osync code to catch these locked, dirty buffers without requeuing | |
737 | * any newly dirty buffers for write. | |
738 | */ | |
739 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) | |
740 | { | |
741 | struct buffer_head *bh; | |
742 | struct list_head tmp; | |
7eaceacc | 743 | struct address_space *mapping; |
1da177e4 | 744 | int err = 0, err2; |
4ee2491e | 745 | struct blk_plug plug; |
1da177e4 LT |
746 | |
747 | INIT_LIST_HEAD(&tmp); | |
4ee2491e | 748 | blk_start_plug(&plug); |
1da177e4 LT |
749 | |
750 | spin_lock(lock); | |
751 | while (!list_empty(list)) { | |
752 | bh = BH_ENTRY(list->next); | |
535ee2fb | 753 | mapping = bh->b_assoc_map; |
58ff407b | 754 | __remove_assoc_queue(bh); |
535ee2fb JK |
755 | /* Avoid race with mark_buffer_dirty_inode() which does |
756 | * a lockless check and we rely on seeing the dirty bit */ | |
757 | smp_mb(); | |
1da177e4 LT |
758 | if (buffer_dirty(bh) || buffer_locked(bh)) { |
759 | list_add(&bh->b_assoc_buffers, &tmp); | |
535ee2fb | 760 | bh->b_assoc_map = mapping; |
1da177e4 LT |
761 | if (buffer_dirty(bh)) { |
762 | get_bh(bh); | |
763 | spin_unlock(lock); | |
764 | /* | |
765 | * Ensure any pending I/O completes so that | |
9cb569d6 CH |
766 | * write_dirty_buffer() actually writes the |
767 | * current contents - it is a noop if I/O is | |
768 | * still in flight on potentially older | |
769 | * contents. | |
1da177e4 | 770 | */ |
721a9602 | 771 | write_dirty_buffer(bh, WRITE_SYNC); |
9cf6b720 JA |
772 | |
773 | /* | |
774 | * Kick off IO for the previous mapping. Note | |
775 | * that we will not run the very last mapping, | |
776 | * wait_on_buffer() will do that for us | |
777 | * through sync_buffer(). | |
778 | */ | |
1da177e4 LT |
779 | brelse(bh); |
780 | spin_lock(lock); | |
781 | } | |
782 | } | |
783 | } | |
784 | ||
4ee2491e JA |
785 | spin_unlock(lock); |
786 | blk_finish_plug(&plug); | |
787 | spin_lock(lock); | |
788 | ||
1da177e4 LT |
789 | while (!list_empty(&tmp)) { |
790 | bh = BH_ENTRY(tmp.prev); | |
1da177e4 | 791 | get_bh(bh); |
535ee2fb JK |
792 | mapping = bh->b_assoc_map; |
793 | __remove_assoc_queue(bh); | |
794 | /* Avoid race with mark_buffer_dirty_inode() which does | |
795 | * a lockless check and we rely on seeing the dirty bit */ | |
796 | smp_mb(); | |
797 | if (buffer_dirty(bh)) { | |
798 | list_add(&bh->b_assoc_buffers, | |
e3892296 | 799 | &mapping->private_list); |
535ee2fb JK |
800 | bh->b_assoc_map = mapping; |
801 | } | |
1da177e4 LT |
802 | spin_unlock(lock); |
803 | wait_on_buffer(bh); | |
804 | if (!buffer_uptodate(bh)) | |
805 | err = -EIO; | |
806 | brelse(bh); | |
807 | spin_lock(lock); | |
808 | } | |
809 | ||
810 | spin_unlock(lock); | |
811 | err2 = osync_buffers_list(lock, list); | |
812 | if (err) | |
813 | return err; | |
814 | else | |
815 | return err2; | |
816 | } | |
817 | ||
818 | /* | |
819 | * Invalidate any and all dirty buffers on a given inode. We are | |
820 | * probably unmounting the fs, but that doesn't mean we have already | |
821 | * done a sync(). Just drop the buffers from the inode list. | |
822 | * | |
823 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which | |
824 | * assumes that all the buffers are against the blockdev. Not true | |
825 | * for reiserfs. | |
826 | */ | |
827 | void invalidate_inode_buffers(struct inode *inode) | |
828 | { | |
829 | if (inode_has_buffers(inode)) { | |
830 | struct address_space *mapping = &inode->i_data; | |
831 | struct list_head *list = &mapping->private_list; | |
252aa6f5 | 832 | struct address_space *buffer_mapping = mapping->private_data; |
1da177e4 LT |
833 | |
834 | spin_lock(&buffer_mapping->private_lock); | |
835 | while (!list_empty(list)) | |
836 | __remove_assoc_queue(BH_ENTRY(list->next)); | |
837 | spin_unlock(&buffer_mapping->private_lock); | |
838 | } | |
839 | } | |
52b19ac9 | 840 | EXPORT_SYMBOL(invalidate_inode_buffers); |
1da177e4 LT |
841 | |
842 | /* | |
843 | * Remove any clean buffers from the inode's buffer list. This is called | |
844 | * when we're trying to free the inode itself. Those buffers can pin it. | |
845 | * | |
846 | * Returns true if all buffers were removed. | |
847 | */ | |
848 | int remove_inode_buffers(struct inode *inode) | |
849 | { | |
850 | int ret = 1; | |
851 | ||
852 | if (inode_has_buffers(inode)) { | |
853 | struct address_space *mapping = &inode->i_data; | |
854 | struct list_head *list = &mapping->private_list; | |
252aa6f5 | 855 | struct address_space *buffer_mapping = mapping->private_data; |
1da177e4 LT |
856 | |
857 | spin_lock(&buffer_mapping->private_lock); | |
858 | while (!list_empty(list)) { | |
859 | struct buffer_head *bh = BH_ENTRY(list->next); | |
860 | if (buffer_dirty(bh)) { | |
861 | ret = 0; | |
862 | break; | |
863 | } | |
864 | __remove_assoc_queue(bh); | |
865 | } | |
866 | spin_unlock(&buffer_mapping->private_lock); | |
867 | } | |
868 | return ret; | |
869 | } | |
870 | ||
871 | /* | |
872 | * Create the appropriate buffers when given a page for data area and | |
873 | * the size of each buffer.. Use the bh->b_this_page linked list to | |
874 | * follow the buffers created. Return NULL if unable to create more | |
875 | * buffers. | |
876 | * | |
877 | * The retry flag is used to differentiate async IO (paging, swapping) | |
878 | * which may not fail from ordinary buffer allocations. | |
879 | */ | |
880 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
881 | int retry) | |
882 | { | |
883 | struct buffer_head *bh, *head; | |
884 | long offset; | |
885 | ||
886 | try_again: | |
887 | head = NULL; | |
888 | offset = PAGE_SIZE; | |
889 | while ((offset -= size) >= 0) { | |
890 | bh = alloc_buffer_head(GFP_NOFS); | |
891 | if (!bh) | |
892 | goto no_grow; | |
893 | ||
1da177e4 LT |
894 | bh->b_this_page = head; |
895 | bh->b_blocknr = -1; | |
896 | head = bh; | |
897 | ||
1da177e4 LT |
898 | bh->b_size = size; |
899 | ||
900 | /* Link the buffer to its page */ | |
901 | set_bh_page(bh, page, offset); | |
1da177e4 LT |
902 | } |
903 | return head; | |
904 | /* | |
905 | * In case anything failed, we just free everything we got. | |
906 | */ | |
907 | no_grow: | |
908 | if (head) { | |
909 | do { | |
910 | bh = head; | |
911 | head = head->b_this_page; | |
912 | free_buffer_head(bh); | |
913 | } while (head); | |
914 | } | |
915 | ||
916 | /* | |
917 | * Return failure for non-async IO requests. Async IO requests | |
918 | * are not allowed to fail, so we have to wait until buffer heads | |
919 | * become available. But we don't want tasks sleeping with | |
920 | * partially complete buffers, so all were released above. | |
921 | */ | |
922 | if (!retry) | |
923 | return NULL; | |
924 | ||
925 | /* We're _really_ low on memory. Now we just | |
926 | * wait for old buffer heads to become free due to | |
927 | * finishing IO. Since this is an async request and | |
928 | * the reserve list is empty, we're sure there are | |
929 | * async buffer heads in use. | |
930 | */ | |
931 | free_more_memory(); | |
932 | goto try_again; | |
933 | } | |
934 | EXPORT_SYMBOL_GPL(alloc_page_buffers); | |
935 | ||
936 | static inline void | |
937 | link_dev_buffers(struct page *page, struct buffer_head *head) | |
938 | { | |
939 | struct buffer_head *bh, *tail; | |
940 | ||
941 | bh = head; | |
942 | do { | |
943 | tail = bh; | |
944 | bh = bh->b_this_page; | |
945 | } while (bh); | |
946 | tail->b_this_page = head; | |
947 | attach_page_buffers(page, head); | |
948 | } | |
949 | ||
bbec0270 LT |
950 | static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) |
951 | { | |
952 | sector_t retval = ~((sector_t)0); | |
953 | loff_t sz = i_size_read(bdev->bd_inode); | |
954 | ||
955 | if (sz) { | |
956 | unsigned int sizebits = blksize_bits(size); | |
957 | retval = (sz >> sizebits); | |
958 | } | |
959 | return retval; | |
960 | } | |
961 | ||
1da177e4 LT |
962 | /* |
963 | * Initialise the state of a blockdev page's buffers. | |
964 | */ | |
676ce6d5 | 965 | static sector_t |
1da177e4 LT |
966 | init_page_buffers(struct page *page, struct block_device *bdev, |
967 | sector_t block, int size) | |
968 | { | |
969 | struct buffer_head *head = page_buffers(page); | |
970 | struct buffer_head *bh = head; | |
971 | int uptodate = PageUptodate(page); | |
bbec0270 | 972 | sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); |
1da177e4 LT |
973 | |
974 | do { | |
975 | if (!buffer_mapped(bh)) { | |
976 | init_buffer(bh, NULL, NULL); | |
977 | bh->b_bdev = bdev; | |
978 | bh->b_blocknr = block; | |
979 | if (uptodate) | |
980 | set_buffer_uptodate(bh); | |
080399aa JM |
981 | if (block < end_block) |
982 | set_buffer_mapped(bh); | |
1da177e4 LT |
983 | } |
984 | block++; | |
985 | bh = bh->b_this_page; | |
986 | } while (bh != head); | |
676ce6d5 HD |
987 | |
988 | /* | |
989 | * Caller needs to validate requested block against end of device. | |
990 | */ | |
991 | return end_block; | |
1da177e4 LT |
992 | } |
993 | ||
994 | /* | |
995 | * Create the page-cache page that contains the requested block. | |
996 | * | |
676ce6d5 | 997 | * This is used purely for blockdev mappings. |
1da177e4 | 998 | */ |
676ce6d5 | 999 | static int |
1da177e4 | 1000 | grow_dev_page(struct block_device *bdev, sector_t block, |
676ce6d5 | 1001 | pgoff_t index, int size, int sizebits) |
1da177e4 LT |
1002 | { |
1003 | struct inode *inode = bdev->bd_inode; | |
1004 | struct page *page; | |
1005 | struct buffer_head *bh; | |
676ce6d5 HD |
1006 | sector_t end_block; |
1007 | int ret = 0; /* Will call free_more_memory() */ | |
1da177e4 | 1008 | |
ea125892 | 1009 | page = find_or_create_page(inode->i_mapping, index, |
769848c0 | 1010 | (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE); |
1da177e4 | 1011 | if (!page) |
676ce6d5 | 1012 | return ret; |
1da177e4 | 1013 | |
e827f923 | 1014 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
1015 | |
1016 | if (page_has_buffers(page)) { | |
1017 | bh = page_buffers(page); | |
1018 | if (bh->b_size == size) { | |
676ce6d5 HD |
1019 | end_block = init_page_buffers(page, bdev, |
1020 | index << sizebits, size); | |
1021 | goto done; | |
1da177e4 LT |
1022 | } |
1023 | if (!try_to_free_buffers(page)) | |
1024 | goto failed; | |
1025 | } | |
1026 | ||
1027 | /* | |
1028 | * Allocate some buffers for this page | |
1029 | */ | |
1030 | bh = alloc_page_buffers(page, size, 0); | |
1031 | if (!bh) | |
1032 | goto failed; | |
1033 | ||
1034 | /* | |
1035 | * Link the page to the buffers and initialise them. Take the | |
1036 | * lock to be atomic wrt __find_get_block(), which does not | |
1037 | * run under the page lock. | |
1038 | */ | |
1039 | spin_lock(&inode->i_mapping->private_lock); | |
1040 | link_dev_buffers(page, bh); | |
676ce6d5 | 1041 | end_block = init_page_buffers(page, bdev, index << sizebits, size); |
1da177e4 | 1042 | spin_unlock(&inode->i_mapping->private_lock); |
676ce6d5 HD |
1043 | done: |
1044 | ret = (block < end_block) ? 1 : -ENXIO; | |
1da177e4 | 1045 | failed: |
1da177e4 LT |
1046 | unlock_page(page); |
1047 | page_cache_release(page); | |
676ce6d5 | 1048 | return ret; |
1da177e4 LT |
1049 | } |
1050 | ||
1051 | /* | |
1052 | * Create buffers for the specified block device block's page. If | |
1053 | * that page was dirty, the buffers are set dirty also. | |
1da177e4 | 1054 | */ |
858119e1 | 1055 | static int |
1da177e4 LT |
1056 | grow_buffers(struct block_device *bdev, sector_t block, int size) |
1057 | { | |
1da177e4 LT |
1058 | pgoff_t index; |
1059 | int sizebits; | |
1060 | ||
1061 | sizebits = -1; | |
1062 | do { | |
1063 | sizebits++; | |
1064 | } while ((size << sizebits) < PAGE_SIZE); | |
1065 | ||
1066 | index = block >> sizebits; | |
1da177e4 | 1067 | |
e5657933 AM |
1068 | /* |
1069 | * Check for a block which wants to lie outside our maximum possible | |
1070 | * pagecache index. (this comparison is done using sector_t types). | |
1071 | */ | |
1072 | if (unlikely(index != block >> sizebits)) { | |
1073 | char b[BDEVNAME_SIZE]; | |
1074 | ||
1075 | printk(KERN_ERR "%s: requested out-of-range block %llu for " | |
1076 | "device %s\n", | |
8e24eea7 | 1077 | __func__, (unsigned long long)block, |
e5657933 AM |
1078 | bdevname(bdev, b)); |
1079 | return -EIO; | |
1080 | } | |
676ce6d5 | 1081 | |
1da177e4 | 1082 | /* Create a page with the proper size buffers.. */ |
676ce6d5 | 1083 | return grow_dev_page(bdev, block, index, size, sizebits); |
1da177e4 LT |
1084 | } |
1085 | ||
75c96f85 | 1086 | static struct buffer_head * |
1da177e4 LT |
1087 | __getblk_slow(struct block_device *bdev, sector_t block, int size) |
1088 | { | |
1089 | /* Size must be multiple of hard sectorsize */ | |
e1defc4f | 1090 | if (unlikely(size & (bdev_logical_block_size(bdev)-1) || |
1da177e4 LT |
1091 | (size < 512 || size > PAGE_SIZE))) { |
1092 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", | |
1093 | size); | |
e1defc4f MP |
1094 | printk(KERN_ERR "logical block size: %d\n", |
1095 | bdev_logical_block_size(bdev)); | |
1da177e4 LT |
1096 | |
1097 | dump_stack(); | |
1098 | return NULL; | |
1099 | } | |
1100 | ||
676ce6d5 HD |
1101 | for (;;) { |
1102 | struct buffer_head *bh; | |
1103 | int ret; | |
1da177e4 LT |
1104 | |
1105 | bh = __find_get_block(bdev, block, size); | |
1106 | if (bh) | |
1107 | return bh; | |
676ce6d5 HD |
1108 | |
1109 | ret = grow_buffers(bdev, block, size); | |
1110 | if (ret < 0) | |
1111 | return NULL; | |
1112 | if (ret == 0) | |
1113 | free_more_memory(); | |
1da177e4 LT |
1114 | } |
1115 | } | |
1116 | ||
1117 | /* | |
1118 | * The relationship between dirty buffers and dirty pages: | |
1119 | * | |
1120 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and | |
1121 | * the page is tagged dirty in its radix tree. | |
1122 | * | |
1123 | * At all times, the dirtiness of the buffers represents the dirtiness of | |
1124 | * subsections of the page. If the page has buffers, the page dirty bit is | |
1125 | * merely a hint about the true dirty state. | |
1126 | * | |
1127 | * When a page is set dirty in its entirety, all its buffers are marked dirty | |
1128 | * (if the page has buffers). | |
1129 | * | |
1130 | * When a buffer is marked dirty, its page is dirtied, but the page's other | |
1131 | * buffers are not. | |
1132 | * | |
1133 | * Also. When blockdev buffers are explicitly read with bread(), they | |
1134 | * individually become uptodate. But their backing page remains not | |
1135 | * uptodate - even if all of its buffers are uptodate. A subsequent | |
1136 | * block_read_full_page() against that page will discover all the uptodate | |
1137 | * buffers, will set the page uptodate and will perform no I/O. | |
1138 | */ | |
1139 | ||
1140 | /** | |
1141 | * mark_buffer_dirty - mark a buffer_head as needing writeout | |
67be2dd1 | 1142 | * @bh: the buffer_head to mark dirty |
1da177e4 LT |
1143 | * |
1144 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set its | |
1145 | * backing page dirty, then tag the page as dirty in its address_space's radix | |
1146 | * tree and then attach the address_space's inode to its superblock's dirty | |
1147 | * inode list. | |
1148 | * | |
1149 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, | |
250df6ed | 1150 | * mapping->tree_lock and mapping->host->i_lock. |
1da177e4 | 1151 | */ |
fc9b52cd | 1152 | void mark_buffer_dirty(struct buffer_head *bh) |
1da177e4 | 1153 | { |
787d2214 | 1154 | WARN_ON_ONCE(!buffer_uptodate(bh)); |
1be62dc1 | 1155 | |
5305cb83 TH |
1156 | trace_block_dirty_buffer(bh); |
1157 | ||
1be62dc1 LT |
1158 | /* |
1159 | * Very *carefully* optimize the it-is-already-dirty case. | |
1160 | * | |
1161 | * Don't let the final "is it dirty" escape to before we | |
1162 | * perhaps modified the buffer. | |
1163 | */ | |
1164 | if (buffer_dirty(bh)) { | |
1165 | smp_mb(); | |
1166 | if (buffer_dirty(bh)) | |
1167 | return; | |
1168 | } | |
1169 | ||
a8e7d49a LT |
1170 | if (!test_set_buffer_dirty(bh)) { |
1171 | struct page *page = bh->b_page; | |
8e9d78ed LT |
1172 | if (!TestSetPageDirty(page)) { |
1173 | struct address_space *mapping = page_mapping(page); | |
1174 | if (mapping) | |
1175 | __set_page_dirty(page, mapping, 0); | |
1176 | } | |
a8e7d49a | 1177 | } |
1da177e4 | 1178 | } |
1fe72eaa | 1179 | EXPORT_SYMBOL(mark_buffer_dirty); |
1da177e4 LT |
1180 | |
1181 | /* | |
1182 | * Decrement a buffer_head's reference count. If all buffers against a page | |
1183 | * have zero reference count, are clean and unlocked, and if the page is clean | |
1184 | * and unlocked then try_to_free_buffers() may strip the buffers from the page | |
1185 | * in preparation for freeing it (sometimes, rarely, buffers are removed from | |
1186 | * a page but it ends up not being freed, and buffers may later be reattached). | |
1187 | */ | |
1188 | void __brelse(struct buffer_head * buf) | |
1189 | { | |
1190 | if (atomic_read(&buf->b_count)) { | |
1191 | put_bh(buf); | |
1192 | return; | |
1193 | } | |
5c752ad9 | 1194 | WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); |
1da177e4 | 1195 | } |
1fe72eaa | 1196 | EXPORT_SYMBOL(__brelse); |
1da177e4 LT |
1197 | |
1198 | /* | |
1199 | * bforget() is like brelse(), except it discards any | |
1200 | * potentially dirty data. | |
1201 | */ | |
1202 | void __bforget(struct buffer_head *bh) | |
1203 | { | |
1204 | clear_buffer_dirty(bh); | |
535ee2fb | 1205 | if (bh->b_assoc_map) { |
1da177e4 LT |
1206 | struct address_space *buffer_mapping = bh->b_page->mapping; |
1207 | ||
1208 | spin_lock(&buffer_mapping->private_lock); | |
1209 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b | 1210 | bh->b_assoc_map = NULL; |
1da177e4 LT |
1211 | spin_unlock(&buffer_mapping->private_lock); |
1212 | } | |
1213 | __brelse(bh); | |
1214 | } | |
1fe72eaa | 1215 | EXPORT_SYMBOL(__bforget); |
1da177e4 LT |
1216 | |
1217 | static struct buffer_head *__bread_slow(struct buffer_head *bh) | |
1218 | { | |
1219 | lock_buffer(bh); | |
1220 | if (buffer_uptodate(bh)) { | |
1221 | unlock_buffer(bh); | |
1222 | return bh; | |
1223 | } else { | |
1224 | get_bh(bh); | |
1225 | bh->b_end_io = end_buffer_read_sync; | |
1226 | submit_bh(READ, bh); | |
1227 | wait_on_buffer(bh); | |
1228 | if (buffer_uptodate(bh)) | |
1229 | return bh; | |
1230 | } | |
1231 | brelse(bh); | |
1232 | return NULL; | |
1233 | } | |
1234 | ||
1235 | /* | |
1236 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). | |
1237 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their | |
1238 | * refcount elevated by one when they're in an LRU. A buffer can only appear | |
1239 | * once in a particular CPU's LRU. A single buffer can be present in multiple | |
1240 | * CPU's LRUs at the same time. | |
1241 | * | |
1242 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and | |
1243 | * sb_find_get_block(). | |
1244 | * | |
1245 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use | |
1246 | * a local interrupt disable for that. | |
1247 | */ | |
1248 | ||
1249 | #define BH_LRU_SIZE 8 | |
1250 | ||
1251 | struct bh_lru { | |
1252 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1253 | }; | |
1254 | ||
1255 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; | |
1256 | ||
1257 | #ifdef CONFIG_SMP | |
1258 | #define bh_lru_lock() local_irq_disable() | |
1259 | #define bh_lru_unlock() local_irq_enable() | |
1260 | #else | |
1261 | #define bh_lru_lock() preempt_disable() | |
1262 | #define bh_lru_unlock() preempt_enable() | |
1263 | #endif | |
1264 | ||
1265 | static inline void check_irqs_on(void) | |
1266 | { | |
1267 | #ifdef irqs_disabled | |
1268 | BUG_ON(irqs_disabled()); | |
1269 | #endif | |
1270 | } | |
1271 | ||
1272 | /* | |
1273 | * The LRU management algorithm is dopey-but-simple. Sorry. | |
1274 | */ | |
1275 | static void bh_lru_install(struct buffer_head *bh) | |
1276 | { | |
1277 | struct buffer_head *evictee = NULL; | |
1da177e4 LT |
1278 | |
1279 | check_irqs_on(); | |
1280 | bh_lru_lock(); | |
c7b92516 | 1281 | if (__this_cpu_read(bh_lrus.bhs[0]) != bh) { |
1da177e4 LT |
1282 | struct buffer_head *bhs[BH_LRU_SIZE]; |
1283 | int in; | |
1284 | int out = 0; | |
1285 | ||
1286 | get_bh(bh); | |
1287 | bhs[out++] = bh; | |
1288 | for (in = 0; in < BH_LRU_SIZE; in++) { | |
c7b92516 CL |
1289 | struct buffer_head *bh2 = |
1290 | __this_cpu_read(bh_lrus.bhs[in]); | |
1da177e4 LT |
1291 | |
1292 | if (bh2 == bh) { | |
1293 | __brelse(bh2); | |
1294 | } else { | |
1295 | if (out >= BH_LRU_SIZE) { | |
1296 | BUG_ON(evictee != NULL); | |
1297 | evictee = bh2; | |
1298 | } else { | |
1299 | bhs[out++] = bh2; | |
1300 | } | |
1301 | } | |
1302 | } | |
1303 | while (out < BH_LRU_SIZE) | |
1304 | bhs[out++] = NULL; | |
c7b92516 | 1305 | memcpy(__this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs)); |
1da177e4 LT |
1306 | } |
1307 | bh_lru_unlock(); | |
1308 | ||
1309 | if (evictee) | |
1310 | __brelse(evictee); | |
1311 | } | |
1312 | ||
1313 | /* | |
1314 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. | |
1315 | */ | |
858119e1 | 1316 | static struct buffer_head * |
3991d3bd | 1317 | lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1318 | { |
1319 | struct buffer_head *ret = NULL; | |
3991d3bd | 1320 | unsigned int i; |
1da177e4 LT |
1321 | |
1322 | check_irqs_on(); | |
1323 | bh_lru_lock(); | |
1da177e4 | 1324 | for (i = 0; i < BH_LRU_SIZE; i++) { |
c7b92516 | 1325 | struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); |
1da177e4 LT |
1326 | |
1327 | if (bh && bh->b_bdev == bdev && | |
1328 | bh->b_blocknr == block && bh->b_size == size) { | |
1329 | if (i) { | |
1330 | while (i) { | |
c7b92516 CL |
1331 | __this_cpu_write(bh_lrus.bhs[i], |
1332 | __this_cpu_read(bh_lrus.bhs[i - 1])); | |
1da177e4 LT |
1333 | i--; |
1334 | } | |
c7b92516 | 1335 | __this_cpu_write(bh_lrus.bhs[0], bh); |
1da177e4 LT |
1336 | } |
1337 | get_bh(bh); | |
1338 | ret = bh; | |
1339 | break; | |
1340 | } | |
1341 | } | |
1342 | bh_lru_unlock(); | |
1343 | return ret; | |
1344 | } | |
1345 | ||
1346 | /* | |
1347 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh | |
1348 | * it in the LRU and mark it as accessed. If it is not present then return | |
1349 | * NULL | |
1350 | */ | |
1351 | struct buffer_head * | |
3991d3bd | 1352 | __find_get_block(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1353 | { |
1354 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); | |
1355 | ||
1356 | if (bh == NULL) { | |
385fd4c5 | 1357 | bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1358 | if (bh) |
1359 | bh_lru_install(bh); | |
1360 | } | |
1361 | if (bh) | |
1362 | touch_buffer(bh); | |
1363 | return bh; | |
1364 | } | |
1365 | EXPORT_SYMBOL(__find_get_block); | |
1366 | ||
1367 | /* | |
1368 | * __getblk will locate (and, if necessary, create) the buffer_head | |
1369 | * which corresponds to the passed block_device, block and size. The | |
1370 | * returned buffer has its reference count incremented. | |
1371 | * | |
1da177e4 LT |
1372 | * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() |
1373 | * attempt is failing. FIXME, perhaps? | |
1374 | */ | |
1375 | struct buffer_head * | |
3991d3bd | 1376 | __getblk(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1377 | { |
1378 | struct buffer_head *bh = __find_get_block(bdev, block, size); | |
1379 | ||
1380 | might_sleep(); | |
1381 | if (bh == NULL) | |
1382 | bh = __getblk_slow(bdev, block, size); | |
1383 | return bh; | |
1384 | } | |
1385 | EXPORT_SYMBOL(__getblk); | |
1386 | ||
1387 | /* | |
1388 | * Do async read-ahead on a buffer.. | |
1389 | */ | |
3991d3bd | 1390 | void __breadahead(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1391 | { |
1392 | struct buffer_head *bh = __getblk(bdev, block, size); | |
a3e713b5 AM |
1393 | if (likely(bh)) { |
1394 | ll_rw_block(READA, 1, &bh); | |
1395 | brelse(bh); | |
1396 | } | |
1da177e4 LT |
1397 | } |
1398 | EXPORT_SYMBOL(__breadahead); | |
1399 | ||
1400 | /** | |
1401 | * __bread() - reads a specified block and returns the bh | |
67be2dd1 | 1402 | * @bdev: the block_device to read from |
1da177e4 LT |
1403 | * @block: number of block |
1404 | * @size: size (in bytes) to read | |
1405 | * | |
1406 | * Reads a specified block, and returns buffer head that contains it. | |
1407 | * It returns NULL if the block was unreadable. | |
1408 | */ | |
1409 | struct buffer_head * | |
3991d3bd | 1410 | __bread(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1411 | { |
1412 | struct buffer_head *bh = __getblk(bdev, block, size); | |
1413 | ||
a3e713b5 | 1414 | if (likely(bh) && !buffer_uptodate(bh)) |
1da177e4 LT |
1415 | bh = __bread_slow(bh); |
1416 | return bh; | |
1417 | } | |
1418 | EXPORT_SYMBOL(__bread); | |
1419 | ||
1420 | /* | |
1421 | * invalidate_bh_lrus() is called rarely - but not only at unmount. | |
1422 | * This doesn't race because it runs in each cpu either in irq | |
1423 | * or with preempt disabled. | |
1424 | */ | |
1425 | static void invalidate_bh_lru(void *arg) | |
1426 | { | |
1427 | struct bh_lru *b = &get_cpu_var(bh_lrus); | |
1428 | int i; | |
1429 | ||
1430 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1431 | brelse(b->bhs[i]); | |
1432 | b->bhs[i] = NULL; | |
1433 | } | |
1434 | put_cpu_var(bh_lrus); | |
1435 | } | |
42be35d0 GBY |
1436 | |
1437 | static bool has_bh_in_lru(int cpu, void *dummy) | |
1438 | { | |
1439 | struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); | |
1440 | int i; | |
1da177e4 | 1441 | |
42be35d0 GBY |
1442 | for (i = 0; i < BH_LRU_SIZE; i++) { |
1443 | if (b->bhs[i]) | |
1444 | return 1; | |
1445 | } | |
1446 | ||
1447 | return 0; | |
1448 | } | |
1449 | ||
f9a14399 | 1450 | void invalidate_bh_lrus(void) |
1da177e4 | 1451 | { |
42be35d0 | 1452 | on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); |
1da177e4 | 1453 | } |
9db5579b | 1454 | EXPORT_SYMBOL_GPL(invalidate_bh_lrus); |
1da177e4 LT |
1455 | |
1456 | void set_bh_page(struct buffer_head *bh, | |
1457 | struct page *page, unsigned long offset) | |
1458 | { | |
1459 | bh->b_page = page; | |
e827f923 | 1460 | BUG_ON(offset >= PAGE_SIZE); |
1da177e4 LT |
1461 | if (PageHighMem(page)) |
1462 | /* | |
1463 | * This catches illegal uses and preserves the offset: | |
1464 | */ | |
1465 | bh->b_data = (char *)(0 + offset); | |
1466 | else | |
1467 | bh->b_data = page_address(page) + offset; | |
1468 | } | |
1469 | EXPORT_SYMBOL(set_bh_page); | |
1470 | ||
1471 | /* | |
1472 | * Called when truncating a buffer on a page completely. | |
1473 | */ | |
858119e1 | 1474 | static void discard_buffer(struct buffer_head * bh) |
1da177e4 LT |
1475 | { |
1476 | lock_buffer(bh); | |
1477 | clear_buffer_dirty(bh); | |
1478 | bh->b_bdev = NULL; | |
1479 | clear_buffer_mapped(bh); | |
1480 | clear_buffer_req(bh); | |
1481 | clear_buffer_new(bh); | |
1482 | clear_buffer_delay(bh); | |
33a266dd | 1483 | clear_buffer_unwritten(bh); |
1da177e4 LT |
1484 | unlock_buffer(bh); |
1485 | } | |
1486 | ||
1da177e4 | 1487 | /** |
814e1d25 | 1488 | * block_invalidatepage - invalidate part or all of a buffer-backed page |
1da177e4 LT |
1489 | * |
1490 | * @page: the page which is affected | |
d47992f8 LC |
1491 | * @offset: start of the range to invalidate |
1492 | * @length: length of the range to invalidate | |
1da177e4 LT |
1493 | * |
1494 | * block_invalidatepage() is called when all or part of the page has become | |
814e1d25 | 1495 | * invalidated by a truncate operation. |
1da177e4 LT |
1496 | * |
1497 | * block_invalidatepage() does not have to release all buffers, but it must | |
1498 | * ensure that no dirty buffer is left outside @offset and that no I/O | |
1499 | * is underway against any of the blocks which are outside the truncation | |
1500 | * point. Because the caller is about to free (and possibly reuse) those | |
1501 | * blocks on-disk. | |
1502 | */ | |
d47992f8 LC |
1503 | void block_invalidatepage(struct page *page, unsigned int offset, |
1504 | unsigned int length) | |
1da177e4 LT |
1505 | { |
1506 | struct buffer_head *head, *bh, *next; | |
1507 | unsigned int curr_off = 0; | |
d47992f8 | 1508 | unsigned int stop = length + offset; |
1da177e4 LT |
1509 | |
1510 | BUG_ON(!PageLocked(page)); | |
1511 | if (!page_has_buffers(page)) | |
1512 | goto out; | |
1513 | ||
d47992f8 LC |
1514 | /* |
1515 | * Check for overflow | |
1516 | */ | |
1517 | BUG_ON(stop > PAGE_CACHE_SIZE || stop < length); | |
1518 | ||
1da177e4 LT |
1519 | head = page_buffers(page); |
1520 | bh = head; | |
1521 | do { | |
1522 | unsigned int next_off = curr_off + bh->b_size; | |
1523 | next = bh->b_this_page; | |
1524 | ||
d47992f8 LC |
1525 | /* |
1526 | * Are we still fully in range ? | |
1527 | */ | |
1528 | if (next_off > stop) | |
1529 | goto out; | |
1530 | ||
1da177e4 LT |
1531 | /* |
1532 | * is this block fully invalidated? | |
1533 | */ | |
1534 | if (offset <= curr_off) | |
1535 | discard_buffer(bh); | |
1536 | curr_off = next_off; | |
1537 | bh = next; | |
1538 | } while (bh != head); | |
1539 | ||
1540 | /* | |
1541 | * We release buffers only if the entire page is being invalidated. | |
1542 | * The get_block cached value has been unconditionally invalidated, | |
1543 | * so real IO is not possible anymore. | |
1544 | */ | |
1545 | if (offset == 0) | |
2ff28e22 | 1546 | try_to_release_page(page, 0); |
1da177e4 | 1547 | out: |
2ff28e22 | 1548 | return; |
1da177e4 LT |
1549 | } |
1550 | EXPORT_SYMBOL(block_invalidatepage); | |
1551 | ||
d47992f8 | 1552 | |
1da177e4 LT |
1553 | /* |
1554 | * We attach and possibly dirty the buffers atomically wrt | |
1555 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers | |
1556 | * is already excluded via the page lock. | |
1557 | */ | |
1558 | void create_empty_buffers(struct page *page, | |
1559 | unsigned long blocksize, unsigned long b_state) | |
1560 | { | |
1561 | struct buffer_head *bh, *head, *tail; | |
1562 | ||
1563 | head = alloc_page_buffers(page, blocksize, 1); | |
1564 | bh = head; | |
1565 | do { | |
1566 | bh->b_state |= b_state; | |
1567 | tail = bh; | |
1568 | bh = bh->b_this_page; | |
1569 | } while (bh); | |
1570 | tail->b_this_page = head; | |
1571 | ||
1572 | spin_lock(&page->mapping->private_lock); | |
1573 | if (PageUptodate(page) || PageDirty(page)) { | |
1574 | bh = head; | |
1575 | do { | |
1576 | if (PageDirty(page)) | |
1577 | set_buffer_dirty(bh); | |
1578 | if (PageUptodate(page)) | |
1579 | set_buffer_uptodate(bh); | |
1580 | bh = bh->b_this_page; | |
1581 | } while (bh != head); | |
1582 | } | |
1583 | attach_page_buffers(page, head); | |
1584 | spin_unlock(&page->mapping->private_lock); | |
1585 | } | |
1586 | EXPORT_SYMBOL(create_empty_buffers); | |
1587 | ||
1588 | /* | |
1589 | * We are taking a block for data and we don't want any output from any | |
1590 | * buffer-cache aliases starting from return from that function and | |
1591 | * until the moment when something will explicitly mark the buffer | |
1592 | * dirty (hopefully that will not happen until we will free that block ;-) | |
1593 | * We don't even need to mark it not-uptodate - nobody can expect | |
1594 | * anything from a newly allocated buffer anyway. We used to used | |
1595 | * unmap_buffer() for such invalidation, but that was wrong. We definitely | |
1596 | * don't want to mark the alias unmapped, for example - it would confuse | |
1597 | * anyone who might pick it with bread() afterwards... | |
1598 | * | |
1599 | * Also.. Note that bforget() doesn't lock the buffer. So there can | |
1600 | * be writeout I/O going on against recently-freed buffers. We don't | |
1601 | * wait on that I/O in bforget() - it's more efficient to wait on the I/O | |
1602 | * only if we really need to. That happens here. | |
1603 | */ | |
1604 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block) | |
1605 | { | |
1606 | struct buffer_head *old_bh; | |
1607 | ||
1608 | might_sleep(); | |
1609 | ||
385fd4c5 | 1610 | old_bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1611 | if (old_bh) { |
1612 | clear_buffer_dirty(old_bh); | |
1613 | wait_on_buffer(old_bh); | |
1614 | clear_buffer_req(old_bh); | |
1615 | __brelse(old_bh); | |
1616 | } | |
1617 | } | |
1618 | EXPORT_SYMBOL(unmap_underlying_metadata); | |
1619 | ||
45bce8f3 LT |
1620 | /* |
1621 | * Size is a power-of-two in the range 512..PAGE_SIZE, | |
1622 | * and the case we care about most is PAGE_SIZE. | |
1623 | * | |
1624 | * So this *could* possibly be written with those | |
1625 | * constraints in mind (relevant mostly if some | |
1626 | * architecture has a slow bit-scan instruction) | |
1627 | */ | |
1628 | static inline int block_size_bits(unsigned int blocksize) | |
1629 | { | |
1630 | return ilog2(blocksize); | |
1631 | } | |
1632 | ||
1633 | static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) | |
1634 | { | |
1635 | BUG_ON(!PageLocked(page)); | |
1636 | ||
1637 | if (!page_has_buffers(page)) | |
1638 | create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state); | |
1639 | return page_buffers(page); | |
1640 | } | |
1641 | ||
1da177e4 LT |
1642 | /* |
1643 | * NOTE! All mapped/uptodate combinations are valid: | |
1644 | * | |
1645 | * Mapped Uptodate Meaning | |
1646 | * | |
1647 | * No No "unknown" - must do get_block() | |
1648 | * No Yes "hole" - zero-filled | |
1649 | * Yes No "allocated" - allocated on disk, not read in | |
1650 | * Yes Yes "valid" - allocated and up-to-date in memory. | |
1651 | * | |
1652 | * "Dirty" is valid only with the last case (mapped+uptodate). | |
1653 | */ | |
1654 | ||
1655 | /* | |
1656 | * While block_write_full_page is writing back the dirty buffers under | |
1657 | * the page lock, whoever dirtied the buffers may decide to clean them | |
1658 | * again at any time. We handle that by only looking at the buffer | |
1659 | * state inside lock_buffer(). | |
1660 | * | |
1661 | * If block_write_full_page() is called for regular writeback | |
1662 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a | |
1663 | * locked buffer. This only can happen if someone has written the buffer | |
1664 | * directly, with submit_bh(). At the address_space level PageWriteback | |
1665 | * prevents this contention from occurring. | |
6e34eedd TT |
1666 | * |
1667 | * If block_write_full_page() is called with wbc->sync_mode == | |
721a9602 JA |
1668 | * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this |
1669 | * causes the writes to be flagged as synchronous writes. | |
1da177e4 LT |
1670 | */ |
1671 | static int __block_write_full_page(struct inode *inode, struct page *page, | |
35c80d5f CM |
1672 | get_block_t *get_block, struct writeback_control *wbc, |
1673 | bh_end_io_t *handler) | |
1da177e4 LT |
1674 | { |
1675 | int err; | |
1676 | sector_t block; | |
1677 | sector_t last_block; | |
f0fbd5fc | 1678 | struct buffer_head *bh, *head; |
45bce8f3 | 1679 | unsigned int blocksize, bbits; |
1da177e4 | 1680 | int nr_underway = 0; |
6e34eedd | 1681 | int write_op = (wbc->sync_mode == WB_SYNC_ALL ? |
721a9602 | 1682 | WRITE_SYNC : WRITE); |
1da177e4 | 1683 | |
45bce8f3 | 1684 | head = create_page_buffers(page, inode, |
1da177e4 | 1685 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
1da177e4 LT |
1686 | |
1687 | /* | |
1688 | * Be very careful. We have no exclusion from __set_page_dirty_buffers | |
1689 | * here, and the (potentially unmapped) buffers may become dirty at | |
1690 | * any time. If a buffer becomes dirty here after we've inspected it | |
1691 | * then we just miss that fact, and the page stays dirty. | |
1692 | * | |
1693 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; | |
1694 | * handle that here by just cleaning them. | |
1695 | */ | |
1696 | ||
1da177e4 | 1697 | bh = head; |
45bce8f3 LT |
1698 | blocksize = bh->b_size; |
1699 | bbits = block_size_bits(blocksize); | |
1700 | ||
1701 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); | |
1702 | last_block = (i_size_read(inode) - 1) >> bbits; | |
1da177e4 LT |
1703 | |
1704 | /* | |
1705 | * Get all the dirty buffers mapped to disk addresses and | |
1706 | * handle any aliases from the underlying blockdev's mapping. | |
1707 | */ | |
1708 | do { | |
1709 | if (block > last_block) { | |
1710 | /* | |
1711 | * mapped buffers outside i_size will occur, because | |
1712 | * this page can be outside i_size when there is a | |
1713 | * truncate in progress. | |
1714 | */ | |
1715 | /* | |
1716 | * The buffer was zeroed by block_write_full_page() | |
1717 | */ | |
1718 | clear_buffer_dirty(bh); | |
1719 | set_buffer_uptodate(bh); | |
29a814d2 AT |
1720 | } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && |
1721 | buffer_dirty(bh)) { | |
b0cf2321 | 1722 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1723 | err = get_block(inode, block, bh, 1); |
1724 | if (err) | |
1725 | goto recover; | |
29a814d2 | 1726 | clear_buffer_delay(bh); |
1da177e4 LT |
1727 | if (buffer_new(bh)) { |
1728 | /* blockdev mappings never come here */ | |
1729 | clear_buffer_new(bh); | |
1730 | unmap_underlying_metadata(bh->b_bdev, | |
1731 | bh->b_blocknr); | |
1732 | } | |
1733 | } | |
1734 | bh = bh->b_this_page; | |
1735 | block++; | |
1736 | } while (bh != head); | |
1737 | ||
1738 | do { | |
1da177e4 LT |
1739 | if (!buffer_mapped(bh)) |
1740 | continue; | |
1741 | /* | |
1742 | * If it's a fully non-blocking write attempt and we cannot | |
1743 | * lock the buffer then redirty the page. Note that this can | |
5b0830cb JA |
1744 | * potentially cause a busy-wait loop from writeback threads |
1745 | * and kswapd activity, but those code paths have their own | |
1746 | * higher-level throttling. | |
1da177e4 | 1747 | */ |
1b430bee | 1748 | if (wbc->sync_mode != WB_SYNC_NONE) { |
1da177e4 | 1749 | lock_buffer(bh); |
ca5de404 | 1750 | } else if (!trylock_buffer(bh)) { |
1da177e4 LT |
1751 | redirty_page_for_writepage(wbc, page); |
1752 | continue; | |
1753 | } | |
1754 | if (test_clear_buffer_dirty(bh)) { | |
35c80d5f | 1755 | mark_buffer_async_write_endio(bh, handler); |
1da177e4 LT |
1756 | } else { |
1757 | unlock_buffer(bh); | |
1758 | } | |
1759 | } while ((bh = bh->b_this_page) != head); | |
1760 | ||
1761 | /* | |
1762 | * The page and its buffers are protected by PageWriteback(), so we can | |
1763 | * drop the bh refcounts early. | |
1764 | */ | |
1765 | BUG_ON(PageWriteback(page)); | |
1766 | set_page_writeback(page); | |
1da177e4 LT |
1767 | |
1768 | do { | |
1769 | struct buffer_head *next = bh->b_this_page; | |
1770 | if (buffer_async_write(bh)) { | |
a64c8610 | 1771 | submit_bh(write_op, bh); |
1da177e4 LT |
1772 | nr_underway++; |
1773 | } | |
1da177e4 LT |
1774 | bh = next; |
1775 | } while (bh != head); | |
05937baa | 1776 | unlock_page(page); |
1da177e4 LT |
1777 | |
1778 | err = 0; | |
1779 | done: | |
1780 | if (nr_underway == 0) { | |
1781 | /* | |
1782 | * The page was marked dirty, but the buffers were | |
1783 | * clean. Someone wrote them back by hand with | |
1784 | * ll_rw_block/submit_bh. A rare case. | |
1785 | */ | |
1da177e4 | 1786 | end_page_writeback(page); |
3d67f2d7 | 1787 | |
1da177e4 LT |
1788 | /* |
1789 | * The page and buffer_heads can be released at any time from | |
1790 | * here on. | |
1791 | */ | |
1da177e4 LT |
1792 | } |
1793 | return err; | |
1794 | ||
1795 | recover: | |
1796 | /* | |
1797 | * ENOSPC, or some other error. We may already have added some | |
1798 | * blocks to the file, so we need to write these out to avoid | |
1799 | * exposing stale data. | |
1800 | * The page is currently locked and not marked for writeback | |
1801 | */ | |
1802 | bh = head; | |
1803 | /* Recovery: lock and submit the mapped buffers */ | |
1804 | do { | |
29a814d2 AT |
1805 | if (buffer_mapped(bh) && buffer_dirty(bh) && |
1806 | !buffer_delay(bh)) { | |
1da177e4 | 1807 | lock_buffer(bh); |
35c80d5f | 1808 | mark_buffer_async_write_endio(bh, handler); |
1da177e4 LT |
1809 | } else { |
1810 | /* | |
1811 | * The buffer may have been set dirty during | |
1812 | * attachment to a dirty page. | |
1813 | */ | |
1814 | clear_buffer_dirty(bh); | |
1815 | } | |
1816 | } while ((bh = bh->b_this_page) != head); | |
1817 | SetPageError(page); | |
1818 | BUG_ON(PageWriteback(page)); | |
7e4c3690 | 1819 | mapping_set_error(page->mapping, err); |
1da177e4 | 1820 | set_page_writeback(page); |
1da177e4 LT |
1821 | do { |
1822 | struct buffer_head *next = bh->b_this_page; | |
1823 | if (buffer_async_write(bh)) { | |
1824 | clear_buffer_dirty(bh); | |
a64c8610 | 1825 | submit_bh(write_op, bh); |
1da177e4 LT |
1826 | nr_underway++; |
1827 | } | |
1da177e4 LT |
1828 | bh = next; |
1829 | } while (bh != head); | |
ffda9d30 | 1830 | unlock_page(page); |
1da177e4 LT |
1831 | goto done; |
1832 | } | |
1833 | ||
afddba49 NP |
1834 | /* |
1835 | * If a page has any new buffers, zero them out here, and mark them uptodate | |
1836 | * and dirty so they'll be written out (in order to prevent uninitialised | |
1837 | * block data from leaking). And clear the new bit. | |
1838 | */ | |
1839 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) | |
1840 | { | |
1841 | unsigned int block_start, block_end; | |
1842 | struct buffer_head *head, *bh; | |
1843 | ||
1844 | BUG_ON(!PageLocked(page)); | |
1845 | if (!page_has_buffers(page)) | |
1846 | return; | |
1847 | ||
1848 | bh = head = page_buffers(page); | |
1849 | block_start = 0; | |
1850 | do { | |
1851 | block_end = block_start + bh->b_size; | |
1852 | ||
1853 | if (buffer_new(bh)) { | |
1854 | if (block_end > from && block_start < to) { | |
1855 | if (!PageUptodate(page)) { | |
1856 | unsigned start, size; | |
1857 | ||
1858 | start = max(from, block_start); | |
1859 | size = min(to, block_end) - start; | |
1860 | ||
eebd2aa3 | 1861 | zero_user(page, start, size); |
afddba49 NP |
1862 | set_buffer_uptodate(bh); |
1863 | } | |
1864 | ||
1865 | clear_buffer_new(bh); | |
1866 | mark_buffer_dirty(bh); | |
1867 | } | |
1868 | } | |
1869 | ||
1870 | block_start = block_end; | |
1871 | bh = bh->b_this_page; | |
1872 | } while (bh != head); | |
1873 | } | |
1874 | EXPORT_SYMBOL(page_zero_new_buffers); | |
1875 | ||
ebdec241 | 1876 | int __block_write_begin(struct page *page, loff_t pos, unsigned len, |
6e1db88d | 1877 | get_block_t *get_block) |
1da177e4 | 1878 | { |
ebdec241 CH |
1879 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
1880 | unsigned to = from + len; | |
6e1db88d | 1881 | struct inode *inode = page->mapping->host; |
1da177e4 LT |
1882 | unsigned block_start, block_end; |
1883 | sector_t block; | |
1884 | int err = 0; | |
1885 | unsigned blocksize, bbits; | |
1886 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1887 | ||
1888 | BUG_ON(!PageLocked(page)); | |
1889 | BUG_ON(from > PAGE_CACHE_SIZE); | |
1890 | BUG_ON(to > PAGE_CACHE_SIZE); | |
1891 | BUG_ON(from > to); | |
1892 | ||
45bce8f3 LT |
1893 | head = create_page_buffers(page, inode, 0); |
1894 | blocksize = head->b_size; | |
1895 | bbits = block_size_bits(blocksize); | |
1da177e4 | 1896 | |
1da177e4 LT |
1897 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); |
1898 | ||
1899 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1900 | block++, block_start=block_end, bh = bh->b_this_page) { | |
1901 | block_end = block_start + blocksize; | |
1902 | if (block_end <= from || block_start >= to) { | |
1903 | if (PageUptodate(page)) { | |
1904 | if (!buffer_uptodate(bh)) | |
1905 | set_buffer_uptodate(bh); | |
1906 | } | |
1907 | continue; | |
1908 | } | |
1909 | if (buffer_new(bh)) | |
1910 | clear_buffer_new(bh); | |
1911 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 1912 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1913 | err = get_block(inode, block, bh, 1); |
1914 | if (err) | |
f3ddbdc6 | 1915 | break; |
1da177e4 | 1916 | if (buffer_new(bh)) { |
1da177e4 LT |
1917 | unmap_underlying_metadata(bh->b_bdev, |
1918 | bh->b_blocknr); | |
1919 | if (PageUptodate(page)) { | |
637aff46 | 1920 | clear_buffer_new(bh); |
1da177e4 | 1921 | set_buffer_uptodate(bh); |
637aff46 | 1922 | mark_buffer_dirty(bh); |
1da177e4 LT |
1923 | continue; |
1924 | } | |
eebd2aa3 CL |
1925 | if (block_end > to || block_start < from) |
1926 | zero_user_segments(page, | |
1927 | to, block_end, | |
1928 | block_start, from); | |
1da177e4 LT |
1929 | continue; |
1930 | } | |
1931 | } | |
1932 | if (PageUptodate(page)) { | |
1933 | if (!buffer_uptodate(bh)) | |
1934 | set_buffer_uptodate(bh); | |
1935 | continue; | |
1936 | } | |
1937 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
33a266dd | 1938 | !buffer_unwritten(bh) && |
1da177e4 LT |
1939 | (block_start < from || block_end > to)) { |
1940 | ll_rw_block(READ, 1, &bh); | |
1941 | *wait_bh++=bh; | |
1942 | } | |
1943 | } | |
1944 | /* | |
1945 | * If we issued read requests - let them complete. | |
1946 | */ | |
1947 | while(wait_bh > wait) { | |
1948 | wait_on_buffer(*--wait_bh); | |
1949 | if (!buffer_uptodate(*wait_bh)) | |
f3ddbdc6 | 1950 | err = -EIO; |
1da177e4 | 1951 | } |
f9f07b6c | 1952 | if (unlikely(err)) |
afddba49 | 1953 | page_zero_new_buffers(page, from, to); |
1da177e4 LT |
1954 | return err; |
1955 | } | |
ebdec241 | 1956 | EXPORT_SYMBOL(__block_write_begin); |
1da177e4 LT |
1957 | |
1958 | static int __block_commit_write(struct inode *inode, struct page *page, | |
1959 | unsigned from, unsigned to) | |
1960 | { | |
1961 | unsigned block_start, block_end; | |
1962 | int partial = 0; | |
1963 | unsigned blocksize; | |
1964 | struct buffer_head *bh, *head; | |
1965 | ||
45bce8f3 LT |
1966 | bh = head = page_buffers(page); |
1967 | blocksize = bh->b_size; | |
1da177e4 | 1968 | |
45bce8f3 LT |
1969 | block_start = 0; |
1970 | do { | |
1da177e4 LT |
1971 | block_end = block_start + blocksize; |
1972 | if (block_end <= from || block_start >= to) { | |
1973 | if (!buffer_uptodate(bh)) | |
1974 | partial = 1; | |
1975 | } else { | |
1976 | set_buffer_uptodate(bh); | |
1977 | mark_buffer_dirty(bh); | |
1978 | } | |
afddba49 | 1979 | clear_buffer_new(bh); |
45bce8f3 LT |
1980 | |
1981 | block_start = block_end; | |
1982 | bh = bh->b_this_page; | |
1983 | } while (bh != head); | |
1da177e4 LT |
1984 | |
1985 | /* | |
1986 | * If this is a partial write which happened to make all buffers | |
1987 | * uptodate then we can optimize away a bogus readpage() for | |
1988 | * the next read(). Here we 'discover' whether the page went | |
1989 | * uptodate as a result of this (potentially partial) write. | |
1990 | */ | |
1991 | if (!partial) | |
1992 | SetPageUptodate(page); | |
1993 | return 0; | |
1994 | } | |
1995 | ||
afddba49 | 1996 | /* |
155130a4 CH |
1997 | * block_write_begin takes care of the basic task of block allocation and |
1998 | * bringing partial write blocks uptodate first. | |
1999 | * | |
7bb46a67 | 2000 | * The filesystem needs to handle block truncation upon failure. |
afddba49 | 2001 | */ |
155130a4 CH |
2002 | int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, |
2003 | unsigned flags, struct page **pagep, get_block_t *get_block) | |
afddba49 | 2004 | { |
6e1db88d | 2005 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
afddba49 | 2006 | struct page *page; |
6e1db88d | 2007 | int status; |
afddba49 | 2008 | |
6e1db88d CH |
2009 | page = grab_cache_page_write_begin(mapping, index, flags); |
2010 | if (!page) | |
2011 | return -ENOMEM; | |
afddba49 | 2012 | |
6e1db88d | 2013 | status = __block_write_begin(page, pos, len, get_block); |
afddba49 | 2014 | if (unlikely(status)) { |
6e1db88d CH |
2015 | unlock_page(page); |
2016 | page_cache_release(page); | |
2017 | page = NULL; | |
afddba49 NP |
2018 | } |
2019 | ||
6e1db88d | 2020 | *pagep = page; |
afddba49 NP |
2021 | return status; |
2022 | } | |
2023 | EXPORT_SYMBOL(block_write_begin); | |
2024 | ||
2025 | int block_write_end(struct file *file, struct address_space *mapping, | |
2026 | loff_t pos, unsigned len, unsigned copied, | |
2027 | struct page *page, void *fsdata) | |
2028 | { | |
2029 | struct inode *inode = mapping->host; | |
2030 | unsigned start; | |
2031 | ||
2032 | start = pos & (PAGE_CACHE_SIZE - 1); | |
2033 | ||
2034 | if (unlikely(copied < len)) { | |
2035 | /* | |
2036 | * The buffers that were written will now be uptodate, so we | |
2037 | * don't have to worry about a readpage reading them and | |
2038 | * overwriting a partial write. However if we have encountered | |
2039 | * a short write and only partially written into a buffer, it | |
2040 | * will not be marked uptodate, so a readpage might come in and | |
2041 | * destroy our partial write. | |
2042 | * | |
2043 | * Do the simplest thing, and just treat any short write to a | |
2044 | * non uptodate page as a zero-length write, and force the | |
2045 | * caller to redo the whole thing. | |
2046 | */ | |
2047 | if (!PageUptodate(page)) | |
2048 | copied = 0; | |
2049 | ||
2050 | page_zero_new_buffers(page, start+copied, start+len); | |
2051 | } | |
2052 | flush_dcache_page(page); | |
2053 | ||
2054 | /* This could be a short (even 0-length) commit */ | |
2055 | __block_commit_write(inode, page, start, start+copied); | |
2056 | ||
2057 | return copied; | |
2058 | } | |
2059 | EXPORT_SYMBOL(block_write_end); | |
2060 | ||
2061 | int generic_write_end(struct file *file, struct address_space *mapping, | |
2062 | loff_t pos, unsigned len, unsigned copied, | |
2063 | struct page *page, void *fsdata) | |
2064 | { | |
2065 | struct inode *inode = mapping->host; | |
c7d206b3 | 2066 | int i_size_changed = 0; |
afddba49 NP |
2067 | |
2068 | copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); | |
2069 | ||
2070 | /* | |
2071 | * No need to use i_size_read() here, the i_size | |
2072 | * cannot change under us because we hold i_mutex. | |
2073 | * | |
2074 | * But it's important to update i_size while still holding page lock: | |
2075 | * page writeout could otherwise come in and zero beyond i_size. | |
2076 | */ | |
2077 | if (pos+copied > inode->i_size) { | |
2078 | i_size_write(inode, pos+copied); | |
c7d206b3 | 2079 | i_size_changed = 1; |
afddba49 NP |
2080 | } |
2081 | ||
2082 | unlock_page(page); | |
2083 | page_cache_release(page); | |
2084 | ||
c7d206b3 JK |
2085 | /* |
2086 | * Don't mark the inode dirty under page lock. First, it unnecessarily | |
2087 | * makes the holding time of page lock longer. Second, it forces lock | |
2088 | * ordering of page lock and transaction start for journaling | |
2089 | * filesystems. | |
2090 | */ | |
2091 | if (i_size_changed) | |
2092 | mark_inode_dirty(inode); | |
2093 | ||
afddba49 NP |
2094 | return copied; |
2095 | } | |
2096 | EXPORT_SYMBOL(generic_write_end); | |
2097 | ||
8ab22b9a HH |
2098 | /* |
2099 | * block_is_partially_uptodate checks whether buffers within a page are | |
2100 | * uptodate or not. | |
2101 | * | |
2102 | * Returns true if all buffers which correspond to a file portion | |
2103 | * we want to read are uptodate. | |
2104 | */ | |
2105 | int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, | |
2106 | unsigned long from) | |
2107 | { | |
8ab22b9a HH |
2108 | unsigned block_start, block_end, blocksize; |
2109 | unsigned to; | |
2110 | struct buffer_head *bh, *head; | |
2111 | int ret = 1; | |
2112 | ||
2113 | if (!page_has_buffers(page)) | |
2114 | return 0; | |
2115 | ||
45bce8f3 LT |
2116 | head = page_buffers(page); |
2117 | blocksize = head->b_size; | |
8ab22b9a HH |
2118 | to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count); |
2119 | to = from + to; | |
2120 | if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize) | |
2121 | return 0; | |
2122 | ||
8ab22b9a HH |
2123 | bh = head; |
2124 | block_start = 0; | |
2125 | do { | |
2126 | block_end = block_start + blocksize; | |
2127 | if (block_end > from && block_start < to) { | |
2128 | if (!buffer_uptodate(bh)) { | |
2129 | ret = 0; | |
2130 | break; | |
2131 | } | |
2132 | if (block_end >= to) | |
2133 | break; | |
2134 | } | |
2135 | block_start = block_end; | |
2136 | bh = bh->b_this_page; | |
2137 | } while (bh != head); | |
2138 | ||
2139 | return ret; | |
2140 | } | |
2141 | EXPORT_SYMBOL(block_is_partially_uptodate); | |
2142 | ||
1da177e4 LT |
2143 | /* |
2144 | * Generic "read page" function for block devices that have the normal | |
2145 | * get_block functionality. This is most of the block device filesystems. | |
2146 | * Reads the page asynchronously --- the unlock_buffer() and | |
2147 | * set/clear_buffer_uptodate() functions propagate buffer state into the | |
2148 | * page struct once IO has completed. | |
2149 | */ | |
2150 | int block_read_full_page(struct page *page, get_block_t *get_block) | |
2151 | { | |
2152 | struct inode *inode = page->mapping->host; | |
2153 | sector_t iblock, lblock; | |
2154 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; | |
45bce8f3 | 2155 | unsigned int blocksize, bbits; |
1da177e4 LT |
2156 | int nr, i; |
2157 | int fully_mapped = 1; | |
2158 | ||
45bce8f3 LT |
2159 | head = create_page_buffers(page, inode, 0); |
2160 | blocksize = head->b_size; | |
2161 | bbits = block_size_bits(blocksize); | |
1da177e4 | 2162 | |
45bce8f3 LT |
2163 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); |
2164 | lblock = (i_size_read(inode)+blocksize-1) >> bbits; | |
1da177e4 LT |
2165 | bh = head; |
2166 | nr = 0; | |
2167 | i = 0; | |
2168 | ||
2169 | do { | |
2170 | if (buffer_uptodate(bh)) | |
2171 | continue; | |
2172 | ||
2173 | if (!buffer_mapped(bh)) { | |
c64610ba AM |
2174 | int err = 0; |
2175 | ||
1da177e4 LT |
2176 | fully_mapped = 0; |
2177 | if (iblock < lblock) { | |
b0cf2321 | 2178 | WARN_ON(bh->b_size != blocksize); |
c64610ba AM |
2179 | err = get_block(inode, iblock, bh, 0); |
2180 | if (err) | |
1da177e4 LT |
2181 | SetPageError(page); |
2182 | } | |
2183 | if (!buffer_mapped(bh)) { | |
eebd2aa3 | 2184 | zero_user(page, i * blocksize, blocksize); |
c64610ba AM |
2185 | if (!err) |
2186 | set_buffer_uptodate(bh); | |
1da177e4 LT |
2187 | continue; |
2188 | } | |
2189 | /* | |
2190 | * get_block() might have updated the buffer | |
2191 | * synchronously | |
2192 | */ | |
2193 | if (buffer_uptodate(bh)) | |
2194 | continue; | |
2195 | } | |
2196 | arr[nr++] = bh; | |
2197 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
2198 | ||
2199 | if (fully_mapped) | |
2200 | SetPageMappedToDisk(page); | |
2201 | ||
2202 | if (!nr) { | |
2203 | /* | |
2204 | * All buffers are uptodate - we can set the page uptodate | |
2205 | * as well. But not if get_block() returned an error. | |
2206 | */ | |
2207 | if (!PageError(page)) | |
2208 | SetPageUptodate(page); | |
2209 | unlock_page(page); | |
2210 | return 0; | |
2211 | } | |
2212 | ||
2213 | /* Stage two: lock the buffers */ | |
2214 | for (i = 0; i < nr; i++) { | |
2215 | bh = arr[i]; | |
2216 | lock_buffer(bh); | |
2217 | mark_buffer_async_read(bh); | |
2218 | } | |
2219 | ||
2220 | /* | |
2221 | * Stage 3: start the IO. Check for uptodateness | |
2222 | * inside the buffer lock in case another process reading | |
2223 | * the underlying blockdev brought it uptodate (the sct fix). | |
2224 | */ | |
2225 | for (i = 0; i < nr; i++) { | |
2226 | bh = arr[i]; | |
2227 | if (buffer_uptodate(bh)) | |
2228 | end_buffer_async_read(bh, 1); | |
2229 | else | |
2230 | submit_bh(READ, bh); | |
2231 | } | |
2232 | return 0; | |
2233 | } | |
1fe72eaa | 2234 | EXPORT_SYMBOL(block_read_full_page); |
1da177e4 LT |
2235 | |
2236 | /* utility function for filesystems that need to do work on expanding | |
89e10787 | 2237 | * truncates. Uses filesystem pagecache writes to allow the filesystem to |
1da177e4 LT |
2238 | * deal with the hole. |
2239 | */ | |
89e10787 | 2240 | int generic_cont_expand_simple(struct inode *inode, loff_t size) |
1da177e4 LT |
2241 | { |
2242 | struct address_space *mapping = inode->i_mapping; | |
2243 | struct page *page; | |
89e10787 | 2244 | void *fsdata; |
1da177e4 LT |
2245 | int err; |
2246 | ||
c08d3b0e | 2247 | err = inode_newsize_ok(inode, size); |
2248 | if (err) | |
1da177e4 LT |
2249 | goto out; |
2250 | ||
89e10787 NP |
2251 | err = pagecache_write_begin(NULL, mapping, size, 0, |
2252 | AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, | |
2253 | &page, &fsdata); | |
2254 | if (err) | |
05eb0b51 | 2255 | goto out; |
05eb0b51 | 2256 | |
89e10787 NP |
2257 | err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); |
2258 | BUG_ON(err > 0); | |
05eb0b51 | 2259 | |
1da177e4 LT |
2260 | out: |
2261 | return err; | |
2262 | } | |
1fe72eaa | 2263 | EXPORT_SYMBOL(generic_cont_expand_simple); |
1da177e4 | 2264 | |
f1e3af72 AB |
2265 | static int cont_expand_zero(struct file *file, struct address_space *mapping, |
2266 | loff_t pos, loff_t *bytes) | |
1da177e4 | 2267 | { |
1da177e4 | 2268 | struct inode *inode = mapping->host; |
1da177e4 | 2269 | unsigned blocksize = 1 << inode->i_blkbits; |
89e10787 NP |
2270 | struct page *page; |
2271 | void *fsdata; | |
2272 | pgoff_t index, curidx; | |
2273 | loff_t curpos; | |
2274 | unsigned zerofrom, offset, len; | |
2275 | int err = 0; | |
1da177e4 | 2276 | |
89e10787 NP |
2277 | index = pos >> PAGE_CACHE_SHIFT; |
2278 | offset = pos & ~PAGE_CACHE_MASK; | |
2279 | ||
2280 | while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { | |
2281 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 LT |
2282 | if (zerofrom & (blocksize-1)) { |
2283 | *bytes |= (blocksize-1); | |
2284 | (*bytes)++; | |
2285 | } | |
89e10787 | 2286 | len = PAGE_CACHE_SIZE - zerofrom; |
1da177e4 | 2287 | |
89e10787 NP |
2288 | err = pagecache_write_begin(file, mapping, curpos, len, |
2289 | AOP_FLAG_UNINTERRUPTIBLE, | |
2290 | &page, &fsdata); | |
2291 | if (err) | |
2292 | goto out; | |
eebd2aa3 | 2293 | zero_user(page, zerofrom, len); |
89e10787 NP |
2294 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2295 | page, fsdata); | |
2296 | if (err < 0) | |
2297 | goto out; | |
2298 | BUG_ON(err != len); | |
2299 | err = 0; | |
061e9746 OH |
2300 | |
2301 | balance_dirty_pages_ratelimited(mapping); | |
89e10787 | 2302 | } |
1da177e4 | 2303 | |
89e10787 NP |
2304 | /* page covers the boundary, find the boundary offset */ |
2305 | if (index == curidx) { | |
2306 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 | 2307 | /* if we will expand the thing last block will be filled */ |
89e10787 NP |
2308 | if (offset <= zerofrom) { |
2309 | goto out; | |
2310 | } | |
2311 | if (zerofrom & (blocksize-1)) { | |
1da177e4 LT |
2312 | *bytes |= (blocksize-1); |
2313 | (*bytes)++; | |
2314 | } | |
89e10787 | 2315 | len = offset - zerofrom; |
1da177e4 | 2316 | |
89e10787 NP |
2317 | err = pagecache_write_begin(file, mapping, curpos, len, |
2318 | AOP_FLAG_UNINTERRUPTIBLE, | |
2319 | &page, &fsdata); | |
2320 | if (err) | |
2321 | goto out; | |
eebd2aa3 | 2322 | zero_user(page, zerofrom, len); |
89e10787 NP |
2323 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2324 | page, fsdata); | |
2325 | if (err < 0) | |
2326 | goto out; | |
2327 | BUG_ON(err != len); | |
2328 | err = 0; | |
1da177e4 | 2329 | } |
89e10787 NP |
2330 | out: |
2331 | return err; | |
2332 | } | |
2333 | ||
2334 | /* | |
2335 | * For moronic filesystems that do not allow holes in file. | |
2336 | * We may have to extend the file. | |
2337 | */ | |
282dc178 | 2338 | int cont_write_begin(struct file *file, struct address_space *mapping, |
89e10787 NP |
2339 | loff_t pos, unsigned len, unsigned flags, |
2340 | struct page **pagep, void **fsdata, | |
2341 | get_block_t *get_block, loff_t *bytes) | |
2342 | { | |
2343 | struct inode *inode = mapping->host; | |
2344 | unsigned blocksize = 1 << inode->i_blkbits; | |
2345 | unsigned zerofrom; | |
2346 | int err; | |
2347 | ||
2348 | err = cont_expand_zero(file, mapping, pos, bytes); | |
2349 | if (err) | |
155130a4 | 2350 | return err; |
89e10787 NP |
2351 | |
2352 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2353 | if (pos+len > *bytes && zerofrom & (blocksize-1)) { | |
2354 | *bytes |= (blocksize-1); | |
2355 | (*bytes)++; | |
1da177e4 | 2356 | } |
1da177e4 | 2357 | |
155130a4 | 2358 | return block_write_begin(mapping, pos, len, flags, pagep, get_block); |
1da177e4 | 2359 | } |
1fe72eaa | 2360 | EXPORT_SYMBOL(cont_write_begin); |
1da177e4 | 2361 | |
1da177e4 LT |
2362 | int block_commit_write(struct page *page, unsigned from, unsigned to) |
2363 | { | |
2364 | struct inode *inode = page->mapping->host; | |
2365 | __block_commit_write(inode,page,from,to); | |
2366 | return 0; | |
2367 | } | |
1fe72eaa | 2368 | EXPORT_SYMBOL(block_commit_write); |
1da177e4 | 2369 | |
54171690 DC |
2370 | /* |
2371 | * block_page_mkwrite() is not allowed to change the file size as it gets | |
2372 | * called from a page fault handler when a page is first dirtied. Hence we must | |
2373 | * be careful to check for EOF conditions here. We set the page up correctly | |
2374 | * for a written page which means we get ENOSPC checking when writing into | |
2375 | * holes and correct delalloc and unwritten extent mapping on filesystems that | |
2376 | * support these features. | |
2377 | * | |
2378 | * We are not allowed to take the i_mutex here so we have to play games to | |
2379 | * protect against truncate races as the page could now be beyond EOF. Because | |
7bb46a67 | 2380 | * truncate writes the inode size before removing pages, once we have the |
54171690 DC |
2381 | * page lock we can determine safely if the page is beyond EOF. If it is not |
2382 | * beyond EOF, then the page is guaranteed safe against truncation until we | |
2383 | * unlock the page. | |
ea13a864 | 2384 | * |
14da9200 JK |
2385 | * Direct callers of this function should protect against filesystem freezing |
2386 | * using sb_start_write() - sb_end_write() functions. | |
54171690 | 2387 | */ |
24da4fab JK |
2388 | int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
2389 | get_block_t get_block) | |
54171690 | 2390 | { |
c2ec175c | 2391 | struct page *page = vmf->page; |
496ad9aa | 2392 | struct inode *inode = file_inode(vma->vm_file); |
54171690 DC |
2393 | unsigned long end; |
2394 | loff_t size; | |
24da4fab | 2395 | int ret; |
54171690 DC |
2396 | |
2397 | lock_page(page); | |
2398 | size = i_size_read(inode); | |
2399 | if ((page->mapping != inode->i_mapping) || | |
18336338 | 2400 | (page_offset(page) > size)) { |
24da4fab JK |
2401 | /* We overload EFAULT to mean page got truncated */ |
2402 | ret = -EFAULT; | |
2403 | goto out_unlock; | |
54171690 DC |
2404 | } |
2405 | ||
2406 | /* page is wholly or partially inside EOF */ | |
2407 | if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) | |
2408 | end = size & ~PAGE_CACHE_MASK; | |
2409 | else | |
2410 | end = PAGE_CACHE_SIZE; | |
2411 | ||
ebdec241 | 2412 | ret = __block_write_begin(page, 0, end, get_block); |
54171690 DC |
2413 | if (!ret) |
2414 | ret = block_commit_write(page, 0, end); | |
2415 | ||
24da4fab JK |
2416 | if (unlikely(ret < 0)) |
2417 | goto out_unlock; | |
ea13a864 | 2418 | set_page_dirty(page); |
1d1d1a76 | 2419 | wait_for_stable_page(page); |
24da4fab JK |
2420 | return 0; |
2421 | out_unlock: | |
2422 | unlock_page(page); | |
54171690 | 2423 | return ret; |
24da4fab JK |
2424 | } |
2425 | EXPORT_SYMBOL(__block_page_mkwrite); | |
2426 | ||
2427 | int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, | |
2428 | get_block_t get_block) | |
2429 | { | |
ea13a864 | 2430 | int ret; |
496ad9aa | 2431 | struct super_block *sb = file_inode(vma->vm_file)->i_sb; |
24da4fab | 2432 | |
14da9200 | 2433 | sb_start_pagefault(sb); |
041bbb6d TT |
2434 | |
2435 | /* | |
2436 | * Update file times before taking page lock. We may end up failing the | |
2437 | * fault so this update may be superfluous but who really cares... | |
2438 | */ | |
2439 | file_update_time(vma->vm_file); | |
2440 | ||
ea13a864 | 2441 | ret = __block_page_mkwrite(vma, vmf, get_block); |
14da9200 | 2442 | sb_end_pagefault(sb); |
24da4fab | 2443 | return block_page_mkwrite_return(ret); |
54171690 | 2444 | } |
1fe72eaa | 2445 | EXPORT_SYMBOL(block_page_mkwrite); |
1da177e4 LT |
2446 | |
2447 | /* | |
03158cd7 | 2448 | * nobh_write_begin()'s prereads are special: the buffer_heads are freed |
1da177e4 LT |
2449 | * immediately, while under the page lock. So it needs a special end_io |
2450 | * handler which does not touch the bh after unlocking it. | |
1da177e4 LT |
2451 | */ |
2452 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2453 | { | |
68671f35 | 2454 | __end_buffer_read_notouch(bh, uptodate); |
1da177e4 LT |
2455 | } |
2456 | ||
03158cd7 NP |
2457 | /* |
2458 | * Attach the singly-linked list of buffers created by nobh_write_begin, to | |
2459 | * the page (converting it to circular linked list and taking care of page | |
2460 | * dirty races). | |
2461 | */ | |
2462 | static void attach_nobh_buffers(struct page *page, struct buffer_head *head) | |
2463 | { | |
2464 | struct buffer_head *bh; | |
2465 | ||
2466 | BUG_ON(!PageLocked(page)); | |
2467 | ||
2468 | spin_lock(&page->mapping->private_lock); | |
2469 | bh = head; | |
2470 | do { | |
2471 | if (PageDirty(page)) | |
2472 | set_buffer_dirty(bh); | |
2473 | if (!bh->b_this_page) | |
2474 | bh->b_this_page = head; | |
2475 | bh = bh->b_this_page; | |
2476 | } while (bh != head); | |
2477 | attach_page_buffers(page, head); | |
2478 | spin_unlock(&page->mapping->private_lock); | |
2479 | } | |
2480 | ||
1da177e4 | 2481 | /* |
ea0f04e5 CH |
2482 | * On entry, the page is fully not uptodate. |
2483 | * On exit the page is fully uptodate in the areas outside (from,to) | |
7bb46a67 | 2484 | * The filesystem needs to handle block truncation upon failure. |
1da177e4 | 2485 | */ |
ea0f04e5 | 2486 | int nobh_write_begin(struct address_space *mapping, |
03158cd7 NP |
2487 | loff_t pos, unsigned len, unsigned flags, |
2488 | struct page **pagep, void **fsdata, | |
1da177e4 LT |
2489 | get_block_t *get_block) |
2490 | { | |
03158cd7 | 2491 | struct inode *inode = mapping->host; |
1da177e4 LT |
2492 | const unsigned blkbits = inode->i_blkbits; |
2493 | const unsigned blocksize = 1 << blkbits; | |
a4b0672d | 2494 | struct buffer_head *head, *bh; |
03158cd7 NP |
2495 | struct page *page; |
2496 | pgoff_t index; | |
2497 | unsigned from, to; | |
1da177e4 | 2498 | unsigned block_in_page; |
a4b0672d | 2499 | unsigned block_start, block_end; |
1da177e4 | 2500 | sector_t block_in_file; |
1da177e4 | 2501 | int nr_reads = 0; |
1da177e4 LT |
2502 | int ret = 0; |
2503 | int is_mapped_to_disk = 1; | |
1da177e4 | 2504 | |
03158cd7 NP |
2505 | index = pos >> PAGE_CACHE_SHIFT; |
2506 | from = pos & (PAGE_CACHE_SIZE - 1); | |
2507 | to = from + len; | |
2508 | ||
54566b2c | 2509 | page = grab_cache_page_write_begin(mapping, index, flags); |
03158cd7 NP |
2510 | if (!page) |
2511 | return -ENOMEM; | |
2512 | *pagep = page; | |
2513 | *fsdata = NULL; | |
2514 | ||
2515 | if (page_has_buffers(page)) { | |
309f77ad NK |
2516 | ret = __block_write_begin(page, pos, len, get_block); |
2517 | if (unlikely(ret)) | |
2518 | goto out_release; | |
2519 | return ret; | |
03158cd7 | 2520 | } |
a4b0672d | 2521 | |
1da177e4 LT |
2522 | if (PageMappedToDisk(page)) |
2523 | return 0; | |
2524 | ||
a4b0672d NP |
2525 | /* |
2526 | * Allocate buffers so that we can keep track of state, and potentially | |
2527 | * attach them to the page if an error occurs. In the common case of | |
2528 | * no error, they will just be freed again without ever being attached | |
2529 | * to the page (which is all OK, because we're under the page lock). | |
2530 | * | |
2531 | * Be careful: the buffer linked list is a NULL terminated one, rather | |
2532 | * than the circular one we're used to. | |
2533 | */ | |
2534 | head = alloc_page_buffers(page, blocksize, 0); | |
03158cd7 NP |
2535 | if (!head) { |
2536 | ret = -ENOMEM; | |
2537 | goto out_release; | |
2538 | } | |
a4b0672d | 2539 | |
1da177e4 | 2540 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); |
1da177e4 LT |
2541 | |
2542 | /* | |
2543 | * We loop across all blocks in the page, whether or not they are | |
2544 | * part of the affected region. This is so we can discover if the | |
2545 | * page is fully mapped-to-disk. | |
2546 | */ | |
a4b0672d | 2547 | for (block_start = 0, block_in_page = 0, bh = head; |
1da177e4 | 2548 | block_start < PAGE_CACHE_SIZE; |
a4b0672d | 2549 | block_in_page++, block_start += blocksize, bh = bh->b_this_page) { |
1da177e4 LT |
2550 | int create; |
2551 | ||
a4b0672d NP |
2552 | block_end = block_start + blocksize; |
2553 | bh->b_state = 0; | |
1da177e4 LT |
2554 | create = 1; |
2555 | if (block_start >= to) | |
2556 | create = 0; | |
2557 | ret = get_block(inode, block_in_file + block_in_page, | |
a4b0672d | 2558 | bh, create); |
1da177e4 LT |
2559 | if (ret) |
2560 | goto failed; | |
a4b0672d | 2561 | if (!buffer_mapped(bh)) |
1da177e4 | 2562 | is_mapped_to_disk = 0; |
a4b0672d NP |
2563 | if (buffer_new(bh)) |
2564 | unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); | |
2565 | if (PageUptodate(page)) { | |
2566 | set_buffer_uptodate(bh); | |
1da177e4 | 2567 | continue; |
a4b0672d NP |
2568 | } |
2569 | if (buffer_new(bh) || !buffer_mapped(bh)) { | |
eebd2aa3 CL |
2570 | zero_user_segments(page, block_start, from, |
2571 | to, block_end); | |
1da177e4 LT |
2572 | continue; |
2573 | } | |
a4b0672d | 2574 | if (buffer_uptodate(bh)) |
1da177e4 LT |
2575 | continue; /* reiserfs does this */ |
2576 | if (block_start < from || block_end > to) { | |
a4b0672d NP |
2577 | lock_buffer(bh); |
2578 | bh->b_end_io = end_buffer_read_nobh; | |
2579 | submit_bh(READ, bh); | |
2580 | nr_reads++; | |
1da177e4 LT |
2581 | } |
2582 | } | |
2583 | ||
2584 | if (nr_reads) { | |
1da177e4 LT |
2585 | /* |
2586 | * The page is locked, so these buffers are protected from | |
2587 | * any VM or truncate activity. Hence we don't need to care | |
2588 | * for the buffer_head refcounts. | |
2589 | */ | |
a4b0672d | 2590 | for (bh = head; bh; bh = bh->b_this_page) { |
1da177e4 LT |
2591 | wait_on_buffer(bh); |
2592 | if (!buffer_uptodate(bh)) | |
2593 | ret = -EIO; | |
1da177e4 LT |
2594 | } |
2595 | if (ret) | |
2596 | goto failed; | |
2597 | } | |
2598 | ||
2599 | if (is_mapped_to_disk) | |
2600 | SetPageMappedToDisk(page); | |
1da177e4 | 2601 | |
03158cd7 | 2602 | *fsdata = head; /* to be released by nobh_write_end */ |
a4b0672d | 2603 | |
1da177e4 LT |
2604 | return 0; |
2605 | ||
2606 | failed: | |
03158cd7 | 2607 | BUG_ON(!ret); |
1da177e4 | 2608 | /* |
a4b0672d NP |
2609 | * Error recovery is a bit difficult. We need to zero out blocks that |
2610 | * were newly allocated, and dirty them to ensure they get written out. | |
2611 | * Buffers need to be attached to the page at this point, otherwise | |
2612 | * the handling of potential IO errors during writeout would be hard | |
2613 | * (could try doing synchronous writeout, but what if that fails too?) | |
1da177e4 | 2614 | */ |
03158cd7 NP |
2615 | attach_nobh_buffers(page, head); |
2616 | page_zero_new_buffers(page, from, to); | |
a4b0672d | 2617 | |
03158cd7 NP |
2618 | out_release: |
2619 | unlock_page(page); | |
2620 | page_cache_release(page); | |
2621 | *pagep = NULL; | |
a4b0672d | 2622 | |
7bb46a67 | 2623 | return ret; |
2624 | } | |
03158cd7 | 2625 | EXPORT_SYMBOL(nobh_write_begin); |
1da177e4 | 2626 | |
03158cd7 NP |
2627 | int nobh_write_end(struct file *file, struct address_space *mapping, |
2628 | loff_t pos, unsigned len, unsigned copied, | |
2629 | struct page *page, void *fsdata) | |
1da177e4 LT |
2630 | { |
2631 | struct inode *inode = page->mapping->host; | |
efdc3131 | 2632 | struct buffer_head *head = fsdata; |
03158cd7 | 2633 | struct buffer_head *bh; |
5b41e74a | 2634 | BUG_ON(fsdata != NULL && page_has_buffers(page)); |
1da177e4 | 2635 | |
d4cf109f | 2636 | if (unlikely(copied < len) && head) |
5b41e74a DM |
2637 | attach_nobh_buffers(page, head); |
2638 | if (page_has_buffers(page)) | |
2639 | return generic_write_end(file, mapping, pos, len, | |
2640 | copied, page, fsdata); | |
a4b0672d | 2641 | |
22c8ca78 | 2642 | SetPageUptodate(page); |
1da177e4 | 2643 | set_page_dirty(page); |
03158cd7 NP |
2644 | if (pos+copied > inode->i_size) { |
2645 | i_size_write(inode, pos+copied); | |
1da177e4 LT |
2646 | mark_inode_dirty(inode); |
2647 | } | |
03158cd7 NP |
2648 | |
2649 | unlock_page(page); | |
2650 | page_cache_release(page); | |
2651 | ||
03158cd7 NP |
2652 | while (head) { |
2653 | bh = head; | |
2654 | head = head->b_this_page; | |
2655 | free_buffer_head(bh); | |
2656 | } | |
2657 | ||
2658 | return copied; | |
1da177e4 | 2659 | } |
03158cd7 | 2660 | EXPORT_SYMBOL(nobh_write_end); |
1da177e4 LT |
2661 | |
2662 | /* | |
2663 | * nobh_writepage() - based on block_full_write_page() except | |
2664 | * that it tries to operate without attaching bufferheads to | |
2665 | * the page. | |
2666 | */ | |
2667 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2668 | struct writeback_control *wbc) | |
2669 | { | |
2670 | struct inode * const inode = page->mapping->host; | |
2671 | loff_t i_size = i_size_read(inode); | |
2672 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2673 | unsigned offset; | |
1da177e4 LT |
2674 | int ret; |
2675 | ||
2676 | /* Is the page fully inside i_size? */ | |
2677 | if (page->index < end_index) | |
2678 | goto out; | |
2679 | ||
2680 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2681 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2682 | if (page->index >= end_index+1 || !offset) { | |
2683 | /* | |
2684 | * The page may have dirty, unmapped buffers. For example, | |
2685 | * they may have been added in ext3_writepage(). Make them | |
2686 | * freeable here, so the page does not leak. | |
2687 | */ | |
2688 | #if 0 | |
2689 | /* Not really sure about this - do we need this ? */ | |
2690 | if (page->mapping->a_ops->invalidatepage) | |
2691 | page->mapping->a_ops->invalidatepage(page, offset); | |
2692 | #endif | |
2693 | unlock_page(page); | |
2694 | return 0; /* don't care */ | |
2695 | } | |
2696 | ||
2697 | /* | |
2698 | * The page straddles i_size. It must be zeroed out on each and every | |
2699 | * writepage invocation because it may be mmapped. "A file is mapped | |
2700 | * in multiples of the page size. For a file that is not a multiple of | |
2701 | * the page size, the remaining memory is zeroed when mapped, and | |
2702 | * writes to that region are not written out to the file." | |
2703 | */ | |
eebd2aa3 | 2704 | zero_user_segment(page, offset, PAGE_CACHE_SIZE); |
1da177e4 LT |
2705 | out: |
2706 | ret = mpage_writepage(page, get_block, wbc); | |
2707 | if (ret == -EAGAIN) | |
35c80d5f CM |
2708 | ret = __block_write_full_page(inode, page, get_block, wbc, |
2709 | end_buffer_async_write); | |
1da177e4 LT |
2710 | return ret; |
2711 | } | |
2712 | EXPORT_SYMBOL(nobh_writepage); | |
2713 | ||
03158cd7 NP |
2714 | int nobh_truncate_page(struct address_space *mapping, |
2715 | loff_t from, get_block_t *get_block) | |
1da177e4 | 2716 | { |
1da177e4 LT |
2717 | pgoff_t index = from >> PAGE_CACHE_SHIFT; |
2718 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
03158cd7 NP |
2719 | unsigned blocksize; |
2720 | sector_t iblock; | |
2721 | unsigned length, pos; | |
2722 | struct inode *inode = mapping->host; | |
1da177e4 | 2723 | struct page *page; |
03158cd7 NP |
2724 | struct buffer_head map_bh; |
2725 | int err; | |
1da177e4 | 2726 | |
03158cd7 NP |
2727 | blocksize = 1 << inode->i_blkbits; |
2728 | length = offset & (blocksize - 1); | |
2729 | ||
2730 | /* Block boundary? Nothing to do */ | |
2731 | if (!length) | |
2732 | return 0; | |
2733 | ||
2734 | length = blocksize - length; | |
2735 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
1da177e4 | 2736 | |
1da177e4 | 2737 | page = grab_cache_page(mapping, index); |
03158cd7 | 2738 | err = -ENOMEM; |
1da177e4 LT |
2739 | if (!page) |
2740 | goto out; | |
2741 | ||
03158cd7 NP |
2742 | if (page_has_buffers(page)) { |
2743 | has_buffers: | |
2744 | unlock_page(page); | |
2745 | page_cache_release(page); | |
2746 | return block_truncate_page(mapping, from, get_block); | |
2747 | } | |
2748 | ||
2749 | /* Find the buffer that contains "offset" */ | |
2750 | pos = blocksize; | |
2751 | while (offset >= pos) { | |
2752 | iblock++; | |
2753 | pos += blocksize; | |
2754 | } | |
2755 | ||
460bcf57 TT |
2756 | map_bh.b_size = blocksize; |
2757 | map_bh.b_state = 0; | |
03158cd7 NP |
2758 | err = get_block(inode, iblock, &map_bh, 0); |
2759 | if (err) | |
2760 | goto unlock; | |
2761 | /* unmapped? It's a hole - nothing to do */ | |
2762 | if (!buffer_mapped(&map_bh)) | |
2763 | goto unlock; | |
2764 | ||
2765 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2766 | if (!PageUptodate(page)) { | |
2767 | err = mapping->a_ops->readpage(NULL, page); | |
2768 | if (err) { | |
2769 | page_cache_release(page); | |
2770 | goto out; | |
2771 | } | |
2772 | lock_page(page); | |
2773 | if (!PageUptodate(page)) { | |
2774 | err = -EIO; | |
2775 | goto unlock; | |
2776 | } | |
2777 | if (page_has_buffers(page)) | |
2778 | goto has_buffers; | |
1da177e4 | 2779 | } |
eebd2aa3 | 2780 | zero_user(page, offset, length); |
03158cd7 NP |
2781 | set_page_dirty(page); |
2782 | err = 0; | |
2783 | ||
2784 | unlock: | |
1da177e4 LT |
2785 | unlock_page(page); |
2786 | page_cache_release(page); | |
2787 | out: | |
03158cd7 | 2788 | return err; |
1da177e4 LT |
2789 | } |
2790 | EXPORT_SYMBOL(nobh_truncate_page); | |
2791 | ||
2792 | int block_truncate_page(struct address_space *mapping, | |
2793 | loff_t from, get_block_t *get_block) | |
2794 | { | |
2795 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2796 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2797 | unsigned blocksize; | |
54b21a79 | 2798 | sector_t iblock; |
1da177e4 LT |
2799 | unsigned length, pos; |
2800 | struct inode *inode = mapping->host; | |
2801 | struct page *page; | |
2802 | struct buffer_head *bh; | |
1da177e4 LT |
2803 | int err; |
2804 | ||
2805 | blocksize = 1 << inode->i_blkbits; | |
2806 | length = offset & (blocksize - 1); | |
2807 | ||
2808 | /* Block boundary? Nothing to do */ | |
2809 | if (!length) | |
2810 | return 0; | |
2811 | ||
2812 | length = blocksize - length; | |
54b21a79 | 2813 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
2814 | |
2815 | page = grab_cache_page(mapping, index); | |
2816 | err = -ENOMEM; | |
2817 | if (!page) | |
2818 | goto out; | |
2819 | ||
2820 | if (!page_has_buffers(page)) | |
2821 | create_empty_buffers(page, blocksize, 0); | |
2822 | ||
2823 | /* Find the buffer that contains "offset" */ | |
2824 | bh = page_buffers(page); | |
2825 | pos = blocksize; | |
2826 | while (offset >= pos) { | |
2827 | bh = bh->b_this_page; | |
2828 | iblock++; | |
2829 | pos += blocksize; | |
2830 | } | |
2831 | ||
2832 | err = 0; | |
2833 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 2834 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
2835 | err = get_block(inode, iblock, bh, 0); |
2836 | if (err) | |
2837 | goto unlock; | |
2838 | /* unmapped? It's a hole - nothing to do */ | |
2839 | if (!buffer_mapped(bh)) | |
2840 | goto unlock; | |
2841 | } | |
2842 | ||
2843 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2844 | if (PageUptodate(page)) | |
2845 | set_buffer_uptodate(bh); | |
2846 | ||
33a266dd | 2847 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { |
1da177e4 LT |
2848 | err = -EIO; |
2849 | ll_rw_block(READ, 1, &bh); | |
2850 | wait_on_buffer(bh); | |
2851 | /* Uhhuh. Read error. Complain and punt. */ | |
2852 | if (!buffer_uptodate(bh)) | |
2853 | goto unlock; | |
2854 | } | |
2855 | ||
eebd2aa3 | 2856 | zero_user(page, offset, length); |
1da177e4 LT |
2857 | mark_buffer_dirty(bh); |
2858 | err = 0; | |
2859 | ||
2860 | unlock: | |
2861 | unlock_page(page); | |
2862 | page_cache_release(page); | |
2863 | out: | |
2864 | return err; | |
2865 | } | |
1fe72eaa | 2866 | EXPORT_SYMBOL(block_truncate_page); |
1da177e4 LT |
2867 | |
2868 | /* | |
2869 | * The generic ->writepage function for buffer-backed address_spaces | |
35c80d5f | 2870 | * this form passes in the end_io handler used to finish the IO. |
1da177e4 | 2871 | */ |
35c80d5f CM |
2872 | int block_write_full_page_endio(struct page *page, get_block_t *get_block, |
2873 | struct writeback_control *wbc, bh_end_io_t *handler) | |
1da177e4 LT |
2874 | { |
2875 | struct inode * const inode = page->mapping->host; | |
2876 | loff_t i_size = i_size_read(inode); | |
2877 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2878 | unsigned offset; | |
1da177e4 LT |
2879 | |
2880 | /* Is the page fully inside i_size? */ | |
2881 | if (page->index < end_index) | |
35c80d5f CM |
2882 | return __block_write_full_page(inode, page, get_block, wbc, |
2883 | handler); | |
1da177e4 LT |
2884 | |
2885 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2886 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2887 | if (page->index >= end_index+1 || !offset) { | |
2888 | /* | |
2889 | * The page may have dirty, unmapped buffers. For example, | |
2890 | * they may have been added in ext3_writepage(). Make them | |
2891 | * freeable here, so the page does not leak. | |
2892 | */ | |
d47992f8 | 2893 | do_invalidatepage(page, 0, PAGE_CACHE_SIZE); |
1da177e4 LT |
2894 | unlock_page(page); |
2895 | return 0; /* don't care */ | |
2896 | } | |
2897 | ||
2898 | /* | |
2899 | * The page straddles i_size. It must be zeroed out on each and every | |
2a61aa40 | 2900 | * writepage invocation because it may be mmapped. "A file is mapped |
1da177e4 LT |
2901 | * in multiples of the page size. For a file that is not a multiple of |
2902 | * the page size, the remaining memory is zeroed when mapped, and | |
2903 | * writes to that region are not written out to the file." | |
2904 | */ | |
eebd2aa3 | 2905 | zero_user_segment(page, offset, PAGE_CACHE_SIZE); |
35c80d5f | 2906 | return __block_write_full_page(inode, page, get_block, wbc, handler); |
1da177e4 | 2907 | } |
1fe72eaa | 2908 | EXPORT_SYMBOL(block_write_full_page_endio); |
1da177e4 | 2909 | |
35c80d5f CM |
2910 | /* |
2911 | * The generic ->writepage function for buffer-backed address_spaces | |
2912 | */ | |
2913 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
2914 | struct writeback_control *wbc) | |
2915 | { | |
2916 | return block_write_full_page_endio(page, get_block, wbc, | |
2917 | end_buffer_async_write); | |
2918 | } | |
1fe72eaa | 2919 | EXPORT_SYMBOL(block_write_full_page); |
35c80d5f | 2920 | |
1da177e4 LT |
2921 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, |
2922 | get_block_t *get_block) | |
2923 | { | |
2924 | struct buffer_head tmp; | |
2925 | struct inode *inode = mapping->host; | |
2926 | tmp.b_state = 0; | |
2927 | tmp.b_blocknr = 0; | |
b0cf2321 | 2928 | tmp.b_size = 1 << inode->i_blkbits; |
1da177e4 LT |
2929 | get_block(inode, block, &tmp, 0); |
2930 | return tmp.b_blocknr; | |
2931 | } | |
1fe72eaa | 2932 | EXPORT_SYMBOL(generic_block_bmap); |
1da177e4 | 2933 | |
6712ecf8 | 2934 | static void end_bio_bh_io_sync(struct bio *bio, int err) |
1da177e4 LT |
2935 | { |
2936 | struct buffer_head *bh = bio->bi_private; | |
2937 | ||
1da177e4 LT |
2938 | if (err == -EOPNOTSUPP) { |
2939 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
1da177e4 LT |
2940 | } |
2941 | ||
08bafc03 KM |
2942 | if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags))) |
2943 | set_bit(BH_Quiet, &bh->b_state); | |
2944 | ||
1da177e4 LT |
2945 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); |
2946 | bio_put(bio); | |
1da177e4 LT |
2947 | } |
2948 | ||
57302e0d LT |
2949 | /* |
2950 | * This allows us to do IO even on the odd last sectors | |
2951 | * of a device, even if the bh block size is some multiple | |
2952 | * of the physical sector size. | |
2953 | * | |
2954 | * We'll just truncate the bio to the size of the device, | |
2955 | * and clear the end of the buffer head manually. | |
2956 | * | |
2957 | * Truly out-of-range accesses will turn into actual IO | |
2958 | * errors, this only handles the "we need to be able to | |
2959 | * do IO at the final sector" case. | |
2960 | */ | |
2961 | static void guard_bh_eod(int rw, struct bio *bio, struct buffer_head *bh) | |
2962 | { | |
2963 | sector_t maxsector; | |
2964 | unsigned bytes; | |
2965 | ||
2966 | maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; | |
2967 | if (!maxsector) | |
2968 | return; | |
2969 | ||
2970 | /* | |
2971 | * If the *whole* IO is past the end of the device, | |
2972 | * let it through, and the IO layer will turn it into | |
2973 | * an EIO. | |
2974 | */ | |
2975 | if (unlikely(bio->bi_sector >= maxsector)) | |
2976 | return; | |
2977 | ||
2978 | maxsector -= bio->bi_sector; | |
2979 | bytes = bio->bi_size; | |
2980 | if (likely((bytes >> 9) <= maxsector)) | |
2981 | return; | |
2982 | ||
2983 | /* Uhhuh. We've got a bh that straddles the device size! */ | |
2984 | bytes = maxsector << 9; | |
2985 | ||
2986 | /* Truncate the bio.. */ | |
2987 | bio->bi_size = bytes; | |
2988 | bio->bi_io_vec[0].bv_len = bytes; | |
2989 | ||
2990 | /* ..and clear the end of the buffer for reads */ | |
27d7c2a0 | 2991 | if ((rw & RW_MASK) == READ) { |
57302e0d LT |
2992 | void *kaddr = kmap_atomic(bh->b_page); |
2993 | memset(kaddr + bh_offset(bh) + bytes, 0, bh->b_size - bytes); | |
2994 | kunmap_atomic(kaddr); | |
6d283dba | 2995 | flush_dcache_page(bh->b_page); |
57302e0d LT |
2996 | } |
2997 | } | |
2998 | ||
71368511 | 2999 | int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags) |
1da177e4 LT |
3000 | { |
3001 | struct bio *bio; | |
3002 | int ret = 0; | |
3003 | ||
3004 | BUG_ON(!buffer_locked(bh)); | |
3005 | BUG_ON(!buffer_mapped(bh)); | |
3006 | BUG_ON(!bh->b_end_io); | |
8fb0e342 AK |
3007 | BUG_ON(buffer_delay(bh)); |
3008 | BUG_ON(buffer_unwritten(bh)); | |
1da177e4 | 3009 | |
1da177e4 | 3010 | /* |
48fd4f93 | 3011 | * Only clear out a write error when rewriting |
1da177e4 | 3012 | */ |
48fd4f93 | 3013 | if (test_set_buffer_req(bh) && (rw & WRITE)) |
1da177e4 LT |
3014 | clear_buffer_write_io_error(bh); |
3015 | ||
3016 | /* | |
3017 | * from here on down, it's all bio -- do the initial mapping, | |
3018 | * submit_bio -> generic_make_request may further map this bio around | |
3019 | */ | |
3020 | bio = bio_alloc(GFP_NOIO, 1); | |
3021 | ||
3022 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); | |
3023 | bio->bi_bdev = bh->b_bdev; | |
3024 | bio->bi_io_vec[0].bv_page = bh->b_page; | |
3025 | bio->bi_io_vec[0].bv_len = bh->b_size; | |
3026 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); | |
3027 | ||
3028 | bio->bi_vcnt = 1; | |
1da177e4 LT |
3029 | bio->bi_size = bh->b_size; |
3030 | ||
3031 | bio->bi_end_io = end_bio_bh_io_sync; | |
3032 | bio->bi_private = bh; | |
71368511 | 3033 | bio->bi_flags |= bio_flags; |
1da177e4 | 3034 | |
57302e0d LT |
3035 | /* Take care of bh's that straddle the end of the device */ |
3036 | guard_bh_eod(rw, bio, bh); | |
3037 | ||
877f962c TT |
3038 | if (buffer_meta(bh)) |
3039 | rw |= REQ_META; | |
3040 | if (buffer_prio(bh)) | |
3041 | rw |= REQ_PRIO; | |
3042 | ||
1da177e4 LT |
3043 | bio_get(bio); |
3044 | submit_bio(rw, bio); | |
3045 | ||
3046 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) | |
3047 | ret = -EOPNOTSUPP; | |
3048 | ||
3049 | bio_put(bio); | |
3050 | return ret; | |
3051 | } | |
71368511 DW |
3052 | EXPORT_SYMBOL_GPL(_submit_bh); |
3053 | ||
3054 | int submit_bh(int rw, struct buffer_head *bh) | |
3055 | { | |
3056 | return _submit_bh(rw, bh, 0); | |
3057 | } | |
1fe72eaa | 3058 | EXPORT_SYMBOL(submit_bh); |
1da177e4 LT |
3059 | |
3060 | /** | |
3061 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
9cb569d6 | 3062 | * @rw: whether to %READ or %WRITE or maybe %READA (readahead) |
1da177e4 LT |
3063 | * @nr: number of &struct buffer_heads in the array |
3064 | * @bhs: array of pointers to &struct buffer_head | |
3065 | * | |
a7662236 JK |
3066 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
3067 | * requests an I/O operation on them, either a %READ or a %WRITE. The third | |
9cb569d6 CH |
3068 | * %READA option is described in the documentation for generic_make_request() |
3069 | * which ll_rw_block() calls. | |
1da177e4 LT |
3070 | * |
3071 | * This function drops any buffer that it cannot get a lock on (with the | |
9cb569d6 CH |
3072 | * BH_Lock state bit), any buffer that appears to be clean when doing a write |
3073 | * request, and any buffer that appears to be up-to-date when doing read | |
3074 | * request. Further it marks as clean buffers that are processed for | |
3075 | * writing (the buffer cache won't assume that they are actually clean | |
3076 | * until the buffer gets unlocked). | |
1da177e4 LT |
3077 | * |
3078 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
3079 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes | |
3080 | * any waiters. | |
3081 | * | |
3082 | * All of the buffers must be for the same device, and must also be a | |
3083 | * multiple of the current approved size for the device. | |
3084 | */ | |
3085 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) | |
3086 | { | |
3087 | int i; | |
3088 | ||
3089 | for (i = 0; i < nr; i++) { | |
3090 | struct buffer_head *bh = bhs[i]; | |
3091 | ||
9cb569d6 | 3092 | if (!trylock_buffer(bh)) |
1da177e4 | 3093 | continue; |
9cb569d6 | 3094 | if (rw == WRITE) { |
1da177e4 | 3095 | if (test_clear_buffer_dirty(bh)) { |
76c3073a | 3096 | bh->b_end_io = end_buffer_write_sync; |
e60e5c50 | 3097 | get_bh(bh); |
9cb569d6 | 3098 | submit_bh(WRITE, bh); |
1da177e4 LT |
3099 | continue; |
3100 | } | |
3101 | } else { | |
1da177e4 | 3102 | if (!buffer_uptodate(bh)) { |
76c3073a | 3103 | bh->b_end_io = end_buffer_read_sync; |
e60e5c50 | 3104 | get_bh(bh); |
1da177e4 LT |
3105 | submit_bh(rw, bh); |
3106 | continue; | |
3107 | } | |
3108 | } | |
3109 | unlock_buffer(bh); | |
1da177e4 LT |
3110 | } |
3111 | } | |
1fe72eaa | 3112 | EXPORT_SYMBOL(ll_rw_block); |
1da177e4 | 3113 | |
9cb569d6 CH |
3114 | void write_dirty_buffer(struct buffer_head *bh, int rw) |
3115 | { | |
3116 | lock_buffer(bh); | |
3117 | if (!test_clear_buffer_dirty(bh)) { | |
3118 | unlock_buffer(bh); | |
3119 | return; | |
3120 | } | |
3121 | bh->b_end_io = end_buffer_write_sync; | |
3122 | get_bh(bh); | |
3123 | submit_bh(rw, bh); | |
3124 | } | |
3125 | EXPORT_SYMBOL(write_dirty_buffer); | |
3126 | ||
1da177e4 LT |
3127 | /* |
3128 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
3129 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
3130 | * the buffer_head. | |
3131 | */ | |
87e99511 | 3132 | int __sync_dirty_buffer(struct buffer_head *bh, int rw) |
1da177e4 LT |
3133 | { |
3134 | int ret = 0; | |
3135 | ||
3136 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
3137 | lock_buffer(bh); | |
3138 | if (test_clear_buffer_dirty(bh)) { | |
3139 | get_bh(bh); | |
3140 | bh->b_end_io = end_buffer_write_sync; | |
87e99511 | 3141 | ret = submit_bh(rw, bh); |
1da177e4 | 3142 | wait_on_buffer(bh); |
1da177e4 LT |
3143 | if (!ret && !buffer_uptodate(bh)) |
3144 | ret = -EIO; | |
3145 | } else { | |
3146 | unlock_buffer(bh); | |
3147 | } | |
3148 | return ret; | |
3149 | } | |
87e99511 CH |
3150 | EXPORT_SYMBOL(__sync_dirty_buffer); |
3151 | ||
3152 | int sync_dirty_buffer(struct buffer_head *bh) | |
3153 | { | |
3154 | return __sync_dirty_buffer(bh, WRITE_SYNC); | |
3155 | } | |
1fe72eaa | 3156 | EXPORT_SYMBOL(sync_dirty_buffer); |
1da177e4 LT |
3157 | |
3158 | /* | |
3159 | * try_to_free_buffers() checks if all the buffers on this particular page | |
3160 | * are unused, and releases them if so. | |
3161 | * | |
3162 | * Exclusion against try_to_free_buffers may be obtained by either | |
3163 | * locking the page or by holding its mapping's private_lock. | |
3164 | * | |
3165 | * If the page is dirty but all the buffers are clean then we need to | |
3166 | * be sure to mark the page clean as well. This is because the page | |
3167 | * may be against a block device, and a later reattachment of buffers | |
3168 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
3169 | * filesystem data on the same device. | |
3170 | * | |
3171 | * The same applies to regular filesystem pages: if all the buffers are | |
3172 | * clean then we set the page clean and proceed. To do that, we require | |
3173 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
3174 | * private_lock. | |
3175 | * | |
3176 | * try_to_free_buffers() is non-blocking. | |
3177 | */ | |
3178 | static inline int buffer_busy(struct buffer_head *bh) | |
3179 | { | |
3180 | return atomic_read(&bh->b_count) | | |
3181 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
3182 | } | |
3183 | ||
3184 | static int | |
3185 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
3186 | { | |
3187 | struct buffer_head *head = page_buffers(page); | |
3188 | struct buffer_head *bh; | |
3189 | ||
3190 | bh = head; | |
3191 | do { | |
de7d5a3b | 3192 | if (buffer_write_io_error(bh) && page->mapping) |
1da177e4 LT |
3193 | set_bit(AS_EIO, &page->mapping->flags); |
3194 | if (buffer_busy(bh)) | |
3195 | goto failed; | |
3196 | bh = bh->b_this_page; | |
3197 | } while (bh != head); | |
3198 | ||
3199 | do { | |
3200 | struct buffer_head *next = bh->b_this_page; | |
3201 | ||
535ee2fb | 3202 | if (bh->b_assoc_map) |
1da177e4 LT |
3203 | __remove_assoc_queue(bh); |
3204 | bh = next; | |
3205 | } while (bh != head); | |
3206 | *buffers_to_free = head; | |
3207 | __clear_page_buffers(page); | |
3208 | return 1; | |
3209 | failed: | |
3210 | return 0; | |
3211 | } | |
3212 | ||
3213 | int try_to_free_buffers(struct page *page) | |
3214 | { | |
3215 | struct address_space * const mapping = page->mapping; | |
3216 | struct buffer_head *buffers_to_free = NULL; | |
3217 | int ret = 0; | |
3218 | ||
3219 | BUG_ON(!PageLocked(page)); | |
ecdfc978 | 3220 | if (PageWriteback(page)) |
1da177e4 LT |
3221 | return 0; |
3222 | ||
3223 | if (mapping == NULL) { /* can this still happen? */ | |
3224 | ret = drop_buffers(page, &buffers_to_free); | |
3225 | goto out; | |
3226 | } | |
3227 | ||
3228 | spin_lock(&mapping->private_lock); | |
3229 | ret = drop_buffers(page, &buffers_to_free); | |
ecdfc978 LT |
3230 | |
3231 | /* | |
3232 | * If the filesystem writes its buffers by hand (eg ext3) | |
3233 | * then we can have clean buffers against a dirty page. We | |
3234 | * clean the page here; otherwise the VM will never notice | |
3235 | * that the filesystem did any IO at all. | |
3236 | * | |
3237 | * Also, during truncate, discard_buffer will have marked all | |
3238 | * the page's buffers clean. We discover that here and clean | |
3239 | * the page also. | |
87df7241 NP |
3240 | * |
3241 | * private_lock must be held over this entire operation in order | |
3242 | * to synchronise against __set_page_dirty_buffers and prevent the | |
3243 | * dirty bit from being lost. | |
ecdfc978 LT |
3244 | */ |
3245 | if (ret) | |
3246 | cancel_dirty_page(page, PAGE_CACHE_SIZE); | |
87df7241 | 3247 | spin_unlock(&mapping->private_lock); |
1da177e4 LT |
3248 | out: |
3249 | if (buffers_to_free) { | |
3250 | struct buffer_head *bh = buffers_to_free; | |
3251 | ||
3252 | do { | |
3253 | struct buffer_head *next = bh->b_this_page; | |
3254 | free_buffer_head(bh); | |
3255 | bh = next; | |
3256 | } while (bh != buffers_to_free); | |
3257 | } | |
3258 | return ret; | |
3259 | } | |
3260 | EXPORT_SYMBOL(try_to_free_buffers); | |
3261 | ||
1da177e4 LT |
3262 | /* |
3263 | * There are no bdflush tunables left. But distributions are | |
3264 | * still running obsolete flush daemons, so we terminate them here. | |
3265 | * | |
3266 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
5b0830cb | 3267 | * The `flush-X' kernel threads fully replace bdflush daemons and this call. |
1da177e4 | 3268 | */ |
bdc480e3 | 3269 | SYSCALL_DEFINE2(bdflush, int, func, long, data) |
1da177e4 LT |
3270 | { |
3271 | static int msg_count; | |
3272 | ||
3273 | if (!capable(CAP_SYS_ADMIN)) | |
3274 | return -EPERM; | |
3275 | ||
3276 | if (msg_count < 5) { | |
3277 | msg_count++; | |
3278 | printk(KERN_INFO | |
3279 | "warning: process `%s' used the obsolete bdflush" | |
3280 | " system call\n", current->comm); | |
3281 | printk(KERN_INFO "Fix your initscripts?\n"); | |
3282 | } | |
3283 | ||
3284 | if (func == 1) | |
3285 | do_exit(0); | |
3286 | return 0; | |
3287 | } | |
3288 | ||
3289 | /* | |
3290 | * Buffer-head allocation | |
3291 | */ | |
a0a9b043 | 3292 | static struct kmem_cache *bh_cachep __read_mostly; |
1da177e4 LT |
3293 | |
3294 | /* | |
3295 | * Once the number of bh's in the machine exceeds this level, we start | |
3296 | * stripping them in writeback. | |
3297 | */ | |
43be594a | 3298 | static unsigned long max_buffer_heads; |
1da177e4 LT |
3299 | |
3300 | int buffer_heads_over_limit; | |
3301 | ||
3302 | struct bh_accounting { | |
3303 | int nr; /* Number of live bh's */ | |
3304 | int ratelimit; /* Limit cacheline bouncing */ | |
3305 | }; | |
3306 | ||
3307 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
3308 | ||
3309 | static void recalc_bh_state(void) | |
3310 | { | |
3311 | int i; | |
3312 | int tot = 0; | |
3313 | ||
ee1be862 | 3314 | if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) |
1da177e4 | 3315 | return; |
c7b92516 | 3316 | __this_cpu_write(bh_accounting.ratelimit, 0); |
8a143426 | 3317 | for_each_online_cpu(i) |
1da177e4 LT |
3318 | tot += per_cpu(bh_accounting, i).nr; |
3319 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
3320 | } | |
c7b92516 | 3321 | |
dd0fc66f | 3322 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
1da177e4 | 3323 | { |
019b4d12 | 3324 | struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); |
1da177e4 | 3325 | if (ret) { |
a35afb83 | 3326 | INIT_LIST_HEAD(&ret->b_assoc_buffers); |
c7b92516 CL |
3327 | preempt_disable(); |
3328 | __this_cpu_inc(bh_accounting.nr); | |
1da177e4 | 3329 | recalc_bh_state(); |
c7b92516 | 3330 | preempt_enable(); |
1da177e4 LT |
3331 | } |
3332 | return ret; | |
3333 | } | |
3334 | EXPORT_SYMBOL(alloc_buffer_head); | |
3335 | ||
3336 | void free_buffer_head(struct buffer_head *bh) | |
3337 | { | |
3338 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
3339 | kmem_cache_free(bh_cachep, bh); | |
c7b92516 CL |
3340 | preempt_disable(); |
3341 | __this_cpu_dec(bh_accounting.nr); | |
1da177e4 | 3342 | recalc_bh_state(); |
c7b92516 | 3343 | preempt_enable(); |
1da177e4 LT |
3344 | } |
3345 | EXPORT_SYMBOL(free_buffer_head); | |
3346 | ||
1da177e4 LT |
3347 | static void buffer_exit_cpu(int cpu) |
3348 | { | |
3349 | int i; | |
3350 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
3351 | ||
3352 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
3353 | brelse(b->bhs[i]); | |
3354 | b->bhs[i] = NULL; | |
3355 | } | |
c7b92516 | 3356 | this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); |
8a143426 | 3357 | per_cpu(bh_accounting, cpu).nr = 0; |
1da177e4 LT |
3358 | } |
3359 | ||
3360 | static int buffer_cpu_notify(struct notifier_block *self, | |
3361 | unsigned long action, void *hcpu) | |
3362 | { | |
8bb78442 | 3363 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) |
1da177e4 LT |
3364 | buffer_exit_cpu((unsigned long)hcpu); |
3365 | return NOTIFY_OK; | |
3366 | } | |
1da177e4 | 3367 | |
389d1b08 | 3368 | /** |
a6b91919 | 3369 | * bh_uptodate_or_lock - Test whether the buffer is uptodate |
389d1b08 AK |
3370 | * @bh: struct buffer_head |
3371 | * | |
3372 | * Return true if the buffer is up-to-date and false, | |
3373 | * with the buffer locked, if not. | |
3374 | */ | |
3375 | int bh_uptodate_or_lock(struct buffer_head *bh) | |
3376 | { | |
3377 | if (!buffer_uptodate(bh)) { | |
3378 | lock_buffer(bh); | |
3379 | if (!buffer_uptodate(bh)) | |
3380 | return 0; | |
3381 | unlock_buffer(bh); | |
3382 | } | |
3383 | return 1; | |
3384 | } | |
3385 | EXPORT_SYMBOL(bh_uptodate_or_lock); | |
3386 | ||
3387 | /** | |
a6b91919 | 3388 | * bh_submit_read - Submit a locked buffer for reading |
389d1b08 AK |
3389 | * @bh: struct buffer_head |
3390 | * | |
3391 | * Returns zero on success and -EIO on error. | |
3392 | */ | |
3393 | int bh_submit_read(struct buffer_head *bh) | |
3394 | { | |
3395 | BUG_ON(!buffer_locked(bh)); | |
3396 | ||
3397 | if (buffer_uptodate(bh)) { | |
3398 | unlock_buffer(bh); | |
3399 | return 0; | |
3400 | } | |
3401 | ||
3402 | get_bh(bh); | |
3403 | bh->b_end_io = end_buffer_read_sync; | |
3404 | submit_bh(READ, bh); | |
3405 | wait_on_buffer(bh); | |
3406 | if (buffer_uptodate(bh)) | |
3407 | return 0; | |
3408 | return -EIO; | |
3409 | } | |
3410 | EXPORT_SYMBOL(bh_submit_read); | |
3411 | ||
1da177e4 LT |
3412 | void __init buffer_init(void) |
3413 | { | |
43be594a | 3414 | unsigned long nrpages; |
1da177e4 | 3415 | |
b98938c3 CL |
3416 | bh_cachep = kmem_cache_create("buffer_head", |
3417 | sizeof(struct buffer_head), 0, | |
3418 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| | |
3419 | SLAB_MEM_SPREAD), | |
019b4d12 | 3420 | NULL); |
1da177e4 LT |
3421 | |
3422 | /* | |
3423 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3424 | */ | |
3425 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3426 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
3427 | hotcpu_notifier(buffer_cpu_notify, 0); | |
3428 | } |