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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/buffer.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 2002 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95 | |
9 | * | |
10 | * Removed a lot of unnecessary code and simplified things now that | |
11 | * the buffer cache isn't our primary cache - Andrew Tridgell 12/96 | |
12 | * | |
13 | * Speed up hash, lru, and free list operations. Use gfp() for allocating | |
14 | * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM | |
15 | * | |
16 | * Added 32k buffer block sizes - these are required older ARM systems. - RMK | |
17 | * | |
18 | * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de> | |
19 | */ | |
20 | ||
1da177e4 LT |
21 | #include <linux/kernel.h> |
22 | #include <linux/syscalls.h> | |
23 | #include <linux/fs.h> | |
24 | #include <linux/mm.h> | |
25 | #include <linux/percpu.h> | |
26 | #include <linux/slab.h> | |
16f7e0fe | 27 | #include <linux/capability.h> |
1da177e4 LT |
28 | #include <linux/blkdev.h> |
29 | #include <linux/file.h> | |
30 | #include <linux/quotaops.h> | |
31 | #include <linux/highmem.h> | |
32 | #include <linux/module.h> | |
33 | #include <linux/writeback.h> | |
34 | #include <linux/hash.h> | |
35 | #include <linux/suspend.h> | |
36 | #include <linux/buffer_head.h> | |
55e829af | 37 | #include <linux/task_io_accounting_ops.h> |
1da177e4 LT |
38 | #include <linux/bio.h> |
39 | #include <linux/notifier.h> | |
40 | #include <linux/cpu.h> | |
41 | #include <linux/bitops.h> | |
42 | #include <linux/mpage.h> | |
fb1c8f93 | 43 | #include <linux/bit_spinlock.h> |
c515e1fd | 44 | #include <linux/cleancache.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 | ||
50 | inline void | |
51 | init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) | |
52 | { | |
53 | bh->b_end_io = handler; | |
54 | bh->b_private = private; | |
55 | } | |
1fe72eaa | 56 | EXPORT_SYMBOL(init_buffer); |
1da177e4 | 57 | |
7eaceacc | 58 | static int sleep_on_buffer(void *word) |
1da177e4 | 59 | { |
1da177e4 LT |
60 | io_schedule(); |
61 | return 0; | |
62 | } | |
63 | ||
fc9b52cd | 64 | void __lock_buffer(struct buffer_head *bh) |
1da177e4 | 65 | { |
7eaceacc | 66 | wait_on_bit_lock(&bh->b_state, BH_Lock, sleep_on_buffer, |
1da177e4 LT |
67 | TASK_UNINTERRUPTIBLE); |
68 | } | |
69 | EXPORT_SYMBOL(__lock_buffer); | |
70 | ||
fc9b52cd | 71 | void unlock_buffer(struct buffer_head *bh) |
1da177e4 | 72 | { |
51b07fc3 | 73 | clear_bit_unlock(BH_Lock, &bh->b_state); |
1da177e4 LT |
74 | smp_mb__after_clear_bit(); |
75 | wake_up_bit(&bh->b_state, BH_Lock); | |
76 | } | |
1fe72eaa | 77 | EXPORT_SYMBOL(unlock_buffer); |
1da177e4 LT |
78 | |
79 | /* | |
80 | * Block until a buffer comes unlocked. This doesn't stop it | |
81 | * from becoming locked again - you have to lock it yourself | |
82 | * if you want to preserve its state. | |
83 | */ | |
84 | void __wait_on_buffer(struct buffer_head * bh) | |
85 | { | |
7eaceacc | 86 | wait_on_bit(&bh->b_state, BH_Lock, sleep_on_buffer, TASK_UNINTERRUPTIBLE); |
1da177e4 | 87 | } |
1fe72eaa | 88 | EXPORT_SYMBOL(__wait_on_buffer); |
1da177e4 LT |
89 | |
90 | static void | |
91 | __clear_page_buffers(struct page *page) | |
92 | { | |
93 | ClearPagePrivate(page); | |
4c21e2f2 | 94 | set_page_private(page, 0); |
1da177e4 LT |
95 | page_cache_release(page); |
96 | } | |
97 | ||
08bafc03 KM |
98 | |
99 | static int quiet_error(struct buffer_head *bh) | |
100 | { | |
101 | if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit()) | |
102 | return 0; | |
103 | return 1; | |
104 | } | |
105 | ||
106 | ||
1da177e4 LT |
107 | static void buffer_io_error(struct buffer_head *bh) |
108 | { | |
109 | char b[BDEVNAME_SIZE]; | |
1da177e4 LT |
110 | printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", |
111 | bdevname(bh->b_bdev, b), | |
112 | (unsigned long long)bh->b_blocknr); | |
113 | } | |
114 | ||
115 | /* | |
68671f35 DM |
116 | * End-of-IO handler helper function which does not touch the bh after |
117 | * unlocking it. | |
118 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but | |
119 | * a race there is benign: unlock_buffer() only use the bh's address for | |
120 | * hashing after unlocking the buffer, so it doesn't actually touch the bh | |
121 | * itself. | |
1da177e4 | 122 | */ |
68671f35 | 123 | static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
124 | { |
125 | if (uptodate) { | |
126 | set_buffer_uptodate(bh); | |
127 | } else { | |
128 | /* This happens, due to failed READA attempts. */ | |
129 | clear_buffer_uptodate(bh); | |
130 | } | |
131 | unlock_buffer(bh); | |
68671f35 DM |
132 | } |
133 | ||
134 | /* | |
135 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and | |
136 | * unlock the buffer. This is what ll_rw_block uses too. | |
137 | */ | |
138 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) | |
139 | { | |
140 | __end_buffer_read_notouch(bh, uptodate); | |
1da177e4 LT |
141 | put_bh(bh); |
142 | } | |
1fe72eaa | 143 | EXPORT_SYMBOL(end_buffer_read_sync); |
1da177e4 LT |
144 | |
145 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) | |
146 | { | |
147 | char b[BDEVNAME_SIZE]; | |
148 | ||
149 | if (uptodate) { | |
150 | set_buffer_uptodate(bh); | |
151 | } else { | |
0edd55fa | 152 | if (!quiet_error(bh)) { |
1da177e4 LT |
153 | buffer_io_error(bh); |
154 | printk(KERN_WARNING "lost page write due to " | |
155 | "I/O error on %s\n", | |
156 | bdevname(bh->b_bdev, b)); | |
157 | } | |
158 | set_buffer_write_io_error(bh); | |
159 | clear_buffer_uptodate(bh); | |
160 | } | |
161 | unlock_buffer(bh); | |
162 | put_bh(bh); | |
163 | } | |
1fe72eaa | 164 | EXPORT_SYMBOL(end_buffer_write_sync); |
1da177e4 | 165 | |
1da177e4 LT |
166 | /* |
167 | * Various filesystems appear to want __find_get_block to be non-blocking. | |
168 | * But it's the page lock which protects the buffers. To get around this, | |
169 | * we get exclusion from try_to_free_buffers with the blockdev mapping's | |
170 | * private_lock. | |
171 | * | |
172 | * Hack idea: for the blockdev mapping, i_bufferlist_lock contention | |
173 | * may be quite high. This code could TryLock the page, and if that | |
174 | * succeeds, there is no need to take private_lock. (But if | |
175 | * private_lock is contended then so is mapping->tree_lock). | |
176 | */ | |
177 | static struct buffer_head * | |
385fd4c5 | 178 | __find_get_block_slow(struct block_device *bdev, sector_t block) |
1da177e4 LT |
179 | { |
180 | struct inode *bd_inode = bdev->bd_inode; | |
181 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
182 | struct buffer_head *ret = NULL; | |
183 | pgoff_t index; | |
184 | struct buffer_head *bh; | |
185 | struct buffer_head *head; | |
186 | struct page *page; | |
187 | int all_mapped = 1; | |
188 | ||
189 | index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); | |
190 | page = find_get_page(bd_mapping, index); | |
191 | if (!page) | |
192 | goto out; | |
193 | ||
194 | spin_lock(&bd_mapping->private_lock); | |
195 | if (!page_has_buffers(page)) | |
196 | goto out_unlock; | |
197 | head = page_buffers(page); | |
198 | bh = head; | |
199 | do { | |
97f76d3d NK |
200 | if (!buffer_mapped(bh)) |
201 | all_mapped = 0; | |
202 | else if (bh->b_blocknr == block) { | |
1da177e4 LT |
203 | ret = bh; |
204 | get_bh(bh); | |
205 | goto out_unlock; | |
206 | } | |
1da177e4 LT |
207 | bh = bh->b_this_page; |
208 | } while (bh != head); | |
209 | ||
210 | /* we might be here because some of the buffers on this page are | |
211 | * not mapped. This is due to various races between | |
212 | * file io on the block device and getblk. It gets dealt with | |
213 | * elsewhere, don't buffer_error if we had some unmapped buffers | |
214 | */ | |
215 | if (all_mapped) { | |
216 | printk("__find_get_block_slow() failed. " | |
217 | "block=%llu, b_blocknr=%llu\n", | |
205f87f6 BP |
218 | (unsigned long long)block, |
219 | (unsigned long long)bh->b_blocknr); | |
220 | printk("b_state=0x%08lx, b_size=%zu\n", | |
221 | bh->b_state, bh->b_size); | |
1da177e4 LT |
222 | printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); |
223 | } | |
224 | out_unlock: | |
225 | spin_unlock(&bd_mapping->private_lock); | |
226 | page_cache_release(page); | |
227 | out: | |
228 | return ret; | |
229 | } | |
230 | ||
231 | /* If invalidate_buffers() will trash dirty buffers, it means some kind | |
232 | of fs corruption is going on. Trashing dirty data always imply losing | |
233 | information that was supposed to be just stored on the physical layer | |
234 | by the user. | |
235 | ||
236 | Thus invalidate_buffers in general usage is not allwowed to trash | |
237 | dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to | |
238 | be preserved. These buffers are simply skipped. | |
239 | ||
240 | We also skip buffers which are still in use. For example this can | |
241 | happen if a userspace program is reading the block device. | |
242 | ||
243 | NOTE: In the case where the user removed a removable-media-disk even if | |
244 | there's still dirty data not synced on disk (due a bug in the device driver | |
245 | or due an error of the user), by not destroying the dirty buffers we could | |
246 | generate corruption also on the next media inserted, thus a parameter is | |
247 | necessary to handle this case in the most safe way possible (trying | |
248 | to not corrupt also the new disk inserted with the data belonging to | |
249 | the old now corrupted disk). Also for the ramdisk the natural thing | |
250 | to do in order to release the ramdisk memory is to destroy dirty buffers. | |
251 | ||
252 | These are two special cases. Normal usage imply the device driver | |
253 | to issue a sync on the device (without waiting I/O completion) and | |
254 | then an invalidate_buffers call that doesn't trash dirty buffers. | |
255 | ||
256 | For handling cache coherency with the blkdev pagecache the 'update' case | |
257 | is been introduced. It is needed to re-read from disk any pinned | |
258 | buffer. NOTE: re-reading from disk is destructive so we can do it only | |
259 | when we assume nobody is changing the buffercache under our I/O and when | |
260 | we think the disk contains more recent information than the buffercache. | |
261 | The update == 1 pass marks the buffers we need to update, the update == 2 | |
262 | pass does the actual I/O. */ | |
f98393a6 | 263 | void invalidate_bdev(struct block_device *bdev) |
1da177e4 | 264 | { |
0e1dfc66 AM |
265 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
266 | ||
267 | if (mapping->nrpages == 0) | |
268 | return; | |
269 | ||
1da177e4 | 270 | invalidate_bh_lrus(); |
fa4b9074 | 271 | lru_add_drain_all(); /* make sure all lru add caches are flushed */ |
fc0ecff6 | 272 | invalidate_mapping_pages(mapping, 0, -1); |
c515e1fd DM |
273 | /* 99% of the time, we don't need to flush the cleancache on the bdev. |
274 | * But, for the strange corners, lets be cautious | |
275 | */ | |
276 | cleancache_flush_inode(mapping); | |
1da177e4 | 277 | } |
1fe72eaa | 278 | EXPORT_SYMBOL(invalidate_bdev); |
1da177e4 LT |
279 | |
280 | /* | |
5b0830cb | 281 | * Kick the writeback threads then try to free up some ZONE_NORMAL memory. |
1da177e4 LT |
282 | */ |
283 | static void free_more_memory(void) | |
284 | { | |
19770b32 | 285 | struct zone *zone; |
0e88460d | 286 | int nid; |
1da177e4 | 287 | |
03ba3782 | 288 | wakeup_flusher_threads(1024); |
1da177e4 LT |
289 | yield(); |
290 | ||
0e88460d | 291 | for_each_online_node(nid) { |
19770b32 MG |
292 | (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS), |
293 | gfp_zone(GFP_NOFS), NULL, | |
294 | &zone); | |
295 | if (zone) | |
54a6eb5c | 296 | try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, |
327c0e96 | 297 | GFP_NOFS, NULL); |
1da177e4 LT |
298 | } |
299 | } | |
300 | ||
301 | /* | |
302 | * I/O completion handler for block_read_full_page() - pages | |
303 | * which come unlocked at the end of I/O. | |
304 | */ | |
305 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) | |
306 | { | |
1da177e4 | 307 | unsigned long flags; |
a3972203 | 308 | struct buffer_head *first; |
1da177e4 LT |
309 | struct buffer_head *tmp; |
310 | struct page *page; | |
311 | int page_uptodate = 1; | |
312 | ||
313 | BUG_ON(!buffer_async_read(bh)); | |
314 | ||
315 | page = bh->b_page; | |
316 | if (uptodate) { | |
317 | set_buffer_uptodate(bh); | |
318 | } else { | |
319 | clear_buffer_uptodate(bh); | |
08bafc03 | 320 | if (!quiet_error(bh)) |
1da177e4 LT |
321 | buffer_io_error(bh); |
322 | SetPageError(page); | |
323 | } | |
324 | ||
325 | /* | |
326 | * Be _very_ careful from here on. Bad things can happen if | |
327 | * two buffer heads end IO at almost the same time and both | |
328 | * decide that the page is now completely done. | |
329 | */ | |
a3972203 NP |
330 | first = page_buffers(page); |
331 | local_irq_save(flags); | |
332 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
1da177e4 LT |
333 | clear_buffer_async_read(bh); |
334 | unlock_buffer(bh); | |
335 | tmp = bh; | |
336 | do { | |
337 | if (!buffer_uptodate(tmp)) | |
338 | page_uptodate = 0; | |
339 | if (buffer_async_read(tmp)) { | |
340 | BUG_ON(!buffer_locked(tmp)); | |
341 | goto still_busy; | |
342 | } | |
343 | tmp = tmp->b_this_page; | |
344 | } while (tmp != bh); | |
a3972203 NP |
345 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
346 | local_irq_restore(flags); | |
1da177e4 LT |
347 | |
348 | /* | |
349 | * If none of the buffers had errors and they are all | |
350 | * uptodate then we can set the page uptodate. | |
351 | */ | |
352 | if (page_uptodate && !PageError(page)) | |
353 | SetPageUptodate(page); | |
354 | unlock_page(page); | |
355 | return; | |
356 | ||
357 | still_busy: | |
a3972203 NP |
358 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
359 | local_irq_restore(flags); | |
1da177e4 LT |
360 | return; |
361 | } | |
362 | ||
363 | /* | |
364 | * Completion handler for block_write_full_page() - pages which are unlocked | |
365 | * during I/O, and which have PageWriteback cleared upon I/O completion. | |
366 | */ | |
35c80d5f | 367 | void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
368 | { |
369 | char b[BDEVNAME_SIZE]; | |
1da177e4 | 370 | unsigned long flags; |
a3972203 | 371 | struct buffer_head *first; |
1da177e4 LT |
372 | struct buffer_head *tmp; |
373 | struct page *page; | |
374 | ||
375 | BUG_ON(!buffer_async_write(bh)); | |
376 | ||
377 | page = bh->b_page; | |
378 | if (uptodate) { | |
379 | set_buffer_uptodate(bh); | |
380 | } else { | |
08bafc03 | 381 | if (!quiet_error(bh)) { |
1da177e4 LT |
382 | buffer_io_error(bh); |
383 | printk(KERN_WARNING "lost page write due to " | |
384 | "I/O error on %s\n", | |
385 | bdevname(bh->b_bdev, b)); | |
386 | } | |
387 | set_bit(AS_EIO, &page->mapping->flags); | |
58ff407b | 388 | set_buffer_write_io_error(bh); |
1da177e4 LT |
389 | clear_buffer_uptodate(bh); |
390 | SetPageError(page); | |
391 | } | |
392 | ||
a3972203 NP |
393 | first = page_buffers(page); |
394 | local_irq_save(flags); | |
395 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
396 | ||
1da177e4 LT |
397 | clear_buffer_async_write(bh); |
398 | unlock_buffer(bh); | |
399 | tmp = bh->b_this_page; | |
400 | while (tmp != bh) { | |
401 | if (buffer_async_write(tmp)) { | |
402 | BUG_ON(!buffer_locked(tmp)); | |
403 | goto still_busy; | |
404 | } | |
405 | tmp = tmp->b_this_page; | |
406 | } | |
a3972203 NP |
407 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
408 | local_irq_restore(flags); | |
1da177e4 LT |
409 | end_page_writeback(page); |
410 | return; | |
411 | ||
412 | still_busy: | |
a3972203 NP |
413 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
414 | local_irq_restore(flags); | |
1da177e4 LT |
415 | return; |
416 | } | |
1fe72eaa | 417 | EXPORT_SYMBOL(end_buffer_async_write); |
1da177e4 LT |
418 | |
419 | /* | |
420 | * If a page's buffers are under async readin (end_buffer_async_read | |
421 | * completion) then there is a possibility that another thread of | |
422 | * control could lock one of the buffers after it has completed | |
423 | * but while some of the other buffers have not completed. This | |
424 | * locked buffer would confuse end_buffer_async_read() into not unlocking | |
425 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() | |
426 | * that this buffer is not under async I/O. | |
427 | * | |
428 | * The page comes unlocked when it has no locked buffer_async buffers | |
429 | * left. | |
430 | * | |
431 | * PageLocked prevents anyone starting new async I/O reads any of | |
432 | * the buffers. | |
433 | * | |
434 | * PageWriteback is used to prevent simultaneous writeout of the same | |
435 | * page. | |
436 | * | |
437 | * PageLocked prevents anyone from starting writeback of a page which is | |
438 | * under read I/O (PageWriteback is only ever set against a locked page). | |
439 | */ | |
440 | static void mark_buffer_async_read(struct buffer_head *bh) | |
441 | { | |
442 | bh->b_end_io = end_buffer_async_read; | |
443 | set_buffer_async_read(bh); | |
444 | } | |
445 | ||
1fe72eaa HS |
446 | static void mark_buffer_async_write_endio(struct buffer_head *bh, |
447 | bh_end_io_t *handler) | |
1da177e4 | 448 | { |
35c80d5f | 449 | bh->b_end_io = handler; |
1da177e4 LT |
450 | set_buffer_async_write(bh); |
451 | } | |
35c80d5f CM |
452 | |
453 | void mark_buffer_async_write(struct buffer_head *bh) | |
454 | { | |
455 | mark_buffer_async_write_endio(bh, end_buffer_async_write); | |
456 | } | |
1da177e4 LT |
457 | EXPORT_SYMBOL(mark_buffer_async_write); |
458 | ||
459 | ||
460 | /* | |
461 | * fs/buffer.c contains helper functions for buffer-backed address space's | |
462 | * fsync functions. A common requirement for buffer-based filesystems is | |
463 | * that certain data from the backing blockdev needs to be written out for | |
464 | * a successful fsync(). For example, ext2 indirect blocks need to be | |
465 | * written back and waited upon before fsync() returns. | |
466 | * | |
467 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), | |
468 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the | |
469 | * management of a list of dependent buffers at ->i_mapping->private_list. | |
470 | * | |
471 | * Locking is a little subtle: try_to_free_buffers() will remove buffers | |
472 | * from their controlling inode's queue when they are being freed. But | |
473 | * try_to_free_buffers() will be operating against the *blockdev* mapping | |
474 | * at the time, not against the S_ISREG file which depends on those buffers. | |
475 | * So the locking for private_list is via the private_lock in the address_space | |
476 | * which backs the buffers. Which is different from the address_space | |
477 | * against which the buffers are listed. So for a particular address_space, | |
478 | * mapping->private_lock does *not* protect mapping->private_list! In fact, | |
479 | * mapping->private_list will always be protected by the backing blockdev's | |
480 | * ->private_lock. | |
481 | * | |
482 | * Which introduces a requirement: all buffers on an address_space's | |
483 | * ->private_list must be from the same address_space: the blockdev's. | |
484 | * | |
485 | * address_spaces which do not place buffers at ->private_list via these | |
486 | * utility functions are free to use private_lock and private_list for | |
487 | * whatever they want. The only requirement is that list_empty(private_list) | |
488 | * be true at clear_inode() time. | |
489 | * | |
490 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The | |
491 | * filesystems should do that. invalidate_inode_buffers() should just go | |
492 | * BUG_ON(!list_empty). | |
493 | * | |
494 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should | |
495 | * take an address_space, not an inode. And it should be called | |
496 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being | |
497 | * queued up. | |
498 | * | |
499 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the | |
500 | * list if it is already on a list. Because if the buffer is on a list, | |
501 | * it *must* already be on the right one. If not, the filesystem is being | |
502 | * silly. This will save a ton of locking. But first we have to ensure | |
503 | * that buffers are taken *off* the old inode's list when they are freed | |
504 | * (presumably in truncate). That requires careful auditing of all | |
505 | * filesystems (do it inside bforget()). It could also be done by bringing | |
506 | * b_inode back. | |
507 | */ | |
508 | ||
509 | /* | |
510 | * The buffer's backing address_space's private_lock must be held | |
511 | */ | |
dbacefc9 | 512 | static void __remove_assoc_queue(struct buffer_head *bh) |
1da177e4 LT |
513 | { |
514 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b JK |
515 | WARN_ON(!bh->b_assoc_map); |
516 | if (buffer_write_io_error(bh)) | |
517 | set_bit(AS_EIO, &bh->b_assoc_map->flags); | |
518 | bh->b_assoc_map = NULL; | |
1da177e4 LT |
519 | } |
520 | ||
521 | int inode_has_buffers(struct inode *inode) | |
522 | { | |
523 | return !list_empty(&inode->i_data.private_list); | |
524 | } | |
525 | ||
526 | /* | |
527 | * osync is designed to support O_SYNC io. It waits synchronously for | |
528 | * all already-submitted IO to complete, but does not queue any new | |
529 | * writes to the disk. | |
530 | * | |
531 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as | |
532 | * you dirty the buffers, and then use osync_inode_buffers to wait for | |
533 | * completion. Any other dirty buffers which are not yet queued for | |
534 | * write will not be flushed to disk by the osync. | |
535 | */ | |
536 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) | |
537 | { | |
538 | struct buffer_head *bh; | |
539 | struct list_head *p; | |
540 | int err = 0; | |
541 | ||
542 | spin_lock(lock); | |
543 | repeat: | |
544 | list_for_each_prev(p, list) { | |
545 | bh = BH_ENTRY(p); | |
546 | if (buffer_locked(bh)) { | |
547 | get_bh(bh); | |
548 | spin_unlock(lock); | |
549 | wait_on_buffer(bh); | |
550 | if (!buffer_uptodate(bh)) | |
551 | err = -EIO; | |
552 | brelse(bh); | |
553 | spin_lock(lock); | |
554 | goto repeat; | |
555 | } | |
556 | } | |
557 | spin_unlock(lock); | |
558 | return err; | |
559 | } | |
560 | ||
01a05b33 | 561 | static void do_thaw_one(struct super_block *sb, void *unused) |
c2d75438 | 562 | { |
c2d75438 | 563 | char b[BDEVNAME_SIZE]; |
01a05b33 AV |
564 | while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) |
565 | printk(KERN_WARNING "Emergency Thaw on %s\n", | |
566 | bdevname(sb->s_bdev, b)); | |
567 | } | |
c2d75438 | 568 | |
01a05b33 AV |
569 | static void do_thaw_all(struct work_struct *work) |
570 | { | |
571 | iterate_supers(do_thaw_one, NULL); | |
053c525f | 572 | kfree(work); |
c2d75438 ES |
573 | printk(KERN_WARNING "Emergency Thaw complete\n"); |
574 | } | |
575 | ||
576 | /** | |
577 | * emergency_thaw_all -- forcibly thaw every frozen filesystem | |
578 | * | |
579 | * Used for emergency unfreeze of all filesystems via SysRq | |
580 | */ | |
581 | void emergency_thaw_all(void) | |
582 | { | |
053c525f JA |
583 | struct work_struct *work; |
584 | ||
585 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
586 | if (work) { | |
587 | INIT_WORK(work, do_thaw_all); | |
588 | schedule_work(work); | |
589 | } | |
c2d75438 ES |
590 | } |
591 | ||
1da177e4 | 592 | /** |
78a4a50a | 593 | * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers |
67be2dd1 | 594 | * @mapping: the mapping which wants those buffers written |
1da177e4 LT |
595 | * |
596 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
597 | * that I/O. | |
598 | * | |
67be2dd1 MW |
599 | * Basically, this is a convenience function for fsync(). |
600 | * @mapping is a file or directory which needs those buffers to be written for | |
601 | * a successful fsync(). | |
1da177e4 LT |
602 | */ |
603 | int sync_mapping_buffers(struct address_space *mapping) | |
604 | { | |
605 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
606 | ||
607 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) | |
608 | return 0; | |
609 | ||
610 | return fsync_buffers_list(&buffer_mapping->private_lock, | |
611 | &mapping->private_list); | |
612 | } | |
613 | EXPORT_SYMBOL(sync_mapping_buffers); | |
614 | ||
615 | /* | |
616 | * Called when we've recently written block `bblock', and it is known that | |
617 | * `bblock' was for a buffer_boundary() buffer. This means that the block at | |
618 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's | |
619 | * dirty, schedule it for IO. So that indirects merge nicely with their data. | |
620 | */ | |
621 | void write_boundary_block(struct block_device *bdev, | |
622 | sector_t bblock, unsigned blocksize) | |
623 | { | |
624 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); | |
625 | if (bh) { | |
626 | if (buffer_dirty(bh)) | |
627 | ll_rw_block(WRITE, 1, &bh); | |
628 | put_bh(bh); | |
629 | } | |
630 | } | |
631 | ||
632 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) | |
633 | { | |
634 | struct address_space *mapping = inode->i_mapping; | |
635 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
636 | ||
637 | mark_buffer_dirty(bh); | |
638 | if (!mapping->assoc_mapping) { | |
639 | mapping->assoc_mapping = buffer_mapping; | |
640 | } else { | |
e827f923 | 641 | BUG_ON(mapping->assoc_mapping != buffer_mapping); |
1da177e4 | 642 | } |
535ee2fb | 643 | if (!bh->b_assoc_map) { |
1da177e4 LT |
644 | spin_lock(&buffer_mapping->private_lock); |
645 | list_move_tail(&bh->b_assoc_buffers, | |
646 | &mapping->private_list); | |
58ff407b | 647 | bh->b_assoc_map = mapping; |
1da177e4 LT |
648 | spin_unlock(&buffer_mapping->private_lock); |
649 | } | |
650 | } | |
651 | EXPORT_SYMBOL(mark_buffer_dirty_inode); | |
652 | ||
787d2214 NP |
653 | /* |
654 | * Mark the page dirty, and set it dirty in the radix tree, and mark the inode | |
655 | * dirty. | |
656 | * | |
657 | * If warn is true, then emit a warning if the page is not uptodate and has | |
658 | * not been truncated. | |
659 | */ | |
a8e7d49a | 660 | static void __set_page_dirty(struct page *page, |
787d2214 NP |
661 | struct address_space *mapping, int warn) |
662 | { | |
19fd6231 | 663 | spin_lock_irq(&mapping->tree_lock); |
787d2214 NP |
664 | if (page->mapping) { /* Race with truncate? */ |
665 | WARN_ON_ONCE(warn && !PageUptodate(page)); | |
e3a7cca1 | 666 | account_page_dirtied(page, mapping); |
787d2214 NP |
667 | radix_tree_tag_set(&mapping->page_tree, |
668 | page_index(page), PAGECACHE_TAG_DIRTY); | |
669 | } | |
19fd6231 | 670 | spin_unlock_irq(&mapping->tree_lock); |
787d2214 | 671 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
787d2214 NP |
672 | } |
673 | ||
1da177e4 LT |
674 | /* |
675 | * Add a page to the dirty page list. | |
676 | * | |
677 | * It is a sad fact of life that this function is called from several places | |
678 | * deeply under spinlocking. It may not sleep. | |
679 | * | |
680 | * If the page has buffers, the uptodate buffers are set dirty, to preserve | |
681 | * dirty-state coherency between the page and the buffers. It the page does | |
682 | * not have buffers then when they are later attached they will all be set | |
683 | * dirty. | |
684 | * | |
685 | * The buffers are dirtied before the page is dirtied. There's a small race | |
686 | * window in which a writepage caller may see the page cleanness but not the | |
687 | * buffer dirtiness. That's fine. If this code were to set the page dirty | |
688 | * before the buffers, a concurrent writepage caller could clear the page dirty | |
689 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean | |
690 | * page on the dirty page list. | |
691 | * | |
692 | * We use private_lock to lock against try_to_free_buffers while using the | |
693 | * page's buffer list. Also use this to protect against clean buffers being | |
694 | * added to the page after it was set dirty. | |
695 | * | |
696 | * FIXME: may need to call ->reservepage here as well. That's rather up to the | |
697 | * address_space though. | |
698 | */ | |
699 | int __set_page_dirty_buffers(struct page *page) | |
700 | { | |
a8e7d49a | 701 | int newly_dirty; |
787d2214 | 702 | struct address_space *mapping = page_mapping(page); |
ebf7a227 NP |
703 | |
704 | if (unlikely(!mapping)) | |
705 | return !TestSetPageDirty(page); | |
1da177e4 LT |
706 | |
707 | spin_lock(&mapping->private_lock); | |
708 | if (page_has_buffers(page)) { | |
709 | struct buffer_head *head = page_buffers(page); | |
710 | struct buffer_head *bh = head; | |
711 | ||
712 | do { | |
713 | set_buffer_dirty(bh); | |
714 | bh = bh->b_this_page; | |
715 | } while (bh != head); | |
716 | } | |
a8e7d49a | 717 | newly_dirty = !TestSetPageDirty(page); |
1da177e4 LT |
718 | spin_unlock(&mapping->private_lock); |
719 | ||
a8e7d49a LT |
720 | if (newly_dirty) |
721 | __set_page_dirty(page, mapping, 1); | |
722 | return newly_dirty; | |
1da177e4 LT |
723 | } |
724 | EXPORT_SYMBOL(__set_page_dirty_buffers); | |
725 | ||
726 | /* | |
727 | * Write out and wait upon a list of buffers. | |
728 | * | |
729 | * We have conflicting pressures: we want to make sure that all | |
730 | * initially dirty buffers get waited on, but that any subsequently | |
731 | * dirtied buffers don't. After all, we don't want fsync to last | |
732 | * forever if somebody is actively writing to the file. | |
733 | * | |
734 | * Do this in two main stages: first we copy dirty buffers to a | |
735 | * temporary inode list, queueing the writes as we go. Then we clean | |
736 | * up, waiting for those writes to complete. | |
737 | * | |
738 | * During this second stage, any subsequent updates to the file may end | |
739 | * up refiling the buffer on the original inode's dirty list again, so | |
740 | * there is a chance we will end up with a buffer queued for write but | |
741 | * not yet completed on that list. So, as a final cleanup we go through | |
742 | * the osync code to catch these locked, dirty buffers without requeuing | |
743 | * any newly dirty buffers for write. | |
744 | */ | |
745 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) | |
746 | { | |
747 | struct buffer_head *bh; | |
748 | struct list_head tmp; | |
7eaceacc | 749 | struct address_space *mapping; |
1da177e4 | 750 | int err = 0, err2; |
4ee2491e | 751 | struct blk_plug plug; |
1da177e4 LT |
752 | |
753 | INIT_LIST_HEAD(&tmp); | |
4ee2491e | 754 | blk_start_plug(&plug); |
1da177e4 LT |
755 | |
756 | spin_lock(lock); | |
757 | while (!list_empty(list)) { | |
758 | bh = BH_ENTRY(list->next); | |
535ee2fb | 759 | mapping = bh->b_assoc_map; |
58ff407b | 760 | __remove_assoc_queue(bh); |
535ee2fb JK |
761 | /* Avoid race with mark_buffer_dirty_inode() which does |
762 | * a lockless check and we rely on seeing the dirty bit */ | |
763 | smp_mb(); | |
1da177e4 LT |
764 | if (buffer_dirty(bh) || buffer_locked(bh)) { |
765 | list_add(&bh->b_assoc_buffers, &tmp); | |
535ee2fb | 766 | bh->b_assoc_map = mapping; |
1da177e4 LT |
767 | if (buffer_dirty(bh)) { |
768 | get_bh(bh); | |
769 | spin_unlock(lock); | |
770 | /* | |
771 | * Ensure any pending I/O completes so that | |
9cb569d6 CH |
772 | * write_dirty_buffer() actually writes the |
773 | * current contents - it is a noop if I/O is | |
774 | * still in flight on potentially older | |
775 | * contents. | |
1da177e4 | 776 | */ |
721a9602 | 777 | write_dirty_buffer(bh, WRITE_SYNC); |
9cf6b720 JA |
778 | |
779 | /* | |
780 | * Kick off IO for the previous mapping. Note | |
781 | * that we will not run the very last mapping, | |
782 | * wait_on_buffer() will do that for us | |
783 | * through sync_buffer(). | |
784 | */ | |
1da177e4 LT |
785 | brelse(bh); |
786 | spin_lock(lock); | |
787 | } | |
788 | } | |
789 | } | |
790 | ||
4ee2491e JA |
791 | spin_unlock(lock); |
792 | blk_finish_plug(&plug); | |
793 | spin_lock(lock); | |
794 | ||
1da177e4 LT |
795 | while (!list_empty(&tmp)) { |
796 | bh = BH_ENTRY(tmp.prev); | |
1da177e4 | 797 | get_bh(bh); |
535ee2fb JK |
798 | mapping = bh->b_assoc_map; |
799 | __remove_assoc_queue(bh); | |
800 | /* Avoid race with mark_buffer_dirty_inode() which does | |
801 | * a lockless check and we rely on seeing the dirty bit */ | |
802 | smp_mb(); | |
803 | if (buffer_dirty(bh)) { | |
804 | list_add(&bh->b_assoc_buffers, | |
e3892296 | 805 | &mapping->private_list); |
535ee2fb JK |
806 | bh->b_assoc_map = mapping; |
807 | } | |
1da177e4 LT |
808 | spin_unlock(lock); |
809 | wait_on_buffer(bh); | |
810 | if (!buffer_uptodate(bh)) | |
811 | err = -EIO; | |
812 | brelse(bh); | |
813 | spin_lock(lock); | |
814 | } | |
815 | ||
816 | spin_unlock(lock); | |
817 | err2 = osync_buffers_list(lock, list); | |
818 | if (err) | |
819 | return err; | |
820 | else | |
821 | return err2; | |
822 | } | |
823 | ||
824 | /* | |
825 | * Invalidate any and all dirty buffers on a given inode. We are | |
826 | * probably unmounting the fs, but that doesn't mean we have already | |
827 | * done a sync(). Just drop the buffers from the inode list. | |
828 | * | |
829 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which | |
830 | * assumes that all the buffers are against the blockdev. Not true | |
831 | * for reiserfs. | |
832 | */ | |
833 | void invalidate_inode_buffers(struct inode *inode) | |
834 | { | |
835 | if (inode_has_buffers(inode)) { | |
836 | struct address_space *mapping = &inode->i_data; | |
837 | struct list_head *list = &mapping->private_list; | |
838 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
839 | ||
840 | spin_lock(&buffer_mapping->private_lock); | |
841 | while (!list_empty(list)) | |
842 | __remove_assoc_queue(BH_ENTRY(list->next)); | |
843 | spin_unlock(&buffer_mapping->private_lock); | |
844 | } | |
845 | } | |
52b19ac9 | 846 | EXPORT_SYMBOL(invalidate_inode_buffers); |
1da177e4 LT |
847 | |
848 | /* | |
849 | * Remove any clean buffers from the inode's buffer list. This is called | |
850 | * when we're trying to free the inode itself. Those buffers can pin it. | |
851 | * | |
852 | * Returns true if all buffers were removed. | |
853 | */ | |
854 | int remove_inode_buffers(struct inode *inode) | |
855 | { | |
856 | int ret = 1; | |
857 | ||
858 | if (inode_has_buffers(inode)) { | |
859 | struct address_space *mapping = &inode->i_data; | |
860 | struct list_head *list = &mapping->private_list; | |
861 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
862 | ||
863 | spin_lock(&buffer_mapping->private_lock); | |
864 | while (!list_empty(list)) { | |
865 | struct buffer_head *bh = BH_ENTRY(list->next); | |
866 | if (buffer_dirty(bh)) { | |
867 | ret = 0; | |
868 | break; | |
869 | } | |
870 | __remove_assoc_queue(bh); | |
871 | } | |
872 | spin_unlock(&buffer_mapping->private_lock); | |
873 | } | |
874 | return ret; | |
875 | } | |
876 | ||
877 | /* | |
878 | * Create the appropriate buffers when given a page for data area and | |
879 | * the size of each buffer.. Use the bh->b_this_page linked list to | |
880 | * follow the buffers created. Return NULL if unable to create more | |
881 | * buffers. | |
882 | * | |
883 | * The retry flag is used to differentiate async IO (paging, swapping) | |
884 | * which may not fail from ordinary buffer allocations. | |
885 | */ | |
886 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
887 | int retry) | |
888 | { | |
889 | struct buffer_head *bh, *head; | |
890 | long offset; | |
891 | ||
892 | try_again: | |
893 | head = NULL; | |
894 | offset = PAGE_SIZE; | |
895 | while ((offset -= size) >= 0) { | |
896 | bh = alloc_buffer_head(GFP_NOFS); | |
897 | if (!bh) | |
898 | goto no_grow; | |
899 | ||
900 | bh->b_bdev = NULL; | |
901 | bh->b_this_page = head; | |
902 | bh->b_blocknr = -1; | |
903 | head = bh; | |
904 | ||
905 | bh->b_state = 0; | |
906 | atomic_set(&bh->b_count, 0); | |
907 | bh->b_size = size; | |
908 | ||
909 | /* Link the buffer to its page */ | |
910 | set_bh_page(bh, page, offset); | |
911 | ||
01ffe339 | 912 | init_buffer(bh, NULL, NULL); |
1da177e4 LT |
913 | } |
914 | return head; | |
915 | /* | |
916 | * In case anything failed, we just free everything we got. | |
917 | */ | |
918 | no_grow: | |
919 | if (head) { | |
920 | do { | |
921 | bh = head; | |
922 | head = head->b_this_page; | |
923 | free_buffer_head(bh); | |
924 | } while (head); | |
925 | } | |
926 | ||
927 | /* | |
928 | * Return failure for non-async IO requests. Async IO requests | |
929 | * are not allowed to fail, so we have to wait until buffer heads | |
930 | * become available. But we don't want tasks sleeping with | |
931 | * partially complete buffers, so all were released above. | |
932 | */ | |
933 | if (!retry) | |
934 | return NULL; | |
935 | ||
936 | /* We're _really_ low on memory. Now we just | |
937 | * wait for old buffer heads to become free due to | |
938 | * finishing IO. Since this is an async request and | |
939 | * the reserve list is empty, we're sure there are | |
940 | * async buffer heads in use. | |
941 | */ | |
942 | free_more_memory(); | |
943 | goto try_again; | |
944 | } | |
945 | EXPORT_SYMBOL_GPL(alloc_page_buffers); | |
946 | ||
947 | static inline void | |
948 | link_dev_buffers(struct page *page, struct buffer_head *head) | |
949 | { | |
950 | struct buffer_head *bh, *tail; | |
951 | ||
952 | bh = head; | |
953 | do { | |
954 | tail = bh; | |
955 | bh = bh->b_this_page; | |
956 | } while (bh); | |
957 | tail->b_this_page = head; | |
958 | attach_page_buffers(page, head); | |
959 | } | |
960 | ||
961 | /* | |
962 | * Initialise the state of a blockdev page's buffers. | |
963 | */ | |
964 | static void | |
965 | init_page_buffers(struct page *page, struct block_device *bdev, | |
966 | sector_t block, int size) | |
967 | { | |
968 | struct buffer_head *head = page_buffers(page); | |
969 | struct buffer_head *bh = head; | |
970 | int uptodate = PageUptodate(page); | |
971 | ||
972 | do { | |
973 | if (!buffer_mapped(bh)) { | |
974 | init_buffer(bh, NULL, NULL); | |
975 | bh->b_bdev = bdev; | |
976 | bh->b_blocknr = block; | |
977 | if (uptodate) | |
978 | set_buffer_uptodate(bh); | |
979 | set_buffer_mapped(bh); | |
980 | } | |
981 | block++; | |
982 | bh = bh->b_this_page; | |
983 | } while (bh != head); | |
984 | } | |
985 | ||
986 | /* | |
987 | * Create the page-cache page that contains the requested block. | |
988 | * | |
989 | * This is user purely for blockdev mappings. | |
990 | */ | |
991 | static struct page * | |
992 | grow_dev_page(struct block_device *bdev, sector_t block, | |
993 | pgoff_t index, int size) | |
994 | { | |
995 | struct inode *inode = bdev->bd_inode; | |
996 | struct page *page; | |
997 | struct buffer_head *bh; | |
998 | ||
ea125892 | 999 | page = find_or_create_page(inode->i_mapping, index, |
769848c0 | 1000 | (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE); |
1da177e4 LT |
1001 | if (!page) |
1002 | return NULL; | |
1003 | ||
e827f923 | 1004 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
1005 | |
1006 | if (page_has_buffers(page)) { | |
1007 | bh = page_buffers(page); | |
1008 | if (bh->b_size == size) { | |
1009 | init_page_buffers(page, bdev, block, size); | |
1010 | return page; | |
1011 | } | |
1012 | if (!try_to_free_buffers(page)) | |
1013 | goto failed; | |
1014 | } | |
1015 | ||
1016 | /* | |
1017 | * Allocate some buffers for this page | |
1018 | */ | |
1019 | bh = alloc_page_buffers(page, size, 0); | |
1020 | if (!bh) | |
1021 | goto failed; | |
1022 | ||
1023 | /* | |
1024 | * Link the page to the buffers and initialise them. Take the | |
1025 | * lock to be atomic wrt __find_get_block(), which does not | |
1026 | * run under the page lock. | |
1027 | */ | |
1028 | spin_lock(&inode->i_mapping->private_lock); | |
1029 | link_dev_buffers(page, bh); | |
1030 | init_page_buffers(page, bdev, block, size); | |
1031 | spin_unlock(&inode->i_mapping->private_lock); | |
1032 | return page; | |
1033 | ||
1034 | failed: | |
1035 | BUG(); | |
1036 | unlock_page(page); | |
1037 | page_cache_release(page); | |
1038 | return NULL; | |
1039 | } | |
1040 | ||
1041 | /* | |
1042 | * Create buffers for the specified block device block's page. If | |
1043 | * that page was dirty, the buffers are set dirty also. | |
1da177e4 | 1044 | */ |
858119e1 | 1045 | static int |
1da177e4 LT |
1046 | grow_buffers(struct block_device *bdev, sector_t block, int size) |
1047 | { | |
1048 | struct page *page; | |
1049 | pgoff_t index; | |
1050 | int sizebits; | |
1051 | ||
1052 | sizebits = -1; | |
1053 | do { | |
1054 | sizebits++; | |
1055 | } while ((size << sizebits) < PAGE_SIZE); | |
1056 | ||
1057 | index = block >> sizebits; | |
1da177e4 | 1058 | |
e5657933 AM |
1059 | /* |
1060 | * Check for a block which wants to lie outside our maximum possible | |
1061 | * pagecache index. (this comparison is done using sector_t types). | |
1062 | */ | |
1063 | if (unlikely(index != block >> sizebits)) { | |
1064 | char b[BDEVNAME_SIZE]; | |
1065 | ||
1066 | printk(KERN_ERR "%s: requested out-of-range block %llu for " | |
1067 | "device %s\n", | |
8e24eea7 | 1068 | __func__, (unsigned long long)block, |
e5657933 AM |
1069 | bdevname(bdev, b)); |
1070 | return -EIO; | |
1071 | } | |
1072 | block = index << sizebits; | |
1da177e4 LT |
1073 | /* Create a page with the proper size buffers.. */ |
1074 | page = grow_dev_page(bdev, block, index, size); | |
1075 | if (!page) | |
1076 | return 0; | |
1077 | unlock_page(page); | |
1078 | page_cache_release(page); | |
1079 | return 1; | |
1080 | } | |
1081 | ||
75c96f85 | 1082 | static struct buffer_head * |
1da177e4 LT |
1083 | __getblk_slow(struct block_device *bdev, sector_t block, int size) |
1084 | { | |
1085 | /* Size must be multiple of hard sectorsize */ | |
e1defc4f | 1086 | if (unlikely(size & (bdev_logical_block_size(bdev)-1) || |
1da177e4 LT |
1087 | (size < 512 || size > PAGE_SIZE))) { |
1088 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", | |
1089 | size); | |
e1defc4f MP |
1090 | printk(KERN_ERR "logical block size: %d\n", |
1091 | bdev_logical_block_size(bdev)); | |
1da177e4 LT |
1092 | |
1093 | dump_stack(); | |
1094 | return NULL; | |
1095 | } | |
1096 | ||
1097 | for (;;) { | |
1098 | struct buffer_head * bh; | |
e5657933 | 1099 | int ret; |
1da177e4 LT |
1100 | |
1101 | bh = __find_get_block(bdev, block, size); | |
1102 | if (bh) | |
1103 | return bh; | |
1104 | ||
e5657933 AM |
1105 | ret = grow_buffers(bdev, block, size); |
1106 | if (ret < 0) | |
1107 | return NULL; | |
1108 | if (ret == 0) | |
1da177e4 LT |
1109 | free_more_memory(); |
1110 | } | |
1111 | } | |
1112 | ||
1113 | /* | |
1114 | * The relationship between dirty buffers and dirty pages: | |
1115 | * | |
1116 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and | |
1117 | * the page is tagged dirty in its radix tree. | |
1118 | * | |
1119 | * At all times, the dirtiness of the buffers represents the dirtiness of | |
1120 | * subsections of the page. If the page has buffers, the page dirty bit is | |
1121 | * merely a hint about the true dirty state. | |
1122 | * | |
1123 | * When a page is set dirty in its entirety, all its buffers are marked dirty | |
1124 | * (if the page has buffers). | |
1125 | * | |
1126 | * When a buffer is marked dirty, its page is dirtied, but the page's other | |
1127 | * buffers are not. | |
1128 | * | |
1129 | * Also. When blockdev buffers are explicitly read with bread(), they | |
1130 | * individually become uptodate. But their backing page remains not | |
1131 | * uptodate - even if all of its buffers are uptodate. A subsequent | |
1132 | * block_read_full_page() against that page will discover all the uptodate | |
1133 | * buffers, will set the page uptodate and will perform no I/O. | |
1134 | */ | |
1135 | ||
1136 | /** | |
1137 | * mark_buffer_dirty - mark a buffer_head as needing writeout | |
67be2dd1 | 1138 | * @bh: the buffer_head to mark dirty |
1da177e4 LT |
1139 | * |
1140 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set its | |
1141 | * backing page dirty, then tag the page as dirty in its address_space's radix | |
1142 | * tree and then attach the address_space's inode to its superblock's dirty | |
1143 | * inode list. | |
1144 | * | |
1145 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, | |
250df6ed | 1146 | * mapping->tree_lock and mapping->host->i_lock. |
1da177e4 | 1147 | */ |
fc9b52cd | 1148 | void mark_buffer_dirty(struct buffer_head *bh) |
1da177e4 | 1149 | { |
787d2214 | 1150 | WARN_ON_ONCE(!buffer_uptodate(bh)); |
1be62dc1 LT |
1151 | |
1152 | /* | |
1153 | * Very *carefully* optimize the it-is-already-dirty case. | |
1154 | * | |
1155 | * Don't let the final "is it dirty" escape to before we | |
1156 | * perhaps modified the buffer. | |
1157 | */ | |
1158 | if (buffer_dirty(bh)) { | |
1159 | smp_mb(); | |
1160 | if (buffer_dirty(bh)) | |
1161 | return; | |
1162 | } | |
1163 | ||
a8e7d49a LT |
1164 | if (!test_set_buffer_dirty(bh)) { |
1165 | struct page *page = bh->b_page; | |
8e9d78ed LT |
1166 | if (!TestSetPageDirty(page)) { |
1167 | struct address_space *mapping = page_mapping(page); | |
1168 | if (mapping) | |
1169 | __set_page_dirty(page, mapping, 0); | |
1170 | } | |
a8e7d49a | 1171 | } |
1da177e4 | 1172 | } |
1fe72eaa | 1173 | EXPORT_SYMBOL(mark_buffer_dirty); |
1da177e4 LT |
1174 | |
1175 | /* | |
1176 | * Decrement a buffer_head's reference count. If all buffers against a page | |
1177 | * have zero reference count, are clean and unlocked, and if the page is clean | |
1178 | * and unlocked then try_to_free_buffers() may strip the buffers from the page | |
1179 | * in preparation for freeing it (sometimes, rarely, buffers are removed from | |
1180 | * a page but it ends up not being freed, and buffers may later be reattached). | |
1181 | */ | |
1182 | void __brelse(struct buffer_head * buf) | |
1183 | { | |
1184 | if (atomic_read(&buf->b_count)) { | |
1185 | put_bh(buf); | |
1186 | return; | |
1187 | } | |
5c752ad9 | 1188 | WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); |
1da177e4 | 1189 | } |
1fe72eaa | 1190 | EXPORT_SYMBOL(__brelse); |
1da177e4 LT |
1191 | |
1192 | /* | |
1193 | * bforget() is like brelse(), except it discards any | |
1194 | * potentially dirty data. | |
1195 | */ | |
1196 | void __bforget(struct buffer_head *bh) | |
1197 | { | |
1198 | clear_buffer_dirty(bh); | |
535ee2fb | 1199 | if (bh->b_assoc_map) { |
1da177e4 LT |
1200 | struct address_space *buffer_mapping = bh->b_page->mapping; |
1201 | ||
1202 | spin_lock(&buffer_mapping->private_lock); | |
1203 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b | 1204 | bh->b_assoc_map = NULL; |
1da177e4 LT |
1205 | spin_unlock(&buffer_mapping->private_lock); |
1206 | } | |
1207 | __brelse(bh); | |
1208 | } | |
1fe72eaa | 1209 | EXPORT_SYMBOL(__bforget); |
1da177e4 LT |
1210 | |
1211 | static struct buffer_head *__bread_slow(struct buffer_head *bh) | |
1212 | { | |
1213 | lock_buffer(bh); | |
1214 | if (buffer_uptodate(bh)) { | |
1215 | unlock_buffer(bh); | |
1216 | return bh; | |
1217 | } else { | |
1218 | get_bh(bh); | |
1219 | bh->b_end_io = end_buffer_read_sync; | |
1220 | submit_bh(READ, bh); | |
1221 | wait_on_buffer(bh); | |
1222 | if (buffer_uptodate(bh)) | |
1223 | return bh; | |
1224 | } | |
1225 | brelse(bh); | |
1226 | return NULL; | |
1227 | } | |
1228 | ||
1229 | /* | |
1230 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). | |
1231 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their | |
1232 | * refcount elevated by one when they're in an LRU. A buffer can only appear | |
1233 | * once in a particular CPU's LRU. A single buffer can be present in multiple | |
1234 | * CPU's LRUs at the same time. | |
1235 | * | |
1236 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and | |
1237 | * sb_find_get_block(). | |
1238 | * | |
1239 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use | |
1240 | * a local interrupt disable for that. | |
1241 | */ | |
1242 | ||
1243 | #define BH_LRU_SIZE 8 | |
1244 | ||
1245 | struct bh_lru { | |
1246 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1247 | }; | |
1248 | ||
1249 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; | |
1250 | ||
1251 | #ifdef CONFIG_SMP | |
1252 | #define bh_lru_lock() local_irq_disable() | |
1253 | #define bh_lru_unlock() local_irq_enable() | |
1254 | #else | |
1255 | #define bh_lru_lock() preempt_disable() | |
1256 | #define bh_lru_unlock() preempt_enable() | |
1257 | #endif | |
1258 | ||
1259 | static inline void check_irqs_on(void) | |
1260 | { | |
1261 | #ifdef irqs_disabled | |
1262 | BUG_ON(irqs_disabled()); | |
1263 | #endif | |
1264 | } | |
1265 | ||
1266 | /* | |
1267 | * The LRU management algorithm is dopey-but-simple. Sorry. | |
1268 | */ | |
1269 | static void bh_lru_install(struct buffer_head *bh) | |
1270 | { | |
1271 | struct buffer_head *evictee = NULL; | |
1da177e4 LT |
1272 | |
1273 | check_irqs_on(); | |
1274 | bh_lru_lock(); | |
c7b92516 | 1275 | if (__this_cpu_read(bh_lrus.bhs[0]) != bh) { |
1da177e4 LT |
1276 | struct buffer_head *bhs[BH_LRU_SIZE]; |
1277 | int in; | |
1278 | int out = 0; | |
1279 | ||
1280 | get_bh(bh); | |
1281 | bhs[out++] = bh; | |
1282 | for (in = 0; in < BH_LRU_SIZE; in++) { | |
c7b92516 CL |
1283 | struct buffer_head *bh2 = |
1284 | __this_cpu_read(bh_lrus.bhs[in]); | |
1da177e4 LT |
1285 | |
1286 | if (bh2 == bh) { | |
1287 | __brelse(bh2); | |
1288 | } else { | |
1289 | if (out >= BH_LRU_SIZE) { | |
1290 | BUG_ON(evictee != NULL); | |
1291 | evictee = bh2; | |
1292 | } else { | |
1293 | bhs[out++] = bh2; | |
1294 | } | |
1295 | } | |
1296 | } | |
1297 | while (out < BH_LRU_SIZE) | |
1298 | bhs[out++] = NULL; | |
c7b92516 | 1299 | memcpy(__this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs)); |
1da177e4 LT |
1300 | } |
1301 | bh_lru_unlock(); | |
1302 | ||
1303 | if (evictee) | |
1304 | __brelse(evictee); | |
1305 | } | |
1306 | ||
1307 | /* | |
1308 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. | |
1309 | */ | |
858119e1 | 1310 | static struct buffer_head * |
3991d3bd | 1311 | lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1312 | { |
1313 | struct buffer_head *ret = NULL; | |
3991d3bd | 1314 | unsigned int i; |
1da177e4 LT |
1315 | |
1316 | check_irqs_on(); | |
1317 | bh_lru_lock(); | |
1da177e4 | 1318 | for (i = 0; i < BH_LRU_SIZE; i++) { |
c7b92516 | 1319 | struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); |
1da177e4 LT |
1320 | |
1321 | if (bh && bh->b_bdev == bdev && | |
1322 | bh->b_blocknr == block && bh->b_size == size) { | |
1323 | if (i) { | |
1324 | while (i) { | |
c7b92516 CL |
1325 | __this_cpu_write(bh_lrus.bhs[i], |
1326 | __this_cpu_read(bh_lrus.bhs[i - 1])); | |
1da177e4 LT |
1327 | i--; |
1328 | } | |
c7b92516 | 1329 | __this_cpu_write(bh_lrus.bhs[0], bh); |
1da177e4 LT |
1330 | } |
1331 | get_bh(bh); | |
1332 | ret = bh; | |
1333 | break; | |
1334 | } | |
1335 | } | |
1336 | bh_lru_unlock(); | |
1337 | return ret; | |
1338 | } | |
1339 | ||
1340 | /* | |
1341 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh | |
1342 | * it in the LRU and mark it as accessed. If it is not present then return | |
1343 | * NULL | |
1344 | */ | |
1345 | struct buffer_head * | |
3991d3bd | 1346 | __find_get_block(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1347 | { |
1348 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); | |
1349 | ||
1350 | if (bh == NULL) { | |
385fd4c5 | 1351 | bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1352 | if (bh) |
1353 | bh_lru_install(bh); | |
1354 | } | |
1355 | if (bh) | |
1356 | touch_buffer(bh); | |
1357 | return bh; | |
1358 | } | |
1359 | EXPORT_SYMBOL(__find_get_block); | |
1360 | ||
1361 | /* | |
1362 | * __getblk will locate (and, if necessary, create) the buffer_head | |
1363 | * which corresponds to the passed block_device, block and size. The | |
1364 | * returned buffer has its reference count incremented. | |
1365 | * | |
1366 | * __getblk() cannot fail - it just keeps trying. If you pass it an | |
1367 | * illegal block number, __getblk() will happily return a buffer_head | |
1368 | * which represents the non-existent block. Very weird. | |
1369 | * | |
1370 | * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() | |
1371 | * attempt is failing. FIXME, perhaps? | |
1372 | */ | |
1373 | struct buffer_head * | |
3991d3bd | 1374 | __getblk(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1375 | { |
1376 | struct buffer_head *bh = __find_get_block(bdev, block, size); | |
1377 | ||
1378 | might_sleep(); | |
1379 | if (bh == NULL) | |
1380 | bh = __getblk_slow(bdev, block, size); | |
1381 | return bh; | |
1382 | } | |
1383 | EXPORT_SYMBOL(__getblk); | |
1384 | ||
1385 | /* | |
1386 | * Do async read-ahead on a buffer.. | |
1387 | */ | |
3991d3bd | 1388 | void __breadahead(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1389 | { |
1390 | struct buffer_head *bh = __getblk(bdev, block, size); | |
a3e713b5 AM |
1391 | if (likely(bh)) { |
1392 | ll_rw_block(READA, 1, &bh); | |
1393 | brelse(bh); | |
1394 | } | |
1da177e4 LT |
1395 | } |
1396 | EXPORT_SYMBOL(__breadahead); | |
1397 | ||
1398 | /** | |
1399 | * __bread() - reads a specified block and returns the bh | |
67be2dd1 | 1400 | * @bdev: the block_device to read from |
1da177e4 LT |
1401 | * @block: number of block |
1402 | * @size: size (in bytes) to read | |
1403 | * | |
1404 | * Reads a specified block, and returns buffer head that contains it. | |
1405 | * It returns NULL if the block was unreadable. | |
1406 | */ | |
1407 | struct buffer_head * | |
3991d3bd | 1408 | __bread(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1409 | { |
1410 | struct buffer_head *bh = __getblk(bdev, block, size); | |
1411 | ||
a3e713b5 | 1412 | if (likely(bh) && !buffer_uptodate(bh)) |
1da177e4 LT |
1413 | bh = __bread_slow(bh); |
1414 | return bh; | |
1415 | } | |
1416 | EXPORT_SYMBOL(__bread); | |
1417 | ||
1418 | /* | |
1419 | * invalidate_bh_lrus() is called rarely - but not only at unmount. | |
1420 | * This doesn't race because it runs in each cpu either in irq | |
1421 | * or with preempt disabled. | |
1422 | */ | |
1423 | static void invalidate_bh_lru(void *arg) | |
1424 | { | |
1425 | struct bh_lru *b = &get_cpu_var(bh_lrus); | |
1426 | int i; | |
1427 | ||
1428 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1429 | brelse(b->bhs[i]); | |
1430 | b->bhs[i] = NULL; | |
1431 | } | |
1432 | put_cpu_var(bh_lrus); | |
1433 | } | |
1434 | ||
f9a14399 | 1435 | void invalidate_bh_lrus(void) |
1da177e4 | 1436 | { |
15c8b6c1 | 1437 | on_each_cpu(invalidate_bh_lru, NULL, 1); |
1da177e4 | 1438 | } |
9db5579b | 1439 | EXPORT_SYMBOL_GPL(invalidate_bh_lrus); |
1da177e4 LT |
1440 | |
1441 | void set_bh_page(struct buffer_head *bh, | |
1442 | struct page *page, unsigned long offset) | |
1443 | { | |
1444 | bh->b_page = page; | |
e827f923 | 1445 | BUG_ON(offset >= PAGE_SIZE); |
1da177e4 LT |
1446 | if (PageHighMem(page)) |
1447 | /* | |
1448 | * This catches illegal uses and preserves the offset: | |
1449 | */ | |
1450 | bh->b_data = (char *)(0 + offset); | |
1451 | else | |
1452 | bh->b_data = page_address(page) + offset; | |
1453 | } | |
1454 | EXPORT_SYMBOL(set_bh_page); | |
1455 | ||
1456 | /* | |
1457 | * Called when truncating a buffer on a page completely. | |
1458 | */ | |
858119e1 | 1459 | static void discard_buffer(struct buffer_head * bh) |
1da177e4 LT |
1460 | { |
1461 | lock_buffer(bh); | |
1462 | clear_buffer_dirty(bh); | |
1463 | bh->b_bdev = NULL; | |
1464 | clear_buffer_mapped(bh); | |
1465 | clear_buffer_req(bh); | |
1466 | clear_buffer_new(bh); | |
1467 | clear_buffer_delay(bh); | |
33a266dd | 1468 | clear_buffer_unwritten(bh); |
1da177e4 LT |
1469 | unlock_buffer(bh); |
1470 | } | |
1471 | ||
1da177e4 LT |
1472 | /** |
1473 | * block_invalidatepage - invalidate part of all of a buffer-backed page | |
1474 | * | |
1475 | * @page: the page which is affected | |
1476 | * @offset: the index of the truncation point | |
1477 | * | |
1478 | * block_invalidatepage() is called when all or part of the page has become | |
1479 | * invalidatedby a truncate operation. | |
1480 | * | |
1481 | * block_invalidatepage() does not have to release all buffers, but it must | |
1482 | * ensure that no dirty buffer is left outside @offset and that no I/O | |
1483 | * is underway against any of the blocks which are outside the truncation | |
1484 | * point. Because the caller is about to free (and possibly reuse) those | |
1485 | * blocks on-disk. | |
1486 | */ | |
2ff28e22 | 1487 | void block_invalidatepage(struct page *page, unsigned long offset) |
1da177e4 LT |
1488 | { |
1489 | struct buffer_head *head, *bh, *next; | |
1490 | unsigned int curr_off = 0; | |
1da177e4 LT |
1491 | |
1492 | BUG_ON(!PageLocked(page)); | |
1493 | if (!page_has_buffers(page)) | |
1494 | goto out; | |
1495 | ||
1496 | head = page_buffers(page); | |
1497 | bh = head; | |
1498 | do { | |
1499 | unsigned int next_off = curr_off + bh->b_size; | |
1500 | next = bh->b_this_page; | |
1501 | ||
1502 | /* | |
1503 | * is this block fully invalidated? | |
1504 | */ | |
1505 | if (offset <= curr_off) | |
1506 | discard_buffer(bh); | |
1507 | curr_off = next_off; | |
1508 | bh = next; | |
1509 | } while (bh != head); | |
1510 | ||
1511 | /* | |
1512 | * We release buffers only if the entire page is being invalidated. | |
1513 | * The get_block cached value has been unconditionally invalidated, | |
1514 | * so real IO is not possible anymore. | |
1515 | */ | |
1516 | if (offset == 0) | |
2ff28e22 | 1517 | try_to_release_page(page, 0); |
1da177e4 | 1518 | out: |
2ff28e22 | 1519 | return; |
1da177e4 LT |
1520 | } |
1521 | EXPORT_SYMBOL(block_invalidatepage); | |
1522 | ||
1523 | /* | |
1524 | * We attach and possibly dirty the buffers atomically wrt | |
1525 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers | |
1526 | * is already excluded via the page lock. | |
1527 | */ | |
1528 | void create_empty_buffers(struct page *page, | |
1529 | unsigned long blocksize, unsigned long b_state) | |
1530 | { | |
1531 | struct buffer_head *bh, *head, *tail; | |
1532 | ||
1533 | head = alloc_page_buffers(page, blocksize, 1); | |
1534 | bh = head; | |
1535 | do { | |
1536 | bh->b_state |= b_state; | |
1537 | tail = bh; | |
1538 | bh = bh->b_this_page; | |
1539 | } while (bh); | |
1540 | tail->b_this_page = head; | |
1541 | ||
1542 | spin_lock(&page->mapping->private_lock); | |
1543 | if (PageUptodate(page) || PageDirty(page)) { | |
1544 | bh = head; | |
1545 | do { | |
1546 | if (PageDirty(page)) | |
1547 | set_buffer_dirty(bh); | |
1548 | if (PageUptodate(page)) | |
1549 | set_buffer_uptodate(bh); | |
1550 | bh = bh->b_this_page; | |
1551 | } while (bh != head); | |
1552 | } | |
1553 | attach_page_buffers(page, head); | |
1554 | spin_unlock(&page->mapping->private_lock); | |
1555 | } | |
1556 | EXPORT_SYMBOL(create_empty_buffers); | |
1557 | ||
1558 | /* | |
1559 | * We are taking a block for data and we don't want any output from any | |
1560 | * buffer-cache aliases starting from return from that function and | |
1561 | * until the moment when something will explicitly mark the buffer | |
1562 | * dirty (hopefully that will not happen until we will free that block ;-) | |
1563 | * We don't even need to mark it not-uptodate - nobody can expect | |
1564 | * anything from a newly allocated buffer anyway. We used to used | |
1565 | * unmap_buffer() for such invalidation, but that was wrong. We definitely | |
1566 | * don't want to mark the alias unmapped, for example - it would confuse | |
1567 | * anyone who might pick it with bread() afterwards... | |
1568 | * | |
1569 | * Also.. Note that bforget() doesn't lock the buffer. So there can | |
1570 | * be writeout I/O going on against recently-freed buffers. We don't | |
1571 | * wait on that I/O in bforget() - it's more efficient to wait on the I/O | |
1572 | * only if we really need to. That happens here. | |
1573 | */ | |
1574 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block) | |
1575 | { | |
1576 | struct buffer_head *old_bh; | |
1577 | ||
1578 | might_sleep(); | |
1579 | ||
385fd4c5 | 1580 | old_bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1581 | if (old_bh) { |
1582 | clear_buffer_dirty(old_bh); | |
1583 | wait_on_buffer(old_bh); | |
1584 | clear_buffer_req(old_bh); | |
1585 | __brelse(old_bh); | |
1586 | } | |
1587 | } | |
1588 | EXPORT_SYMBOL(unmap_underlying_metadata); | |
1589 | ||
1590 | /* | |
1591 | * NOTE! All mapped/uptodate combinations are valid: | |
1592 | * | |
1593 | * Mapped Uptodate Meaning | |
1594 | * | |
1595 | * No No "unknown" - must do get_block() | |
1596 | * No Yes "hole" - zero-filled | |
1597 | * Yes No "allocated" - allocated on disk, not read in | |
1598 | * Yes Yes "valid" - allocated and up-to-date in memory. | |
1599 | * | |
1600 | * "Dirty" is valid only with the last case (mapped+uptodate). | |
1601 | */ | |
1602 | ||
1603 | /* | |
1604 | * While block_write_full_page is writing back the dirty buffers under | |
1605 | * the page lock, whoever dirtied the buffers may decide to clean them | |
1606 | * again at any time. We handle that by only looking at the buffer | |
1607 | * state inside lock_buffer(). | |
1608 | * | |
1609 | * If block_write_full_page() is called for regular writeback | |
1610 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a | |
1611 | * locked buffer. This only can happen if someone has written the buffer | |
1612 | * directly, with submit_bh(). At the address_space level PageWriteback | |
1613 | * prevents this contention from occurring. | |
6e34eedd TT |
1614 | * |
1615 | * If block_write_full_page() is called with wbc->sync_mode == | |
721a9602 JA |
1616 | * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this |
1617 | * causes the writes to be flagged as synchronous writes. | |
1da177e4 LT |
1618 | */ |
1619 | static int __block_write_full_page(struct inode *inode, struct page *page, | |
35c80d5f CM |
1620 | get_block_t *get_block, struct writeback_control *wbc, |
1621 | bh_end_io_t *handler) | |
1da177e4 LT |
1622 | { |
1623 | int err; | |
1624 | sector_t block; | |
1625 | sector_t last_block; | |
f0fbd5fc | 1626 | struct buffer_head *bh, *head; |
b0cf2321 | 1627 | const unsigned blocksize = 1 << inode->i_blkbits; |
1da177e4 | 1628 | int nr_underway = 0; |
6e34eedd | 1629 | int write_op = (wbc->sync_mode == WB_SYNC_ALL ? |
721a9602 | 1630 | WRITE_SYNC : WRITE); |
1da177e4 LT |
1631 | |
1632 | BUG_ON(!PageLocked(page)); | |
1633 | ||
1634 | last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; | |
1635 | ||
1636 | if (!page_has_buffers(page)) { | |
b0cf2321 | 1637 | create_empty_buffers(page, blocksize, |
1da177e4 LT |
1638 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
1639 | } | |
1640 | ||
1641 | /* | |
1642 | * Be very careful. We have no exclusion from __set_page_dirty_buffers | |
1643 | * here, and the (potentially unmapped) buffers may become dirty at | |
1644 | * any time. If a buffer becomes dirty here after we've inspected it | |
1645 | * then we just miss that fact, and the page stays dirty. | |
1646 | * | |
1647 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; | |
1648 | * handle that here by just cleaning them. | |
1649 | */ | |
1650 | ||
54b21a79 | 1651 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
1652 | head = page_buffers(page); |
1653 | bh = head; | |
1654 | ||
1655 | /* | |
1656 | * Get all the dirty buffers mapped to disk addresses and | |
1657 | * handle any aliases from the underlying blockdev's mapping. | |
1658 | */ | |
1659 | do { | |
1660 | if (block > last_block) { | |
1661 | /* | |
1662 | * mapped buffers outside i_size will occur, because | |
1663 | * this page can be outside i_size when there is a | |
1664 | * truncate in progress. | |
1665 | */ | |
1666 | /* | |
1667 | * The buffer was zeroed by block_write_full_page() | |
1668 | */ | |
1669 | clear_buffer_dirty(bh); | |
1670 | set_buffer_uptodate(bh); | |
29a814d2 AT |
1671 | } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && |
1672 | buffer_dirty(bh)) { | |
b0cf2321 | 1673 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1674 | err = get_block(inode, block, bh, 1); |
1675 | if (err) | |
1676 | goto recover; | |
29a814d2 | 1677 | clear_buffer_delay(bh); |
1da177e4 LT |
1678 | if (buffer_new(bh)) { |
1679 | /* blockdev mappings never come here */ | |
1680 | clear_buffer_new(bh); | |
1681 | unmap_underlying_metadata(bh->b_bdev, | |
1682 | bh->b_blocknr); | |
1683 | } | |
1684 | } | |
1685 | bh = bh->b_this_page; | |
1686 | block++; | |
1687 | } while (bh != head); | |
1688 | ||
1689 | do { | |
1da177e4 LT |
1690 | if (!buffer_mapped(bh)) |
1691 | continue; | |
1692 | /* | |
1693 | * If it's a fully non-blocking write attempt and we cannot | |
1694 | * lock the buffer then redirty the page. Note that this can | |
5b0830cb JA |
1695 | * potentially cause a busy-wait loop from writeback threads |
1696 | * and kswapd activity, but those code paths have their own | |
1697 | * higher-level throttling. | |
1da177e4 | 1698 | */ |
1b430bee | 1699 | if (wbc->sync_mode != WB_SYNC_NONE) { |
1da177e4 | 1700 | lock_buffer(bh); |
ca5de404 | 1701 | } else if (!trylock_buffer(bh)) { |
1da177e4 LT |
1702 | redirty_page_for_writepage(wbc, page); |
1703 | continue; | |
1704 | } | |
1705 | if (test_clear_buffer_dirty(bh)) { | |
35c80d5f | 1706 | mark_buffer_async_write_endio(bh, handler); |
1da177e4 LT |
1707 | } else { |
1708 | unlock_buffer(bh); | |
1709 | } | |
1710 | } while ((bh = bh->b_this_page) != head); | |
1711 | ||
1712 | /* | |
1713 | * The page and its buffers are protected by PageWriteback(), so we can | |
1714 | * drop the bh refcounts early. | |
1715 | */ | |
1716 | BUG_ON(PageWriteback(page)); | |
1717 | set_page_writeback(page); | |
1da177e4 LT |
1718 | |
1719 | do { | |
1720 | struct buffer_head *next = bh->b_this_page; | |
1721 | if (buffer_async_write(bh)) { | |
a64c8610 | 1722 | submit_bh(write_op, bh); |
1da177e4 LT |
1723 | nr_underway++; |
1724 | } | |
1da177e4 LT |
1725 | bh = next; |
1726 | } while (bh != head); | |
05937baa | 1727 | unlock_page(page); |
1da177e4 LT |
1728 | |
1729 | err = 0; | |
1730 | done: | |
1731 | if (nr_underway == 0) { | |
1732 | /* | |
1733 | * The page was marked dirty, but the buffers were | |
1734 | * clean. Someone wrote them back by hand with | |
1735 | * ll_rw_block/submit_bh. A rare case. | |
1736 | */ | |
1da177e4 | 1737 | end_page_writeback(page); |
3d67f2d7 | 1738 | |
1da177e4 LT |
1739 | /* |
1740 | * The page and buffer_heads can be released at any time from | |
1741 | * here on. | |
1742 | */ | |
1da177e4 LT |
1743 | } |
1744 | return err; | |
1745 | ||
1746 | recover: | |
1747 | /* | |
1748 | * ENOSPC, or some other error. We may already have added some | |
1749 | * blocks to the file, so we need to write these out to avoid | |
1750 | * exposing stale data. | |
1751 | * The page is currently locked and not marked for writeback | |
1752 | */ | |
1753 | bh = head; | |
1754 | /* Recovery: lock and submit the mapped buffers */ | |
1755 | do { | |
29a814d2 AT |
1756 | if (buffer_mapped(bh) && buffer_dirty(bh) && |
1757 | !buffer_delay(bh)) { | |
1da177e4 | 1758 | lock_buffer(bh); |
35c80d5f | 1759 | mark_buffer_async_write_endio(bh, handler); |
1da177e4 LT |
1760 | } else { |
1761 | /* | |
1762 | * The buffer may have been set dirty during | |
1763 | * attachment to a dirty page. | |
1764 | */ | |
1765 | clear_buffer_dirty(bh); | |
1766 | } | |
1767 | } while ((bh = bh->b_this_page) != head); | |
1768 | SetPageError(page); | |
1769 | BUG_ON(PageWriteback(page)); | |
7e4c3690 | 1770 | mapping_set_error(page->mapping, err); |
1da177e4 | 1771 | set_page_writeback(page); |
1da177e4 LT |
1772 | do { |
1773 | struct buffer_head *next = bh->b_this_page; | |
1774 | if (buffer_async_write(bh)) { | |
1775 | clear_buffer_dirty(bh); | |
a64c8610 | 1776 | submit_bh(write_op, bh); |
1da177e4 LT |
1777 | nr_underway++; |
1778 | } | |
1da177e4 LT |
1779 | bh = next; |
1780 | } while (bh != head); | |
ffda9d30 | 1781 | unlock_page(page); |
1da177e4 LT |
1782 | goto done; |
1783 | } | |
1784 | ||
afddba49 NP |
1785 | /* |
1786 | * If a page has any new buffers, zero them out here, and mark them uptodate | |
1787 | * and dirty so they'll be written out (in order to prevent uninitialised | |
1788 | * block data from leaking). And clear the new bit. | |
1789 | */ | |
1790 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) | |
1791 | { | |
1792 | unsigned int block_start, block_end; | |
1793 | struct buffer_head *head, *bh; | |
1794 | ||
1795 | BUG_ON(!PageLocked(page)); | |
1796 | if (!page_has_buffers(page)) | |
1797 | return; | |
1798 | ||
1799 | bh = head = page_buffers(page); | |
1800 | block_start = 0; | |
1801 | do { | |
1802 | block_end = block_start + bh->b_size; | |
1803 | ||
1804 | if (buffer_new(bh)) { | |
1805 | if (block_end > from && block_start < to) { | |
1806 | if (!PageUptodate(page)) { | |
1807 | unsigned start, size; | |
1808 | ||
1809 | start = max(from, block_start); | |
1810 | size = min(to, block_end) - start; | |
1811 | ||
eebd2aa3 | 1812 | zero_user(page, start, size); |
afddba49 NP |
1813 | set_buffer_uptodate(bh); |
1814 | } | |
1815 | ||
1816 | clear_buffer_new(bh); | |
1817 | mark_buffer_dirty(bh); | |
1818 | } | |
1819 | } | |
1820 | ||
1821 | block_start = block_end; | |
1822 | bh = bh->b_this_page; | |
1823 | } while (bh != head); | |
1824 | } | |
1825 | EXPORT_SYMBOL(page_zero_new_buffers); | |
1826 | ||
ebdec241 | 1827 | int __block_write_begin(struct page *page, loff_t pos, unsigned len, |
6e1db88d | 1828 | get_block_t *get_block) |
1da177e4 | 1829 | { |
ebdec241 CH |
1830 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
1831 | unsigned to = from + len; | |
6e1db88d | 1832 | struct inode *inode = page->mapping->host; |
1da177e4 LT |
1833 | unsigned block_start, block_end; |
1834 | sector_t block; | |
1835 | int err = 0; | |
1836 | unsigned blocksize, bbits; | |
1837 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1838 | ||
1839 | BUG_ON(!PageLocked(page)); | |
1840 | BUG_ON(from > PAGE_CACHE_SIZE); | |
1841 | BUG_ON(to > PAGE_CACHE_SIZE); | |
1842 | BUG_ON(from > to); | |
1843 | ||
1844 | blocksize = 1 << inode->i_blkbits; | |
1845 | if (!page_has_buffers(page)) | |
1846 | create_empty_buffers(page, blocksize, 0); | |
1847 | head = page_buffers(page); | |
1848 | ||
1849 | bbits = inode->i_blkbits; | |
1850 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); | |
1851 | ||
1852 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1853 | block++, block_start=block_end, bh = bh->b_this_page) { | |
1854 | block_end = block_start + blocksize; | |
1855 | if (block_end <= from || block_start >= to) { | |
1856 | if (PageUptodate(page)) { | |
1857 | if (!buffer_uptodate(bh)) | |
1858 | set_buffer_uptodate(bh); | |
1859 | } | |
1860 | continue; | |
1861 | } | |
1862 | if (buffer_new(bh)) | |
1863 | clear_buffer_new(bh); | |
1864 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 1865 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1866 | err = get_block(inode, block, bh, 1); |
1867 | if (err) | |
f3ddbdc6 | 1868 | break; |
1da177e4 | 1869 | if (buffer_new(bh)) { |
1da177e4 LT |
1870 | unmap_underlying_metadata(bh->b_bdev, |
1871 | bh->b_blocknr); | |
1872 | if (PageUptodate(page)) { | |
637aff46 | 1873 | clear_buffer_new(bh); |
1da177e4 | 1874 | set_buffer_uptodate(bh); |
637aff46 | 1875 | mark_buffer_dirty(bh); |
1da177e4 LT |
1876 | continue; |
1877 | } | |
eebd2aa3 CL |
1878 | if (block_end > to || block_start < from) |
1879 | zero_user_segments(page, | |
1880 | to, block_end, | |
1881 | block_start, from); | |
1da177e4 LT |
1882 | continue; |
1883 | } | |
1884 | } | |
1885 | if (PageUptodate(page)) { | |
1886 | if (!buffer_uptodate(bh)) | |
1887 | set_buffer_uptodate(bh); | |
1888 | continue; | |
1889 | } | |
1890 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
33a266dd | 1891 | !buffer_unwritten(bh) && |
1da177e4 LT |
1892 | (block_start < from || block_end > to)) { |
1893 | ll_rw_block(READ, 1, &bh); | |
1894 | *wait_bh++=bh; | |
1895 | } | |
1896 | } | |
1897 | /* | |
1898 | * If we issued read requests - let them complete. | |
1899 | */ | |
1900 | while(wait_bh > wait) { | |
1901 | wait_on_buffer(*--wait_bh); | |
1902 | if (!buffer_uptodate(*wait_bh)) | |
f3ddbdc6 | 1903 | err = -EIO; |
1da177e4 | 1904 | } |
6e1db88d | 1905 | if (unlikely(err)) { |
afddba49 | 1906 | page_zero_new_buffers(page, from, to); |
6e1db88d CH |
1907 | ClearPageUptodate(page); |
1908 | } | |
1da177e4 LT |
1909 | return err; |
1910 | } | |
ebdec241 | 1911 | EXPORT_SYMBOL(__block_write_begin); |
1da177e4 LT |
1912 | |
1913 | static int __block_commit_write(struct inode *inode, struct page *page, | |
1914 | unsigned from, unsigned to) | |
1915 | { | |
1916 | unsigned block_start, block_end; | |
1917 | int partial = 0; | |
1918 | unsigned blocksize; | |
1919 | struct buffer_head *bh, *head; | |
1920 | ||
1921 | blocksize = 1 << inode->i_blkbits; | |
1922 | ||
1923 | for(bh = head = page_buffers(page), block_start = 0; | |
1924 | bh != head || !block_start; | |
1925 | block_start=block_end, bh = bh->b_this_page) { | |
1926 | block_end = block_start + blocksize; | |
1927 | if (block_end <= from || block_start >= to) { | |
1928 | if (!buffer_uptodate(bh)) | |
1929 | partial = 1; | |
1930 | } else { | |
1931 | set_buffer_uptodate(bh); | |
1932 | mark_buffer_dirty(bh); | |
1933 | } | |
afddba49 | 1934 | clear_buffer_new(bh); |
1da177e4 LT |
1935 | } |
1936 | ||
1937 | /* | |
1938 | * If this is a partial write which happened to make all buffers | |
1939 | * uptodate then we can optimize away a bogus readpage() for | |
1940 | * the next read(). Here we 'discover' whether the page went | |
1941 | * uptodate as a result of this (potentially partial) write. | |
1942 | */ | |
1943 | if (!partial) | |
1944 | SetPageUptodate(page); | |
1945 | return 0; | |
1946 | } | |
1947 | ||
afddba49 | 1948 | /* |
155130a4 CH |
1949 | * block_write_begin takes care of the basic task of block allocation and |
1950 | * bringing partial write blocks uptodate first. | |
1951 | * | |
7bb46a67 | 1952 | * The filesystem needs to handle block truncation upon failure. |
afddba49 | 1953 | */ |
155130a4 CH |
1954 | int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, |
1955 | unsigned flags, struct page **pagep, get_block_t *get_block) | |
afddba49 | 1956 | { |
6e1db88d | 1957 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
afddba49 | 1958 | struct page *page; |
6e1db88d | 1959 | int status; |
afddba49 | 1960 | |
6e1db88d CH |
1961 | page = grab_cache_page_write_begin(mapping, index, flags); |
1962 | if (!page) | |
1963 | return -ENOMEM; | |
afddba49 | 1964 | |
6e1db88d | 1965 | status = __block_write_begin(page, pos, len, get_block); |
afddba49 | 1966 | if (unlikely(status)) { |
6e1db88d CH |
1967 | unlock_page(page); |
1968 | page_cache_release(page); | |
1969 | page = NULL; | |
afddba49 NP |
1970 | } |
1971 | ||
6e1db88d | 1972 | *pagep = page; |
afddba49 NP |
1973 | return status; |
1974 | } | |
1975 | EXPORT_SYMBOL(block_write_begin); | |
1976 | ||
1977 | int block_write_end(struct file *file, struct address_space *mapping, | |
1978 | loff_t pos, unsigned len, unsigned copied, | |
1979 | struct page *page, void *fsdata) | |
1980 | { | |
1981 | struct inode *inode = mapping->host; | |
1982 | unsigned start; | |
1983 | ||
1984 | start = pos & (PAGE_CACHE_SIZE - 1); | |
1985 | ||
1986 | if (unlikely(copied < len)) { | |
1987 | /* | |
1988 | * The buffers that were written will now be uptodate, so we | |
1989 | * don't have to worry about a readpage reading them and | |
1990 | * overwriting a partial write. However if we have encountered | |
1991 | * a short write and only partially written into a buffer, it | |
1992 | * will not be marked uptodate, so a readpage might come in and | |
1993 | * destroy our partial write. | |
1994 | * | |
1995 | * Do the simplest thing, and just treat any short write to a | |
1996 | * non uptodate page as a zero-length write, and force the | |
1997 | * caller to redo the whole thing. | |
1998 | */ | |
1999 | if (!PageUptodate(page)) | |
2000 | copied = 0; | |
2001 | ||
2002 | page_zero_new_buffers(page, start+copied, start+len); | |
2003 | } | |
2004 | flush_dcache_page(page); | |
2005 | ||
2006 | /* This could be a short (even 0-length) commit */ | |
2007 | __block_commit_write(inode, page, start, start+copied); | |
2008 | ||
2009 | return copied; | |
2010 | } | |
2011 | EXPORT_SYMBOL(block_write_end); | |
2012 | ||
2013 | int generic_write_end(struct file *file, struct address_space *mapping, | |
2014 | loff_t pos, unsigned len, unsigned copied, | |
2015 | struct page *page, void *fsdata) | |
2016 | { | |
2017 | struct inode *inode = mapping->host; | |
c7d206b3 | 2018 | int i_size_changed = 0; |
afddba49 NP |
2019 | |
2020 | copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); | |
2021 | ||
2022 | /* | |
2023 | * No need to use i_size_read() here, the i_size | |
2024 | * cannot change under us because we hold i_mutex. | |
2025 | * | |
2026 | * But it's important to update i_size while still holding page lock: | |
2027 | * page writeout could otherwise come in and zero beyond i_size. | |
2028 | */ | |
2029 | if (pos+copied > inode->i_size) { | |
2030 | i_size_write(inode, pos+copied); | |
c7d206b3 | 2031 | i_size_changed = 1; |
afddba49 NP |
2032 | } |
2033 | ||
2034 | unlock_page(page); | |
2035 | page_cache_release(page); | |
2036 | ||
c7d206b3 JK |
2037 | /* |
2038 | * Don't mark the inode dirty under page lock. First, it unnecessarily | |
2039 | * makes the holding time of page lock longer. Second, it forces lock | |
2040 | * ordering of page lock and transaction start for journaling | |
2041 | * filesystems. | |
2042 | */ | |
2043 | if (i_size_changed) | |
2044 | mark_inode_dirty(inode); | |
2045 | ||
afddba49 NP |
2046 | return copied; |
2047 | } | |
2048 | EXPORT_SYMBOL(generic_write_end); | |
2049 | ||
8ab22b9a HH |
2050 | /* |
2051 | * block_is_partially_uptodate checks whether buffers within a page are | |
2052 | * uptodate or not. | |
2053 | * | |
2054 | * Returns true if all buffers which correspond to a file portion | |
2055 | * we want to read are uptodate. | |
2056 | */ | |
2057 | int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, | |
2058 | unsigned long from) | |
2059 | { | |
2060 | struct inode *inode = page->mapping->host; | |
2061 | unsigned block_start, block_end, blocksize; | |
2062 | unsigned to; | |
2063 | struct buffer_head *bh, *head; | |
2064 | int ret = 1; | |
2065 | ||
2066 | if (!page_has_buffers(page)) | |
2067 | return 0; | |
2068 | ||
2069 | blocksize = 1 << inode->i_blkbits; | |
2070 | to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count); | |
2071 | to = from + to; | |
2072 | if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize) | |
2073 | return 0; | |
2074 | ||
2075 | head = page_buffers(page); | |
2076 | bh = head; | |
2077 | block_start = 0; | |
2078 | do { | |
2079 | block_end = block_start + blocksize; | |
2080 | if (block_end > from && block_start < to) { | |
2081 | if (!buffer_uptodate(bh)) { | |
2082 | ret = 0; | |
2083 | break; | |
2084 | } | |
2085 | if (block_end >= to) | |
2086 | break; | |
2087 | } | |
2088 | block_start = block_end; | |
2089 | bh = bh->b_this_page; | |
2090 | } while (bh != head); | |
2091 | ||
2092 | return ret; | |
2093 | } | |
2094 | EXPORT_SYMBOL(block_is_partially_uptodate); | |
2095 | ||
1da177e4 LT |
2096 | /* |
2097 | * Generic "read page" function for block devices that have the normal | |
2098 | * get_block functionality. This is most of the block device filesystems. | |
2099 | * Reads the page asynchronously --- the unlock_buffer() and | |
2100 | * set/clear_buffer_uptodate() functions propagate buffer state into the | |
2101 | * page struct once IO has completed. | |
2102 | */ | |
2103 | int block_read_full_page(struct page *page, get_block_t *get_block) | |
2104 | { | |
2105 | struct inode *inode = page->mapping->host; | |
2106 | sector_t iblock, lblock; | |
2107 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; | |
2108 | unsigned int blocksize; | |
2109 | int nr, i; | |
2110 | int fully_mapped = 1; | |
2111 | ||
cd7619d6 | 2112 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
2113 | blocksize = 1 << inode->i_blkbits; |
2114 | if (!page_has_buffers(page)) | |
2115 | create_empty_buffers(page, blocksize, 0); | |
2116 | head = page_buffers(page); | |
2117 | ||
2118 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
2119 | lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; | |
2120 | bh = head; | |
2121 | nr = 0; | |
2122 | i = 0; | |
2123 | ||
2124 | do { | |
2125 | if (buffer_uptodate(bh)) | |
2126 | continue; | |
2127 | ||
2128 | if (!buffer_mapped(bh)) { | |
c64610ba AM |
2129 | int err = 0; |
2130 | ||
1da177e4 LT |
2131 | fully_mapped = 0; |
2132 | if (iblock < lblock) { | |
b0cf2321 | 2133 | WARN_ON(bh->b_size != blocksize); |
c64610ba AM |
2134 | err = get_block(inode, iblock, bh, 0); |
2135 | if (err) | |
1da177e4 LT |
2136 | SetPageError(page); |
2137 | } | |
2138 | if (!buffer_mapped(bh)) { | |
eebd2aa3 | 2139 | zero_user(page, i * blocksize, blocksize); |
c64610ba AM |
2140 | if (!err) |
2141 | set_buffer_uptodate(bh); | |
1da177e4 LT |
2142 | continue; |
2143 | } | |
2144 | /* | |
2145 | * get_block() might have updated the buffer | |
2146 | * synchronously | |
2147 | */ | |
2148 | if (buffer_uptodate(bh)) | |
2149 | continue; | |
2150 | } | |
2151 | arr[nr++] = bh; | |
2152 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
2153 | ||
2154 | if (fully_mapped) | |
2155 | SetPageMappedToDisk(page); | |
2156 | ||
2157 | if (!nr) { | |
2158 | /* | |
2159 | * All buffers are uptodate - we can set the page uptodate | |
2160 | * as well. But not if get_block() returned an error. | |
2161 | */ | |
2162 | if (!PageError(page)) | |
2163 | SetPageUptodate(page); | |
2164 | unlock_page(page); | |
2165 | return 0; | |
2166 | } | |
2167 | ||
2168 | /* Stage two: lock the buffers */ | |
2169 | for (i = 0; i < nr; i++) { | |
2170 | bh = arr[i]; | |
2171 | lock_buffer(bh); | |
2172 | mark_buffer_async_read(bh); | |
2173 | } | |
2174 | ||
2175 | /* | |
2176 | * Stage 3: start the IO. Check for uptodateness | |
2177 | * inside the buffer lock in case another process reading | |
2178 | * the underlying blockdev brought it uptodate (the sct fix). | |
2179 | */ | |
2180 | for (i = 0; i < nr; i++) { | |
2181 | bh = arr[i]; | |
2182 | if (buffer_uptodate(bh)) | |
2183 | end_buffer_async_read(bh, 1); | |
2184 | else | |
2185 | submit_bh(READ, bh); | |
2186 | } | |
2187 | return 0; | |
2188 | } | |
1fe72eaa | 2189 | EXPORT_SYMBOL(block_read_full_page); |
1da177e4 LT |
2190 | |
2191 | /* utility function for filesystems that need to do work on expanding | |
89e10787 | 2192 | * truncates. Uses filesystem pagecache writes to allow the filesystem to |
1da177e4 LT |
2193 | * deal with the hole. |
2194 | */ | |
89e10787 | 2195 | int generic_cont_expand_simple(struct inode *inode, loff_t size) |
1da177e4 LT |
2196 | { |
2197 | struct address_space *mapping = inode->i_mapping; | |
2198 | struct page *page; | |
89e10787 | 2199 | void *fsdata; |
1da177e4 LT |
2200 | int err; |
2201 | ||
c08d3b0e | 2202 | err = inode_newsize_ok(inode, size); |
2203 | if (err) | |
1da177e4 LT |
2204 | goto out; |
2205 | ||
89e10787 NP |
2206 | err = pagecache_write_begin(NULL, mapping, size, 0, |
2207 | AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, | |
2208 | &page, &fsdata); | |
2209 | if (err) | |
05eb0b51 | 2210 | goto out; |
05eb0b51 | 2211 | |
89e10787 NP |
2212 | err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); |
2213 | BUG_ON(err > 0); | |
05eb0b51 | 2214 | |
1da177e4 LT |
2215 | out: |
2216 | return err; | |
2217 | } | |
1fe72eaa | 2218 | EXPORT_SYMBOL(generic_cont_expand_simple); |
1da177e4 | 2219 | |
f1e3af72 AB |
2220 | static int cont_expand_zero(struct file *file, struct address_space *mapping, |
2221 | loff_t pos, loff_t *bytes) | |
1da177e4 | 2222 | { |
1da177e4 | 2223 | struct inode *inode = mapping->host; |
1da177e4 | 2224 | unsigned blocksize = 1 << inode->i_blkbits; |
89e10787 NP |
2225 | struct page *page; |
2226 | void *fsdata; | |
2227 | pgoff_t index, curidx; | |
2228 | loff_t curpos; | |
2229 | unsigned zerofrom, offset, len; | |
2230 | int err = 0; | |
1da177e4 | 2231 | |
89e10787 NP |
2232 | index = pos >> PAGE_CACHE_SHIFT; |
2233 | offset = pos & ~PAGE_CACHE_MASK; | |
2234 | ||
2235 | while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { | |
2236 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 LT |
2237 | if (zerofrom & (blocksize-1)) { |
2238 | *bytes |= (blocksize-1); | |
2239 | (*bytes)++; | |
2240 | } | |
89e10787 | 2241 | len = PAGE_CACHE_SIZE - zerofrom; |
1da177e4 | 2242 | |
89e10787 NP |
2243 | err = pagecache_write_begin(file, mapping, curpos, len, |
2244 | AOP_FLAG_UNINTERRUPTIBLE, | |
2245 | &page, &fsdata); | |
2246 | if (err) | |
2247 | goto out; | |
eebd2aa3 | 2248 | zero_user(page, zerofrom, len); |
89e10787 NP |
2249 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2250 | page, fsdata); | |
2251 | if (err < 0) | |
2252 | goto out; | |
2253 | BUG_ON(err != len); | |
2254 | err = 0; | |
061e9746 OH |
2255 | |
2256 | balance_dirty_pages_ratelimited(mapping); | |
89e10787 | 2257 | } |
1da177e4 | 2258 | |
89e10787 NP |
2259 | /* page covers the boundary, find the boundary offset */ |
2260 | if (index == curidx) { | |
2261 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 | 2262 | /* if we will expand the thing last block will be filled */ |
89e10787 NP |
2263 | if (offset <= zerofrom) { |
2264 | goto out; | |
2265 | } | |
2266 | if (zerofrom & (blocksize-1)) { | |
1da177e4 LT |
2267 | *bytes |= (blocksize-1); |
2268 | (*bytes)++; | |
2269 | } | |
89e10787 | 2270 | len = offset - zerofrom; |
1da177e4 | 2271 | |
89e10787 NP |
2272 | err = pagecache_write_begin(file, mapping, curpos, len, |
2273 | AOP_FLAG_UNINTERRUPTIBLE, | |
2274 | &page, &fsdata); | |
2275 | if (err) | |
2276 | goto out; | |
eebd2aa3 | 2277 | zero_user(page, zerofrom, len); |
89e10787 NP |
2278 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2279 | page, fsdata); | |
2280 | if (err < 0) | |
2281 | goto out; | |
2282 | BUG_ON(err != len); | |
2283 | err = 0; | |
1da177e4 | 2284 | } |
89e10787 NP |
2285 | out: |
2286 | return err; | |
2287 | } | |
2288 | ||
2289 | /* | |
2290 | * For moronic filesystems that do not allow holes in file. | |
2291 | * We may have to extend the file. | |
2292 | */ | |
282dc178 | 2293 | int cont_write_begin(struct file *file, struct address_space *mapping, |
89e10787 NP |
2294 | loff_t pos, unsigned len, unsigned flags, |
2295 | struct page **pagep, void **fsdata, | |
2296 | get_block_t *get_block, loff_t *bytes) | |
2297 | { | |
2298 | struct inode *inode = mapping->host; | |
2299 | unsigned blocksize = 1 << inode->i_blkbits; | |
2300 | unsigned zerofrom; | |
2301 | int err; | |
2302 | ||
2303 | err = cont_expand_zero(file, mapping, pos, bytes); | |
2304 | if (err) | |
155130a4 | 2305 | return err; |
89e10787 NP |
2306 | |
2307 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2308 | if (pos+len > *bytes && zerofrom & (blocksize-1)) { | |
2309 | *bytes |= (blocksize-1); | |
2310 | (*bytes)++; | |
1da177e4 | 2311 | } |
1da177e4 | 2312 | |
155130a4 | 2313 | return block_write_begin(mapping, pos, len, flags, pagep, get_block); |
1da177e4 | 2314 | } |
1fe72eaa | 2315 | EXPORT_SYMBOL(cont_write_begin); |
1da177e4 | 2316 | |
1da177e4 LT |
2317 | int block_commit_write(struct page *page, unsigned from, unsigned to) |
2318 | { | |
2319 | struct inode *inode = page->mapping->host; | |
2320 | __block_commit_write(inode,page,from,to); | |
2321 | return 0; | |
2322 | } | |
1fe72eaa | 2323 | EXPORT_SYMBOL(block_commit_write); |
1da177e4 | 2324 | |
54171690 DC |
2325 | /* |
2326 | * block_page_mkwrite() is not allowed to change the file size as it gets | |
2327 | * called from a page fault handler when a page is first dirtied. Hence we must | |
2328 | * be careful to check for EOF conditions here. We set the page up correctly | |
2329 | * for a written page which means we get ENOSPC checking when writing into | |
2330 | * holes and correct delalloc and unwritten extent mapping on filesystems that | |
2331 | * support these features. | |
2332 | * | |
2333 | * We are not allowed to take the i_mutex here so we have to play games to | |
2334 | * protect against truncate races as the page could now be beyond EOF. Because | |
7bb46a67 | 2335 | * truncate writes the inode size before removing pages, once we have the |
54171690 DC |
2336 | * page lock we can determine safely if the page is beyond EOF. If it is not |
2337 | * beyond EOF, then the page is guaranteed safe against truncation until we | |
2338 | * unlock the page. | |
ea13a864 JK |
2339 | * |
2340 | * Direct callers of this function should call vfs_check_frozen() so that page | |
2341 | * fault does not busyloop until the fs is thawed. | |
54171690 | 2342 | */ |
24da4fab JK |
2343 | int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
2344 | get_block_t get_block) | |
54171690 | 2345 | { |
c2ec175c | 2346 | struct page *page = vmf->page; |
54171690 DC |
2347 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; |
2348 | unsigned long end; | |
2349 | loff_t size; | |
24da4fab | 2350 | int ret; |
54171690 DC |
2351 | |
2352 | lock_page(page); | |
2353 | size = i_size_read(inode); | |
2354 | if ((page->mapping != inode->i_mapping) || | |
18336338 | 2355 | (page_offset(page) > size)) { |
24da4fab JK |
2356 | /* We overload EFAULT to mean page got truncated */ |
2357 | ret = -EFAULT; | |
2358 | goto out_unlock; | |
54171690 DC |
2359 | } |
2360 | ||
2361 | /* page is wholly or partially inside EOF */ | |
2362 | if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) | |
2363 | end = size & ~PAGE_CACHE_MASK; | |
2364 | else | |
2365 | end = PAGE_CACHE_SIZE; | |
2366 | ||
ebdec241 | 2367 | ret = __block_write_begin(page, 0, end, get_block); |
54171690 DC |
2368 | if (!ret) |
2369 | ret = block_commit_write(page, 0, end); | |
2370 | ||
24da4fab JK |
2371 | if (unlikely(ret < 0)) |
2372 | goto out_unlock; | |
ea13a864 JK |
2373 | /* |
2374 | * Freezing in progress? We check after the page is marked dirty and | |
2375 | * with page lock held so if the test here fails, we are sure freezing | |
2376 | * code will wait during syncing until the page fault is done - at that | |
2377 | * point page will be dirty and unlocked so freezing code will write it | |
2378 | * and writeprotect it again. | |
2379 | */ | |
2380 | set_page_dirty(page); | |
2381 | if (inode->i_sb->s_frozen != SB_UNFROZEN) { | |
2382 | ret = -EAGAIN; | |
2383 | goto out_unlock; | |
2384 | } | |
d76ee18a | 2385 | wait_on_page_writeback(page); |
24da4fab JK |
2386 | return 0; |
2387 | out_unlock: | |
2388 | unlock_page(page); | |
54171690 | 2389 | return ret; |
24da4fab JK |
2390 | } |
2391 | EXPORT_SYMBOL(__block_page_mkwrite); | |
2392 | ||
2393 | int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, | |
2394 | get_block_t get_block) | |
2395 | { | |
ea13a864 JK |
2396 | int ret; |
2397 | struct super_block *sb = vma->vm_file->f_path.dentry->d_inode->i_sb; | |
24da4fab | 2398 | |
ea13a864 JK |
2399 | /* |
2400 | * This check is racy but catches the common case. The check in | |
2401 | * __block_page_mkwrite() is reliable. | |
2402 | */ | |
2403 | vfs_check_frozen(sb, SB_FREEZE_WRITE); | |
2404 | ret = __block_page_mkwrite(vma, vmf, get_block); | |
24da4fab | 2405 | return block_page_mkwrite_return(ret); |
54171690 | 2406 | } |
1fe72eaa | 2407 | EXPORT_SYMBOL(block_page_mkwrite); |
1da177e4 LT |
2408 | |
2409 | /* | |
03158cd7 | 2410 | * nobh_write_begin()'s prereads are special: the buffer_heads are freed |
1da177e4 LT |
2411 | * immediately, while under the page lock. So it needs a special end_io |
2412 | * handler which does not touch the bh after unlocking it. | |
1da177e4 LT |
2413 | */ |
2414 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2415 | { | |
68671f35 | 2416 | __end_buffer_read_notouch(bh, uptodate); |
1da177e4 LT |
2417 | } |
2418 | ||
03158cd7 NP |
2419 | /* |
2420 | * Attach the singly-linked list of buffers created by nobh_write_begin, to | |
2421 | * the page (converting it to circular linked list and taking care of page | |
2422 | * dirty races). | |
2423 | */ | |
2424 | static void attach_nobh_buffers(struct page *page, struct buffer_head *head) | |
2425 | { | |
2426 | struct buffer_head *bh; | |
2427 | ||
2428 | BUG_ON(!PageLocked(page)); | |
2429 | ||
2430 | spin_lock(&page->mapping->private_lock); | |
2431 | bh = head; | |
2432 | do { | |
2433 | if (PageDirty(page)) | |
2434 | set_buffer_dirty(bh); | |
2435 | if (!bh->b_this_page) | |
2436 | bh->b_this_page = head; | |
2437 | bh = bh->b_this_page; | |
2438 | } while (bh != head); | |
2439 | attach_page_buffers(page, head); | |
2440 | spin_unlock(&page->mapping->private_lock); | |
2441 | } | |
2442 | ||
1da177e4 | 2443 | /* |
ea0f04e5 CH |
2444 | * On entry, the page is fully not uptodate. |
2445 | * On exit the page is fully uptodate in the areas outside (from,to) | |
7bb46a67 | 2446 | * The filesystem needs to handle block truncation upon failure. |
1da177e4 | 2447 | */ |
ea0f04e5 | 2448 | int nobh_write_begin(struct address_space *mapping, |
03158cd7 NP |
2449 | loff_t pos, unsigned len, unsigned flags, |
2450 | struct page **pagep, void **fsdata, | |
1da177e4 LT |
2451 | get_block_t *get_block) |
2452 | { | |
03158cd7 | 2453 | struct inode *inode = mapping->host; |
1da177e4 LT |
2454 | const unsigned blkbits = inode->i_blkbits; |
2455 | const unsigned blocksize = 1 << blkbits; | |
a4b0672d | 2456 | struct buffer_head *head, *bh; |
03158cd7 NP |
2457 | struct page *page; |
2458 | pgoff_t index; | |
2459 | unsigned from, to; | |
1da177e4 | 2460 | unsigned block_in_page; |
a4b0672d | 2461 | unsigned block_start, block_end; |
1da177e4 | 2462 | sector_t block_in_file; |
1da177e4 | 2463 | int nr_reads = 0; |
1da177e4 LT |
2464 | int ret = 0; |
2465 | int is_mapped_to_disk = 1; | |
1da177e4 | 2466 | |
03158cd7 NP |
2467 | index = pos >> PAGE_CACHE_SHIFT; |
2468 | from = pos & (PAGE_CACHE_SIZE - 1); | |
2469 | to = from + len; | |
2470 | ||
54566b2c | 2471 | page = grab_cache_page_write_begin(mapping, index, flags); |
03158cd7 NP |
2472 | if (!page) |
2473 | return -ENOMEM; | |
2474 | *pagep = page; | |
2475 | *fsdata = NULL; | |
2476 | ||
2477 | if (page_has_buffers(page)) { | |
309f77ad NK |
2478 | ret = __block_write_begin(page, pos, len, get_block); |
2479 | if (unlikely(ret)) | |
2480 | goto out_release; | |
2481 | return ret; | |
03158cd7 | 2482 | } |
a4b0672d | 2483 | |
1da177e4 LT |
2484 | if (PageMappedToDisk(page)) |
2485 | return 0; | |
2486 | ||
a4b0672d NP |
2487 | /* |
2488 | * Allocate buffers so that we can keep track of state, and potentially | |
2489 | * attach them to the page if an error occurs. In the common case of | |
2490 | * no error, they will just be freed again without ever being attached | |
2491 | * to the page (which is all OK, because we're under the page lock). | |
2492 | * | |
2493 | * Be careful: the buffer linked list is a NULL terminated one, rather | |
2494 | * than the circular one we're used to. | |
2495 | */ | |
2496 | head = alloc_page_buffers(page, blocksize, 0); | |
03158cd7 NP |
2497 | if (!head) { |
2498 | ret = -ENOMEM; | |
2499 | goto out_release; | |
2500 | } | |
a4b0672d | 2501 | |
1da177e4 | 2502 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); |
1da177e4 LT |
2503 | |
2504 | /* | |
2505 | * We loop across all blocks in the page, whether or not they are | |
2506 | * part of the affected region. This is so we can discover if the | |
2507 | * page is fully mapped-to-disk. | |
2508 | */ | |
a4b0672d | 2509 | for (block_start = 0, block_in_page = 0, bh = head; |
1da177e4 | 2510 | block_start < PAGE_CACHE_SIZE; |
a4b0672d | 2511 | block_in_page++, block_start += blocksize, bh = bh->b_this_page) { |
1da177e4 LT |
2512 | int create; |
2513 | ||
a4b0672d NP |
2514 | block_end = block_start + blocksize; |
2515 | bh->b_state = 0; | |
1da177e4 LT |
2516 | create = 1; |
2517 | if (block_start >= to) | |
2518 | create = 0; | |
2519 | ret = get_block(inode, block_in_file + block_in_page, | |
a4b0672d | 2520 | bh, create); |
1da177e4 LT |
2521 | if (ret) |
2522 | goto failed; | |
a4b0672d | 2523 | if (!buffer_mapped(bh)) |
1da177e4 | 2524 | is_mapped_to_disk = 0; |
a4b0672d NP |
2525 | if (buffer_new(bh)) |
2526 | unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); | |
2527 | if (PageUptodate(page)) { | |
2528 | set_buffer_uptodate(bh); | |
1da177e4 | 2529 | continue; |
a4b0672d NP |
2530 | } |
2531 | if (buffer_new(bh) || !buffer_mapped(bh)) { | |
eebd2aa3 CL |
2532 | zero_user_segments(page, block_start, from, |
2533 | to, block_end); | |
1da177e4 LT |
2534 | continue; |
2535 | } | |
a4b0672d | 2536 | if (buffer_uptodate(bh)) |
1da177e4 LT |
2537 | continue; /* reiserfs does this */ |
2538 | if (block_start < from || block_end > to) { | |
a4b0672d NP |
2539 | lock_buffer(bh); |
2540 | bh->b_end_io = end_buffer_read_nobh; | |
2541 | submit_bh(READ, bh); | |
2542 | nr_reads++; | |
1da177e4 LT |
2543 | } |
2544 | } | |
2545 | ||
2546 | if (nr_reads) { | |
1da177e4 LT |
2547 | /* |
2548 | * The page is locked, so these buffers are protected from | |
2549 | * any VM or truncate activity. Hence we don't need to care | |
2550 | * for the buffer_head refcounts. | |
2551 | */ | |
a4b0672d | 2552 | for (bh = head; bh; bh = bh->b_this_page) { |
1da177e4 LT |
2553 | wait_on_buffer(bh); |
2554 | if (!buffer_uptodate(bh)) | |
2555 | ret = -EIO; | |
1da177e4 LT |
2556 | } |
2557 | if (ret) | |
2558 | goto failed; | |
2559 | } | |
2560 | ||
2561 | if (is_mapped_to_disk) | |
2562 | SetPageMappedToDisk(page); | |
1da177e4 | 2563 | |
03158cd7 | 2564 | *fsdata = head; /* to be released by nobh_write_end */ |
a4b0672d | 2565 | |
1da177e4 LT |
2566 | return 0; |
2567 | ||
2568 | failed: | |
03158cd7 | 2569 | BUG_ON(!ret); |
1da177e4 | 2570 | /* |
a4b0672d NP |
2571 | * Error recovery is a bit difficult. We need to zero out blocks that |
2572 | * were newly allocated, and dirty them to ensure they get written out. | |
2573 | * Buffers need to be attached to the page at this point, otherwise | |
2574 | * the handling of potential IO errors during writeout would be hard | |
2575 | * (could try doing synchronous writeout, but what if that fails too?) | |
1da177e4 | 2576 | */ |
03158cd7 NP |
2577 | attach_nobh_buffers(page, head); |
2578 | page_zero_new_buffers(page, from, to); | |
a4b0672d | 2579 | |
03158cd7 NP |
2580 | out_release: |
2581 | unlock_page(page); | |
2582 | page_cache_release(page); | |
2583 | *pagep = NULL; | |
a4b0672d | 2584 | |
7bb46a67 | 2585 | return ret; |
2586 | } | |
03158cd7 | 2587 | EXPORT_SYMBOL(nobh_write_begin); |
1da177e4 | 2588 | |
03158cd7 NP |
2589 | int nobh_write_end(struct file *file, struct address_space *mapping, |
2590 | loff_t pos, unsigned len, unsigned copied, | |
2591 | struct page *page, void *fsdata) | |
1da177e4 LT |
2592 | { |
2593 | struct inode *inode = page->mapping->host; | |
efdc3131 | 2594 | struct buffer_head *head = fsdata; |
03158cd7 | 2595 | struct buffer_head *bh; |
5b41e74a | 2596 | BUG_ON(fsdata != NULL && page_has_buffers(page)); |
1da177e4 | 2597 | |
d4cf109f | 2598 | if (unlikely(copied < len) && head) |
5b41e74a DM |
2599 | attach_nobh_buffers(page, head); |
2600 | if (page_has_buffers(page)) | |
2601 | return generic_write_end(file, mapping, pos, len, | |
2602 | copied, page, fsdata); | |
a4b0672d | 2603 | |
22c8ca78 | 2604 | SetPageUptodate(page); |
1da177e4 | 2605 | set_page_dirty(page); |
03158cd7 NP |
2606 | if (pos+copied > inode->i_size) { |
2607 | i_size_write(inode, pos+copied); | |
1da177e4 LT |
2608 | mark_inode_dirty(inode); |
2609 | } | |
03158cd7 NP |
2610 | |
2611 | unlock_page(page); | |
2612 | page_cache_release(page); | |
2613 | ||
03158cd7 NP |
2614 | while (head) { |
2615 | bh = head; | |
2616 | head = head->b_this_page; | |
2617 | free_buffer_head(bh); | |
2618 | } | |
2619 | ||
2620 | return copied; | |
1da177e4 | 2621 | } |
03158cd7 | 2622 | EXPORT_SYMBOL(nobh_write_end); |
1da177e4 LT |
2623 | |
2624 | /* | |
2625 | * nobh_writepage() - based on block_full_write_page() except | |
2626 | * that it tries to operate without attaching bufferheads to | |
2627 | * the page. | |
2628 | */ | |
2629 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2630 | struct writeback_control *wbc) | |
2631 | { | |
2632 | struct inode * const inode = page->mapping->host; | |
2633 | loff_t i_size = i_size_read(inode); | |
2634 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2635 | unsigned offset; | |
1da177e4 LT |
2636 | int ret; |
2637 | ||
2638 | /* Is the page fully inside i_size? */ | |
2639 | if (page->index < end_index) | |
2640 | goto out; | |
2641 | ||
2642 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2643 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2644 | if (page->index >= end_index+1 || !offset) { | |
2645 | /* | |
2646 | * The page may have dirty, unmapped buffers. For example, | |
2647 | * they may have been added in ext3_writepage(). Make them | |
2648 | * freeable here, so the page does not leak. | |
2649 | */ | |
2650 | #if 0 | |
2651 | /* Not really sure about this - do we need this ? */ | |
2652 | if (page->mapping->a_ops->invalidatepage) | |
2653 | page->mapping->a_ops->invalidatepage(page, offset); | |
2654 | #endif | |
2655 | unlock_page(page); | |
2656 | return 0; /* don't care */ | |
2657 | } | |
2658 | ||
2659 | /* | |
2660 | * The page straddles i_size. It must be zeroed out on each and every | |
2661 | * writepage invocation because it may be mmapped. "A file is mapped | |
2662 | * in multiples of the page size. For a file that is not a multiple of | |
2663 | * the page size, the remaining memory is zeroed when mapped, and | |
2664 | * writes to that region are not written out to the file." | |
2665 | */ | |
eebd2aa3 | 2666 | zero_user_segment(page, offset, PAGE_CACHE_SIZE); |
1da177e4 LT |
2667 | out: |
2668 | ret = mpage_writepage(page, get_block, wbc); | |
2669 | if (ret == -EAGAIN) | |
35c80d5f CM |
2670 | ret = __block_write_full_page(inode, page, get_block, wbc, |
2671 | end_buffer_async_write); | |
1da177e4 LT |
2672 | return ret; |
2673 | } | |
2674 | EXPORT_SYMBOL(nobh_writepage); | |
2675 | ||
03158cd7 NP |
2676 | int nobh_truncate_page(struct address_space *mapping, |
2677 | loff_t from, get_block_t *get_block) | |
1da177e4 | 2678 | { |
1da177e4 LT |
2679 | pgoff_t index = from >> PAGE_CACHE_SHIFT; |
2680 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
03158cd7 NP |
2681 | unsigned blocksize; |
2682 | sector_t iblock; | |
2683 | unsigned length, pos; | |
2684 | struct inode *inode = mapping->host; | |
1da177e4 | 2685 | struct page *page; |
03158cd7 NP |
2686 | struct buffer_head map_bh; |
2687 | int err; | |
1da177e4 | 2688 | |
03158cd7 NP |
2689 | blocksize = 1 << inode->i_blkbits; |
2690 | length = offset & (blocksize - 1); | |
2691 | ||
2692 | /* Block boundary? Nothing to do */ | |
2693 | if (!length) | |
2694 | return 0; | |
2695 | ||
2696 | length = blocksize - length; | |
2697 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
1da177e4 | 2698 | |
1da177e4 | 2699 | page = grab_cache_page(mapping, index); |
03158cd7 | 2700 | err = -ENOMEM; |
1da177e4 LT |
2701 | if (!page) |
2702 | goto out; | |
2703 | ||
03158cd7 NP |
2704 | if (page_has_buffers(page)) { |
2705 | has_buffers: | |
2706 | unlock_page(page); | |
2707 | page_cache_release(page); | |
2708 | return block_truncate_page(mapping, from, get_block); | |
2709 | } | |
2710 | ||
2711 | /* Find the buffer that contains "offset" */ | |
2712 | pos = blocksize; | |
2713 | while (offset >= pos) { | |
2714 | iblock++; | |
2715 | pos += blocksize; | |
2716 | } | |
2717 | ||
460bcf57 TT |
2718 | map_bh.b_size = blocksize; |
2719 | map_bh.b_state = 0; | |
03158cd7 NP |
2720 | err = get_block(inode, iblock, &map_bh, 0); |
2721 | if (err) | |
2722 | goto unlock; | |
2723 | /* unmapped? It's a hole - nothing to do */ | |
2724 | if (!buffer_mapped(&map_bh)) | |
2725 | goto unlock; | |
2726 | ||
2727 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2728 | if (!PageUptodate(page)) { | |
2729 | err = mapping->a_ops->readpage(NULL, page); | |
2730 | if (err) { | |
2731 | page_cache_release(page); | |
2732 | goto out; | |
2733 | } | |
2734 | lock_page(page); | |
2735 | if (!PageUptodate(page)) { | |
2736 | err = -EIO; | |
2737 | goto unlock; | |
2738 | } | |
2739 | if (page_has_buffers(page)) | |
2740 | goto has_buffers; | |
1da177e4 | 2741 | } |
eebd2aa3 | 2742 | zero_user(page, offset, length); |
03158cd7 NP |
2743 | set_page_dirty(page); |
2744 | err = 0; | |
2745 | ||
2746 | unlock: | |
1da177e4 LT |
2747 | unlock_page(page); |
2748 | page_cache_release(page); | |
2749 | out: | |
03158cd7 | 2750 | return err; |
1da177e4 LT |
2751 | } |
2752 | EXPORT_SYMBOL(nobh_truncate_page); | |
2753 | ||
2754 | int block_truncate_page(struct address_space *mapping, | |
2755 | loff_t from, get_block_t *get_block) | |
2756 | { | |
2757 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2758 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2759 | unsigned blocksize; | |
54b21a79 | 2760 | sector_t iblock; |
1da177e4 LT |
2761 | unsigned length, pos; |
2762 | struct inode *inode = mapping->host; | |
2763 | struct page *page; | |
2764 | struct buffer_head *bh; | |
1da177e4 LT |
2765 | int err; |
2766 | ||
2767 | blocksize = 1 << inode->i_blkbits; | |
2768 | length = offset & (blocksize - 1); | |
2769 | ||
2770 | /* Block boundary? Nothing to do */ | |
2771 | if (!length) | |
2772 | return 0; | |
2773 | ||
2774 | length = blocksize - length; | |
54b21a79 | 2775 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
2776 | |
2777 | page = grab_cache_page(mapping, index); | |
2778 | err = -ENOMEM; | |
2779 | if (!page) | |
2780 | goto out; | |
2781 | ||
2782 | if (!page_has_buffers(page)) | |
2783 | create_empty_buffers(page, blocksize, 0); | |
2784 | ||
2785 | /* Find the buffer that contains "offset" */ | |
2786 | bh = page_buffers(page); | |
2787 | pos = blocksize; | |
2788 | while (offset >= pos) { | |
2789 | bh = bh->b_this_page; | |
2790 | iblock++; | |
2791 | pos += blocksize; | |
2792 | } | |
2793 | ||
2794 | err = 0; | |
2795 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 2796 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
2797 | err = get_block(inode, iblock, bh, 0); |
2798 | if (err) | |
2799 | goto unlock; | |
2800 | /* unmapped? It's a hole - nothing to do */ | |
2801 | if (!buffer_mapped(bh)) | |
2802 | goto unlock; | |
2803 | } | |
2804 | ||
2805 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2806 | if (PageUptodate(page)) | |
2807 | set_buffer_uptodate(bh); | |
2808 | ||
33a266dd | 2809 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { |
1da177e4 LT |
2810 | err = -EIO; |
2811 | ll_rw_block(READ, 1, &bh); | |
2812 | wait_on_buffer(bh); | |
2813 | /* Uhhuh. Read error. Complain and punt. */ | |
2814 | if (!buffer_uptodate(bh)) | |
2815 | goto unlock; | |
2816 | } | |
2817 | ||
eebd2aa3 | 2818 | zero_user(page, offset, length); |
1da177e4 LT |
2819 | mark_buffer_dirty(bh); |
2820 | err = 0; | |
2821 | ||
2822 | unlock: | |
2823 | unlock_page(page); | |
2824 | page_cache_release(page); | |
2825 | out: | |
2826 | return err; | |
2827 | } | |
1fe72eaa | 2828 | EXPORT_SYMBOL(block_truncate_page); |
1da177e4 LT |
2829 | |
2830 | /* | |
2831 | * The generic ->writepage function for buffer-backed address_spaces | |
35c80d5f | 2832 | * this form passes in the end_io handler used to finish the IO. |
1da177e4 | 2833 | */ |
35c80d5f CM |
2834 | int block_write_full_page_endio(struct page *page, get_block_t *get_block, |
2835 | struct writeback_control *wbc, bh_end_io_t *handler) | |
1da177e4 LT |
2836 | { |
2837 | struct inode * const inode = page->mapping->host; | |
2838 | loff_t i_size = i_size_read(inode); | |
2839 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2840 | unsigned offset; | |
1da177e4 LT |
2841 | |
2842 | /* Is the page fully inside i_size? */ | |
2843 | if (page->index < end_index) | |
35c80d5f CM |
2844 | return __block_write_full_page(inode, page, get_block, wbc, |
2845 | handler); | |
1da177e4 LT |
2846 | |
2847 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2848 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2849 | if (page->index >= end_index+1 || !offset) { | |
2850 | /* | |
2851 | * The page may have dirty, unmapped buffers. For example, | |
2852 | * they may have been added in ext3_writepage(). Make them | |
2853 | * freeable here, so the page does not leak. | |
2854 | */ | |
aaa4059b | 2855 | do_invalidatepage(page, 0); |
1da177e4 LT |
2856 | unlock_page(page); |
2857 | return 0; /* don't care */ | |
2858 | } | |
2859 | ||
2860 | /* | |
2861 | * The page straddles i_size. It must be zeroed out on each and every | |
2a61aa40 | 2862 | * writepage invocation because it may be mmapped. "A file is mapped |
1da177e4 LT |
2863 | * in multiples of the page size. For a file that is not a multiple of |
2864 | * the page size, the remaining memory is zeroed when mapped, and | |
2865 | * writes to that region are not written out to the file." | |
2866 | */ | |
eebd2aa3 | 2867 | zero_user_segment(page, offset, PAGE_CACHE_SIZE); |
35c80d5f | 2868 | return __block_write_full_page(inode, page, get_block, wbc, handler); |
1da177e4 | 2869 | } |
1fe72eaa | 2870 | EXPORT_SYMBOL(block_write_full_page_endio); |
1da177e4 | 2871 | |
35c80d5f CM |
2872 | /* |
2873 | * The generic ->writepage function for buffer-backed address_spaces | |
2874 | */ | |
2875 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
2876 | struct writeback_control *wbc) | |
2877 | { | |
2878 | return block_write_full_page_endio(page, get_block, wbc, | |
2879 | end_buffer_async_write); | |
2880 | } | |
1fe72eaa | 2881 | EXPORT_SYMBOL(block_write_full_page); |
35c80d5f | 2882 | |
1da177e4 LT |
2883 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, |
2884 | get_block_t *get_block) | |
2885 | { | |
2886 | struct buffer_head tmp; | |
2887 | struct inode *inode = mapping->host; | |
2888 | tmp.b_state = 0; | |
2889 | tmp.b_blocknr = 0; | |
b0cf2321 | 2890 | tmp.b_size = 1 << inode->i_blkbits; |
1da177e4 LT |
2891 | get_block(inode, block, &tmp, 0); |
2892 | return tmp.b_blocknr; | |
2893 | } | |
1fe72eaa | 2894 | EXPORT_SYMBOL(generic_block_bmap); |
1da177e4 | 2895 | |
6712ecf8 | 2896 | static void end_bio_bh_io_sync(struct bio *bio, int err) |
1da177e4 LT |
2897 | { |
2898 | struct buffer_head *bh = bio->bi_private; | |
2899 | ||
1da177e4 LT |
2900 | if (err == -EOPNOTSUPP) { |
2901 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
1da177e4 LT |
2902 | } |
2903 | ||
08bafc03 KM |
2904 | if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags))) |
2905 | set_bit(BH_Quiet, &bh->b_state); | |
2906 | ||
1da177e4 LT |
2907 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); |
2908 | bio_put(bio); | |
1da177e4 LT |
2909 | } |
2910 | ||
2911 | int submit_bh(int rw, struct buffer_head * bh) | |
2912 | { | |
2913 | struct bio *bio; | |
2914 | int ret = 0; | |
2915 | ||
2916 | BUG_ON(!buffer_locked(bh)); | |
2917 | BUG_ON(!buffer_mapped(bh)); | |
2918 | BUG_ON(!bh->b_end_io); | |
8fb0e342 AK |
2919 | BUG_ON(buffer_delay(bh)); |
2920 | BUG_ON(buffer_unwritten(bh)); | |
1da177e4 | 2921 | |
1da177e4 | 2922 | /* |
48fd4f93 | 2923 | * Only clear out a write error when rewriting |
1da177e4 | 2924 | */ |
48fd4f93 | 2925 | if (test_set_buffer_req(bh) && (rw & WRITE)) |
1da177e4 LT |
2926 | clear_buffer_write_io_error(bh); |
2927 | ||
2928 | /* | |
2929 | * from here on down, it's all bio -- do the initial mapping, | |
2930 | * submit_bio -> generic_make_request may further map this bio around | |
2931 | */ | |
2932 | bio = bio_alloc(GFP_NOIO, 1); | |
2933 | ||
2934 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); | |
2935 | bio->bi_bdev = bh->b_bdev; | |
2936 | bio->bi_io_vec[0].bv_page = bh->b_page; | |
2937 | bio->bi_io_vec[0].bv_len = bh->b_size; | |
2938 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); | |
2939 | ||
2940 | bio->bi_vcnt = 1; | |
2941 | bio->bi_idx = 0; | |
2942 | bio->bi_size = bh->b_size; | |
2943 | ||
2944 | bio->bi_end_io = end_bio_bh_io_sync; | |
2945 | bio->bi_private = bh; | |
2946 | ||
2947 | bio_get(bio); | |
2948 | submit_bio(rw, bio); | |
2949 | ||
2950 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) | |
2951 | ret = -EOPNOTSUPP; | |
2952 | ||
2953 | bio_put(bio); | |
2954 | return ret; | |
2955 | } | |
1fe72eaa | 2956 | EXPORT_SYMBOL(submit_bh); |
1da177e4 LT |
2957 | |
2958 | /** | |
2959 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
9cb569d6 | 2960 | * @rw: whether to %READ or %WRITE or maybe %READA (readahead) |
1da177e4 LT |
2961 | * @nr: number of &struct buffer_heads in the array |
2962 | * @bhs: array of pointers to &struct buffer_head | |
2963 | * | |
a7662236 JK |
2964 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
2965 | * requests an I/O operation on them, either a %READ or a %WRITE. The third | |
9cb569d6 CH |
2966 | * %READA option is described in the documentation for generic_make_request() |
2967 | * which ll_rw_block() calls. | |
1da177e4 LT |
2968 | * |
2969 | * This function drops any buffer that it cannot get a lock on (with the | |
9cb569d6 CH |
2970 | * BH_Lock state bit), any buffer that appears to be clean when doing a write |
2971 | * request, and any buffer that appears to be up-to-date when doing read | |
2972 | * request. Further it marks as clean buffers that are processed for | |
2973 | * writing (the buffer cache won't assume that they are actually clean | |
2974 | * until the buffer gets unlocked). | |
1da177e4 LT |
2975 | * |
2976 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
2977 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes | |
2978 | * any waiters. | |
2979 | * | |
2980 | * All of the buffers must be for the same device, and must also be a | |
2981 | * multiple of the current approved size for the device. | |
2982 | */ | |
2983 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) | |
2984 | { | |
2985 | int i; | |
2986 | ||
2987 | for (i = 0; i < nr; i++) { | |
2988 | struct buffer_head *bh = bhs[i]; | |
2989 | ||
9cb569d6 | 2990 | if (!trylock_buffer(bh)) |
1da177e4 | 2991 | continue; |
9cb569d6 | 2992 | if (rw == WRITE) { |
1da177e4 | 2993 | if (test_clear_buffer_dirty(bh)) { |
76c3073a | 2994 | bh->b_end_io = end_buffer_write_sync; |
e60e5c50 | 2995 | get_bh(bh); |
9cb569d6 | 2996 | submit_bh(WRITE, bh); |
1da177e4 LT |
2997 | continue; |
2998 | } | |
2999 | } else { | |
1da177e4 | 3000 | if (!buffer_uptodate(bh)) { |
76c3073a | 3001 | bh->b_end_io = end_buffer_read_sync; |
e60e5c50 | 3002 | get_bh(bh); |
1da177e4 LT |
3003 | submit_bh(rw, bh); |
3004 | continue; | |
3005 | } | |
3006 | } | |
3007 | unlock_buffer(bh); | |
1da177e4 LT |
3008 | } |
3009 | } | |
1fe72eaa | 3010 | EXPORT_SYMBOL(ll_rw_block); |
1da177e4 | 3011 | |
9cb569d6 CH |
3012 | void write_dirty_buffer(struct buffer_head *bh, int rw) |
3013 | { | |
3014 | lock_buffer(bh); | |
3015 | if (!test_clear_buffer_dirty(bh)) { | |
3016 | unlock_buffer(bh); | |
3017 | return; | |
3018 | } | |
3019 | bh->b_end_io = end_buffer_write_sync; | |
3020 | get_bh(bh); | |
3021 | submit_bh(rw, bh); | |
3022 | } | |
3023 | EXPORT_SYMBOL(write_dirty_buffer); | |
3024 | ||
1da177e4 LT |
3025 | /* |
3026 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
3027 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
3028 | * the buffer_head. | |
3029 | */ | |
87e99511 | 3030 | int __sync_dirty_buffer(struct buffer_head *bh, int rw) |
1da177e4 LT |
3031 | { |
3032 | int ret = 0; | |
3033 | ||
3034 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
3035 | lock_buffer(bh); | |
3036 | if (test_clear_buffer_dirty(bh)) { | |
3037 | get_bh(bh); | |
3038 | bh->b_end_io = end_buffer_write_sync; | |
87e99511 | 3039 | ret = submit_bh(rw, bh); |
1da177e4 | 3040 | wait_on_buffer(bh); |
1da177e4 LT |
3041 | if (!ret && !buffer_uptodate(bh)) |
3042 | ret = -EIO; | |
3043 | } else { | |
3044 | unlock_buffer(bh); | |
3045 | } | |
3046 | return ret; | |
3047 | } | |
87e99511 CH |
3048 | EXPORT_SYMBOL(__sync_dirty_buffer); |
3049 | ||
3050 | int sync_dirty_buffer(struct buffer_head *bh) | |
3051 | { | |
3052 | return __sync_dirty_buffer(bh, WRITE_SYNC); | |
3053 | } | |
1fe72eaa | 3054 | EXPORT_SYMBOL(sync_dirty_buffer); |
1da177e4 LT |
3055 | |
3056 | /* | |
3057 | * try_to_free_buffers() checks if all the buffers on this particular page | |
3058 | * are unused, and releases them if so. | |
3059 | * | |
3060 | * Exclusion against try_to_free_buffers may be obtained by either | |
3061 | * locking the page or by holding its mapping's private_lock. | |
3062 | * | |
3063 | * If the page is dirty but all the buffers are clean then we need to | |
3064 | * be sure to mark the page clean as well. This is because the page | |
3065 | * may be against a block device, and a later reattachment of buffers | |
3066 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
3067 | * filesystem data on the same device. | |
3068 | * | |
3069 | * The same applies to regular filesystem pages: if all the buffers are | |
3070 | * clean then we set the page clean and proceed. To do that, we require | |
3071 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
3072 | * private_lock. | |
3073 | * | |
3074 | * try_to_free_buffers() is non-blocking. | |
3075 | */ | |
3076 | static inline int buffer_busy(struct buffer_head *bh) | |
3077 | { | |
3078 | return atomic_read(&bh->b_count) | | |
3079 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
3080 | } | |
3081 | ||
3082 | static int | |
3083 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
3084 | { | |
3085 | struct buffer_head *head = page_buffers(page); | |
3086 | struct buffer_head *bh; | |
3087 | ||
3088 | bh = head; | |
3089 | do { | |
de7d5a3b | 3090 | if (buffer_write_io_error(bh) && page->mapping) |
1da177e4 LT |
3091 | set_bit(AS_EIO, &page->mapping->flags); |
3092 | if (buffer_busy(bh)) | |
3093 | goto failed; | |
3094 | bh = bh->b_this_page; | |
3095 | } while (bh != head); | |
3096 | ||
3097 | do { | |
3098 | struct buffer_head *next = bh->b_this_page; | |
3099 | ||
535ee2fb | 3100 | if (bh->b_assoc_map) |
1da177e4 LT |
3101 | __remove_assoc_queue(bh); |
3102 | bh = next; | |
3103 | } while (bh != head); | |
3104 | *buffers_to_free = head; | |
3105 | __clear_page_buffers(page); | |
3106 | return 1; | |
3107 | failed: | |
3108 | return 0; | |
3109 | } | |
3110 | ||
3111 | int try_to_free_buffers(struct page *page) | |
3112 | { | |
3113 | struct address_space * const mapping = page->mapping; | |
3114 | struct buffer_head *buffers_to_free = NULL; | |
3115 | int ret = 0; | |
3116 | ||
3117 | BUG_ON(!PageLocked(page)); | |
ecdfc978 | 3118 | if (PageWriteback(page)) |
1da177e4 LT |
3119 | return 0; |
3120 | ||
3121 | if (mapping == NULL) { /* can this still happen? */ | |
3122 | ret = drop_buffers(page, &buffers_to_free); | |
3123 | goto out; | |
3124 | } | |
3125 | ||
3126 | spin_lock(&mapping->private_lock); | |
3127 | ret = drop_buffers(page, &buffers_to_free); | |
ecdfc978 LT |
3128 | |
3129 | /* | |
3130 | * If the filesystem writes its buffers by hand (eg ext3) | |
3131 | * then we can have clean buffers against a dirty page. We | |
3132 | * clean the page here; otherwise the VM will never notice | |
3133 | * that the filesystem did any IO at all. | |
3134 | * | |
3135 | * Also, during truncate, discard_buffer will have marked all | |
3136 | * the page's buffers clean. We discover that here and clean | |
3137 | * the page also. | |
87df7241 NP |
3138 | * |
3139 | * private_lock must be held over this entire operation in order | |
3140 | * to synchronise against __set_page_dirty_buffers and prevent the | |
3141 | * dirty bit from being lost. | |
ecdfc978 LT |
3142 | */ |
3143 | if (ret) | |
3144 | cancel_dirty_page(page, PAGE_CACHE_SIZE); | |
87df7241 | 3145 | spin_unlock(&mapping->private_lock); |
1da177e4 LT |
3146 | out: |
3147 | if (buffers_to_free) { | |
3148 | struct buffer_head *bh = buffers_to_free; | |
3149 | ||
3150 | do { | |
3151 | struct buffer_head *next = bh->b_this_page; | |
3152 | free_buffer_head(bh); | |
3153 | bh = next; | |
3154 | } while (bh != buffers_to_free); | |
3155 | } | |
3156 | return ret; | |
3157 | } | |
3158 | EXPORT_SYMBOL(try_to_free_buffers); | |
3159 | ||
1da177e4 LT |
3160 | /* |
3161 | * There are no bdflush tunables left. But distributions are | |
3162 | * still running obsolete flush daemons, so we terminate them here. | |
3163 | * | |
3164 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
5b0830cb | 3165 | * The `flush-X' kernel threads fully replace bdflush daemons and this call. |
1da177e4 | 3166 | */ |
bdc480e3 | 3167 | SYSCALL_DEFINE2(bdflush, int, func, long, data) |
1da177e4 LT |
3168 | { |
3169 | static int msg_count; | |
3170 | ||
3171 | if (!capable(CAP_SYS_ADMIN)) | |
3172 | return -EPERM; | |
3173 | ||
3174 | if (msg_count < 5) { | |
3175 | msg_count++; | |
3176 | printk(KERN_INFO | |
3177 | "warning: process `%s' used the obsolete bdflush" | |
3178 | " system call\n", current->comm); | |
3179 | printk(KERN_INFO "Fix your initscripts?\n"); | |
3180 | } | |
3181 | ||
3182 | if (func == 1) | |
3183 | do_exit(0); | |
3184 | return 0; | |
3185 | } | |
3186 | ||
3187 | /* | |
3188 | * Buffer-head allocation | |
3189 | */ | |
e18b890b | 3190 | static struct kmem_cache *bh_cachep; |
1da177e4 LT |
3191 | |
3192 | /* | |
3193 | * Once the number of bh's in the machine exceeds this level, we start | |
3194 | * stripping them in writeback. | |
3195 | */ | |
3196 | static int max_buffer_heads; | |
3197 | ||
3198 | int buffer_heads_over_limit; | |
3199 | ||
3200 | struct bh_accounting { | |
3201 | int nr; /* Number of live bh's */ | |
3202 | int ratelimit; /* Limit cacheline bouncing */ | |
3203 | }; | |
3204 | ||
3205 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
3206 | ||
3207 | static void recalc_bh_state(void) | |
3208 | { | |
3209 | int i; | |
3210 | int tot = 0; | |
3211 | ||
ee1be862 | 3212 | if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) |
1da177e4 | 3213 | return; |
c7b92516 | 3214 | __this_cpu_write(bh_accounting.ratelimit, 0); |
8a143426 | 3215 | for_each_online_cpu(i) |
1da177e4 LT |
3216 | tot += per_cpu(bh_accounting, i).nr; |
3217 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
3218 | } | |
c7b92516 | 3219 | |
dd0fc66f | 3220 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
1da177e4 | 3221 | { |
019b4d12 | 3222 | struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); |
1da177e4 | 3223 | if (ret) { |
a35afb83 | 3224 | INIT_LIST_HEAD(&ret->b_assoc_buffers); |
c7b92516 CL |
3225 | preempt_disable(); |
3226 | __this_cpu_inc(bh_accounting.nr); | |
1da177e4 | 3227 | recalc_bh_state(); |
c7b92516 | 3228 | preempt_enable(); |
1da177e4 LT |
3229 | } |
3230 | return ret; | |
3231 | } | |
3232 | EXPORT_SYMBOL(alloc_buffer_head); | |
3233 | ||
3234 | void free_buffer_head(struct buffer_head *bh) | |
3235 | { | |
3236 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
3237 | kmem_cache_free(bh_cachep, bh); | |
c7b92516 CL |
3238 | preempt_disable(); |
3239 | __this_cpu_dec(bh_accounting.nr); | |
1da177e4 | 3240 | recalc_bh_state(); |
c7b92516 | 3241 | preempt_enable(); |
1da177e4 LT |
3242 | } |
3243 | EXPORT_SYMBOL(free_buffer_head); | |
3244 | ||
1da177e4 LT |
3245 | static void buffer_exit_cpu(int cpu) |
3246 | { | |
3247 | int i; | |
3248 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
3249 | ||
3250 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
3251 | brelse(b->bhs[i]); | |
3252 | b->bhs[i] = NULL; | |
3253 | } | |
c7b92516 | 3254 | this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); |
8a143426 | 3255 | per_cpu(bh_accounting, cpu).nr = 0; |
1da177e4 LT |
3256 | } |
3257 | ||
3258 | static int buffer_cpu_notify(struct notifier_block *self, | |
3259 | unsigned long action, void *hcpu) | |
3260 | { | |
8bb78442 | 3261 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) |
1da177e4 LT |
3262 | buffer_exit_cpu((unsigned long)hcpu); |
3263 | return NOTIFY_OK; | |
3264 | } | |
1da177e4 | 3265 | |
389d1b08 | 3266 | /** |
a6b91919 | 3267 | * bh_uptodate_or_lock - Test whether the buffer is uptodate |
389d1b08 AK |
3268 | * @bh: struct buffer_head |
3269 | * | |
3270 | * Return true if the buffer is up-to-date and false, | |
3271 | * with the buffer locked, if not. | |
3272 | */ | |
3273 | int bh_uptodate_or_lock(struct buffer_head *bh) | |
3274 | { | |
3275 | if (!buffer_uptodate(bh)) { | |
3276 | lock_buffer(bh); | |
3277 | if (!buffer_uptodate(bh)) | |
3278 | return 0; | |
3279 | unlock_buffer(bh); | |
3280 | } | |
3281 | return 1; | |
3282 | } | |
3283 | EXPORT_SYMBOL(bh_uptodate_or_lock); | |
3284 | ||
3285 | /** | |
a6b91919 | 3286 | * bh_submit_read - Submit a locked buffer for reading |
389d1b08 AK |
3287 | * @bh: struct buffer_head |
3288 | * | |
3289 | * Returns zero on success and -EIO on error. | |
3290 | */ | |
3291 | int bh_submit_read(struct buffer_head *bh) | |
3292 | { | |
3293 | BUG_ON(!buffer_locked(bh)); | |
3294 | ||
3295 | if (buffer_uptodate(bh)) { | |
3296 | unlock_buffer(bh); | |
3297 | return 0; | |
3298 | } | |
3299 | ||
3300 | get_bh(bh); | |
3301 | bh->b_end_io = end_buffer_read_sync; | |
3302 | submit_bh(READ, bh); | |
3303 | wait_on_buffer(bh); | |
3304 | if (buffer_uptodate(bh)) | |
3305 | return 0; | |
3306 | return -EIO; | |
3307 | } | |
3308 | EXPORT_SYMBOL(bh_submit_read); | |
3309 | ||
1da177e4 LT |
3310 | void __init buffer_init(void) |
3311 | { | |
3312 | int nrpages; | |
3313 | ||
b98938c3 CL |
3314 | bh_cachep = kmem_cache_create("buffer_head", |
3315 | sizeof(struct buffer_head), 0, | |
3316 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| | |
3317 | SLAB_MEM_SPREAD), | |
019b4d12 | 3318 | NULL); |
1da177e4 LT |
3319 | |
3320 | /* | |
3321 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3322 | */ | |
3323 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3324 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
3325 | hotcpu_notifier(buffer_cpu_notify, 0); | |
3326 | } |