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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 | ||
21 | #include <linux/kernel.h> | |
22 | #include <linux/sched/signal.h> | |
23 | #include <linux/syscalls.h> | |
24 | #include <linux/fs.h> | |
25 | #include <linux/iomap.h> | |
26 | #include <linux/mm.h> | |
27 | #include <linux/percpu.h> | |
28 | #include <linux/slab.h> | |
29 | #include <linux/capability.h> | |
30 | #include <linux/blkdev.h> | |
31 | #include <linux/file.h> | |
32 | #include <linux/quotaops.h> | |
33 | #include <linux/highmem.h> | |
34 | #include <linux/export.h> | |
35 | #include <linux/backing-dev.h> | |
36 | #include <linux/writeback.h> | |
37 | #include <linux/hash.h> | |
38 | #include <linux/suspend.h> | |
39 | #include <linux/buffer_head.h> | |
40 | #include <linux/task_io_accounting_ops.h> | |
41 | #include <linux/bio.h> | |
42 | #include <linux/cpu.h> | |
43 | #include <linux/bitops.h> | |
44 | #include <linux/mpage.h> | |
45 | #include <linux/bit_spinlock.h> | |
46 | #include <linux/pagevec.h> | |
47 | #include <linux/sched/mm.h> | |
48 | #include <trace/events/block.h> | |
49 | ||
50 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); | |
51 | static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, | |
52 | enum rw_hint hint, struct writeback_control *wbc); | |
53 | ||
54 | #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) | |
55 | ||
56 | inline void touch_buffer(struct buffer_head *bh) | |
57 | { | |
58 | trace_block_touch_buffer(bh); | |
59 | mark_page_accessed(bh->b_page); | |
60 | } | |
61 | EXPORT_SYMBOL(touch_buffer); | |
62 | ||
63 | void __lock_buffer(struct buffer_head *bh) | |
64 | { | |
65 | wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); | |
66 | } | |
67 | EXPORT_SYMBOL(__lock_buffer); | |
68 | ||
69 | void unlock_buffer(struct buffer_head *bh) | |
70 | { | |
71 | clear_bit_unlock(BH_Lock, &bh->b_state); | |
72 | smp_mb__after_atomic(); | |
73 | wake_up_bit(&bh->b_state, BH_Lock); | |
74 | } | |
75 | EXPORT_SYMBOL(unlock_buffer); | |
76 | ||
77 | /* | |
78 | * Returns if the page has dirty or writeback buffers. If all the buffers | |
79 | * are unlocked and clean then the PageDirty information is stale. If | |
80 | * any of the pages are locked, it is assumed they are locked for IO. | |
81 | */ | |
82 | void buffer_check_dirty_writeback(struct page *page, | |
83 | bool *dirty, bool *writeback) | |
84 | { | |
85 | struct buffer_head *head, *bh; | |
86 | *dirty = false; | |
87 | *writeback = false; | |
88 | ||
89 | BUG_ON(!PageLocked(page)); | |
90 | ||
91 | if (!page_has_buffers(page)) | |
92 | return; | |
93 | ||
94 | if (PageWriteback(page)) | |
95 | *writeback = true; | |
96 | ||
97 | head = page_buffers(page); | |
98 | bh = head; | |
99 | do { | |
100 | if (buffer_locked(bh)) | |
101 | *writeback = true; | |
102 | ||
103 | if (buffer_dirty(bh)) | |
104 | *dirty = true; | |
105 | ||
106 | bh = bh->b_this_page; | |
107 | } while (bh != head); | |
108 | } | |
109 | EXPORT_SYMBOL(buffer_check_dirty_writeback); | |
110 | ||
111 | /* | |
112 | * Block until a buffer comes unlocked. This doesn't stop it | |
113 | * from becoming locked again - you have to lock it yourself | |
114 | * if you want to preserve its state. | |
115 | */ | |
116 | void __wait_on_buffer(struct buffer_head * bh) | |
117 | { | |
118 | wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); | |
119 | } | |
120 | EXPORT_SYMBOL(__wait_on_buffer); | |
121 | ||
122 | static void | |
123 | __clear_page_buffers(struct page *page) | |
124 | { | |
125 | ClearPagePrivate(page); | |
126 | set_page_private(page, 0); | |
127 | put_page(page); | |
128 | } | |
129 | ||
130 | static void buffer_io_error(struct buffer_head *bh, char *msg) | |
131 | { | |
132 | if (!test_bit(BH_Quiet, &bh->b_state)) | |
133 | printk_ratelimited(KERN_ERR | |
134 | "Buffer I/O error on dev %pg, logical block %llu%s\n", | |
135 | bh->b_bdev, (unsigned long long)bh->b_blocknr, msg); | |
136 | } | |
137 | ||
138 | /* | |
139 | * End-of-IO handler helper function which does not touch the bh after | |
140 | * unlocking it. | |
141 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but | |
142 | * a race there is benign: unlock_buffer() only use the bh's address for | |
143 | * hashing after unlocking the buffer, so it doesn't actually touch the bh | |
144 | * itself. | |
145 | */ | |
146 | static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) | |
147 | { | |
148 | if (uptodate) { | |
149 | set_buffer_uptodate(bh); | |
150 | } else { | |
151 | /* This happens, due to failed read-ahead attempts. */ | |
152 | clear_buffer_uptodate(bh); | |
153 | } | |
154 | unlock_buffer(bh); | |
155 | } | |
156 | ||
157 | /* | |
158 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and | |
159 | * unlock the buffer. This is what ll_rw_block uses too. | |
160 | */ | |
161 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) | |
162 | { | |
163 | __end_buffer_read_notouch(bh, uptodate); | |
164 | put_bh(bh); | |
165 | } | |
166 | EXPORT_SYMBOL(end_buffer_read_sync); | |
167 | ||
168 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) | |
169 | { | |
170 | if (uptodate) { | |
171 | set_buffer_uptodate(bh); | |
172 | } else { | |
173 | buffer_io_error(bh, ", lost sync page write"); | |
174 | mark_buffer_write_io_error(bh); | |
175 | clear_buffer_uptodate(bh); | |
176 | } | |
177 | unlock_buffer(bh); | |
178 | put_bh(bh); | |
179 | } | |
180 | EXPORT_SYMBOL(end_buffer_write_sync); | |
181 | ||
182 | /* | |
183 | * Various filesystems appear to want __find_get_block to be non-blocking. | |
184 | * But it's the page lock which protects the buffers. To get around this, | |
185 | * we get exclusion from try_to_free_buffers with the blockdev mapping's | |
186 | * private_lock. | |
187 | * | |
188 | * Hack idea: for the blockdev mapping, private_lock contention | |
189 | * may be quite high. This code could TryLock the page, and if that | |
190 | * succeeds, there is no need to take private_lock. | |
191 | */ | |
192 | static struct buffer_head * | |
193 | __find_get_block_slow(struct block_device *bdev, sector_t block) | |
194 | { | |
195 | struct inode *bd_inode = bdev->bd_inode; | |
196 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
197 | struct buffer_head *ret = NULL; | |
198 | pgoff_t index; | |
199 | struct buffer_head *bh; | |
200 | struct buffer_head *head; | |
201 | struct page *page; | |
202 | int all_mapped = 1; | |
203 | static DEFINE_RATELIMIT_STATE(last_warned, HZ, 1); | |
204 | ||
205 | index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); | |
206 | page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED); | |
207 | if (!page) | |
208 | goto out; | |
209 | ||
210 | spin_lock(&bd_mapping->private_lock); | |
211 | if (!page_has_buffers(page)) | |
212 | goto out_unlock; | |
213 | head = page_buffers(page); | |
214 | bh = head; | |
215 | do { | |
216 | if (!buffer_mapped(bh)) | |
217 | all_mapped = 0; | |
218 | else if (bh->b_blocknr == block) { | |
219 | ret = bh; | |
220 | get_bh(bh); | |
221 | goto out_unlock; | |
222 | } | |
223 | bh = bh->b_this_page; | |
224 | } while (bh != head); | |
225 | ||
226 | /* we might be here because some of the buffers on this page are | |
227 | * not mapped. This is due to various races between | |
228 | * file io on the block device and getblk. It gets dealt with | |
229 | * elsewhere, don't buffer_error if we had some unmapped buffers | |
230 | */ | |
231 | ratelimit_set_flags(&last_warned, RATELIMIT_MSG_ON_RELEASE); | |
232 | if (all_mapped && __ratelimit(&last_warned)) { | |
233 | printk("__find_get_block_slow() failed. block=%llu, " | |
234 | "b_blocknr=%llu, b_state=0x%08lx, b_size=%zu, " | |
235 | "device %pg blocksize: %d\n", | |
236 | (unsigned long long)block, | |
237 | (unsigned long long)bh->b_blocknr, | |
238 | bh->b_state, bh->b_size, bdev, | |
239 | 1 << bd_inode->i_blkbits); | |
240 | } | |
241 | out_unlock: | |
242 | spin_unlock(&bd_mapping->private_lock); | |
243 | put_page(page); | |
244 | out: | |
245 | return ret; | |
246 | } | |
247 | ||
248 | /* | |
249 | * I/O completion handler for block_read_full_page() - pages | |
250 | * which come unlocked at the end of I/O. | |
251 | */ | |
252 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) | |
253 | { | |
254 | unsigned long flags; | |
255 | struct buffer_head *first; | |
256 | struct buffer_head *tmp; | |
257 | struct page *page; | |
258 | int page_uptodate = 1; | |
259 | ||
260 | BUG_ON(!buffer_async_read(bh)); | |
261 | ||
262 | page = bh->b_page; | |
263 | if (uptodate) { | |
264 | set_buffer_uptodate(bh); | |
265 | } else { | |
266 | clear_buffer_uptodate(bh); | |
267 | buffer_io_error(bh, ", async page read"); | |
268 | SetPageError(page); | |
269 | } | |
270 | ||
271 | /* | |
272 | * Be _very_ careful from here on. Bad things can happen if | |
273 | * two buffer heads end IO at almost the same time and both | |
274 | * decide that the page is now completely done. | |
275 | */ | |
276 | first = page_buffers(page); | |
277 | local_irq_save(flags); | |
278 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
279 | clear_buffer_async_read(bh); | |
280 | unlock_buffer(bh); | |
281 | tmp = bh; | |
282 | do { | |
283 | if (!buffer_uptodate(tmp)) | |
284 | page_uptodate = 0; | |
285 | if (buffer_async_read(tmp)) { | |
286 | BUG_ON(!buffer_locked(tmp)); | |
287 | goto still_busy; | |
288 | } | |
289 | tmp = tmp->b_this_page; | |
290 | } while (tmp != bh); | |
291 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); | |
292 | local_irq_restore(flags); | |
293 | ||
294 | /* | |
295 | * If none of the buffers had errors and they are all | |
296 | * uptodate then we can set the page uptodate. | |
297 | */ | |
298 | if (page_uptodate && !PageError(page)) | |
299 | SetPageUptodate(page); | |
300 | unlock_page(page); | |
301 | return; | |
302 | ||
303 | still_busy: | |
304 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); | |
305 | local_irq_restore(flags); | |
306 | return; | |
307 | } | |
308 | ||
309 | /* | |
310 | * Completion handler for block_write_full_page() - pages which are unlocked | |
311 | * during I/O, and which have PageWriteback cleared upon I/O completion. | |
312 | */ | |
313 | void end_buffer_async_write(struct buffer_head *bh, int uptodate) | |
314 | { | |
315 | unsigned long flags; | |
316 | struct buffer_head *first; | |
317 | struct buffer_head *tmp; | |
318 | struct page *page; | |
319 | ||
320 | BUG_ON(!buffer_async_write(bh)); | |
321 | ||
322 | page = bh->b_page; | |
323 | if (uptodate) { | |
324 | set_buffer_uptodate(bh); | |
325 | } else { | |
326 | buffer_io_error(bh, ", lost async page write"); | |
327 | mark_buffer_write_io_error(bh); | |
328 | clear_buffer_uptodate(bh); | |
329 | SetPageError(page); | |
330 | } | |
331 | ||
332 | first = page_buffers(page); | |
333 | local_irq_save(flags); | |
334 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
335 | ||
336 | clear_buffer_async_write(bh); | |
337 | unlock_buffer(bh); | |
338 | tmp = bh->b_this_page; | |
339 | while (tmp != bh) { | |
340 | if (buffer_async_write(tmp)) { | |
341 | BUG_ON(!buffer_locked(tmp)); | |
342 | goto still_busy; | |
343 | } | |
344 | tmp = tmp->b_this_page; | |
345 | } | |
346 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); | |
347 | local_irq_restore(flags); | |
348 | end_page_writeback(page); | |
349 | return; | |
350 | ||
351 | still_busy: | |
352 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); | |
353 | local_irq_restore(flags); | |
354 | return; | |
355 | } | |
356 | EXPORT_SYMBOL(end_buffer_async_write); | |
357 | ||
358 | /* | |
359 | * If a page's buffers are under async readin (end_buffer_async_read | |
360 | * completion) then there is a possibility that another thread of | |
361 | * control could lock one of the buffers after it has completed | |
362 | * but while some of the other buffers have not completed. This | |
363 | * locked buffer would confuse end_buffer_async_read() into not unlocking | |
364 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() | |
365 | * that this buffer is not under async I/O. | |
366 | * | |
367 | * The page comes unlocked when it has no locked buffer_async buffers | |
368 | * left. | |
369 | * | |
370 | * PageLocked prevents anyone starting new async I/O reads any of | |
371 | * the buffers. | |
372 | * | |
373 | * PageWriteback is used to prevent simultaneous writeout of the same | |
374 | * page. | |
375 | * | |
376 | * PageLocked prevents anyone from starting writeback of a page which is | |
377 | * under read I/O (PageWriteback is only ever set against a locked page). | |
378 | */ | |
379 | static void mark_buffer_async_read(struct buffer_head *bh) | |
380 | { | |
381 | bh->b_end_io = end_buffer_async_read; | |
382 | set_buffer_async_read(bh); | |
383 | } | |
384 | ||
385 | static void mark_buffer_async_write_endio(struct buffer_head *bh, | |
386 | bh_end_io_t *handler) | |
387 | { | |
388 | bh->b_end_io = handler; | |
389 | set_buffer_async_write(bh); | |
390 | } | |
391 | ||
392 | void mark_buffer_async_write(struct buffer_head *bh) | |
393 | { | |
394 | mark_buffer_async_write_endio(bh, end_buffer_async_write); | |
395 | } | |
396 | EXPORT_SYMBOL(mark_buffer_async_write); | |
397 | ||
398 | ||
399 | /* | |
400 | * fs/buffer.c contains helper functions for buffer-backed address space's | |
401 | * fsync functions. A common requirement for buffer-based filesystems is | |
402 | * that certain data from the backing blockdev needs to be written out for | |
403 | * a successful fsync(). For example, ext2 indirect blocks need to be | |
404 | * written back and waited upon before fsync() returns. | |
405 | * | |
406 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), | |
407 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the | |
408 | * management of a list of dependent buffers at ->i_mapping->private_list. | |
409 | * | |
410 | * Locking is a little subtle: try_to_free_buffers() will remove buffers | |
411 | * from their controlling inode's queue when they are being freed. But | |
412 | * try_to_free_buffers() will be operating against the *blockdev* mapping | |
413 | * at the time, not against the S_ISREG file which depends on those buffers. | |
414 | * So the locking for private_list is via the private_lock in the address_space | |
415 | * which backs the buffers. Which is different from the address_space | |
416 | * against which the buffers are listed. So for a particular address_space, | |
417 | * mapping->private_lock does *not* protect mapping->private_list! In fact, | |
418 | * mapping->private_list will always be protected by the backing blockdev's | |
419 | * ->private_lock. | |
420 | * | |
421 | * Which introduces a requirement: all buffers on an address_space's | |
422 | * ->private_list must be from the same address_space: the blockdev's. | |
423 | * | |
424 | * address_spaces which do not place buffers at ->private_list via these | |
425 | * utility functions are free to use private_lock and private_list for | |
426 | * whatever they want. The only requirement is that list_empty(private_list) | |
427 | * be true at clear_inode() time. | |
428 | * | |
429 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The | |
430 | * filesystems should do that. invalidate_inode_buffers() should just go | |
431 | * BUG_ON(!list_empty). | |
432 | * | |
433 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should | |
434 | * take an address_space, not an inode. And it should be called | |
435 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being | |
436 | * queued up. | |
437 | * | |
438 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the | |
439 | * list if it is already on a list. Because if the buffer is on a list, | |
440 | * it *must* already be on the right one. If not, the filesystem is being | |
441 | * silly. This will save a ton of locking. But first we have to ensure | |
442 | * that buffers are taken *off* the old inode's list when they are freed | |
443 | * (presumably in truncate). That requires careful auditing of all | |
444 | * filesystems (do it inside bforget()). It could also be done by bringing | |
445 | * b_inode back. | |
446 | */ | |
447 | ||
448 | /* | |
449 | * The buffer's backing address_space's private_lock must be held | |
450 | */ | |
451 | static void __remove_assoc_queue(struct buffer_head *bh) | |
452 | { | |
453 | list_del_init(&bh->b_assoc_buffers); | |
454 | WARN_ON(!bh->b_assoc_map); | |
455 | bh->b_assoc_map = NULL; | |
456 | } | |
457 | ||
458 | int inode_has_buffers(struct inode *inode) | |
459 | { | |
460 | return !list_empty(&inode->i_data.private_list); | |
461 | } | |
462 | ||
463 | /* | |
464 | * osync is designed to support O_SYNC io. It waits synchronously for | |
465 | * all already-submitted IO to complete, but does not queue any new | |
466 | * writes to the disk. | |
467 | * | |
468 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as | |
469 | * you dirty the buffers, and then use osync_inode_buffers to wait for | |
470 | * completion. Any other dirty buffers which are not yet queued for | |
471 | * write will not be flushed to disk by the osync. | |
472 | */ | |
473 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) | |
474 | { | |
475 | struct buffer_head *bh; | |
476 | struct list_head *p; | |
477 | int err = 0; | |
478 | ||
479 | spin_lock(lock); | |
480 | repeat: | |
481 | list_for_each_prev(p, list) { | |
482 | bh = BH_ENTRY(p); | |
483 | if (buffer_locked(bh)) { | |
484 | get_bh(bh); | |
485 | spin_unlock(lock); | |
486 | wait_on_buffer(bh); | |
487 | if (!buffer_uptodate(bh)) | |
488 | err = -EIO; | |
489 | brelse(bh); | |
490 | spin_lock(lock); | |
491 | goto repeat; | |
492 | } | |
493 | } | |
494 | spin_unlock(lock); | |
495 | return err; | |
496 | } | |
497 | ||
498 | void emergency_thaw_bdev(struct super_block *sb) | |
499 | { | |
500 | while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) | |
501 | printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev); | |
502 | } | |
503 | ||
504 | /** | |
505 | * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers | |
506 | * @mapping: the mapping which wants those buffers written | |
507 | * | |
508 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
509 | * that I/O. | |
510 | * | |
511 | * Basically, this is a convenience function for fsync(). | |
512 | * @mapping is a file or directory which needs those buffers to be written for | |
513 | * a successful fsync(). | |
514 | */ | |
515 | int sync_mapping_buffers(struct address_space *mapping) | |
516 | { | |
517 | struct address_space *buffer_mapping = mapping->private_data; | |
518 | ||
519 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) | |
520 | return 0; | |
521 | ||
522 | return fsync_buffers_list(&buffer_mapping->private_lock, | |
523 | &mapping->private_list); | |
524 | } | |
525 | EXPORT_SYMBOL(sync_mapping_buffers); | |
526 | ||
527 | /* | |
528 | * Called when we've recently written block `bblock', and it is known that | |
529 | * `bblock' was for a buffer_boundary() buffer. This means that the block at | |
530 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's | |
531 | * dirty, schedule it for IO. So that indirects merge nicely with their data. | |
532 | */ | |
533 | void write_boundary_block(struct block_device *bdev, | |
534 | sector_t bblock, unsigned blocksize) | |
535 | { | |
536 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); | |
537 | if (bh) { | |
538 | if (buffer_dirty(bh)) | |
539 | ll_rw_block(REQ_OP_WRITE, 0, 1, &bh); | |
540 | put_bh(bh); | |
541 | } | |
542 | } | |
543 | ||
544 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) | |
545 | { | |
546 | struct address_space *mapping = inode->i_mapping; | |
547 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
548 | ||
549 | mark_buffer_dirty(bh); | |
550 | if (!mapping->private_data) { | |
551 | mapping->private_data = buffer_mapping; | |
552 | } else { | |
553 | BUG_ON(mapping->private_data != buffer_mapping); | |
554 | } | |
555 | if (!bh->b_assoc_map) { | |
556 | spin_lock(&buffer_mapping->private_lock); | |
557 | list_move_tail(&bh->b_assoc_buffers, | |
558 | &mapping->private_list); | |
559 | bh->b_assoc_map = mapping; | |
560 | spin_unlock(&buffer_mapping->private_lock); | |
561 | } | |
562 | } | |
563 | EXPORT_SYMBOL(mark_buffer_dirty_inode); | |
564 | ||
565 | /* | |
566 | * Mark the page dirty, and set it dirty in the page cache, and mark the inode | |
567 | * dirty. | |
568 | * | |
569 | * If warn is true, then emit a warning if the page is not uptodate and has | |
570 | * not been truncated. | |
571 | * | |
572 | * The caller must hold lock_page_memcg(). | |
573 | */ | |
574 | void __set_page_dirty(struct page *page, struct address_space *mapping, | |
575 | int warn) | |
576 | { | |
577 | unsigned long flags; | |
578 | ||
579 | xa_lock_irqsave(&mapping->i_pages, flags); | |
580 | if (page->mapping) { /* Race with truncate? */ | |
581 | WARN_ON_ONCE(warn && !PageUptodate(page)); | |
582 | account_page_dirtied(page, mapping); | |
583 | __xa_set_mark(&mapping->i_pages, page_index(page), | |
584 | PAGECACHE_TAG_DIRTY); | |
585 | } | |
586 | xa_unlock_irqrestore(&mapping->i_pages, flags); | |
587 | } | |
588 | EXPORT_SYMBOL_GPL(__set_page_dirty); | |
589 | ||
590 | /* | |
591 | * Add a page to the dirty page list. | |
592 | * | |
593 | * It is a sad fact of life that this function is called from several places | |
594 | * deeply under spinlocking. It may not sleep. | |
595 | * | |
596 | * If the page has buffers, the uptodate buffers are set dirty, to preserve | |
597 | * dirty-state coherency between the page and the buffers. It the page does | |
598 | * not have buffers then when they are later attached they will all be set | |
599 | * dirty. | |
600 | * | |
601 | * The buffers are dirtied before the page is dirtied. There's a small race | |
602 | * window in which a writepage caller may see the page cleanness but not the | |
603 | * buffer dirtiness. That's fine. If this code were to set the page dirty | |
604 | * before the buffers, a concurrent writepage caller could clear the page dirty | |
605 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean | |
606 | * page on the dirty page list. | |
607 | * | |
608 | * We use private_lock to lock against try_to_free_buffers while using the | |
609 | * page's buffer list. Also use this to protect against clean buffers being | |
610 | * added to the page after it was set dirty. | |
611 | * | |
612 | * FIXME: may need to call ->reservepage here as well. That's rather up to the | |
613 | * address_space though. | |
614 | */ | |
615 | int __set_page_dirty_buffers(struct page *page) | |
616 | { | |
617 | int newly_dirty; | |
618 | struct address_space *mapping = page_mapping(page); | |
619 | ||
620 | if (unlikely(!mapping)) | |
621 | return !TestSetPageDirty(page); | |
622 | ||
623 | spin_lock(&mapping->private_lock); | |
624 | if (page_has_buffers(page)) { | |
625 | struct buffer_head *head = page_buffers(page); | |
626 | struct buffer_head *bh = head; | |
627 | ||
628 | do { | |
629 | set_buffer_dirty(bh); | |
630 | bh = bh->b_this_page; | |
631 | } while (bh != head); | |
632 | } | |
633 | /* | |
634 | * Lock out page->mem_cgroup migration to keep PageDirty | |
635 | * synchronized with per-memcg dirty page counters. | |
636 | */ | |
637 | lock_page_memcg(page); | |
638 | newly_dirty = !TestSetPageDirty(page); | |
639 | spin_unlock(&mapping->private_lock); | |
640 | ||
641 | if (newly_dirty) | |
642 | __set_page_dirty(page, mapping, 1); | |
643 | ||
644 | unlock_page_memcg(page); | |
645 | ||
646 | if (newly_dirty) | |
647 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); | |
648 | ||
649 | return newly_dirty; | |
650 | } | |
651 | EXPORT_SYMBOL(__set_page_dirty_buffers); | |
652 | ||
653 | /* | |
654 | * Write out and wait upon a list of buffers. | |
655 | * | |
656 | * We have conflicting pressures: we want to make sure that all | |
657 | * initially dirty buffers get waited on, but that any subsequently | |
658 | * dirtied buffers don't. After all, we don't want fsync to last | |
659 | * forever if somebody is actively writing to the file. | |
660 | * | |
661 | * Do this in two main stages: first we copy dirty buffers to a | |
662 | * temporary inode list, queueing the writes as we go. Then we clean | |
663 | * up, waiting for those writes to complete. | |
664 | * | |
665 | * During this second stage, any subsequent updates to the file may end | |
666 | * up refiling the buffer on the original inode's dirty list again, so | |
667 | * there is a chance we will end up with a buffer queued for write but | |
668 | * not yet completed on that list. So, as a final cleanup we go through | |
669 | * the osync code to catch these locked, dirty buffers without requeuing | |
670 | * any newly dirty buffers for write. | |
671 | */ | |
672 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) | |
673 | { | |
674 | struct buffer_head *bh; | |
675 | struct list_head tmp; | |
676 | struct address_space *mapping; | |
677 | int err = 0, err2; | |
678 | struct blk_plug plug; | |
679 | ||
680 | INIT_LIST_HEAD(&tmp); | |
681 | blk_start_plug(&plug); | |
682 | ||
683 | spin_lock(lock); | |
684 | while (!list_empty(list)) { | |
685 | bh = BH_ENTRY(list->next); | |
686 | mapping = bh->b_assoc_map; | |
687 | __remove_assoc_queue(bh); | |
688 | /* Avoid race with mark_buffer_dirty_inode() which does | |
689 | * a lockless check and we rely on seeing the dirty bit */ | |
690 | smp_mb(); | |
691 | if (buffer_dirty(bh) || buffer_locked(bh)) { | |
692 | list_add(&bh->b_assoc_buffers, &tmp); | |
693 | bh->b_assoc_map = mapping; | |
694 | if (buffer_dirty(bh)) { | |
695 | get_bh(bh); | |
696 | spin_unlock(lock); | |
697 | /* | |
698 | * Ensure any pending I/O completes so that | |
699 | * write_dirty_buffer() actually writes the | |
700 | * current contents - it is a noop if I/O is | |
701 | * still in flight on potentially older | |
702 | * contents. | |
703 | */ | |
704 | write_dirty_buffer(bh, REQ_SYNC); | |
705 | ||
706 | /* | |
707 | * Kick off IO for the previous mapping. Note | |
708 | * that we will not run the very last mapping, | |
709 | * wait_on_buffer() will do that for us | |
710 | * through sync_buffer(). | |
711 | */ | |
712 | brelse(bh); | |
713 | spin_lock(lock); | |
714 | } | |
715 | } | |
716 | } | |
717 | ||
718 | spin_unlock(lock); | |
719 | blk_finish_plug(&plug); | |
720 | spin_lock(lock); | |
721 | ||
722 | while (!list_empty(&tmp)) { | |
723 | bh = BH_ENTRY(tmp.prev); | |
724 | get_bh(bh); | |
725 | mapping = bh->b_assoc_map; | |
726 | __remove_assoc_queue(bh); | |
727 | /* Avoid race with mark_buffer_dirty_inode() which does | |
728 | * a lockless check and we rely on seeing the dirty bit */ | |
729 | smp_mb(); | |
730 | if (buffer_dirty(bh)) { | |
731 | list_add(&bh->b_assoc_buffers, | |
732 | &mapping->private_list); | |
733 | bh->b_assoc_map = mapping; | |
734 | } | |
735 | spin_unlock(lock); | |
736 | wait_on_buffer(bh); | |
737 | if (!buffer_uptodate(bh)) | |
738 | err = -EIO; | |
739 | brelse(bh); | |
740 | spin_lock(lock); | |
741 | } | |
742 | ||
743 | spin_unlock(lock); | |
744 | err2 = osync_buffers_list(lock, list); | |
745 | if (err) | |
746 | return err; | |
747 | else | |
748 | return err2; | |
749 | } | |
750 | ||
751 | /* | |
752 | * Invalidate any and all dirty buffers on a given inode. We are | |
753 | * probably unmounting the fs, but that doesn't mean we have already | |
754 | * done a sync(). Just drop the buffers from the inode list. | |
755 | * | |
756 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which | |
757 | * assumes that all the buffers are against the blockdev. Not true | |
758 | * for reiserfs. | |
759 | */ | |
760 | void invalidate_inode_buffers(struct inode *inode) | |
761 | { | |
762 | if (inode_has_buffers(inode)) { | |
763 | struct address_space *mapping = &inode->i_data; | |
764 | struct list_head *list = &mapping->private_list; | |
765 | struct address_space *buffer_mapping = mapping->private_data; | |
766 | ||
767 | spin_lock(&buffer_mapping->private_lock); | |
768 | while (!list_empty(list)) | |
769 | __remove_assoc_queue(BH_ENTRY(list->next)); | |
770 | spin_unlock(&buffer_mapping->private_lock); | |
771 | } | |
772 | } | |
773 | EXPORT_SYMBOL(invalidate_inode_buffers); | |
774 | ||
775 | /* | |
776 | * Remove any clean buffers from the inode's buffer list. This is called | |
777 | * when we're trying to free the inode itself. Those buffers can pin it. | |
778 | * | |
779 | * Returns true if all buffers were removed. | |
780 | */ | |
781 | int remove_inode_buffers(struct inode *inode) | |
782 | { | |
783 | int ret = 1; | |
784 | ||
785 | if (inode_has_buffers(inode)) { | |
786 | struct address_space *mapping = &inode->i_data; | |
787 | struct list_head *list = &mapping->private_list; | |
788 | struct address_space *buffer_mapping = mapping->private_data; | |
789 | ||
790 | spin_lock(&buffer_mapping->private_lock); | |
791 | while (!list_empty(list)) { | |
792 | struct buffer_head *bh = BH_ENTRY(list->next); | |
793 | if (buffer_dirty(bh)) { | |
794 | ret = 0; | |
795 | break; | |
796 | } | |
797 | __remove_assoc_queue(bh); | |
798 | } | |
799 | spin_unlock(&buffer_mapping->private_lock); | |
800 | } | |
801 | return ret; | |
802 | } | |
803 | ||
804 | /* | |
805 | * Create the appropriate buffers when given a page for data area and | |
806 | * the size of each buffer.. Use the bh->b_this_page linked list to | |
807 | * follow the buffers created. Return NULL if unable to create more | |
808 | * buffers. | |
809 | * | |
810 | * The retry flag is used to differentiate async IO (paging, swapping) | |
811 | * which may not fail from ordinary buffer allocations. | |
812 | */ | |
813 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
814 | bool retry) | |
815 | { | |
816 | struct buffer_head *bh, *head; | |
817 | gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT; | |
818 | long offset; | |
819 | struct mem_cgroup *memcg; | |
820 | ||
821 | if (retry) | |
822 | gfp |= __GFP_NOFAIL; | |
823 | ||
824 | memcg = get_mem_cgroup_from_page(page); | |
825 | memalloc_use_memcg(memcg); | |
826 | ||
827 | head = NULL; | |
828 | offset = PAGE_SIZE; | |
829 | while ((offset -= size) >= 0) { | |
830 | bh = alloc_buffer_head(gfp); | |
831 | if (!bh) | |
832 | goto no_grow; | |
833 | ||
834 | bh->b_this_page = head; | |
835 | bh->b_blocknr = -1; | |
836 | head = bh; | |
837 | ||
838 | bh->b_size = size; | |
839 | ||
840 | /* Link the buffer to its page */ | |
841 | set_bh_page(bh, page, offset); | |
842 | } | |
843 | out: | |
844 | memalloc_unuse_memcg(); | |
845 | mem_cgroup_put(memcg); | |
846 | return head; | |
847 | /* | |
848 | * In case anything failed, we just free everything we got. | |
849 | */ | |
850 | no_grow: | |
851 | if (head) { | |
852 | do { | |
853 | bh = head; | |
854 | head = head->b_this_page; | |
855 | free_buffer_head(bh); | |
856 | } while (head); | |
857 | } | |
858 | ||
859 | goto out; | |
860 | } | |
861 | EXPORT_SYMBOL_GPL(alloc_page_buffers); | |
862 | ||
863 | static inline void | |
864 | link_dev_buffers(struct page *page, struct buffer_head *head) | |
865 | { | |
866 | struct buffer_head *bh, *tail; | |
867 | ||
868 | bh = head; | |
869 | do { | |
870 | tail = bh; | |
871 | bh = bh->b_this_page; | |
872 | } while (bh); | |
873 | tail->b_this_page = head; | |
874 | attach_page_buffers(page, head); | |
875 | } | |
876 | ||
877 | static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) | |
878 | { | |
879 | sector_t retval = ~((sector_t)0); | |
880 | loff_t sz = i_size_read(bdev->bd_inode); | |
881 | ||
882 | if (sz) { | |
883 | unsigned int sizebits = blksize_bits(size); | |
884 | retval = (sz >> sizebits); | |
885 | } | |
886 | return retval; | |
887 | } | |
888 | ||
889 | /* | |
890 | * Initialise the state of a blockdev page's buffers. | |
891 | */ | |
892 | static sector_t | |
893 | init_page_buffers(struct page *page, struct block_device *bdev, | |
894 | sector_t block, int size) | |
895 | { | |
896 | struct buffer_head *head = page_buffers(page); | |
897 | struct buffer_head *bh = head; | |
898 | int uptodate = PageUptodate(page); | |
899 | sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); | |
900 | ||
901 | do { | |
902 | if (!buffer_mapped(bh)) { | |
903 | bh->b_end_io = NULL; | |
904 | bh->b_private = NULL; | |
905 | bh->b_bdev = bdev; | |
906 | bh->b_blocknr = block; | |
907 | if (uptodate) | |
908 | set_buffer_uptodate(bh); | |
909 | if (block < end_block) | |
910 | set_buffer_mapped(bh); | |
911 | } | |
912 | block++; | |
913 | bh = bh->b_this_page; | |
914 | } while (bh != head); | |
915 | ||
916 | /* | |
917 | * Caller needs to validate requested block against end of device. | |
918 | */ | |
919 | return end_block; | |
920 | } | |
921 | ||
922 | /* | |
923 | * Create the page-cache page that contains the requested block. | |
924 | * | |
925 | * This is used purely for blockdev mappings. | |
926 | */ | |
927 | static int | |
928 | grow_dev_page(struct block_device *bdev, sector_t block, | |
929 | pgoff_t index, int size, int sizebits, gfp_t gfp) | |
930 | { | |
931 | struct inode *inode = bdev->bd_inode; | |
932 | struct page *page; | |
933 | struct buffer_head *bh; | |
934 | sector_t end_block; | |
935 | int ret = 0; /* Will call free_more_memory() */ | |
936 | gfp_t gfp_mask; | |
937 | ||
938 | gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp; | |
939 | ||
940 | /* | |
941 | * XXX: __getblk_slow() can not really deal with failure and | |
942 | * will endlessly loop on improvised global reclaim. Prefer | |
943 | * looping in the allocator rather than here, at least that | |
944 | * code knows what it's doing. | |
945 | */ | |
946 | gfp_mask |= __GFP_NOFAIL; | |
947 | ||
948 | page = find_or_create_page(inode->i_mapping, index, gfp_mask); | |
949 | ||
950 | BUG_ON(!PageLocked(page)); | |
951 | ||
952 | if (page_has_buffers(page)) { | |
953 | bh = page_buffers(page); | |
954 | if (bh->b_size == size) { | |
955 | end_block = init_page_buffers(page, bdev, | |
956 | (sector_t)index << sizebits, | |
957 | size); | |
958 | goto done; | |
959 | } | |
960 | if (!try_to_free_buffers(page)) | |
961 | goto failed; | |
962 | } | |
963 | ||
964 | /* | |
965 | * Allocate some buffers for this page | |
966 | */ | |
967 | bh = alloc_page_buffers(page, size, true); | |
968 | ||
969 | /* | |
970 | * Link the page to the buffers and initialise them. Take the | |
971 | * lock to be atomic wrt __find_get_block(), which does not | |
972 | * run under the page lock. | |
973 | */ | |
974 | spin_lock(&inode->i_mapping->private_lock); | |
975 | link_dev_buffers(page, bh); | |
976 | end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits, | |
977 | size); | |
978 | spin_unlock(&inode->i_mapping->private_lock); | |
979 | done: | |
980 | ret = (block < end_block) ? 1 : -ENXIO; | |
981 | failed: | |
982 | unlock_page(page); | |
983 | put_page(page); | |
984 | return ret; | |
985 | } | |
986 | ||
987 | /* | |
988 | * Create buffers for the specified block device block's page. If | |
989 | * that page was dirty, the buffers are set dirty also. | |
990 | */ | |
991 | static int | |
992 | grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) | |
993 | { | |
994 | pgoff_t index; | |
995 | int sizebits; | |
996 | ||
997 | sizebits = -1; | |
998 | do { | |
999 | sizebits++; | |
1000 | } while ((size << sizebits) < PAGE_SIZE); | |
1001 | ||
1002 | index = block >> sizebits; | |
1003 | ||
1004 | /* | |
1005 | * Check for a block which wants to lie outside our maximum possible | |
1006 | * pagecache index. (this comparison is done using sector_t types). | |
1007 | */ | |
1008 | if (unlikely(index != block >> sizebits)) { | |
1009 | printk(KERN_ERR "%s: requested out-of-range block %llu for " | |
1010 | "device %pg\n", | |
1011 | __func__, (unsigned long long)block, | |
1012 | bdev); | |
1013 | return -EIO; | |
1014 | } | |
1015 | ||
1016 | /* Create a page with the proper size buffers.. */ | |
1017 | return grow_dev_page(bdev, block, index, size, sizebits, gfp); | |
1018 | } | |
1019 | ||
1020 | static struct buffer_head * | |
1021 | __getblk_slow(struct block_device *bdev, sector_t block, | |
1022 | unsigned size, gfp_t gfp) | |
1023 | { | |
1024 | /* Size must be multiple of hard sectorsize */ | |
1025 | if (unlikely(size & (bdev_logical_block_size(bdev)-1) || | |
1026 | (size < 512 || size > PAGE_SIZE))) { | |
1027 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", | |
1028 | size); | |
1029 | printk(KERN_ERR "logical block size: %d\n", | |
1030 | bdev_logical_block_size(bdev)); | |
1031 | ||
1032 | dump_stack(); | |
1033 | return NULL; | |
1034 | } | |
1035 | ||
1036 | for (;;) { | |
1037 | struct buffer_head *bh; | |
1038 | int ret; | |
1039 | ||
1040 | bh = __find_get_block(bdev, block, size); | |
1041 | if (bh) | |
1042 | return bh; | |
1043 | ||
1044 | ret = grow_buffers(bdev, block, size, gfp); | |
1045 | if (ret < 0) | |
1046 | return NULL; | |
1047 | } | |
1048 | } | |
1049 | ||
1050 | /* | |
1051 | * The relationship between dirty buffers and dirty pages: | |
1052 | * | |
1053 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and | |
1054 | * the page is tagged dirty in the page cache. | |
1055 | * | |
1056 | * At all times, the dirtiness of the buffers represents the dirtiness of | |
1057 | * subsections of the page. If the page has buffers, the page dirty bit is | |
1058 | * merely a hint about the true dirty state. | |
1059 | * | |
1060 | * When a page is set dirty in its entirety, all its buffers are marked dirty | |
1061 | * (if the page has buffers). | |
1062 | * | |
1063 | * When a buffer is marked dirty, its page is dirtied, but the page's other | |
1064 | * buffers are not. | |
1065 | * | |
1066 | * Also. When blockdev buffers are explicitly read with bread(), they | |
1067 | * individually become uptodate. But their backing page remains not | |
1068 | * uptodate - even if all of its buffers are uptodate. A subsequent | |
1069 | * block_read_full_page() against that page will discover all the uptodate | |
1070 | * buffers, will set the page uptodate and will perform no I/O. | |
1071 | */ | |
1072 | ||
1073 | /** | |
1074 | * mark_buffer_dirty - mark a buffer_head as needing writeout | |
1075 | * @bh: the buffer_head to mark dirty | |
1076 | * | |
1077 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set | |
1078 | * its backing page dirty, then tag the page as dirty in the page cache | |
1079 | * and then attach the address_space's inode to its superblock's dirty | |
1080 | * inode list. | |
1081 | * | |
1082 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, | |
1083 | * i_pages lock and mapping->host->i_lock. | |
1084 | */ | |
1085 | void mark_buffer_dirty(struct buffer_head *bh) | |
1086 | { | |
1087 | WARN_ON_ONCE(!buffer_uptodate(bh)); | |
1088 | ||
1089 | trace_block_dirty_buffer(bh); | |
1090 | ||
1091 | /* | |
1092 | * Very *carefully* optimize the it-is-already-dirty case. | |
1093 | * | |
1094 | * Don't let the final "is it dirty" escape to before we | |
1095 | * perhaps modified the buffer. | |
1096 | */ | |
1097 | if (buffer_dirty(bh)) { | |
1098 | smp_mb(); | |
1099 | if (buffer_dirty(bh)) | |
1100 | return; | |
1101 | } | |
1102 | ||
1103 | if (!test_set_buffer_dirty(bh)) { | |
1104 | struct page *page = bh->b_page; | |
1105 | struct address_space *mapping = NULL; | |
1106 | ||
1107 | lock_page_memcg(page); | |
1108 | if (!TestSetPageDirty(page)) { | |
1109 | mapping = page_mapping(page); | |
1110 | if (mapping) | |
1111 | __set_page_dirty(page, mapping, 0); | |
1112 | } | |
1113 | unlock_page_memcg(page); | |
1114 | if (mapping) | |
1115 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); | |
1116 | } | |
1117 | } | |
1118 | EXPORT_SYMBOL(mark_buffer_dirty); | |
1119 | ||
1120 | void mark_buffer_write_io_error(struct buffer_head *bh) | |
1121 | { | |
1122 | set_buffer_write_io_error(bh); | |
1123 | /* FIXME: do we need to set this in both places? */ | |
1124 | if (bh->b_page && bh->b_page->mapping) | |
1125 | mapping_set_error(bh->b_page->mapping, -EIO); | |
1126 | if (bh->b_assoc_map) | |
1127 | mapping_set_error(bh->b_assoc_map, -EIO); | |
1128 | } | |
1129 | EXPORT_SYMBOL(mark_buffer_write_io_error); | |
1130 | ||
1131 | /* | |
1132 | * Decrement a buffer_head's reference count. If all buffers against a page | |
1133 | * have zero reference count, are clean and unlocked, and if the page is clean | |
1134 | * and unlocked then try_to_free_buffers() may strip the buffers from the page | |
1135 | * in preparation for freeing it (sometimes, rarely, buffers are removed from | |
1136 | * a page but it ends up not being freed, and buffers may later be reattached). | |
1137 | */ | |
1138 | void __brelse(struct buffer_head * buf) | |
1139 | { | |
1140 | if (atomic_read(&buf->b_count)) { | |
1141 | put_bh(buf); | |
1142 | return; | |
1143 | } | |
1144 | WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); | |
1145 | } | |
1146 | EXPORT_SYMBOL(__brelse); | |
1147 | ||
1148 | /* | |
1149 | * bforget() is like brelse(), except it discards any | |
1150 | * potentially dirty data. | |
1151 | */ | |
1152 | void __bforget(struct buffer_head *bh) | |
1153 | { | |
1154 | clear_buffer_dirty(bh); | |
1155 | if (bh->b_assoc_map) { | |
1156 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
1157 | ||
1158 | spin_lock(&buffer_mapping->private_lock); | |
1159 | list_del_init(&bh->b_assoc_buffers); | |
1160 | bh->b_assoc_map = NULL; | |
1161 | spin_unlock(&buffer_mapping->private_lock); | |
1162 | } | |
1163 | __brelse(bh); | |
1164 | } | |
1165 | EXPORT_SYMBOL(__bforget); | |
1166 | ||
1167 | static struct buffer_head *__bread_slow(struct buffer_head *bh) | |
1168 | { | |
1169 | lock_buffer(bh); | |
1170 | if (buffer_uptodate(bh)) { | |
1171 | unlock_buffer(bh); | |
1172 | return bh; | |
1173 | } else { | |
1174 | get_bh(bh); | |
1175 | bh->b_end_io = end_buffer_read_sync; | |
1176 | submit_bh(REQ_OP_READ, 0, bh); | |
1177 | wait_on_buffer(bh); | |
1178 | if (buffer_uptodate(bh)) | |
1179 | return bh; | |
1180 | } | |
1181 | brelse(bh); | |
1182 | return NULL; | |
1183 | } | |
1184 | ||
1185 | /* | |
1186 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). | |
1187 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their | |
1188 | * refcount elevated by one when they're in an LRU. A buffer can only appear | |
1189 | * once in a particular CPU's LRU. A single buffer can be present in multiple | |
1190 | * CPU's LRUs at the same time. | |
1191 | * | |
1192 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and | |
1193 | * sb_find_get_block(). | |
1194 | * | |
1195 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use | |
1196 | * a local interrupt disable for that. | |
1197 | */ | |
1198 | ||
1199 | #define BH_LRU_SIZE 16 | |
1200 | ||
1201 | struct bh_lru { | |
1202 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1203 | }; | |
1204 | ||
1205 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; | |
1206 | ||
1207 | #ifdef CONFIG_SMP | |
1208 | #define bh_lru_lock() local_irq_disable() | |
1209 | #define bh_lru_unlock() local_irq_enable() | |
1210 | #else | |
1211 | #define bh_lru_lock() preempt_disable() | |
1212 | #define bh_lru_unlock() preempt_enable() | |
1213 | #endif | |
1214 | ||
1215 | static inline void check_irqs_on(void) | |
1216 | { | |
1217 | #ifdef irqs_disabled | |
1218 | BUG_ON(irqs_disabled()); | |
1219 | #endif | |
1220 | } | |
1221 | ||
1222 | /* | |
1223 | * Install a buffer_head into this cpu's LRU. If not already in the LRU, it is | |
1224 | * inserted at the front, and the buffer_head at the back if any is evicted. | |
1225 | * Or, if already in the LRU it is moved to the front. | |
1226 | */ | |
1227 | static void bh_lru_install(struct buffer_head *bh) | |
1228 | { | |
1229 | struct buffer_head *evictee = bh; | |
1230 | struct bh_lru *b; | |
1231 | int i; | |
1232 | ||
1233 | check_irqs_on(); | |
1234 | bh_lru_lock(); | |
1235 | ||
1236 | b = this_cpu_ptr(&bh_lrus); | |
1237 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1238 | swap(evictee, b->bhs[i]); | |
1239 | if (evictee == bh) { | |
1240 | bh_lru_unlock(); | |
1241 | return; | |
1242 | } | |
1243 | } | |
1244 | ||
1245 | get_bh(bh); | |
1246 | bh_lru_unlock(); | |
1247 | brelse(evictee); | |
1248 | } | |
1249 | ||
1250 | /* | |
1251 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. | |
1252 | */ | |
1253 | static struct buffer_head * | |
1254 | lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) | |
1255 | { | |
1256 | struct buffer_head *ret = NULL; | |
1257 | unsigned int i; | |
1258 | ||
1259 | check_irqs_on(); | |
1260 | bh_lru_lock(); | |
1261 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1262 | struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); | |
1263 | ||
1264 | if (bh && bh->b_blocknr == block && bh->b_bdev == bdev && | |
1265 | bh->b_size == size) { | |
1266 | if (i) { | |
1267 | while (i) { | |
1268 | __this_cpu_write(bh_lrus.bhs[i], | |
1269 | __this_cpu_read(bh_lrus.bhs[i - 1])); | |
1270 | i--; | |
1271 | } | |
1272 | __this_cpu_write(bh_lrus.bhs[0], bh); | |
1273 | } | |
1274 | get_bh(bh); | |
1275 | ret = bh; | |
1276 | break; | |
1277 | } | |
1278 | } | |
1279 | bh_lru_unlock(); | |
1280 | return ret; | |
1281 | } | |
1282 | ||
1283 | /* | |
1284 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh | |
1285 | * it in the LRU and mark it as accessed. If it is not present then return | |
1286 | * NULL | |
1287 | */ | |
1288 | struct buffer_head * | |
1289 | __find_get_block(struct block_device *bdev, sector_t block, unsigned size) | |
1290 | { | |
1291 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); | |
1292 | ||
1293 | if (bh == NULL) { | |
1294 | /* __find_get_block_slow will mark the page accessed */ | |
1295 | bh = __find_get_block_slow(bdev, block); | |
1296 | if (bh) | |
1297 | bh_lru_install(bh); | |
1298 | } else | |
1299 | touch_buffer(bh); | |
1300 | ||
1301 | return bh; | |
1302 | } | |
1303 | EXPORT_SYMBOL(__find_get_block); | |
1304 | ||
1305 | /* | |
1306 | * __getblk_gfp() will locate (and, if necessary, create) the buffer_head | |
1307 | * which corresponds to the passed block_device, block and size. The | |
1308 | * returned buffer has its reference count incremented. | |
1309 | * | |
1310 | * __getblk_gfp() will lock up the machine if grow_dev_page's | |
1311 | * try_to_free_buffers() attempt is failing. FIXME, perhaps? | |
1312 | */ | |
1313 | struct buffer_head * | |
1314 | __getblk_gfp(struct block_device *bdev, sector_t block, | |
1315 | unsigned size, gfp_t gfp) | |
1316 | { | |
1317 | struct buffer_head *bh = __find_get_block(bdev, block, size); | |
1318 | ||
1319 | might_sleep(); | |
1320 | if (bh == NULL) | |
1321 | bh = __getblk_slow(bdev, block, size, gfp); | |
1322 | return bh; | |
1323 | } | |
1324 | EXPORT_SYMBOL(__getblk_gfp); | |
1325 | ||
1326 | /* | |
1327 | * Do async read-ahead on a buffer.. | |
1328 | */ | |
1329 | void __breadahead(struct block_device *bdev, sector_t block, unsigned size) | |
1330 | { | |
1331 | struct buffer_head *bh = __getblk(bdev, block, size); | |
1332 | if (likely(bh)) { | |
1333 | ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 1, &bh); | |
1334 | brelse(bh); | |
1335 | } | |
1336 | } | |
1337 | EXPORT_SYMBOL(__breadahead); | |
1338 | ||
1339 | /** | |
1340 | * __bread_gfp() - reads a specified block and returns the bh | |
1341 | * @bdev: the block_device to read from | |
1342 | * @block: number of block | |
1343 | * @size: size (in bytes) to read | |
1344 | * @gfp: page allocation flag | |
1345 | * | |
1346 | * Reads a specified block, and returns buffer head that contains it. | |
1347 | * The page cache can be allocated from non-movable area | |
1348 | * not to prevent page migration if you set gfp to zero. | |
1349 | * It returns NULL if the block was unreadable. | |
1350 | */ | |
1351 | struct buffer_head * | |
1352 | __bread_gfp(struct block_device *bdev, sector_t block, | |
1353 | unsigned size, gfp_t gfp) | |
1354 | { | |
1355 | struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); | |
1356 | ||
1357 | if (likely(bh) && !buffer_uptodate(bh)) | |
1358 | bh = __bread_slow(bh); | |
1359 | return bh; | |
1360 | } | |
1361 | EXPORT_SYMBOL(__bread_gfp); | |
1362 | ||
1363 | /* | |
1364 | * invalidate_bh_lrus() is called rarely - but not only at unmount. | |
1365 | * This doesn't race because it runs in each cpu either in irq | |
1366 | * or with preempt disabled. | |
1367 | */ | |
1368 | static void invalidate_bh_lru(void *arg) | |
1369 | { | |
1370 | struct bh_lru *b = &get_cpu_var(bh_lrus); | |
1371 | int i; | |
1372 | ||
1373 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1374 | brelse(b->bhs[i]); | |
1375 | b->bhs[i] = NULL; | |
1376 | } | |
1377 | put_cpu_var(bh_lrus); | |
1378 | } | |
1379 | ||
1380 | static bool has_bh_in_lru(int cpu, void *dummy) | |
1381 | { | |
1382 | struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); | |
1383 | int i; | |
1384 | ||
1385 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1386 | if (b->bhs[i]) | |
1387 | return 1; | |
1388 | } | |
1389 | ||
1390 | return 0; | |
1391 | } | |
1392 | ||
1393 | void invalidate_bh_lrus(void) | |
1394 | { | |
1395 | on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); | |
1396 | } | |
1397 | EXPORT_SYMBOL_GPL(invalidate_bh_lrus); | |
1398 | ||
1399 | void set_bh_page(struct buffer_head *bh, | |
1400 | struct page *page, unsigned long offset) | |
1401 | { | |
1402 | bh->b_page = page; | |
1403 | BUG_ON(offset >= PAGE_SIZE); | |
1404 | if (PageHighMem(page)) | |
1405 | /* | |
1406 | * This catches illegal uses and preserves the offset: | |
1407 | */ | |
1408 | bh->b_data = (char *)(0 + offset); | |
1409 | else | |
1410 | bh->b_data = page_address(page) + offset; | |
1411 | } | |
1412 | EXPORT_SYMBOL(set_bh_page); | |
1413 | ||
1414 | /* | |
1415 | * Called when truncating a buffer on a page completely. | |
1416 | */ | |
1417 | ||
1418 | /* Bits that are cleared during an invalidate */ | |
1419 | #define BUFFER_FLAGS_DISCARD \ | |
1420 | (1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \ | |
1421 | 1 << BH_Delay | 1 << BH_Unwritten) | |
1422 | ||
1423 | static void discard_buffer(struct buffer_head * bh) | |
1424 | { | |
1425 | unsigned long b_state, b_state_old; | |
1426 | ||
1427 | lock_buffer(bh); | |
1428 | clear_buffer_dirty(bh); | |
1429 | bh->b_bdev = NULL; | |
1430 | b_state = bh->b_state; | |
1431 | for (;;) { | |
1432 | b_state_old = cmpxchg(&bh->b_state, b_state, | |
1433 | (b_state & ~BUFFER_FLAGS_DISCARD)); | |
1434 | if (b_state_old == b_state) | |
1435 | break; | |
1436 | b_state = b_state_old; | |
1437 | } | |
1438 | unlock_buffer(bh); | |
1439 | } | |
1440 | ||
1441 | /** | |
1442 | * block_invalidatepage - invalidate part or all of a buffer-backed page | |
1443 | * | |
1444 | * @page: the page which is affected | |
1445 | * @offset: start of the range to invalidate | |
1446 | * @length: length of the range to invalidate | |
1447 | * | |
1448 | * block_invalidatepage() is called when all or part of the page has become | |
1449 | * invalidated by a truncate operation. | |
1450 | * | |
1451 | * block_invalidatepage() does not have to release all buffers, but it must | |
1452 | * ensure that no dirty buffer is left outside @offset and that no I/O | |
1453 | * is underway against any of the blocks which are outside the truncation | |
1454 | * point. Because the caller is about to free (and possibly reuse) those | |
1455 | * blocks on-disk. | |
1456 | */ | |
1457 | void block_invalidatepage(struct page *page, unsigned int offset, | |
1458 | unsigned int length) | |
1459 | { | |
1460 | struct buffer_head *head, *bh, *next; | |
1461 | unsigned int curr_off = 0; | |
1462 | unsigned int stop = length + offset; | |
1463 | ||
1464 | BUG_ON(!PageLocked(page)); | |
1465 | if (!page_has_buffers(page)) | |
1466 | goto out; | |
1467 | ||
1468 | /* | |
1469 | * Check for overflow | |
1470 | */ | |
1471 | BUG_ON(stop > PAGE_SIZE || stop < length); | |
1472 | ||
1473 | head = page_buffers(page); | |
1474 | bh = head; | |
1475 | do { | |
1476 | unsigned int next_off = curr_off + bh->b_size; | |
1477 | next = bh->b_this_page; | |
1478 | ||
1479 | /* | |
1480 | * Are we still fully in range ? | |
1481 | */ | |
1482 | if (next_off > stop) | |
1483 | goto out; | |
1484 | ||
1485 | /* | |
1486 | * is this block fully invalidated? | |
1487 | */ | |
1488 | if (offset <= curr_off) | |
1489 | discard_buffer(bh); | |
1490 | curr_off = next_off; | |
1491 | bh = next; | |
1492 | } while (bh != head); | |
1493 | ||
1494 | /* | |
1495 | * We release buffers only if the entire page is being invalidated. | |
1496 | * The get_block cached value has been unconditionally invalidated, | |
1497 | * so real IO is not possible anymore. | |
1498 | */ | |
1499 | if (length == PAGE_SIZE) | |
1500 | try_to_release_page(page, 0); | |
1501 | out: | |
1502 | return; | |
1503 | } | |
1504 | EXPORT_SYMBOL(block_invalidatepage); | |
1505 | ||
1506 | ||
1507 | /* | |
1508 | * We attach and possibly dirty the buffers atomically wrt | |
1509 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers | |
1510 | * is already excluded via the page lock. | |
1511 | */ | |
1512 | void create_empty_buffers(struct page *page, | |
1513 | unsigned long blocksize, unsigned long b_state) | |
1514 | { | |
1515 | struct buffer_head *bh, *head, *tail; | |
1516 | ||
1517 | head = alloc_page_buffers(page, blocksize, true); | |
1518 | bh = head; | |
1519 | do { | |
1520 | bh->b_state |= b_state; | |
1521 | tail = bh; | |
1522 | bh = bh->b_this_page; | |
1523 | } while (bh); | |
1524 | tail->b_this_page = head; | |
1525 | ||
1526 | spin_lock(&page->mapping->private_lock); | |
1527 | if (PageUptodate(page) || PageDirty(page)) { | |
1528 | bh = head; | |
1529 | do { | |
1530 | if (PageDirty(page)) | |
1531 | set_buffer_dirty(bh); | |
1532 | if (PageUptodate(page)) | |
1533 | set_buffer_uptodate(bh); | |
1534 | bh = bh->b_this_page; | |
1535 | } while (bh != head); | |
1536 | } | |
1537 | attach_page_buffers(page, head); | |
1538 | spin_unlock(&page->mapping->private_lock); | |
1539 | } | |
1540 | EXPORT_SYMBOL(create_empty_buffers); | |
1541 | ||
1542 | /** | |
1543 | * clean_bdev_aliases: clean a range of buffers in block device | |
1544 | * @bdev: Block device to clean buffers in | |
1545 | * @block: Start of a range of blocks to clean | |
1546 | * @len: Number of blocks to clean | |
1547 | * | |
1548 | * We are taking a range of blocks for data and we don't want writeback of any | |
1549 | * buffer-cache aliases starting from return from this function and until the | |
1550 | * moment when something will explicitly mark the buffer dirty (hopefully that | |
1551 | * will not happen until we will free that block ;-) We don't even need to mark | |
1552 | * it not-uptodate - nobody can expect anything from a newly allocated buffer | |
1553 | * anyway. We used to use unmap_buffer() for such invalidation, but that was | |
1554 | * wrong. We definitely don't want to mark the alias unmapped, for example - it | |
1555 | * would confuse anyone who might pick it with bread() afterwards... | |
1556 | * | |
1557 | * Also.. Note that bforget() doesn't lock the buffer. So there can be | |
1558 | * writeout I/O going on against recently-freed buffers. We don't wait on that | |
1559 | * I/O in bforget() - it's more efficient to wait on the I/O only if we really | |
1560 | * need to. That happens here. | |
1561 | */ | |
1562 | void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) | |
1563 | { | |
1564 | struct inode *bd_inode = bdev->bd_inode; | |
1565 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
1566 | struct pagevec pvec; | |
1567 | pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); | |
1568 | pgoff_t end; | |
1569 | int i, count; | |
1570 | struct buffer_head *bh; | |
1571 | struct buffer_head *head; | |
1572 | ||
1573 | end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits); | |
1574 | pagevec_init(&pvec); | |
1575 | while (pagevec_lookup_range(&pvec, bd_mapping, &index, end)) { | |
1576 | count = pagevec_count(&pvec); | |
1577 | for (i = 0; i < count; i++) { | |
1578 | struct page *page = pvec.pages[i]; | |
1579 | ||
1580 | if (!page_has_buffers(page)) | |
1581 | continue; | |
1582 | /* | |
1583 | * We use page lock instead of bd_mapping->private_lock | |
1584 | * to pin buffers here since we can afford to sleep and | |
1585 | * it scales better than a global spinlock lock. | |
1586 | */ | |
1587 | lock_page(page); | |
1588 | /* Recheck when the page is locked which pins bhs */ | |
1589 | if (!page_has_buffers(page)) | |
1590 | goto unlock_page; | |
1591 | head = page_buffers(page); | |
1592 | bh = head; | |
1593 | do { | |
1594 | if (!buffer_mapped(bh) || (bh->b_blocknr < block)) | |
1595 | goto next; | |
1596 | if (bh->b_blocknr >= block + len) | |
1597 | break; | |
1598 | clear_buffer_dirty(bh); | |
1599 | wait_on_buffer(bh); | |
1600 | clear_buffer_req(bh); | |
1601 | next: | |
1602 | bh = bh->b_this_page; | |
1603 | } while (bh != head); | |
1604 | unlock_page: | |
1605 | unlock_page(page); | |
1606 | } | |
1607 | pagevec_release(&pvec); | |
1608 | cond_resched(); | |
1609 | /* End of range already reached? */ | |
1610 | if (index > end || !index) | |
1611 | break; | |
1612 | } | |
1613 | } | |
1614 | EXPORT_SYMBOL(clean_bdev_aliases); | |
1615 | ||
1616 | /* | |
1617 | * Size is a power-of-two in the range 512..PAGE_SIZE, | |
1618 | * and the case we care about most is PAGE_SIZE. | |
1619 | * | |
1620 | * So this *could* possibly be written with those | |
1621 | * constraints in mind (relevant mostly if some | |
1622 | * architecture has a slow bit-scan instruction) | |
1623 | */ | |
1624 | static inline int block_size_bits(unsigned int blocksize) | |
1625 | { | |
1626 | return ilog2(blocksize); | |
1627 | } | |
1628 | ||
1629 | static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) | |
1630 | { | |
1631 | BUG_ON(!PageLocked(page)); | |
1632 | ||
1633 | if (!page_has_buffers(page)) | |
1634 | create_empty_buffers(page, 1 << READ_ONCE(inode->i_blkbits), | |
1635 | b_state); | |
1636 | return page_buffers(page); | |
1637 | } | |
1638 | ||
1639 | /* | |
1640 | * NOTE! All mapped/uptodate combinations are valid: | |
1641 | * | |
1642 | * Mapped Uptodate Meaning | |
1643 | * | |
1644 | * No No "unknown" - must do get_block() | |
1645 | * No Yes "hole" - zero-filled | |
1646 | * Yes No "allocated" - allocated on disk, not read in | |
1647 | * Yes Yes "valid" - allocated and up-to-date in memory. | |
1648 | * | |
1649 | * "Dirty" is valid only with the last case (mapped+uptodate). | |
1650 | */ | |
1651 | ||
1652 | /* | |
1653 | * While block_write_full_page is writing back the dirty buffers under | |
1654 | * the page lock, whoever dirtied the buffers may decide to clean them | |
1655 | * again at any time. We handle that by only looking at the buffer | |
1656 | * state inside lock_buffer(). | |
1657 | * | |
1658 | * If block_write_full_page() is called for regular writeback | |
1659 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a | |
1660 | * locked buffer. This only can happen if someone has written the buffer | |
1661 | * directly, with submit_bh(). At the address_space level PageWriteback | |
1662 | * prevents this contention from occurring. | |
1663 | * | |
1664 | * If block_write_full_page() is called with wbc->sync_mode == | |
1665 | * WB_SYNC_ALL, the writes are posted using REQ_SYNC; this | |
1666 | * causes the writes to be flagged as synchronous writes. | |
1667 | */ | |
1668 | int __block_write_full_page(struct inode *inode, struct page *page, | |
1669 | get_block_t *get_block, struct writeback_control *wbc, | |
1670 | bh_end_io_t *handler) | |
1671 | { | |
1672 | int err; | |
1673 | sector_t block; | |
1674 | sector_t last_block; | |
1675 | struct buffer_head *bh, *head; | |
1676 | unsigned int blocksize, bbits; | |
1677 | int nr_underway = 0; | |
1678 | int write_flags = wbc_to_write_flags(wbc); | |
1679 | ||
1680 | head = create_page_buffers(page, inode, | |
1681 | (1 << BH_Dirty)|(1 << BH_Uptodate)); | |
1682 | ||
1683 | /* | |
1684 | * Be very careful. We have no exclusion from __set_page_dirty_buffers | |
1685 | * here, and the (potentially unmapped) buffers may become dirty at | |
1686 | * any time. If a buffer becomes dirty here after we've inspected it | |
1687 | * then we just miss that fact, and the page stays dirty. | |
1688 | * | |
1689 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; | |
1690 | * handle that here by just cleaning them. | |
1691 | */ | |
1692 | ||
1693 | bh = head; | |
1694 | blocksize = bh->b_size; | |
1695 | bbits = block_size_bits(blocksize); | |
1696 | ||
1697 | block = (sector_t)page->index << (PAGE_SHIFT - bbits); | |
1698 | last_block = (i_size_read(inode) - 1) >> bbits; | |
1699 | ||
1700 | /* | |
1701 | * Get all the dirty buffers mapped to disk addresses and | |
1702 | * handle any aliases from the underlying blockdev's mapping. | |
1703 | */ | |
1704 | do { | |
1705 | if (block > last_block) { | |
1706 | /* | |
1707 | * mapped buffers outside i_size will occur, because | |
1708 | * this page can be outside i_size when there is a | |
1709 | * truncate in progress. | |
1710 | */ | |
1711 | /* | |
1712 | * The buffer was zeroed by block_write_full_page() | |
1713 | */ | |
1714 | clear_buffer_dirty(bh); | |
1715 | set_buffer_uptodate(bh); | |
1716 | } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && | |
1717 | buffer_dirty(bh)) { | |
1718 | WARN_ON(bh->b_size != blocksize); | |
1719 | err = get_block(inode, block, bh, 1); | |
1720 | if (err) | |
1721 | goto recover; | |
1722 | clear_buffer_delay(bh); | |
1723 | if (buffer_new(bh)) { | |
1724 | /* blockdev mappings never come here */ | |
1725 | clear_buffer_new(bh); | |
1726 | clean_bdev_bh_alias(bh); | |
1727 | } | |
1728 | } | |
1729 | bh = bh->b_this_page; | |
1730 | block++; | |
1731 | } while (bh != head); | |
1732 | ||
1733 | do { | |
1734 | if (!buffer_mapped(bh)) | |
1735 | continue; | |
1736 | /* | |
1737 | * If it's a fully non-blocking write attempt and we cannot | |
1738 | * lock the buffer then redirty the page. Note that this can | |
1739 | * potentially cause a busy-wait loop from writeback threads | |
1740 | * and kswapd activity, but those code paths have their own | |
1741 | * higher-level throttling. | |
1742 | */ | |
1743 | if (wbc->sync_mode != WB_SYNC_NONE) { | |
1744 | lock_buffer(bh); | |
1745 | } else if (!trylock_buffer(bh)) { | |
1746 | redirty_page_for_writepage(wbc, page); | |
1747 | continue; | |
1748 | } | |
1749 | if (test_clear_buffer_dirty(bh)) { | |
1750 | mark_buffer_async_write_endio(bh, handler); | |
1751 | } else { | |
1752 | unlock_buffer(bh); | |
1753 | } | |
1754 | } while ((bh = bh->b_this_page) != head); | |
1755 | ||
1756 | /* | |
1757 | * The page and its buffers are protected by PageWriteback(), so we can | |
1758 | * drop the bh refcounts early. | |
1759 | */ | |
1760 | BUG_ON(PageWriteback(page)); | |
1761 | set_page_writeback(page); | |
1762 | ||
1763 | do { | |
1764 | struct buffer_head *next = bh->b_this_page; | |
1765 | if (buffer_async_write(bh)) { | |
1766 | submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, | |
1767 | inode->i_write_hint, wbc); | |
1768 | nr_underway++; | |
1769 | } | |
1770 | bh = next; | |
1771 | } while (bh != head); | |
1772 | unlock_page(page); | |
1773 | ||
1774 | err = 0; | |
1775 | done: | |
1776 | if (nr_underway == 0) { | |
1777 | /* | |
1778 | * The page was marked dirty, but the buffers were | |
1779 | * clean. Someone wrote them back by hand with | |
1780 | * ll_rw_block/submit_bh. A rare case. | |
1781 | */ | |
1782 | end_page_writeback(page); | |
1783 | ||
1784 | /* | |
1785 | * The page and buffer_heads can be released at any time from | |
1786 | * here on. | |
1787 | */ | |
1788 | } | |
1789 | return err; | |
1790 | ||
1791 | recover: | |
1792 | /* | |
1793 | * ENOSPC, or some other error. We may already have added some | |
1794 | * blocks to the file, so we need to write these out to avoid | |
1795 | * exposing stale data. | |
1796 | * The page is currently locked and not marked for writeback | |
1797 | */ | |
1798 | bh = head; | |
1799 | /* Recovery: lock and submit the mapped buffers */ | |
1800 | do { | |
1801 | if (buffer_mapped(bh) && buffer_dirty(bh) && | |
1802 | !buffer_delay(bh)) { | |
1803 | lock_buffer(bh); | |
1804 | mark_buffer_async_write_endio(bh, handler); | |
1805 | } else { | |
1806 | /* | |
1807 | * The buffer may have been set dirty during | |
1808 | * attachment to a dirty page. | |
1809 | */ | |
1810 | clear_buffer_dirty(bh); | |
1811 | } | |
1812 | } while ((bh = bh->b_this_page) != head); | |
1813 | SetPageError(page); | |
1814 | BUG_ON(PageWriteback(page)); | |
1815 | mapping_set_error(page->mapping, err); | |
1816 | set_page_writeback(page); | |
1817 | do { | |
1818 | struct buffer_head *next = bh->b_this_page; | |
1819 | if (buffer_async_write(bh)) { | |
1820 | clear_buffer_dirty(bh); | |
1821 | submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, | |
1822 | inode->i_write_hint, wbc); | |
1823 | nr_underway++; | |
1824 | } | |
1825 | bh = next; | |
1826 | } while (bh != head); | |
1827 | unlock_page(page); | |
1828 | goto done; | |
1829 | } | |
1830 | EXPORT_SYMBOL(__block_write_full_page); | |
1831 | ||
1832 | /* | |
1833 | * If a page has any new buffers, zero them out here, and mark them uptodate | |
1834 | * and dirty so they'll be written out (in order to prevent uninitialised | |
1835 | * block data from leaking). And clear the new bit. | |
1836 | */ | |
1837 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) | |
1838 | { | |
1839 | unsigned int block_start, block_end; | |
1840 | struct buffer_head *head, *bh; | |
1841 | ||
1842 | BUG_ON(!PageLocked(page)); | |
1843 | if (!page_has_buffers(page)) | |
1844 | return; | |
1845 | ||
1846 | bh = head = page_buffers(page); | |
1847 | block_start = 0; | |
1848 | do { | |
1849 | block_end = block_start + bh->b_size; | |
1850 | ||
1851 | if (buffer_new(bh)) { | |
1852 | if (block_end > from && block_start < to) { | |
1853 | if (!PageUptodate(page)) { | |
1854 | unsigned start, size; | |
1855 | ||
1856 | start = max(from, block_start); | |
1857 | size = min(to, block_end) - start; | |
1858 | ||
1859 | zero_user(page, start, size); | |
1860 | set_buffer_uptodate(bh); | |
1861 | } | |
1862 | ||
1863 | clear_buffer_new(bh); | |
1864 | mark_buffer_dirty(bh); | |
1865 | } | |
1866 | } | |
1867 | ||
1868 | block_start = block_end; | |
1869 | bh = bh->b_this_page; | |
1870 | } while (bh != head); | |
1871 | } | |
1872 | EXPORT_SYMBOL(page_zero_new_buffers); | |
1873 | ||
1874 | static void | |
1875 | iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, | |
1876 | struct iomap *iomap) | |
1877 | { | |
1878 | loff_t offset = block << inode->i_blkbits; | |
1879 | ||
1880 | bh->b_bdev = iomap->bdev; | |
1881 | ||
1882 | /* | |
1883 | * Block points to offset in file we need to map, iomap contains | |
1884 | * the offset at which the map starts. If the map ends before the | |
1885 | * current block, then do not map the buffer and let the caller | |
1886 | * handle it. | |
1887 | */ | |
1888 | BUG_ON(offset >= iomap->offset + iomap->length); | |
1889 | ||
1890 | switch (iomap->type) { | |
1891 | case IOMAP_HOLE: | |
1892 | /* | |
1893 | * If the buffer is not up to date or beyond the current EOF, | |
1894 | * we need to mark it as new to ensure sub-block zeroing is | |
1895 | * executed if necessary. | |
1896 | */ | |
1897 | if (!buffer_uptodate(bh) || | |
1898 | (offset >= i_size_read(inode))) | |
1899 | set_buffer_new(bh); | |
1900 | break; | |
1901 | case IOMAP_DELALLOC: | |
1902 | if (!buffer_uptodate(bh) || | |
1903 | (offset >= i_size_read(inode))) | |
1904 | set_buffer_new(bh); | |
1905 | set_buffer_uptodate(bh); | |
1906 | set_buffer_mapped(bh); | |
1907 | set_buffer_delay(bh); | |
1908 | break; | |
1909 | case IOMAP_UNWRITTEN: | |
1910 | /* | |
1911 | * For unwritten regions, we always need to ensure that regions | |
1912 | * in the block we are not writing to are zeroed. Mark the | |
1913 | * buffer as new to ensure this. | |
1914 | */ | |
1915 | set_buffer_new(bh); | |
1916 | set_buffer_unwritten(bh); | |
1917 | /* FALLTHRU */ | |
1918 | case IOMAP_MAPPED: | |
1919 | if ((iomap->flags & IOMAP_F_NEW) || | |
1920 | offset >= i_size_read(inode)) | |
1921 | set_buffer_new(bh); | |
1922 | bh->b_blocknr = (iomap->addr + offset - iomap->offset) >> | |
1923 | inode->i_blkbits; | |
1924 | set_buffer_mapped(bh); | |
1925 | break; | |
1926 | } | |
1927 | } | |
1928 | ||
1929 | int __block_write_begin_int(struct page *page, loff_t pos, unsigned len, | |
1930 | get_block_t *get_block, struct iomap *iomap) | |
1931 | { | |
1932 | unsigned from = pos & (PAGE_SIZE - 1); | |
1933 | unsigned to = from + len; | |
1934 | struct inode *inode = page->mapping->host; | |
1935 | unsigned block_start, block_end; | |
1936 | sector_t block; | |
1937 | int err = 0; | |
1938 | unsigned blocksize, bbits; | |
1939 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1940 | ||
1941 | BUG_ON(!PageLocked(page)); | |
1942 | BUG_ON(from > PAGE_SIZE); | |
1943 | BUG_ON(to > PAGE_SIZE); | |
1944 | BUG_ON(from > to); | |
1945 | ||
1946 | head = create_page_buffers(page, inode, 0); | |
1947 | blocksize = head->b_size; | |
1948 | bbits = block_size_bits(blocksize); | |
1949 | ||
1950 | block = (sector_t)page->index << (PAGE_SHIFT - bbits); | |
1951 | ||
1952 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1953 | block++, block_start=block_end, bh = bh->b_this_page) { | |
1954 | block_end = block_start + blocksize; | |
1955 | if (block_end <= from || block_start >= to) { | |
1956 | if (PageUptodate(page)) { | |
1957 | if (!buffer_uptodate(bh)) | |
1958 | set_buffer_uptodate(bh); | |
1959 | } | |
1960 | continue; | |
1961 | } | |
1962 | if (buffer_new(bh)) | |
1963 | clear_buffer_new(bh); | |
1964 | if (!buffer_mapped(bh)) { | |
1965 | WARN_ON(bh->b_size != blocksize); | |
1966 | if (get_block) { | |
1967 | err = get_block(inode, block, bh, 1); | |
1968 | if (err) | |
1969 | break; | |
1970 | } else { | |
1971 | iomap_to_bh(inode, block, bh, iomap); | |
1972 | } | |
1973 | ||
1974 | if (buffer_new(bh)) { | |
1975 | clean_bdev_bh_alias(bh); | |
1976 | if (PageUptodate(page)) { | |
1977 | clear_buffer_new(bh); | |
1978 | set_buffer_uptodate(bh); | |
1979 | mark_buffer_dirty(bh); | |
1980 | continue; | |
1981 | } | |
1982 | if (block_end > to || block_start < from) | |
1983 | zero_user_segments(page, | |
1984 | to, block_end, | |
1985 | block_start, from); | |
1986 | continue; | |
1987 | } | |
1988 | } | |
1989 | if (PageUptodate(page)) { | |
1990 | if (!buffer_uptodate(bh)) | |
1991 | set_buffer_uptodate(bh); | |
1992 | continue; | |
1993 | } | |
1994 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
1995 | !buffer_unwritten(bh) && | |
1996 | (block_start < from || block_end > to)) { | |
1997 | ll_rw_block(REQ_OP_READ, 0, 1, &bh); | |
1998 | *wait_bh++=bh; | |
1999 | } | |
2000 | } | |
2001 | /* | |
2002 | * If we issued read requests - let them complete. | |
2003 | */ | |
2004 | while(wait_bh > wait) { | |
2005 | wait_on_buffer(*--wait_bh); | |
2006 | if (!buffer_uptodate(*wait_bh)) | |
2007 | err = -EIO; | |
2008 | } | |
2009 | if (unlikely(err)) | |
2010 | page_zero_new_buffers(page, from, to); | |
2011 | return err; | |
2012 | } | |
2013 | ||
2014 | int __block_write_begin(struct page *page, loff_t pos, unsigned len, | |
2015 | get_block_t *get_block) | |
2016 | { | |
2017 | return __block_write_begin_int(page, pos, len, get_block, NULL); | |
2018 | } | |
2019 | EXPORT_SYMBOL(__block_write_begin); | |
2020 | ||
2021 | static int __block_commit_write(struct inode *inode, struct page *page, | |
2022 | unsigned from, unsigned to) | |
2023 | { | |
2024 | unsigned block_start, block_end; | |
2025 | int partial = 0; | |
2026 | unsigned blocksize; | |
2027 | struct buffer_head *bh, *head; | |
2028 | ||
2029 | bh = head = page_buffers(page); | |
2030 | blocksize = bh->b_size; | |
2031 | ||
2032 | block_start = 0; | |
2033 | do { | |
2034 | block_end = block_start + blocksize; | |
2035 | if (block_end <= from || block_start >= to) { | |
2036 | if (!buffer_uptodate(bh)) | |
2037 | partial = 1; | |
2038 | } else { | |
2039 | set_buffer_uptodate(bh); | |
2040 | mark_buffer_dirty(bh); | |
2041 | } | |
2042 | clear_buffer_new(bh); | |
2043 | ||
2044 | block_start = block_end; | |
2045 | bh = bh->b_this_page; | |
2046 | } while (bh != head); | |
2047 | ||
2048 | /* | |
2049 | * If this is a partial write which happened to make all buffers | |
2050 | * uptodate then we can optimize away a bogus readpage() for | |
2051 | * the next read(). Here we 'discover' whether the page went | |
2052 | * uptodate as a result of this (potentially partial) write. | |
2053 | */ | |
2054 | if (!partial) | |
2055 | SetPageUptodate(page); | |
2056 | return 0; | |
2057 | } | |
2058 | ||
2059 | /* | |
2060 | * block_write_begin takes care of the basic task of block allocation and | |
2061 | * bringing partial write blocks uptodate first. | |
2062 | * | |
2063 | * The filesystem needs to handle block truncation upon failure. | |
2064 | */ | |
2065 | int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, | |
2066 | unsigned flags, struct page **pagep, get_block_t *get_block) | |
2067 | { | |
2068 | pgoff_t index = pos >> PAGE_SHIFT; | |
2069 | struct page *page; | |
2070 | int status; | |
2071 | ||
2072 | page = grab_cache_page_write_begin(mapping, index, flags); | |
2073 | if (!page) | |
2074 | return -ENOMEM; | |
2075 | ||
2076 | status = __block_write_begin(page, pos, len, get_block); | |
2077 | if (unlikely(status)) { | |
2078 | unlock_page(page); | |
2079 | put_page(page); | |
2080 | page = NULL; | |
2081 | } | |
2082 | ||
2083 | *pagep = page; | |
2084 | return status; | |
2085 | } | |
2086 | EXPORT_SYMBOL(block_write_begin); | |
2087 | ||
2088 | int __generic_write_end(struct inode *inode, loff_t pos, unsigned copied, | |
2089 | struct page *page) | |
2090 | { | |
2091 | loff_t old_size = inode->i_size; | |
2092 | bool i_size_changed = false; | |
2093 | ||
2094 | /* | |
2095 | * No need to use i_size_read() here, the i_size cannot change under us | |
2096 | * because we hold i_rwsem. | |
2097 | * | |
2098 | * But it's important to update i_size while still holding page lock: | |
2099 | * page writeout could otherwise come in and zero beyond i_size. | |
2100 | */ | |
2101 | if (pos + copied > inode->i_size) { | |
2102 | i_size_write(inode, pos + copied); | |
2103 | i_size_changed = true; | |
2104 | } | |
2105 | ||
2106 | unlock_page(page); | |
2107 | put_page(page); | |
2108 | ||
2109 | if (old_size < pos) | |
2110 | pagecache_isize_extended(inode, old_size, pos); | |
2111 | /* | |
2112 | * Don't mark the inode dirty under page lock. First, it unnecessarily | |
2113 | * makes the holding time of page lock longer. Second, it forces lock | |
2114 | * ordering of page lock and transaction start for journaling | |
2115 | * filesystems. | |
2116 | */ | |
2117 | if (i_size_changed) | |
2118 | mark_inode_dirty(inode); | |
2119 | return copied; | |
2120 | } | |
2121 | ||
2122 | int block_write_end(struct file *file, struct address_space *mapping, | |
2123 | loff_t pos, unsigned len, unsigned copied, | |
2124 | struct page *page, void *fsdata) | |
2125 | { | |
2126 | struct inode *inode = mapping->host; | |
2127 | unsigned start; | |
2128 | ||
2129 | start = pos & (PAGE_SIZE - 1); | |
2130 | ||
2131 | if (unlikely(copied < len)) { | |
2132 | /* | |
2133 | * The buffers that were written will now be uptodate, so we | |
2134 | * don't have to worry about a readpage reading them and | |
2135 | * overwriting a partial write. However if we have encountered | |
2136 | * a short write and only partially written into a buffer, it | |
2137 | * will not be marked uptodate, so a readpage might come in and | |
2138 | * destroy our partial write. | |
2139 | * | |
2140 | * Do the simplest thing, and just treat any short write to a | |
2141 | * non uptodate page as a zero-length write, and force the | |
2142 | * caller to redo the whole thing. | |
2143 | */ | |
2144 | if (!PageUptodate(page)) | |
2145 | copied = 0; | |
2146 | ||
2147 | page_zero_new_buffers(page, start+copied, start+len); | |
2148 | } | |
2149 | flush_dcache_page(page); | |
2150 | ||
2151 | /* This could be a short (even 0-length) commit */ | |
2152 | __block_commit_write(inode, page, start, start+copied); | |
2153 | ||
2154 | return copied; | |
2155 | } | |
2156 | EXPORT_SYMBOL(block_write_end); | |
2157 | ||
2158 | int generic_write_end(struct file *file, struct address_space *mapping, | |
2159 | loff_t pos, unsigned len, unsigned copied, | |
2160 | struct page *page, void *fsdata) | |
2161 | { | |
2162 | copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); | |
2163 | return __generic_write_end(mapping->host, pos, copied, page); | |
2164 | } | |
2165 | EXPORT_SYMBOL(generic_write_end); | |
2166 | ||
2167 | /* | |
2168 | * block_is_partially_uptodate checks whether buffers within a page are | |
2169 | * uptodate or not. | |
2170 | * | |
2171 | * Returns true if all buffers which correspond to a file portion | |
2172 | * we want to read are uptodate. | |
2173 | */ | |
2174 | int block_is_partially_uptodate(struct page *page, unsigned long from, | |
2175 | unsigned long count) | |
2176 | { | |
2177 | unsigned block_start, block_end, blocksize; | |
2178 | unsigned to; | |
2179 | struct buffer_head *bh, *head; | |
2180 | int ret = 1; | |
2181 | ||
2182 | if (!page_has_buffers(page)) | |
2183 | return 0; | |
2184 | ||
2185 | head = page_buffers(page); | |
2186 | blocksize = head->b_size; | |
2187 | to = min_t(unsigned, PAGE_SIZE - from, count); | |
2188 | to = from + to; | |
2189 | if (from < blocksize && to > PAGE_SIZE - blocksize) | |
2190 | return 0; | |
2191 | ||
2192 | bh = head; | |
2193 | block_start = 0; | |
2194 | do { | |
2195 | block_end = block_start + blocksize; | |
2196 | if (block_end > from && block_start < to) { | |
2197 | if (!buffer_uptodate(bh)) { | |
2198 | ret = 0; | |
2199 | break; | |
2200 | } | |
2201 | if (block_end >= to) | |
2202 | break; | |
2203 | } | |
2204 | block_start = block_end; | |
2205 | bh = bh->b_this_page; | |
2206 | } while (bh != head); | |
2207 | ||
2208 | return ret; | |
2209 | } | |
2210 | EXPORT_SYMBOL(block_is_partially_uptodate); | |
2211 | ||
2212 | /* | |
2213 | * Generic "read page" function for block devices that have the normal | |
2214 | * get_block functionality. This is most of the block device filesystems. | |
2215 | * Reads the page asynchronously --- the unlock_buffer() and | |
2216 | * set/clear_buffer_uptodate() functions propagate buffer state into the | |
2217 | * page struct once IO has completed. | |
2218 | */ | |
2219 | int block_read_full_page(struct page *page, get_block_t *get_block) | |
2220 | { | |
2221 | struct inode *inode = page->mapping->host; | |
2222 | sector_t iblock, lblock; | |
2223 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; | |
2224 | unsigned int blocksize, bbits; | |
2225 | int nr, i; | |
2226 | int fully_mapped = 1; | |
2227 | ||
2228 | head = create_page_buffers(page, inode, 0); | |
2229 | blocksize = head->b_size; | |
2230 | bbits = block_size_bits(blocksize); | |
2231 | ||
2232 | iblock = (sector_t)page->index << (PAGE_SHIFT - bbits); | |
2233 | lblock = (i_size_read(inode)+blocksize-1) >> bbits; | |
2234 | bh = head; | |
2235 | nr = 0; | |
2236 | i = 0; | |
2237 | ||
2238 | do { | |
2239 | if (buffer_uptodate(bh)) | |
2240 | continue; | |
2241 | ||
2242 | if (!buffer_mapped(bh)) { | |
2243 | int err = 0; | |
2244 | ||
2245 | fully_mapped = 0; | |
2246 | if (iblock < lblock) { | |
2247 | WARN_ON(bh->b_size != blocksize); | |
2248 | err = get_block(inode, iblock, bh, 0); | |
2249 | if (err) | |
2250 | SetPageError(page); | |
2251 | } | |
2252 | if (!buffer_mapped(bh)) { | |
2253 | zero_user(page, i * blocksize, blocksize); | |
2254 | if (!err) | |
2255 | set_buffer_uptodate(bh); | |
2256 | continue; | |
2257 | } | |
2258 | /* | |
2259 | * get_block() might have updated the buffer | |
2260 | * synchronously | |
2261 | */ | |
2262 | if (buffer_uptodate(bh)) | |
2263 | continue; | |
2264 | } | |
2265 | arr[nr++] = bh; | |
2266 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
2267 | ||
2268 | if (fully_mapped) | |
2269 | SetPageMappedToDisk(page); | |
2270 | ||
2271 | if (!nr) { | |
2272 | /* | |
2273 | * All buffers are uptodate - we can set the page uptodate | |
2274 | * as well. But not if get_block() returned an error. | |
2275 | */ | |
2276 | if (!PageError(page)) | |
2277 | SetPageUptodate(page); | |
2278 | unlock_page(page); | |
2279 | return 0; | |
2280 | } | |
2281 | ||
2282 | /* Stage two: lock the buffers */ | |
2283 | for (i = 0; i < nr; i++) { | |
2284 | bh = arr[i]; | |
2285 | lock_buffer(bh); | |
2286 | mark_buffer_async_read(bh); | |
2287 | } | |
2288 | ||
2289 | /* | |
2290 | * Stage 3: start the IO. Check for uptodateness | |
2291 | * inside the buffer lock in case another process reading | |
2292 | * the underlying blockdev brought it uptodate (the sct fix). | |
2293 | */ | |
2294 | for (i = 0; i < nr; i++) { | |
2295 | bh = arr[i]; | |
2296 | if (buffer_uptodate(bh)) | |
2297 | end_buffer_async_read(bh, 1); | |
2298 | else | |
2299 | submit_bh(REQ_OP_READ, 0, bh); | |
2300 | } | |
2301 | return 0; | |
2302 | } | |
2303 | EXPORT_SYMBOL(block_read_full_page); | |
2304 | ||
2305 | /* utility function for filesystems that need to do work on expanding | |
2306 | * truncates. Uses filesystem pagecache writes to allow the filesystem to | |
2307 | * deal with the hole. | |
2308 | */ | |
2309 | int generic_cont_expand_simple(struct inode *inode, loff_t size) | |
2310 | { | |
2311 | struct address_space *mapping = inode->i_mapping; | |
2312 | struct page *page; | |
2313 | void *fsdata; | |
2314 | int err; | |
2315 | ||
2316 | err = inode_newsize_ok(inode, size); | |
2317 | if (err) | |
2318 | goto out; | |
2319 | ||
2320 | err = pagecache_write_begin(NULL, mapping, size, 0, | |
2321 | AOP_FLAG_CONT_EXPAND, &page, &fsdata); | |
2322 | if (err) | |
2323 | goto out; | |
2324 | ||
2325 | err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); | |
2326 | BUG_ON(err > 0); | |
2327 | ||
2328 | out: | |
2329 | return err; | |
2330 | } | |
2331 | EXPORT_SYMBOL(generic_cont_expand_simple); | |
2332 | ||
2333 | static int cont_expand_zero(struct file *file, struct address_space *mapping, | |
2334 | loff_t pos, loff_t *bytes) | |
2335 | { | |
2336 | struct inode *inode = mapping->host; | |
2337 | unsigned int blocksize = i_blocksize(inode); | |
2338 | struct page *page; | |
2339 | void *fsdata; | |
2340 | pgoff_t index, curidx; | |
2341 | loff_t curpos; | |
2342 | unsigned zerofrom, offset, len; | |
2343 | int err = 0; | |
2344 | ||
2345 | index = pos >> PAGE_SHIFT; | |
2346 | offset = pos & ~PAGE_MASK; | |
2347 | ||
2348 | while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) { | |
2349 | zerofrom = curpos & ~PAGE_MASK; | |
2350 | if (zerofrom & (blocksize-1)) { | |
2351 | *bytes |= (blocksize-1); | |
2352 | (*bytes)++; | |
2353 | } | |
2354 | len = PAGE_SIZE - zerofrom; | |
2355 | ||
2356 | err = pagecache_write_begin(file, mapping, curpos, len, 0, | |
2357 | &page, &fsdata); | |
2358 | if (err) | |
2359 | goto out; | |
2360 | zero_user(page, zerofrom, len); | |
2361 | err = pagecache_write_end(file, mapping, curpos, len, len, | |
2362 | page, fsdata); | |
2363 | if (err < 0) | |
2364 | goto out; | |
2365 | BUG_ON(err != len); | |
2366 | err = 0; | |
2367 | ||
2368 | balance_dirty_pages_ratelimited(mapping); | |
2369 | ||
2370 | if (fatal_signal_pending(current)) { | |
2371 | err = -EINTR; | |
2372 | goto out; | |
2373 | } | |
2374 | } | |
2375 | ||
2376 | /* page covers the boundary, find the boundary offset */ | |
2377 | if (index == curidx) { | |
2378 | zerofrom = curpos & ~PAGE_MASK; | |
2379 | /* if we will expand the thing last block will be filled */ | |
2380 | if (offset <= zerofrom) { | |
2381 | goto out; | |
2382 | } | |
2383 | if (zerofrom & (blocksize-1)) { | |
2384 | *bytes |= (blocksize-1); | |
2385 | (*bytes)++; | |
2386 | } | |
2387 | len = offset - zerofrom; | |
2388 | ||
2389 | err = pagecache_write_begin(file, mapping, curpos, len, 0, | |
2390 | &page, &fsdata); | |
2391 | if (err) | |
2392 | goto out; | |
2393 | zero_user(page, zerofrom, len); | |
2394 | err = pagecache_write_end(file, mapping, curpos, len, len, | |
2395 | page, fsdata); | |
2396 | if (err < 0) | |
2397 | goto out; | |
2398 | BUG_ON(err != len); | |
2399 | err = 0; | |
2400 | } | |
2401 | out: | |
2402 | return err; | |
2403 | } | |
2404 | ||
2405 | /* | |
2406 | * For moronic filesystems that do not allow holes in file. | |
2407 | * We may have to extend the file. | |
2408 | */ | |
2409 | int cont_write_begin(struct file *file, struct address_space *mapping, | |
2410 | loff_t pos, unsigned len, unsigned flags, | |
2411 | struct page **pagep, void **fsdata, | |
2412 | get_block_t *get_block, loff_t *bytes) | |
2413 | { | |
2414 | struct inode *inode = mapping->host; | |
2415 | unsigned int blocksize = i_blocksize(inode); | |
2416 | unsigned int zerofrom; | |
2417 | int err; | |
2418 | ||
2419 | err = cont_expand_zero(file, mapping, pos, bytes); | |
2420 | if (err) | |
2421 | return err; | |
2422 | ||
2423 | zerofrom = *bytes & ~PAGE_MASK; | |
2424 | if (pos+len > *bytes && zerofrom & (blocksize-1)) { | |
2425 | *bytes |= (blocksize-1); | |
2426 | (*bytes)++; | |
2427 | } | |
2428 | ||
2429 | return block_write_begin(mapping, pos, len, flags, pagep, get_block); | |
2430 | } | |
2431 | EXPORT_SYMBOL(cont_write_begin); | |
2432 | ||
2433 | int block_commit_write(struct page *page, unsigned from, unsigned to) | |
2434 | { | |
2435 | struct inode *inode = page->mapping->host; | |
2436 | __block_commit_write(inode,page,from,to); | |
2437 | return 0; | |
2438 | } | |
2439 | EXPORT_SYMBOL(block_commit_write); | |
2440 | ||
2441 | /* | |
2442 | * block_page_mkwrite() is not allowed to change the file size as it gets | |
2443 | * called from a page fault handler when a page is first dirtied. Hence we must | |
2444 | * be careful to check for EOF conditions here. We set the page up correctly | |
2445 | * for a written page which means we get ENOSPC checking when writing into | |
2446 | * holes and correct delalloc and unwritten extent mapping on filesystems that | |
2447 | * support these features. | |
2448 | * | |
2449 | * We are not allowed to take the i_mutex here so we have to play games to | |
2450 | * protect against truncate races as the page could now be beyond EOF. Because | |
2451 | * truncate writes the inode size before removing pages, once we have the | |
2452 | * page lock we can determine safely if the page is beyond EOF. If it is not | |
2453 | * beyond EOF, then the page is guaranteed safe against truncation until we | |
2454 | * unlock the page. | |
2455 | * | |
2456 | * Direct callers of this function should protect against filesystem freezing | |
2457 | * using sb_start_pagefault() - sb_end_pagefault() functions. | |
2458 | */ | |
2459 | int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, | |
2460 | get_block_t get_block) | |
2461 | { | |
2462 | struct page *page = vmf->page; | |
2463 | struct inode *inode = file_inode(vma->vm_file); | |
2464 | unsigned long end; | |
2465 | loff_t size; | |
2466 | int ret; | |
2467 | ||
2468 | lock_page(page); | |
2469 | size = i_size_read(inode); | |
2470 | if ((page->mapping != inode->i_mapping) || | |
2471 | (page_offset(page) > size)) { | |
2472 | /* We overload EFAULT to mean page got truncated */ | |
2473 | ret = -EFAULT; | |
2474 | goto out_unlock; | |
2475 | } | |
2476 | ||
2477 | /* page is wholly or partially inside EOF */ | |
2478 | if (((page->index + 1) << PAGE_SHIFT) > size) | |
2479 | end = size & ~PAGE_MASK; | |
2480 | else | |
2481 | end = PAGE_SIZE; | |
2482 | ||
2483 | ret = __block_write_begin(page, 0, end, get_block); | |
2484 | if (!ret) | |
2485 | ret = block_commit_write(page, 0, end); | |
2486 | ||
2487 | if (unlikely(ret < 0)) | |
2488 | goto out_unlock; | |
2489 | set_page_dirty(page); | |
2490 | wait_for_stable_page(page); | |
2491 | return 0; | |
2492 | out_unlock: | |
2493 | unlock_page(page); | |
2494 | return ret; | |
2495 | } | |
2496 | EXPORT_SYMBOL(block_page_mkwrite); | |
2497 | ||
2498 | /* | |
2499 | * nobh_write_begin()'s prereads are special: the buffer_heads are freed | |
2500 | * immediately, while under the page lock. So it needs a special end_io | |
2501 | * handler which does not touch the bh after unlocking it. | |
2502 | */ | |
2503 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2504 | { | |
2505 | __end_buffer_read_notouch(bh, uptodate); | |
2506 | } | |
2507 | ||
2508 | /* | |
2509 | * Attach the singly-linked list of buffers created by nobh_write_begin, to | |
2510 | * the page (converting it to circular linked list and taking care of page | |
2511 | * dirty races). | |
2512 | */ | |
2513 | static void attach_nobh_buffers(struct page *page, struct buffer_head *head) | |
2514 | { | |
2515 | struct buffer_head *bh; | |
2516 | ||
2517 | BUG_ON(!PageLocked(page)); | |
2518 | ||
2519 | spin_lock(&page->mapping->private_lock); | |
2520 | bh = head; | |
2521 | do { | |
2522 | if (PageDirty(page)) | |
2523 | set_buffer_dirty(bh); | |
2524 | if (!bh->b_this_page) | |
2525 | bh->b_this_page = head; | |
2526 | bh = bh->b_this_page; | |
2527 | } while (bh != head); | |
2528 | attach_page_buffers(page, head); | |
2529 | spin_unlock(&page->mapping->private_lock); | |
2530 | } | |
2531 | ||
2532 | /* | |
2533 | * On entry, the page is fully not uptodate. | |
2534 | * On exit the page is fully uptodate in the areas outside (from,to) | |
2535 | * The filesystem needs to handle block truncation upon failure. | |
2536 | */ | |
2537 | int nobh_write_begin(struct address_space *mapping, | |
2538 | loff_t pos, unsigned len, unsigned flags, | |
2539 | struct page **pagep, void **fsdata, | |
2540 | get_block_t *get_block) | |
2541 | { | |
2542 | struct inode *inode = mapping->host; | |
2543 | const unsigned blkbits = inode->i_blkbits; | |
2544 | const unsigned blocksize = 1 << blkbits; | |
2545 | struct buffer_head *head, *bh; | |
2546 | struct page *page; | |
2547 | pgoff_t index; | |
2548 | unsigned from, to; | |
2549 | unsigned block_in_page; | |
2550 | unsigned block_start, block_end; | |
2551 | sector_t block_in_file; | |
2552 | int nr_reads = 0; | |
2553 | int ret = 0; | |
2554 | int is_mapped_to_disk = 1; | |
2555 | ||
2556 | index = pos >> PAGE_SHIFT; | |
2557 | from = pos & (PAGE_SIZE - 1); | |
2558 | to = from + len; | |
2559 | ||
2560 | page = grab_cache_page_write_begin(mapping, index, flags); | |
2561 | if (!page) | |
2562 | return -ENOMEM; | |
2563 | *pagep = page; | |
2564 | *fsdata = NULL; | |
2565 | ||
2566 | if (page_has_buffers(page)) { | |
2567 | ret = __block_write_begin(page, pos, len, get_block); | |
2568 | if (unlikely(ret)) | |
2569 | goto out_release; | |
2570 | return ret; | |
2571 | } | |
2572 | ||
2573 | if (PageMappedToDisk(page)) | |
2574 | return 0; | |
2575 | ||
2576 | /* | |
2577 | * Allocate buffers so that we can keep track of state, and potentially | |
2578 | * attach them to the page if an error occurs. In the common case of | |
2579 | * no error, they will just be freed again without ever being attached | |
2580 | * to the page (which is all OK, because we're under the page lock). | |
2581 | * | |
2582 | * Be careful: the buffer linked list is a NULL terminated one, rather | |
2583 | * than the circular one we're used to. | |
2584 | */ | |
2585 | head = alloc_page_buffers(page, blocksize, false); | |
2586 | if (!head) { | |
2587 | ret = -ENOMEM; | |
2588 | goto out_release; | |
2589 | } | |
2590 | ||
2591 | block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); | |
2592 | ||
2593 | /* | |
2594 | * We loop across all blocks in the page, whether or not they are | |
2595 | * part of the affected region. This is so we can discover if the | |
2596 | * page is fully mapped-to-disk. | |
2597 | */ | |
2598 | for (block_start = 0, block_in_page = 0, bh = head; | |
2599 | block_start < PAGE_SIZE; | |
2600 | block_in_page++, block_start += blocksize, bh = bh->b_this_page) { | |
2601 | int create; | |
2602 | ||
2603 | block_end = block_start + blocksize; | |
2604 | bh->b_state = 0; | |
2605 | create = 1; | |
2606 | if (block_start >= to) | |
2607 | create = 0; | |
2608 | ret = get_block(inode, block_in_file + block_in_page, | |
2609 | bh, create); | |
2610 | if (ret) | |
2611 | goto failed; | |
2612 | if (!buffer_mapped(bh)) | |
2613 | is_mapped_to_disk = 0; | |
2614 | if (buffer_new(bh)) | |
2615 | clean_bdev_bh_alias(bh); | |
2616 | if (PageUptodate(page)) { | |
2617 | set_buffer_uptodate(bh); | |
2618 | continue; | |
2619 | } | |
2620 | if (buffer_new(bh) || !buffer_mapped(bh)) { | |
2621 | zero_user_segments(page, block_start, from, | |
2622 | to, block_end); | |
2623 | continue; | |
2624 | } | |
2625 | if (buffer_uptodate(bh)) | |
2626 | continue; /* reiserfs does this */ | |
2627 | if (block_start < from || block_end > to) { | |
2628 | lock_buffer(bh); | |
2629 | bh->b_end_io = end_buffer_read_nobh; | |
2630 | submit_bh(REQ_OP_READ, 0, bh); | |
2631 | nr_reads++; | |
2632 | } | |
2633 | } | |
2634 | ||
2635 | if (nr_reads) { | |
2636 | /* | |
2637 | * The page is locked, so these buffers are protected from | |
2638 | * any VM or truncate activity. Hence we don't need to care | |
2639 | * for the buffer_head refcounts. | |
2640 | */ | |
2641 | for (bh = head; bh; bh = bh->b_this_page) { | |
2642 | wait_on_buffer(bh); | |
2643 | if (!buffer_uptodate(bh)) | |
2644 | ret = -EIO; | |
2645 | } | |
2646 | if (ret) | |
2647 | goto failed; | |
2648 | } | |
2649 | ||
2650 | if (is_mapped_to_disk) | |
2651 | SetPageMappedToDisk(page); | |
2652 | ||
2653 | *fsdata = head; /* to be released by nobh_write_end */ | |
2654 | ||
2655 | return 0; | |
2656 | ||
2657 | failed: | |
2658 | BUG_ON(!ret); | |
2659 | /* | |
2660 | * Error recovery is a bit difficult. We need to zero out blocks that | |
2661 | * were newly allocated, and dirty them to ensure they get written out. | |
2662 | * Buffers need to be attached to the page at this point, otherwise | |
2663 | * the handling of potential IO errors during writeout would be hard | |
2664 | * (could try doing synchronous writeout, but what if that fails too?) | |
2665 | */ | |
2666 | attach_nobh_buffers(page, head); | |
2667 | page_zero_new_buffers(page, from, to); | |
2668 | ||
2669 | out_release: | |
2670 | unlock_page(page); | |
2671 | put_page(page); | |
2672 | *pagep = NULL; | |
2673 | ||
2674 | return ret; | |
2675 | } | |
2676 | EXPORT_SYMBOL(nobh_write_begin); | |
2677 | ||
2678 | int nobh_write_end(struct file *file, struct address_space *mapping, | |
2679 | loff_t pos, unsigned len, unsigned copied, | |
2680 | struct page *page, void *fsdata) | |
2681 | { | |
2682 | struct inode *inode = page->mapping->host; | |
2683 | struct buffer_head *head = fsdata; | |
2684 | struct buffer_head *bh; | |
2685 | BUG_ON(fsdata != NULL && page_has_buffers(page)); | |
2686 | ||
2687 | if (unlikely(copied < len) && head) | |
2688 | attach_nobh_buffers(page, head); | |
2689 | if (page_has_buffers(page)) | |
2690 | return generic_write_end(file, mapping, pos, len, | |
2691 | copied, page, fsdata); | |
2692 | ||
2693 | SetPageUptodate(page); | |
2694 | set_page_dirty(page); | |
2695 | if (pos+copied > inode->i_size) { | |
2696 | i_size_write(inode, pos+copied); | |
2697 | mark_inode_dirty(inode); | |
2698 | } | |
2699 | ||
2700 | unlock_page(page); | |
2701 | put_page(page); | |
2702 | ||
2703 | while (head) { | |
2704 | bh = head; | |
2705 | head = head->b_this_page; | |
2706 | free_buffer_head(bh); | |
2707 | } | |
2708 | ||
2709 | return copied; | |
2710 | } | |
2711 | EXPORT_SYMBOL(nobh_write_end); | |
2712 | ||
2713 | /* | |
2714 | * nobh_writepage() - based on block_full_write_page() except | |
2715 | * that it tries to operate without attaching bufferheads to | |
2716 | * the page. | |
2717 | */ | |
2718 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2719 | struct writeback_control *wbc) | |
2720 | { | |
2721 | struct inode * const inode = page->mapping->host; | |
2722 | loff_t i_size = i_size_read(inode); | |
2723 | const pgoff_t end_index = i_size >> PAGE_SHIFT; | |
2724 | unsigned offset; | |
2725 | int ret; | |
2726 | ||
2727 | /* Is the page fully inside i_size? */ | |
2728 | if (page->index < end_index) | |
2729 | goto out; | |
2730 | ||
2731 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2732 | offset = i_size & (PAGE_SIZE-1); | |
2733 | if (page->index >= end_index+1 || !offset) { | |
2734 | /* | |
2735 | * The page may have dirty, unmapped buffers. For example, | |
2736 | * they may have been added in ext3_writepage(). Make them | |
2737 | * freeable here, so the page does not leak. | |
2738 | */ | |
2739 | #if 0 | |
2740 | /* Not really sure about this - do we need this ? */ | |
2741 | if (page->mapping->a_ops->invalidatepage) | |
2742 | page->mapping->a_ops->invalidatepage(page, offset); | |
2743 | #endif | |
2744 | unlock_page(page); | |
2745 | return 0; /* don't care */ | |
2746 | } | |
2747 | ||
2748 | /* | |
2749 | * The page straddles i_size. It must be zeroed out on each and every | |
2750 | * writepage invocation because it may be mmapped. "A file is mapped | |
2751 | * in multiples of the page size. For a file that is not a multiple of | |
2752 | * the page size, the remaining memory is zeroed when mapped, and | |
2753 | * writes to that region are not written out to the file." | |
2754 | */ | |
2755 | zero_user_segment(page, offset, PAGE_SIZE); | |
2756 | out: | |
2757 | ret = mpage_writepage(page, get_block, wbc); | |
2758 | if (ret == -EAGAIN) | |
2759 | ret = __block_write_full_page(inode, page, get_block, wbc, | |
2760 | end_buffer_async_write); | |
2761 | return ret; | |
2762 | } | |
2763 | EXPORT_SYMBOL(nobh_writepage); | |
2764 | ||
2765 | int nobh_truncate_page(struct address_space *mapping, | |
2766 | loff_t from, get_block_t *get_block) | |
2767 | { | |
2768 | pgoff_t index = from >> PAGE_SHIFT; | |
2769 | unsigned offset = from & (PAGE_SIZE-1); | |
2770 | unsigned blocksize; | |
2771 | sector_t iblock; | |
2772 | unsigned length, pos; | |
2773 | struct inode *inode = mapping->host; | |
2774 | struct page *page; | |
2775 | struct buffer_head map_bh; | |
2776 | int err; | |
2777 | ||
2778 | blocksize = i_blocksize(inode); | |
2779 | length = offset & (blocksize - 1); | |
2780 | ||
2781 | /* Block boundary? Nothing to do */ | |
2782 | if (!length) | |
2783 | return 0; | |
2784 | ||
2785 | length = blocksize - length; | |
2786 | iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); | |
2787 | ||
2788 | page = grab_cache_page(mapping, index); | |
2789 | err = -ENOMEM; | |
2790 | if (!page) | |
2791 | goto out; | |
2792 | ||
2793 | if (page_has_buffers(page)) { | |
2794 | has_buffers: | |
2795 | unlock_page(page); | |
2796 | put_page(page); | |
2797 | return block_truncate_page(mapping, from, get_block); | |
2798 | } | |
2799 | ||
2800 | /* Find the buffer that contains "offset" */ | |
2801 | pos = blocksize; | |
2802 | while (offset >= pos) { | |
2803 | iblock++; | |
2804 | pos += blocksize; | |
2805 | } | |
2806 | ||
2807 | map_bh.b_size = blocksize; | |
2808 | map_bh.b_state = 0; | |
2809 | err = get_block(inode, iblock, &map_bh, 0); | |
2810 | if (err) | |
2811 | goto unlock; | |
2812 | /* unmapped? It's a hole - nothing to do */ | |
2813 | if (!buffer_mapped(&map_bh)) | |
2814 | goto unlock; | |
2815 | ||
2816 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2817 | if (!PageUptodate(page)) { | |
2818 | err = mapping->a_ops->readpage(NULL, page); | |
2819 | if (err) { | |
2820 | put_page(page); | |
2821 | goto out; | |
2822 | } | |
2823 | lock_page(page); | |
2824 | if (!PageUptodate(page)) { | |
2825 | err = -EIO; | |
2826 | goto unlock; | |
2827 | } | |
2828 | if (page_has_buffers(page)) | |
2829 | goto has_buffers; | |
2830 | } | |
2831 | zero_user(page, offset, length); | |
2832 | set_page_dirty(page); | |
2833 | err = 0; | |
2834 | ||
2835 | unlock: | |
2836 | unlock_page(page); | |
2837 | put_page(page); | |
2838 | out: | |
2839 | return err; | |
2840 | } | |
2841 | EXPORT_SYMBOL(nobh_truncate_page); | |
2842 | ||
2843 | int block_truncate_page(struct address_space *mapping, | |
2844 | loff_t from, get_block_t *get_block) | |
2845 | { | |
2846 | pgoff_t index = from >> PAGE_SHIFT; | |
2847 | unsigned offset = from & (PAGE_SIZE-1); | |
2848 | unsigned blocksize; | |
2849 | sector_t iblock; | |
2850 | unsigned length, pos; | |
2851 | struct inode *inode = mapping->host; | |
2852 | struct page *page; | |
2853 | struct buffer_head *bh; | |
2854 | int err; | |
2855 | ||
2856 | blocksize = i_blocksize(inode); | |
2857 | length = offset & (blocksize - 1); | |
2858 | ||
2859 | /* Block boundary? Nothing to do */ | |
2860 | if (!length) | |
2861 | return 0; | |
2862 | ||
2863 | length = blocksize - length; | |
2864 | iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); | |
2865 | ||
2866 | page = grab_cache_page(mapping, index); | |
2867 | err = -ENOMEM; | |
2868 | if (!page) | |
2869 | goto out; | |
2870 | ||
2871 | if (!page_has_buffers(page)) | |
2872 | create_empty_buffers(page, blocksize, 0); | |
2873 | ||
2874 | /* Find the buffer that contains "offset" */ | |
2875 | bh = page_buffers(page); | |
2876 | pos = blocksize; | |
2877 | while (offset >= pos) { | |
2878 | bh = bh->b_this_page; | |
2879 | iblock++; | |
2880 | pos += blocksize; | |
2881 | } | |
2882 | ||
2883 | err = 0; | |
2884 | if (!buffer_mapped(bh)) { | |
2885 | WARN_ON(bh->b_size != blocksize); | |
2886 | err = get_block(inode, iblock, bh, 0); | |
2887 | if (err) | |
2888 | goto unlock; | |
2889 | /* unmapped? It's a hole - nothing to do */ | |
2890 | if (!buffer_mapped(bh)) | |
2891 | goto unlock; | |
2892 | } | |
2893 | ||
2894 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2895 | if (PageUptodate(page)) | |
2896 | set_buffer_uptodate(bh); | |
2897 | ||
2898 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { | |
2899 | err = -EIO; | |
2900 | ll_rw_block(REQ_OP_READ, 0, 1, &bh); | |
2901 | wait_on_buffer(bh); | |
2902 | /* Uhhuh. Read error. Complain and punt. */ | |
2903 | if (!buffer_uptodate(bh)) | |
2904 | goto unlock; | |
2905 | } | |
2906 | ||
2907 | zero_user(page, offset, length); | |
2908 | mark_buffer_dirty(bh); | |
2909 | err = 0; | |
2910 | ||
2911 | unlock: | |
2912 | unlock_page(page); | |
2913 | put_page(page); | |
2914 | out: | |
2915 | return err; | |
2916 | } | |
2917 | EXPORT_SYMBOL(block_truncate_page); | |
2918 | ||
2919 | /* | |
2920 | * The generic ->writepage function for buffer-backed address_spaces | |
2921 | */ | |
2922 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
2923 | struct writeback_control *wbc) | |
2924 | { | |
2925 | struct inode * const inode = page->mapping->host; | |
2926 | loff_t i_size = i_size_read(inode); | |
2927 | const pgoff_t end_index = i_size >> PAGE_SHIFT; | |
2928 | unsigned offset; | |
2929 | ||
2930 | /* Is the page fully inside i_size? */ | |
2931 | if (page->index < end_index) | |
2932 | return __block_write_full_page(inode, page, get_block, wbc, | |
2933 | end_buffer_async_write); | |
2934 | ||
2935 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2936 | offset = i_size & (PAGE_SIZE-1); | |
2937 | if (page->index >= end_index+1 || !offset) { | |
2938 | /* | |
2939 | * The page may have dirty, unmapped buffers. For example, | |
2940 | * they may have been added in ext3_writepage(). Make them | |
2941 | * freeable here, so the page does not leak. | |
2942 | */ | |
2943 | do_invalidatepage(page, 0, PAGE_SIZE); | |
2944 | unlock_page(page); | |
2945 | return 0; /* don't care */ | |
2946 | } | |
2947 | ||
2948 | /* | |
2949 | * The page straddles i_size. It must be zeroed out on each and every | |
2950 | * writepage invocation because it may be mmapped. "A file is mapped | |
2951 | * in multiples of the page size. For a file that is not a multiple of | |
2952 | * the page size, the remaining memory is zeroed when mapped, and | |
2953 | * writes to that region are not written out to the file." | |
2954 | */ | |
2955 | zero_user_segment(page, offset, PAGE_SIZE); | |
2956 | return __block_write_full_page(inode, page, get_block, wbc, | |
2957 | end_buffer_async_write); | |
2958 | } | |
2959 | EXPORT_SYMBOL(block_write_full_page); | |
2960 | ||
2961 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, | |
2962 | get_block_t *get_block) | |
2963 | { | |
2964 | struct inode *inode = mapping->host; | |
2965 | struct buffer_head tmp = { | |
2966 | .b_size = i_blocksize(inode), | |
2967 | }; | |
2968 | ||
2969 | get_block(inode, block, &tmp, 0); | |
2970 | return tmp.b_blocknr; | |
2971 | } | |
2972 | EXPORT_SYMBOL(generic_block_bmap); | |
2973 | ||
2974 | static void end_bio_bh_io_sync(struct bio *bio) | |
2975 | { | |
2976 | struct buffer_head *bh = bio->bi_private; | |
2977 | ||
2978 | if (unlikely(bio_flagged(bio, BIO_QUIET))) | |
2979 | set_bit(BH_Quiet, &bh->b_state); | |
2980 | ||
2981 | bh->b_end_io(bh, !bio->bi_status); | |
2982 | bio_put(bio); | |
2983 | } | |
2984 | ||
2985 | /* | |
2986 | * This allows us to do IO even on the odd last sectors | |
2987 | * of a device, even if the block size is some multiple | |
2988 | * of the physical sector size. | |
2989 | * | |
2990 | * We'll just truncate the bio to the size of the device, | |
2991 | * and clear the end of the buffer head manually. | |
2992 | * | |
2993 | * Truly out-of-range accesses will turn into actual IO | |
2994 | * errors, this only handles the "we need to be able to | |
2995 | * do IO at the final sector" case. | |
2996 | */ | |
2997 | void guard_bio_eod(int op, struct bio *bio) | |
2998 | { | |
2999 | sector_t maxsector; | |
3000 | struct bio_vec *bvec = bio_last_bvec_all(bio); | |
3001 | unsigned truncated_bytes; | |
3002 | struct hd_struct *part; | |
3003 | ||
3004 | rcu_read_lock(); | |
3005 | part = __disk_get_part(bio->bi_disk, bio->bi_partno); | |
3006 | if (part) | |
3007 | maxsector = part_nr_sects_read(part); | |
3008 | else | |
3009 | maxsector = get_capacity(bio->bi_disk); | |
3010 | rcu_read_unlock(); | |
3011 | ||
3012 | if (!maxsector) | |
3013 | return; | |
3014 | ||
3015 | /* | |
3016 | * If the *whole* IO is past the end of the device, | |
3017 | * let it through, and the IO layer will turn it into | |
3018 | * an EIO. | |
3019 | */ | |
3020 | if (unlikely(bio->bi_iter.bi_sector >= maxsector)) | |
3021 | return; | |
3022 | ||
3023 | maxsector -= bio->bi_iter.bi_sector; | |
3024 | if (likely((bio->bi_iter.bi_size >> 9) <= maxsector)) | |
3025 | return; | |
3026 | ||
3027 | /* Uhhuh. We've got a bio that straddles the device size! */ | |
3028 | truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9); | |
3029 | ||
3030 | /* | |
3031 | * The bio contains more than one segment which spans EOD, just return | |
3032 | * and let IO layer turn it into an EIO | |
3033 | */ | |
3034 | if (truncated_bytes > bvec->bv_len) | |
3035 | return; | |
3036 | ||
3037 | /* Truncate the bio.. */ | |
3038 | bio->bi_iter.bi_size -= truncated_bytes; | |
3039 | bvec->bv_len -= truncated_bytes; | |
3040 | ||
3041 | /* ..and clear the end of the buffer for reads */ | |
3042 | if (op == REQ_OP_READ) { | |
3043 | struct bio_vec bv; | |
3044 | ||
3045 | mp_bvec_last_segment(bvec, &bv); | |
3046 | zero_user(bv.bv_page, bv.bv_offset + bv.bv_len, | |
3047 | truncated_bytes); | |
3048 | } | |
3049 | } | |
3050 | ||
3051 | static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, | |
3052 | enum rw_hint write_hint, struct writeback_control *wbc) | |
3053 | { | |
3054 | struct bio *bio; | |
3055 | ||
3056 | BUG_ON(!buffer_locked(bh)); | |
3057 | BUG_ON(!buffer_mapped(bh)); | |
3058 | BUG_ON(!bh->b_end_io); | |
3059 | BUG_ON(buffer_delay(bh)); | |
3060 | BUG_ON(buffer_unwritten(bh)); | |
3061 | ||
3062 | /* | |
3063 | * Only clear out a write error when rewriting | |
3064 | */ | |
3065 | if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE)) | |
3066 | clear_buffer_write_io_error(bh); | |
3067 | ||
3068 | /* | |
3069 | * from here on down, it's all bio -- do the initial mapping, | |
3070 | * submit_bio -> generic_make_request may further map this bio around | |
3071 | */ | |
3072 | bio = bio_alloc(GFP_NOIO, 1); | |
3073 | ||
3074 | bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); | |
3075 | bio_set_dev(bio, bh->b_bdev); | |
3076 | bio->bi_write_hint = write_hint; | |
3077 | ||
3078 | bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh)); | |
3079 | BUG_ON(bio->bi_iter.bi_size != bh->b_size); | |
3080 | ||
3081 | bio->bi_end_io = end_bio_bh_io_sync; | |
3082 | bio->bi_private = bh; | |
3083 | ||
3084 | /* Take care of bh's that straddle the end of the device */ | |
3085 | guard_bio_eod(op, bio); | |
3086 | ||
3087 | if (buffer_meta(bh)) | |
3088 | op_flags |= REQ_META; | |
3089 | if (buffer_prio(bh)) | |
3090 | op_flags |= REQ_PRIO; | |
3091 | bio_set_op_attrs(bio, op, op_flags); | |
3092 | ||
3093 | if (wbc) { | |
3094 | wbc_init_bio(wbc, bio); | |
3095 | wbc_account_io(wbc, bh->b_page, bh->b_size); | |
3096 | } | |
3097 | ||
3098 | submit_bio(bio); | |
3099 | return 0; | |
3100 | } | |
3101 | ||
3102 | int submit_bh(int op, int op_flags, struct buffer_head *bh) | |
3103 | { | |
3104 | return submit_bh_wbc(op, op_flags, bh, 0, NULL); | |
3105 | } | |
3106 | EXPORT_SYMBOL(submit_bh); | |
3107 | ||
3108 | /** | |
3109 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
3110 | * @op: whether to %READ or %WRITE | |
3111 | * @op_flags: req_flag_bits | |
3112 | * @nr: number of &struct buffer_heads in the array | |
3113 | * @bhs: array of pointers to &struct buffer_head | |
3114 | * | |
3115 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and | |
3116 | * requests an I/O operation on them, either a %REQ_OP_READ or a %REQ_OP_WRITE. | |
3117 | * @op_flags contains flags modifying the detailed I/O behavior, most notably | |
3118 | * %REQ_RAHEAD. | |
3119 | * | |
3120 | * This function drops any buffer that it cannot get a lock on (with the | |
3121 | * BH_Lock state bit), any buffer that appears to be clean when doing a write | |
3122 | * request, and any buffer that appears to be up-to-date when doing read | |
3123 | * request. Further it marks as clean buffers that are processed for | |
3124 | * writing (the buffer cache won't assume that they are actually clean | |
3125 | * until the buffer gets unlocked). | |
3126 | * | |
3127 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
3128 | * the buffer up-to-date (if appropriate), unlocks the buffer and wakes | |
3129 | * any waiters. | |
3130 | * | |
3131 | * All of the buffers must be for the same device, and must also be a | |
3132 | * multiple of the current approved size for the device. | |
3133 | */ | |
3134 | void ll_rw_block(int op, int op_flags, int nr, struct buffer_head *bhs[]) | |
3135 | { | |
3136 | int i; | |
3137 | ||
3138 | for (i = 0; i < nr; i++) { | |
3139 | struct buffer_head *bh = bhs[i]; | |
3140 | ||
3141 | if (!trylock_buffer(bh)) | |
3142 | continue; | |
3143 | if (op == WRITE) { | |
3144 | if (test_clear_buffer_dirty(bh)) { | |
3145 | bh->b_end_io = end_buffer_write_sync; | |
3146 | get_bh(bh); | |
3147 | submit_bh(op, op_flags, bh); | |
3148 | continue; | |
3149 | } | |
3150 | } else { | |
3151 | if (!buffer_uptodate(bh)) { | |
3152 | bh->b_end_io = end_buffer_read_sync; | |
3153 | get_bh(bh); | |
3154 | submit_bh(op, op_flags, bh); | |
3155 | continue; | |
3156 | } | |
3157 | } | |
3158 | unlock_buffer(bh); | |
3159 | } | |
3160 | } | |
3161 | EXPORT_SYMBOL(ll_rw_block); | |
3162 | ||
3163 | void write_dirty_buffer(struct buffer_head *bh, int op_flags) | |
3164 | { | |
3165 | lock_buffer(bh); | |
3166 | if (!test_clear_buffer_dirty(bh)) { | |
3167 | unlock_buffer(bh); | |
3168 | return; | |
3169 | } | |
3170 | bh->b_end_io = end_buffer_write_sync; | |
3171 | get_bh(bh); | |
3172 | submit_bh(REQ_OP_WRITE, op_flags, bh); | |
3173 | } | |
3174 | EXPORT_SYMBOL(write_dirty_buffer); | |
3175 | ||
3176 | /* | |
3177 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
3178 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
3179 | * the buffer_head. | |
3180 | */ | |
3181 | int __sync_dirty_buffer(struct buffer_head *bh, int op_flags) | |
3182 | { | |
3183 | int ret = 0; | |
3184 | ||
3185 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
3186 | lock_buffer(bh); | |
3187 | if (test_clear_buffer_dirty(bh)) { | |
3188 | get_bh(bh); | |
3189 | bh->b_end_io = end_buffer_write_sync; | |
3190 | ret = submit_bh(REQ_OP_WRITE, op_flags, bh); | |
3191 | wait_on_buffer(bh); | |
3192 | if (!ret && !buffer_uptodate(bh)) | |
3193 | ret = -EIO; | |
3194 | } else { | |
3195 | unlock_buffer(bh); | |
3196 | } | |
3197 | return ret; | |
3198 | } | |
3199 | EXPORT_SYMBOL(__sync_dirty_buffer); | |
3200 | ||
3201 | int sync_dirty_buffer(struct buffer_head *bh) | |
3202 | { | |
3203 | return __sync_dirty_buffer(bh, REQ_SYNC); | |
3204 | } | |
3205 | EXPORT_SYMBOL(sync_dirty_buffer); | |
3206 | ||
3207 | /* | |
3208 | * try_to_free_buffers() checks if all the buffers on this particular page | |
3209 | * are unused, and releases them if so. | |
3210 | * | |
3211 | * Exclusion against try_to_free_buffers may be obtained by either | |
3212 | * locking the page or by holding its mapping's private_lock. | |
3213 | * | |
3214 | * If the page is dirty but all the buffers are clean then we need to | |
3215 | * be sure to mark the page clean as well. This is because the page | |
3216 | * may be against a block device, and a later reattachment of buffers | |
3217 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
3218 | * filesystem data on the same device. | |
3219 | * | |
3220 | * The same applies to regular filesystem pages: if all the buffers are | |
3221 | * clean then we set the page clean and proceed. To do that, we require | |
3222 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
3223 | * private_lock. | |
3224 | * | |
3225 | * try_to_free_buffers() is non-blocking. | |
3226 | */ | |
3227 | static inline int buffer_busy(struct buffer_head *bh) | |
3228 | { | |
3229 | return atomic_read(&bh->b_count) | | |
3230 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
3231 | } | |
3232 | ||
3233 | static int | |
3234 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
3235 | { | |
3236 | struct buffer_head *head = page_buffers(page); | |
3237 | struct buffer_head *bh; | |
3238 | ||
3239 | bh = head; | |
3240 | do { | |
3241 | if (buffer_busy(bh)) | |
3242 | goto failed; | |
3243 | bh = bh->b_this_page; | |
3244 | } while (bh != head); | |
3245 | ||
3246 | do { | |
3247 | struct buffer_head *next = bh->b_this_page; | |
3248 | ||
3249 | if (bh->b_assoc_map) | |
3250 | __remove_assoc_queue(bh); | |
3251 | bh = next; | |
3252 | } while (bh != head); | |
3253 | *buffers_to_free = head; | |
3254 | __clear_page_buffers(page); | |
3255 | return 1; | |
3256 | failed: | |
3257 | return 0; | |
3258 | } | |
3259 | ||
3260 | int try_to_free_buffers(struct page *page) | |
3261 | { | |
3262 | struct address_space * const mapping = page->mapping; | |
3263 | struct buffer_head *buffers_to_free = NULL; | |
3264 | int ret = 0; | |
3265 | ||
3266 | BUG_ON(!PageLocked(page)); | |
3267 | if (PageWriteback(page)) | |
3268 | return 0; | |
3269 | ||
3270 | if (mapping == NULL) { /* can this still happen? */ | |
3271 | ret = drop_buffers(page, &buffers_to_free); | |
3272 | goto out; | |
3273 | } | |
3274 | ||
3275 | spin_lock(&mapping->private_lock); | |
3276 | ret = drop_buffers(page, &buffers_to_free); | |
3277 | ||
3278 | /* | |
3279 | * If the filesystem writes its buffers by hand (eg ext3) | |
3280 | * then we can have clean buffers against a dirty page. We | |
3281 | * clean the page here; otherwise the VM will never notice | |
3282 | * that the filesystem did any IO at all. | |
3283 | * | |
3284 | * Also, during truncate, discard_buffer will have marked all | |
3285 | * the page's buffers clean. We discover that here and clean | |
3286 | * the page also. | |
3287 | * | |
3288 | * private_lock must be held over this entire operation in order | |
3289 | * to synchronise against __set_page_dirty_buffers and prevent the | |
3290 | * dirty bit from being lost. | |
3291 | */ | |
3292 | if (ret) | |
3293 | cancel_dirty_page(page); | |
3294 | spin_unlock(&mapping->private_lock); | |
3295 | out: | |
3296 | if (buffers_to_free) { | |
3297 | struct buffer_head *bh = buffers_to_free; | |
3298 | ||
3299 | do { | |
3300 | struct buffer_head *next = bh->b_this_page; | |
3301 | free_buffer_head(bh); | |
3302 | bh = next; | |
3303 | } while (bh != buffers_to_free); | |
3304 | } | |
3305 | return ret; | |
3306 | } | |
3307 | EXPORT_SYMBOL(try_to_free_buffers); | |
3308 | ||
3309 | /* | |
3310 | * There are no bdflush tunables left. But distributions are | |
3311 | * still running obsolete flush daemons, so we terminate them here. | |
3312 | * | |
3313 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
3314 | * The `flush-X' kernel threads fully replace bdflush daemons and this call. | |
3315 | */ | |
3316 | SYSCALL_DEFINE2(bdflush, int, func, long, data) | |
3317 | { | |
3318 | static int msg_count; | |
3319 | ||
3320 | if (!capable(CAP_SYS_ADMIN)) | |
3321 | return -EPERM; | |
3322 | ||
3323 | if (msg_count < 5) { | |
3324 | msg_count++; | |
3325 | printk(KERN_INFO | |
3326 | "warning: process `%s' used the obsolete bdflush" | |
3327 | " system call\n", current->comm); | |
3328 | printk(KERN_INFO "Fix your initscripts?\n"); | |
3329 | } | |
3330 | ||
3331 | if (func == 1) | |
3332 | do_exit(0); | |
3333 | return 0; | |
3334 | } | |
3335 | ||
3336 | /* | |
3337 | * Buffer-head allocation | |
3338 | */ | |
3339 | static struct kmem_cache *bh_cachep __read_mostly; | |
3340 | ||
3341 | /* | |
3342 | * Once the number of bh's in the machine exceeds this level, we start | |
3343 | * stripping them in writeback. | |
3344 | */ | |
3345 | static unsigned long max_buffer_heads; | |
3346 | ||
3347 | int buffer_heads_over_limit; | |
3348 | ||
3349 | struct bh_accounting { | |
3350 | int nr; /* Number of live bh's */ | |
3351 | int ratelimit; /* Limit cacheline bouncing */ | |
3352 | }; | |
3353 | ||
3354 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
3355 | ||
3356 | static void recalc_bh_state(void) | |
3357 | { | |
3358 | int i; | |
3359 | int tot = 0; | |
3360 | ||
3361 | if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) | |
3362 | return; | |
3363 | __this_cpu_write(bh_accounting.ratelimit, 0); | |
3364 | for_each_online_cpu(i) | |
3365 | tot += per_cpu(bh_accounting, i).nr; | |
3366 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
3367 | } | |
3368 | ||
3369 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) | |
3370 | { | |
3371 | struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); | |
3372 | if (ret) { | |
3373 | INIT_LIST_HEAD(&ret->b_assoc_buffers); | |
3374 | preempt_disable(); | |
3375 | __this_cpu_inc(bh_accounting.nr); | |
3376 | recalc_bh_state(); | |
3377 | preempt_enable(); | |
3378 | } | |
3379 | return ret; | |
3380 | } | |
3381 | EXPORT_SYMBOL(alloc_buffer_head); | |
3382 | ||
3383 | void free_buffer_head(struct buffer_head *bh) | |
3384 | { | |
3385 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
3386 | kmem_cache_free(bh_cachep, bh); | |
3387 | preempt_disable(); | |
3388 | __this_cpu_dec(bh_accounting.nr); | |
3389 | recalc_bh_state(); | |
3390 | preempt_enable(); | |
3391 | } | |
3392 | EXPORT_SYMBOL(free_buffer_head); | |
3393 | ||
3394 | static int buffer_exit_cpu_dead(unsigned int cpu) | |
3395 | { | |
3396 | int i; | |
3397 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
3398 | ||
3399 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
3400 | brelse(b->bhs[i]); | |
3401 | b->bhs[i] = NULL; | |
3402 | } | |
3403 | this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); | |
3404 | per_cpu(bh_accounting, cpu).nr = 0; | |
3405 | return 0; | |
3406 | } | |
3407 | ||
3408 | /** | |
3409 | * bh_uptodate_or_lock - Test whether the buffer is uptodate | |
3410 | * @bh: struct buffer_head | |
3411 | * | |
3412 | * Return true if the buffer is up-to-date and false, | |
3413 | * with the buffer locked, if not. | |
3414 | */ | |
3415 | int bh_uptodate_or_lock(struct buffer_head *bh) | |
3416 | { | |
3417 | if (!buffer_uptodate(bh)) { | |
3418 | lock_buffer(bh); | |
3419 | if (!buffer_uptodate(bh)) | |
3420 | return 0; | |
3421 | unlock_buffer(bh); | |
3422 | } | |
3423 | return 1; | |
3424 | } | |
3425 | EXPORT_SYMBOL(bh_uptodate_or_lock); | |
3426 | ||
3427 | /** | |
3428 | * bh_submit_read - Submit a locked buffer for reading | |
3429 | * @bh: struct buffer_head | |
3430 | * | |
3431 | * Returns zero on success and -EIO on error. | |
3432 | */ | |
3433 | int bh_submit_read(struct buffer_head *bh) | |
3434 | { | |
3435 | BUG_ON(!buffer_locked(bh)); | |
3436 | ||
3437 | if (buffer_uptodate(bh)) { | |
3438 | unlock_buffer(bh); | |
3439 | return 0; | |
3440 | } | |
3441 | ||
3442 | get_bh(bh); | |
3443 | bh->b_end_io = end_buffer_read_sync; | |
3444 | submit_bh(REQ_OP_READ, 0, bh); | |
3445 | wait_on_buffer(bh); | |
3446 | if (buffer_uptodate(bh)) | |
3447 | return 0; | |
3448 | return -EIO; | |
3449 | } | |
3450 | EXPORT_SYMBOL(bh_submit_read); | |
3451 | ||
3452 | void __init buffer_init(void) | |
3453 | { | |
3454 | unsigned long nrpages; | |
3455 | int ret; | |
3456 | ||
3457 | bh_cachep = kmem_cache_create("buffer_head", | |
3458 | sizeof(struct buffer_head), 0, | |
3459 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| | |
3460 | SLAB_MEM_SPREAD), | |
3461 | NULL); | |
3462 | ||
3463 | /* | |
3464 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3465 | */ | |
3466 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3467 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
3468 | ret = cpuhp_setup_state_nocalls(CPUHP_FS_BUFF_DEAD, "fs/buffer:dead", | |
3469 | NULL, buffer_exit_cpu_dead); | |
3470 | WARN_ON(ret < 0); | |
3471 | } |