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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/buffer.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 2002 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95 | |
9 | * | |
10 | * Removed a lot of unnecessary code and simplified things now that | |
11 | * the buffer cache isn't our primary cache - Andrew Tridgell 12/96 | |
12 | * | |
13 | * Speed up hash, lru, and free list operations. Use gfp() for allocating | |
14 | * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM | |
15 | * | |
16 | * Added 32k buffer block sizes - these are required older ARM systems. - RMK | |
17 | * | |
18 | * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de> | |
19 | */ | |
20 | ||
1da177e4 | 21 | #include <linux/kernel.h> |
f361bf4a | 22 | #include <linux/sched/signal.h> |
1da177e4 LT |
23 | #include <linux/syscalls.h> |
24 | #include <linux/fs.h> | |
ae259a9c | 25 | #include <linux/iomap.h> |
1da177e4 LT |
26 | #include <linux/mm.h> |
27 | #include <linux/percpu.h> | |
28 | #include <linux/slab.h> | |
16f7e0fe | 29 | #include <linux/capability.h> |
1da177e4 LT |
30 | #include <linux/blkdev.h> |
31 | #include <linux/file.h> | |
32 | #include <linux/quotaops.h> | |
33 | #include <linux/highmem.h> | |
630d9c47 | 34 | #include <linux/export.h> |
bafc0dba | 35 | #include <linux/backing-dev.h> |
1da177e4 LT |
36 | #include <linux/writeback.h> |
37 | #include <linux/hash.h> | |
38 | #include <linux/suspend.h> | |
39 | #include <linux/buffer_head.h> | |
55e829af | 40 | #include <linux/task_io_accounting_ops.h> |
1da177e4 | 41 | #include <linux/bio.h> |
1da177e4 LT |
42 | #include <linux/cpu.h> |
43 | #include <linux/bitops.h> | |
44 | #include <linux/mpage.h> | |
fb1c8f93 | 45 | #include <linux/bit_spinlock.h> |
29f3ad7d | 46 | #include <linux/pagevec.h> |
f745c6f5 | 47 | #include <linux/sched/mm.h> |
5305cb83 | 48 | #include <trace/events/block.h> |
1da177e4 LT |
49 | |
50 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); | |
2a222ca9 | 51 | static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, |
8e8f9298 | 52 | enum rw_hint hint, struct writeback_control *wbc); |
1da177e4 LT |
53 | |
54 | #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) | |
55 | ||
f0059afd TH |
56 | inline void touch_buffer(struct buffer_head *bh) |
57 | { | |
5305cb83 | 58 | trace_block_touch_buffer(bh); |
f0059afd TH |
59 | mark_page_accessed(bh->b_page); |
60 | } | |
61 | EXPORT_SYMBOL(touch_buffer); | |
62 | ||
fc9b52cd | 63 | void __lock_buffer(struct buffer_head *bh) |
1da177e4 | 64 | { |
74316201 | 65 | wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); |
1da177e4 LT |
66 | } |
67 | EXPORT_SYMBOL(__lock_buffer); | |
68 | ||
fc9b52cd | 69 | void unlock_buffer(struct buffer_head *bh) |
1da177e4 | 70 | { |
51b07fc3 | 71 | clear_bit_unlock(BH_Lock, &bh->b_state); |
4e857c58 | 72 | smp_mb__after_atomic(); |
1da177e4 LT |
73 | wake_up_bit(&bh->b_state, BH_Lock); |
74 | } | |
1fe72eaa | 75 | EXPORT_SYMBOL(unlock_buffer); |
1da177e4 | 76 | |
b4597226 MG |
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 | ||
1da177e4 LT |
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 | { | |
74316201 | 118 | wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); |
1da177e4 | 119 | } |
1fe72eaa | 120 | EXPORT_SYMBOL(__wait_on_buffer); |
1da177e4 LT |
121 | |
122 | static void | |
123 | __clear_page_buffers(struct page *page) | |
124 | { | |
125 | ClearPagePrivate(page); | |
4c21e2f2 | 126 | set_page_private(page, 0); |
09cbfeaf | 127 | put_page(page); |
1da177e4 LT |
128 | } |
129 | ||
b744c2ac | 130 | static void buffer_io_error(struct buffer_head *bh, char *msg) |
1da177e4 | 131 | { |
432f16e6 RE |
132 | if (!test_bit(BH_Quiet, &bh->b_state)) |
133 | printk_ratelimited(KERN_ERR | |
a1c6f057 DM |
134 | "Buffer I/O error on dev %pg, logical block %llu%s\n", |
135 | bh->b_bdev, (unsigned long long)bh->b_blocknr, msg); | |
1da177e4 LT |
136 | } |
137 | ||
138 | /* | |
68671f35 DM |
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. | |
1da177e4 | 145 | */ |
68671f35 | 146 | static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
147 | { |
148 | if (uptodate) { | |
149 | set_buffer_uptodate(bh); | |
150 | } else { | |
70246286 | 151 | /* This happens, due to failed read-ahead attempts. */ |
1da177e4 LT |
152 | clear_buffer_uptodate(bh); |
153 | } | |
154 | unlock_buffer(bh); | |
68671f35 DM |
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); | |
1da177e4 LT |
164 | put_bh(bh); |
165 | } | |
1fe72eaa | 166 | EXPORT_SYMBOL(end_buffer_read_sync); |
1da177e4 LT |
167 | |
168 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) | |
169 | { | |
1da177e4 LT |
170 | if (uptodate) { |
171 | set_buffer_uptodate(bh); | |
172 | } else { | |
432f16e6 | 173 | buffer_io_error(bh, ", lost sync page write"); |
87354e5d | 174 | mark_buffer_write_io_error(bh); |
1da177e4 LT |
175 | clear_buffer_uptodate(bh); |
176 | } | |
177 | unlock_buffer(bh); | |
178 | put_bh(bh); | |
179 | } | |
1fe72eaa | 180 | EXPORT_SYMBOL(end_buffer_write_sync); |
1da177e4 | 181 | |
1da177e4 LT |
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 | * | |
b93b0163 | 188 | * Hack idea: for the blockdev mapping, private_lock contention |
1da177e4 | 189 | * may be quite high. This code could TryLock the page, and if that |
b93b0163 | 190 | * succeeds, there is no need to take private_lock. |
1da177e4 LT |
191 | */ |
192 | static struct buffer_head * | |
385fd4c5 | 193 | __find_get_block_slow(struct block_device *bdev, sector_t block) |
1da177e4 LT |
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 | ||
09cbfeaf | 204 | index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); |
2457aec6 | 205 | page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED); |
1da177e4 LT |
206 | if (!page) |
207 | goto out; | |
208 | ||
209 | spin_lock(&bd_mapping->private_lock); | |
210 | if (!page_has_buffers(page)) | |
211 | goto out_unlock; | |
212 | head = page_buffers(page); | |
213 | bh = head; | |
214 | do { | |
97f76d3d NK |
215 | if (!buffer_mapped(bh)) |
216 | all_mapped = 0; | |
217 | else if (bh->b_blocknr == block) { | |
1da177e4 LT |
218 | ret = bh; |
219 | get_bh(bh); | |
220 | goto out_unlock; | |
221 | } | |
1da177e4 LT |
222 | bh = bh->b_this_page; |
223 | } while (bh != head); | |
224 | ||
225 | /* we might be here because some of the buffers on this page are | |
226 | * not mapped. This is due to various races between | |
227 | * file io on the block device and getblk. It gets dealt with | |
228 | * elsewhere, don't buffer_error if we had some unmapped buffers | |
229 | */ | |
230 | if (all_mapped) { | |
231 | printk("__find_get_block_slow() failed. " | |
232 | "block=%llu, b_blocknr=%llu\n", | |
205f87f6 BP |
233 | (unsigned long long)block, |
234 | (unsigned long long)bh->b_blocknr); | |
235 | printk("b_state=0x%08lx, b_size=%zu\n", | |
236 | bh->b_state, bh->b_size); | |
a1c6f057 | 237 | printk("device %pg blocksize: %d\n", bdev, |
72a2ebd8 | 238 | 1 << bd_inode->i_blkbits); |
1da177e4 LT |
239 | } |
240 | out_unlock: | |
241 | spin_unlock(&bd_mapping->private_lock); | |
09cbfeaf | 242 | put_page(page); |
1da177e4 LT |
243 | out: |
244 | return ret; | |
245 | } | |
246 | ||
1da177e4 LT |
247 | /* |
248 | * I/O completion handler for block_read_full_page() - pages | |
249 | * which come unlocked at the end of I/O. | |
250 | */ | |
251 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) | |
252 | { | |
1da177e4 | 253 | unsigned long flags; |
a3972203 | 254 | struct buffer_head *first; |
1da177e4 LT |
255 | struct buffer_head *tmp; |
256 | struct page *page; | |
257 | int page_uptodate = 1; | |
258 | ||
259 | BUG_ON(!buffer_async_read(bh)); | |
260 | ||
261 | page = bh->b_page; | |
262 | if (uptodate) { | |
263 | set_buffer_uptodate(bh); | |
264 | } else { | |
265 | clear_buffer_uptodate(bh); | |
432f16e6 | 266 | buffer_io_error(bh, ", async page read"); |
1da177e4 LT |
267 | SetPageError(page); |
268 | } | |
269 | ||
270 | /* | |
271 | * Be _very_ careful from here on. Bad things can happen if | |
272 | * two buffer heads end IO at almost the same time and both | |
273 | * decide that the page is now completely done. | |
274 | */ | |
a3972203 NP |
275 | first = page_buffers(page); |
276 | local_irq_save(flags); | |
277 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
1da177e4 LT |
278 | clear_buffer_async_read(bh); |
279 | unlock_buffer(bh); | |
280 | tmp = bh; | |
281 | do { | |
282 | if (!buffer_uptodate(tmp)) | |
283 | page_uptodate = 0; | |
284 | if (buffer_async_read(tmp)) { | |
285 | BUG_ON(!buffer_locked(tmp)); | |
286 | goto still_busy; | |
287 | } | |
288 | tmp = tmp->b_this_page; | |
289 | } while (tmp != bh); | |
a3972203 NP |
290 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
291 | local_irq_restore(flags); | |
1da177e4 LT |
292 | |
293 | /* | |
294 | * If none of the buffers had errors and they are all | |
295 | * uptodate then we can set the page uptodate. | |
296 | */ | |
297 | if (page_uptodate && !PageError(page)) | |
298 | SetPageUptodate(page); | |
299 | unlock_page(page); | |
300 | return; | |
301 | ||
302 | still_busy: | |
a3972203 NP |
303 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
304 | local_irq_restore(flags); | |
1da177e4 LT |
305 | return; |
306 | } | |
307 | ||
308 | /* | |
309 | * Completion handler for block_write_full_page() - pages which are unlocked | |
310 | * during I/O, and which have PageWriteback cleared upon I/O completion. | |
311 | */ | |
35c80d5f | 312 | void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
1da177e4 | 313 | { |
1da177e4 | 314 | unsigned long flags; |
a3972203 | 315 | struct buffer_head *first; |
1da177e4 LT |
316 | struct buffer_head *tmp; |
317 | struct page *page; | |
318 | ||
319 | BUG_ON(!buffer_async_write(bh)); | |
320 | ||
321 | page = bh->b_page; | |
322 | if (uptodate) { | |
323 | set_buffer_uptodate(bh); | |
324 | } else { | |
432f16e6 | 325 | buffer_io_error(bh, ", lost async page write"); |
87354e5d | 326 | mark_buffer_write_io_error(bh); |
1da177e4 LT |
327 | clear_buffer_uptodate(bh); |
328 | SetPageError(page); | |
329 | } | |
330 | ||
a3972203 NP |
331 | first = page_buffers(page); |
332 | local_irq_save(flags); | |
333 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
334 | ||
1da177e4 LT |
335 | clear_buffer_async_write(bh); |
336 | unlock_buffer(bh); | |
337 | tmp = bh->b_this_page; | |
338 | while (tmp != bh) { | |
339 | if (buffer_async_write(tmp)) { | |
340 | BUG_ON(!buffer_locked(tmp)); | |
341 | goto still_busy; | |
342 | } | |
343 | tmp = tmp->b_this_page; | |
344 | } | |
a3972203 NP |
345 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
346 | local_irq_restore(flags); | |
1da177e4 LT |
347 | end_page_writeback(page); |
348 | return; | |
349 | ||
350 | still_busy: | |
a3972203 NP |
351 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
352 | local_irq_restore(flags); | |
1da177e4 LT |
353 | return; |
354 | } | |
1fe72eaa | 355 | EXPORT_SYMBOL(end_buffer_async_write); |
1da177e4 LT |
356 | |
357 | /* | |
358 | * If a page's buffers are under async readin (end_buffer_async_read | |
359 | * completion) then there is a possibility that another thread of | |
360 | * control could lock one of the buffers after it has completed | |
361 | * but while some of the other buffers have not completed. This | |
362 | * locked buffer would confuse end_buffer_async_read() into not unlocking | |
363 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() | |
364 | * that this buffer is not under async I/O. | |
365 | * | |
366 | * The page comes unlocked when it has no locked buffer_async buffers | |
367 | * left. | |
368 | * | |
369 | * PageLocked prevents anyone starting new async I/O reads any of | |
370 | * the buffers. | |
371 | * | |
372 | * PageWriteback is used to prevent simultaneous writeout of the same | |
373 | * page. | |
374 | * | |
375 | * PageLocked prevents anyone from starting writeback of a page which is | |
376 | * under read I/O (PageWriteback is only ever set against a locked page). | |
377 | */ | |
378 | static void mark_buffer_async_read(struct buffer_head *bh) | |
379 | { | |
380 | bh->b_end_io = end_buffer_async_read; | |
381 | set_buffer_async_read(bh); | |
382 | } | |
383 | ||
1fe72eaa HS |
384 | static void mark_buffer_async_write_endio(struct buffer_head *bh, |
385 | bh_end_io_t *handler) | |
1da177e4 | 386 | { |
35c80d5f | 387 | bh->b_end_io = handler; |
1da177e4 LT |
388 | set_buffer_async_write(bh); |
389 | } | |
35c80d5f CM |
390 | |
391 | void mark_buffer_async_write(struct buffer_head *bh) | |
392 | { | |
393 | mark_buffer_async_write_endio(bh, end_buffer_async_write); | |
394 | } | |
1da177e4 LT |
395 | EXPORT_SYMBOL(mark_buffer_async_write); |
396 | ||
397 | ||
398 | /* | |
399 | * fs/buffer.c contains helper functions for buffer-backed address space's | |
400 | * fsync functions. A common requirement for buffer-based filesystems is | |
401 | * that certain data from the backing blockdev needs to be written out for | |
402 | * a successful fsync(). For example, ext2 indirect blocks need to be | |
403 | * written back and waited upon before fsync() returns. | |
404 | * | |
405 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), | |
406 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the | |
407 | * management of a list of dependent buffers at ->i_mapping->private_list. | |
408 | * | |
409 | * Locking is a little subtle: try_to_free_buffers() will remove buffers | |
410 | * from their controlling inode's queue when they are being freed. But | |
411 | * try_to_free_buffers() will be operating against the *blockdev* mapping | |
412 | * at the time, not against the S_ISREG file which depends on those buffers. | |
413 | * So the locking for private_list is via the private_lock in the address_space | |
414 | * which backs the buffers. Which is different from the address_space | |
415 | * against which the buffers are listed. So for a particular address_space, | |
416 | * mapping->private_lock does *not* protect mapping->private_list! In fact, | |
417 | * mapping->private_list will always be protected by the backing blockdev's | |
418 | * ->private_lock. | |
419 | * | |
420 | * Which introduces a requirement: all buffers on an address_space's | |
421 | * ->private_list must be from the same address_space: the blockdev's. | |
422 | * | |
423 | * address_spaces which do not place buffers at ->private_list via these | |
424 | * utility functions are free to use private_lock and private_list for | |
425 | * whatever they want. The only requirement is that list_empty(private_list) | |
426 | * be true at clear_inode() time. | |
427 | * | |
428 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The | |
429 | * filesystems should do that. invalidate_inode_buffers() should just go | |
430 | * BUG_ON(!list_empty). | |
431 | * | |
432 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should | |
433 | * take an address_space, not an inode. And it should be called | |
434 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being | |
435 | * queued up. | |
436 | * | |
437 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the | |
438 | * list if it is already on a list. Because if the buffer is on a list, | |
439 | * it *must* already be on the right one. If not, the filesystem is being | |
440 | * silly. This will save a ton of locking. But first we have to ensure | |
441 | * that buffers are taken *off* the old inode's list when they are freed | |
442 | * (presumably in truncate). That requires careful auditing of all | |
443 | * filesystems (do it inside bforget()). It could also be done by bringing | |
444 | * b_inode back. | |
445 | */ | |
446 | ||
447 | /* | |
448 | * The buffer's backing address_space's private_lock must be held | |
449 | */ | |
dbacefc9 | 450 | static void __remove_assoc_queue(struct buffer_head *bh) |
1da177e4 LT |
451 | { |
452 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b | 453 | WARN_ON(!bh->b_assoc_map); |
58ff407b | 454 | bh->b_assoc_map = NULL; |
1da177e4 LT |
455 | } |
456 | ||
457 | int inode_has_buffers(struct inode *inode) | |
458 | { | |
459 | return !list_empty(&inode->i_data.private_list); | |
460 | } | |
461 | ||
462 | /* | |
463 | * osync is designed to support O_SYNC io. It waits synchronously for | |
464 | * all already-submitted IO to complete, but does not queue any new | |
465 | * writes to the disk. | |
466 | * | |
467 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as | |
468 | * you dirty the buffers, and then use osync_inode_buffers to wait for | |
469 | * completion. Any other dirty buffers which are not yet queued for | |
470 | * write will not be flushed to disk by the osync. | |
471 | */ | |
472 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) | |
473 | { | |
474 | struct buffer_head *bh; | |
475 | struct list_head *p; | |
476 | int err = 0; | |
477 | ||
478 | spin_lock(lock); | |
479 | repeat: | |
480 | list_for_each_prev(p, list) { | |
481 | bh = BH_ENTRY(p); | |
482 | if (buffer_locked(bh)) { | |
483 | get_bh(bh); | |
484 | spin_unlock(lock); | |
485 | wait_on_buffer(bh); | |
486 | if (!buffer_uptodate(bh)) | |
487 | err = -EIO; | |
488 | brelse(bh); | |
489 | spin_lock(lock); | |
490 | goto repeat; | |
491 | } | |
492 | } | |
493 | spin_unlock(lock); | |
494 | return err; | |
495 | } | |
496 | ||
08fdc8a0 | 497 | void emergency_thaw_bdev(struct super_block *sb) |
c2d75438 | 498 | { |
01a05b33 | 499 | while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) |
a1c6f057 | 500 | printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev); |
01a05b33 | 501 | } |
c2d75438 | 502 | |
1da177e4 | 503 | /** |
78a4a50a | 504 | * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers |
67be2dd1 | 505 | * @mapping: the mapping which wants those buffers written |
1da177e4 LT |
506 | * |
507 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
508 | * that I/O. | |
509 | * | |
67be2dd1 MW |
510 | * Basically, this is a convenience function for fsync(). |
511 | * @mapping is a file or directory which needs those buffers to be written for | |
512 | * a successful fsync(). | |
1da177e4 LT |
513 | */ |
514 | int sync_mapping_buffers(struct address_space *mapping) | |
515 | { | |
252aa6f5 | 516 | struct address_space *buffer_mapping = mapping->private_data; |
1da177e4 LT |
517 | |
518 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) | |
519 | return 0; | |
520 | ||
521 | return fsync_buffers_list(&buffer_mapping->private_lock, | |
522 | &mapping->private_list); | |
523 | } | |
524 | EXPORT_SYMBOL(sync_mapping_buffers); | |
525 | ||
526 | /* | |
527 | * Called when we've recently written block `bblock', and it is known that | |
528 | * `bblock' was for a buffer_boundary() buffer. This means that the block at | |
529 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's | |
530 | * dirty, schedule it for IO. So that indirects merge nicely with their data. | |
531 | */ | |
532 | void write_boundary_block(struct block_device *bdev, | |
533 | sector_t bblock, unsigned blocksize) | |
534 | { | |
535 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); | |
536 | if (bh) { | |
537 | if (buffer_dirty(bh)) | |
dfec8a14 | 538 | ll_rw_block(REQ_OP_WRITE, 0, 1, &bh); |
1da177e4 LT |
539 | put_bh(bh); |
540 | } | |
541 | } | |
542 | ||
543 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) | |
544 | { | |
545 | struct address_space *mapping = inode->i_mapping; | |
546 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
547 | ||
548 | mark_buffer_dirty(bh); | |
252aa6f5 RA |
549 | if (!mapping->private_data) { |
550 | mapping->private_data = buffer_mapping; | |
1da177e4 | 551 | } else { |
252aa6f5 | 552 | BUG_ON(mapping->private_data != buffer_mapping); |
1da177e4 | 553 | } |
535ee2fb | 554 | if (!bh->b_assoc_map) { |
1da177e4 LT |
555 | spin_lock(&buffer_mapping->private_lock); |
556 | list_move_tail(&bh->b_assoc_buffers, | |
557 | &mapping->private_list); | |
58ff407b | 558 | bh->b_assoc_map = mapping; |
1da177e4 LT |
559 | spin_unlock(&buffer_mapping->private_lock); |
560 | } | |
561 | } | |
562 | EXPORT_SYMBOL(mark_buffer_dirty_inode); | |
563 | ||
787d2214 | 564 | /* |
ec82e1c1 | 565 | * Mark the page dirty, and set it dirty in the page cache, and mark the inode |
787d2214 NP |
566 | * dirty. |
567 | * | |
568 | * If warn is true, then emit a warning if the page is not uptodate and has | |
569 | * not been truncated. | |
c4843a75 | 570 | * |
81f8c3a4 | 571 | * The caller must hold lock_page_memcg(). |
787d2214 | 572 | */ |
f82b3764 | 573 | void __set_page_dirty(struct page *page, struct address_space *mapping, |
62cccb8c | 574 | int warn) |
787d2214 | 575 | { |
227d53b3 KM |
576 | unsigned long flags; |
577 | ||
b93b0163 | 578 | xa_lock_irqsave(&mapping->i_pages, flags); |
787d2214 NP |
579 | if (page->mapping) { /* Race with truncate? */ |
580 | WARN_ON_ONCE(warn && !PageUptodate(page)); | |
62cccb8c | 581 | account_page_dirtied(page, mapping); |
ec82e1c1 MW |
582 | __xa_set_mark(&mapping->i_pages, page_index(page), |
583 | PAGECACHE_TAG_DIRTY); | |
787d2214 | 584 | } |
b93b0163 | 585 | xa_unlock_irqrestore(&mapping->i_pages, flags); |
787d2214 | 586 | } |
f82b3764 | 587 | EXPORT_SYMBOL_GPL(__set_page_dirty); |
787d2214 | 588 | |
1da177e4 LT |
589 | /* |
590 | * Add a page to the dirty page list. | |
591 | * | |
592 | * It is a sad fact of life that this function is called from several places | |
593 | * deeply under spinlocking. It may not sleep. | |
594 | * | |
595 | * If the page has buffers, the uptodate buffers are set dirty, to preserve | |
596 | * dirty-state coherency between the page and the buffers. It the page does | |
597 | * not have buffers then when they are later attached they will all be set | |
598 | * dirty. | |
599 | * | |
600 | * The buffers are dirtied before the page is dirtied. There's a small race | |
601 | * window in which a writepage caller may see the page cleanness but not the | |
602 | * buffer dirtiness. That's fine. If this code were to set the page dirty | |
603 | * before the buffers, a concurrent writepage caller could clear the page dirty | |
604 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean | |
605 | * page on the dirty page list. | |
606 | * | |
607 | * We use private_lock to lock against try_to_free_buffers while using the | |
608 | * page's buffer list. Also use this to protect against clean buffers being | |
609 | * added to the page after it was set dirty. | |
610 | * | |
611 | * FIXME: may need to call ->reservepage here as well. That's rather up to the | |
612 | * address_space though. | |
613 | */ | |
614 | int __set_page_dirty_buffers(struct page *page) | |
615 | { | |
a8e7d49a | 616 | int newly_dirty; |
787d2214 | 617 | struct address_space *mapping = page_mapping(page); |
ebf7a227 NP |
618 | |
619 | if (unlikely(!mapping)) | |
620 | return !TestSetPageDirty(page); | |
1da177e4 LT |
621 | |
622 | spin_lock(&mapping->private_lock); | |
623 | if (page_has_buffers(page)) { | |
624 | struct buffer_head *head = page_buffers(page); | |
625 | struct buffer_head *bh = head; | |
626 | ||
627 | do { | |
628 | set_buffer_dirty(bh); | |
629 | bh = bh->b_this_page; | |
630 | } while (bh != head); | |
631 | } | |
c4843a75 | 632 | /* |
81f8c3a4 JW |
633 | * Lock out page->mem_cgroup migration to keep PageDirty |
634 | * synchronized with per-memcg dirty page counters. | |
c4843a75 | 635 | */ |
62cccb8c | 636 | lock_page_memcg(page); |
a8e7d49a | 637 | newly_dirty = !TestSetPageDirty(page); |
1da177e4 LT |
638 | spin_unlock(&mapping->private_lock); |
639 | ||
a8e7d49a | 640 | if (newly_dirty) |
62cccb8c | 641 | __set_page_dirty(page, mapping, 1); |
c4843a75 | 642 | |
62cccb8c | 643 | unlock_page_memcg(page); |
c4843a75 GT |
644 | |
645 | if (newly_dirty) | |
646 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); | |
647 | ||
a8e7d49a | 648 | return newly_dirty; |
1da177e4 LT |
649 | } |
650 | EXPORT_SYMBOL(__set_page_dirty_buffers); | |
651 | ||
652 | /* | |
653 | * Write out and wait upon a list of buffers. | |
654 | * | |
655 | * We have conflicting pressures: we want to make sure that all | |
656 | * initially dirty buffers get waited on, but that any subsequently | |
657 | * dirtied buffers don't. After all, we don't want fsync to last | |
658 | * forever if somebody is actively writing to the file. | |
659 | * | |
660 | * Do this in two main stages: first we copy dirty buffers to a | |
661 | * temporary inode list, queueing the writes as we go. Then we clean | |
662 | * up, waiting for those writes to complete. | |
663 | * | |
664 | * During this second stage, any subsequent updates to the file may end | |
665 | * up refiling the buffer on the original inode's dirty list again, so | |
666 | * there is a chance we will end up with a buffer queued for write but | |
667 | * not yet completed on that list. So, as a final cleanup we go through | |
668 | * the osync code to catch these locked, dirty buffers without requeuing | |
669 | * any newly dirty buffers for write. | |
670 | */ | |
671 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) | |
672 | { | |
673 | struct buffer_head *bh; | |
674 | struct list_head tmp; | |
7eaceacc | 675 | struct address_space *mapping; |
1da177e4 | 676 | int err = 0, err2; |
4ee2491e | 677 | struct blk_plug plug; |
1da177e4 LT |
678 | |
679 | INIT_LIST_HEAD(&tmp); | |
4ee2491e | 680 | blk_start_plug(&plug); |
1da177e4 LT |
681 | |
682 | spin_lock(lock); | |
683 | while (!list_empty(list)) { | |
684 | bh = BH_ENTRY(list->next); | |
535ee2fb | 685 | mapping = bh->b_assoc_map; |
58ff407b | 686 | __remove_assoc_queue(bh); |
535ee2fb JK |
687 | /* Avoid race with mark_buffer_dirty_inode() which does |
688 | * a lockless check and we rely on seeing the dirty bit */ | |
689 | smp_mb(); | |
1da177e4 LT |
690 | if (buffer_dirty(bh) || buffer_locked(bh)) { |
691 | list_add(&bh->b_assoc_buffers, &tmp); | |
535ee2fb | 692 | bh->b_assoc_map = mapping; |
1da177e4 LT |
693 | if (buffer_dirty(bh)) { |
694 | get_bh(bh); | |
695 | spin_unlock(lock); | |
696 | /* | |
697 | * Ensure any pending I/O completes so that | |
9cb569d6 CH |
698 | * write_dirty_buffer() actually writes the |
699 | * current contents - it is a noop if I/O is | |
700 | * still in flight on potentially older | |
701 | * contents. | |
1da177e4 | 702 | */ |
70fd7614 | 703 | write_dirty_buffer(bh, REQ_SYNC); |
9cf6b720 JA |
704 | |
705 | /* | |
706 | * Kick off IO for the previous mapping. Note | |
707 | * that we will not run the very last mapping, | |
708 | * wait_on_buffer() will do that for us | |
709 | * through sync_buffer(). | |
710 | */ | |
1da177e4 LT |
711 | brelse(bh); |
712 | spin_lock(lock); | |
713 | } | |
714 | } | |
715 | } | |
716 | ||
4ee2491e JA |
717 | spin_unlock(lock); |
718 | blk_finish_plug(&plug); | |
719 | spin_lock(lock); | |
720 | ||
1da177e4 LT |
721 | while (!list_empty(&tmp)) { |
722 | bh = BH_ENTRY(tmp.prev); | |
1da177e4 | 723 | get_bh(bh); |
535ee2fb JK |
724 | mapping = bh->b_assoc_map; |
725 | __remove_assoc_queue(bh); | |
726 | /* Avoid race with mark_buffer_dirty_inode() which does | |
727 | * a lockless check and we rely on seeing the dirty bit */ | |
728 | smp_mb(); | |
729 | if (buffer_dirty(bh)) { | |
730 | list_add(&bh->b_assoc_buffers, | |
e3892296 | 731 | &mapping->private_list); |
535ee2fb JK |
732 | bh->b_assoc_map = mapping; |
733 | } | |
1da177e4 LT |
734 | spin_unlock(lock); |
735 | wait_on_buffer(bh); | |
736 | if (!buffer_uptodate(bh)) | |
737 | err = -EIO; | |
738 | brelse(bh); | |
739 | spin_lock(lock); | |
740 | } | |
741 | ||
742 | spin_unlock(lock); | |
743 | err2 = osync_buffers_list(lock, list); | |
744 | if (err) | |
745 | return err; | |
746 | else | |
747 | return err2; | |
748 | } | |
749 | ||
750 | /* | |
751 | * Invalidate any and all dirty buffers on a given inode. We are | |
752 | * probably unmounting the fs, but that doesn't mean we have already | |
753 | * done a sync(). Just drop the buffers from the inode list. | |
754 | * | |
755 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which | |
756 | * assumes that all the buffers are against the blockdev. Not true | |
757 | * for reiserfs. | |
758 | */ | |
759 | void invalidate_inode_buffers(struct inode *inode) | |
760 | { | |
761 | if (inode_has_buffers(inode)) { | |
762 | struct address_space *mapping = &inode->i_data; | |
763 | struct list_head *list = &mapping->private_list; | |
252aa6f5 | 764 | struct address_space *buffer_mapping = mapping->private_data; |
1da177e4 LT |
765 | |
766 | spin_lock(&buffer_mapping->private_lock); | |
767 | while (!list_empty(list)) | |
768 | __remove_assoc_queue(BH_ENTRY(list->next)); | |
769 | spin_unlock(&buffer_mapping->private_lock); | |
770 | } | |
771 | } | |
52b19ac9 | 772 | EXPORT_SYMBOL(invalidate_inode_buffers); |
1da177e4 LT |
773 | |
774 | /* | |
775 | * Remove any clean buffers from the inode's buffer list. This is called | |
776 | * when we're trying to free the inode itself. Those buffers can pin it. | |
777 | * | |
778 | * Returns true if all buffers were removed. | |
779 | */ | |
780 | int remove_inode_buffers(struct inode *inode) | |
781 | { | |
782 | int ret = 1; | |
783 | ||
784 | if (inode_has_buffers(inode)) { | |
785 | struct address_space *mapping = &inode->i_data; | |
786 | struct list_head *list = &mapping->private_list; | |
252aa6f5 | 787 | struct address_space *buffer_mapping = mapping->private_data; |
1da177e4 LT |
788 | |
789 | spin_lock(&buffer_mapping->private_lock); | |
790 | while (!list_empty(list)) { | |
791 | struct buffer_head *bh = BH_ENTRY(list->next); | |
792 | if (buffer_dirty(bh)) { | |
793 | ret = 0; | |
794 | break; | |
795 | } | |
796 | __remove_assoc_queue(bh); | |
797 | } | |
798 | spin_unlock(&buffer_mapping->private_lock); | |
799 | } | |
800 | return ret; | |
801 | } | |
802 | ||
803 | /* | |
804 | * Create the appropriate buffers when given a page for data area and | |
805 | * the size of each buffer.. Use the bh->b_this_page linked list to | |
806 | * follow the buffers created. Return NULL if unable to create more | |
807 | * buffers. | |
808 | * | |
809 | * The retry flag is used to differentiate async IO (paging, swapping) | |
810 | * which may not fail from ordinary buffer allocations. | |
811 | */ | |
812 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
640ab98f | 813 | bool retry) |
1da177e4 LT |
814 | { |
815 | struct buffer_head *bh, *head; | |
f745c6f5 | 816 | gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT; |
1da177e4 | 817 | long offset; |
f745c6f5 | 818 | struct mem_cgroup *memcg; |
1da177e4 | 819 | |
640ab98f JA |
820 | if (retry) |
821 | gfp |= __GFP_NOFAIL; | |
822 | ||
f745c6f5 SB |
823 | memcg = get_mem_cgroup_from_page(page); |
824 | memalloc_use_memcg(memcg); | |
825 | ||
1da177e4 LT |
826 | head = NULL; |
827 | offset = PAGE_SIZE; | |
828 | while ((offset -= size) >= 0) { | |
640ab98f | 829 | bh = alloc_buffer_head(gfp); |
1da177e4 LT |
830 | if (!bh) |
831 | goto no_grow; | |
832 | ||
1da177e4 LT |
833 | bh->b_this_page = head; |
834 | bh->b_blocknr = -1; | |
835 | head = bh; | |
836 | ||
1da177e4 LT |
837 | bh->b_size = size; |
838 | ||
839 | /* Link the buffer to its page */ | |
840 | set_bh_page(bh, page, offset); | |
1da177e4 | 841 | } |
f745c6f5 SB |
842 | out: |
843 | memalloc_unuse_memcg(); | |
844 | mem_cgroup_put(memcg); | |
1da177e4 LT |
845 | return head; |
846 | /* | |
847 | * In case anything failed, we just free everything we got. | |
848 | */ | |
849 | no_grow: | |
850 | if (head) { | |
851 | do { | |
852 | bh = head; | |
853 | head = head->b_this_page; | |
854 | free_buffer_head(bh); | |
855 | } while (head); | |
856 | } | |
857 | ||
f745c6f5 | 858 | goto out; |
1da177e4 LT |
859 | } |
860 | EXPORT_SYMBOL_GPL(alloc_page_buffers); | |
861 | ||
862 | static inline void | |
863 | link_dev_buffers(struct page *page, struct buffer_head *head) | |
864 | { | |
865 | struct buffer_head *bh, *tail; | |
866 | ||
867 | bh = head; | |
868 | do { | |
869 | tail = bh; | |
870 | bh = bh->b_this_page; | |
871 | } while (bh); | |
872 | tail->b_this_page = head; | |
873 | attach_page_buffers(page, head); | |
874 | } | |
875 | ||
bbec0270 LT |
876 | static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) |
877 | { | |
878 | sector_t retval = ~((sector_t)0); | |
879 | loff_t sz = i_size_read(bdev->bd_inode); | |
880 | ||
881 | if (sz) { | |
882 | unsigned int sizebits = blksize_bits(size); | |
883 | retval = (sz >> sizebits); | |
884 | } | |
885 | return retval; | |
886 | } | |
887 | ||
1da177e4 LT |
888 | /* |
889 | * Initialise the state of a blockdev page's buffers. | |
890 | */ | |
676ce6d5 | 891 | static sector_t |
1da177e4 LT |
892 | init_page_buffers(struct page *page, struct block_device *bdev, |
893 | sector_t block, int size) | |
894 | { | |
895 | struct buffer_head *head = page_buffers(page); | |
896 | struct buffer_head *bh = head; | |
897 | int uptodate = PageUptodate(page); | |
bbec0270 | 898 | sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size); |
1da177e4 LT |
899 | |
900 | do { | |
901 | if (!buffer_mapped(bh)) { | |
01950a34 EB |
902 | bh->b_end_io = NULL; |
903 | bh->b_private = NULL; | |
1da177e4 LT |
904 | bh->b_bdev = bdev; |
905 | bh->b_blocknr = block; | |
906 | if (uptodate) | |
907 | set_buffer_uptodate(bh); | |
080399aa JM |
908 | if (block < end_block) |
909 | set_buffer_mapped(bh); | |
1da177e4 LT |
910 | } |
911 | block++; | |
912 | bh = bh->b_this_page; | |
913 | } while (bh != head); | |
676ce6d5 HD |
914 | |
915 | /* | |
916 | * Caller needs to validate requested block against end of device. | |
917 | */ | |
918 | return end_block; | |
1da177e4 LT |
919 | } |
920 | ||
921 | /* | |
922 | * Create the page-cache page that contains the requested block. | |
923 | * | |
676ce6d5 | 924 | * This is used purely for blockdev mappings. |
1da177e4 | 925 | */ |
676ce6d5 | 926 | static int |
1da177e4 | 927 | grow_dev_page(struct block_device *bdev, sector_t block, |
3b5e6454 | 928 | pgoff_t index, int size, int sizebits, gfp_t gfp) |
1da177e4 LT |
929 | { |
930 | struct inode *inode = bdev->bd_inode; | |
931 | struct page *page; | |
932 | struct buffer_head *bh; | |
676ce6d5 HD |
933 | sector_t end_block; |
934 | int ret = 0; /* Will call free_more_memory() */ | |
84235de3 | 935 | gfp_t gfp_mask; |
1da177e4 | 936 | |
c62d2555 | 937 | gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp; |
3b5e6454 | 938 | |
84235de3 JW |
939 | /* |
940 | * XXX: __getblk_slow() can not really deal with failure and | |
941 | * will endlessly loop on improvised global reclaim. Prefer | |
942 | * looping in the allocator rather than here, at least that | |
943 | * code knows what it's doing. | |
944 | */ | |
945 | gfp_mask |= __GFP_NOFAIL; | |
946 | ||
947 | page = find_or_create_page(inode->i_mapping, index, gfp_mask); | |
1da177e4 | 948 | |
e827f923 | 949 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
950 | |
951 | if (page_has_buffers(page)) { | |
952 | bh = page_buffers(page); | |
953 | if (bh->b_size == size) { | |
676ce6d5 | 954 | end_block = init_page_buffers(page, bdev, |
f2d5a944 AA |
955 | (sector_t)index << sizebits, |
956 | size); | |
676ce6d5 | 957 | goto done; |
1da177e4 LT |
958 | } |
959 | if (!try_to_free_buffers(page)) | |
960 | goto failed; | |
961 | } | |
962 | ||
963 | /* | |
964 | * Allocate some buffers for this page | |
965 | */ | |
94dc24c0 | 966 | bh = alloc_page_buffers(page, size, true); |
1da177e4 LT |
967 | |
968 | /* | |
969 | * Link the page to the buffers and initialise them. Take the | |
970 | * lock to be atomic wrt __find_get_block(), which does not | |
971 | * run under the page lock. | |
972 | */ | |
973 | spin_lock(&inode->i_mapping->private_lock); | |
974 | link_dev_buffers(page, bh); | |
f2d5a944 AA |
975 | end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits, |
976 | size); | |
1da177e4 | 977 | spin_unlock(&inode->i_mapping->private_lock); |
676ce6d5 HD |
978 | done: |
979 | ret = (block < end_block) ? 1 : -ENXIO; | |
1da177e4 | 980 | failed: |
1da177e4 | 981 | unlock_page(page); |
09cbfeaf | 982 | put_page(page); |
676ce6d5 | 983 | return ret; |
1da177e4 LT |
984 | } |
985 | ||
986 | /* | |
987 | * Create buffers for the specified block device block's page. If | |
988 | * that page was dirty, the buffers are set dirty also. | |
1da177e4 | 989 | */ |
858119e1 | 990 | static int |
3b5e6454 | 991 | grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) |
1da177e4 | 992 | { |
1da177e4 LT |
993 | pgoff_t index; |
994 | int sizebits; | |
995 | ||
996 | sizebits = -1; | |
997 | do { | |
998 | sizebits++; | |
999 | } while ((size << sizebits) < PAGE_SIZE); | |
1000 | ||
1001 | index = block >> sizebits; | |
1da177e4 | 1002 | |
e5657933 AM |
1003 | /* |
1004 | * Check for a block which wants to lie outside our maximum possible | |
1005 | * pagecache index. (this comparison is done using sector_t types). | |
1006 | */ | |
1007 | if (unlikely(index != block >> sizebits)) { | |
e5657933 | 1008 | printk(KERN_ERR "%s: requested out-of-range block %llu for " |
a1c6f057 | 1009 | "device %pg\n", |
8e24eea7 | 1010 | __func__, (unsigned long long)block, |
a1c6f057 | 1011 | bdev); |
e5657933 AM |
1012 | return -EIO; |
1013 | } | |
676ce6d5 | 1014 | |
1da177e4 | 1015 | /* Create a page with the proper size buffers.. */ |
3b5e6454 | 1016 | return grow_dev_page(bdev, block, index, size, sizebits, gfp); |
1da177e4 LT |
1017 | } |
1018 | ||
0026ba40 | 1019 | static struct buffer_head * |
3b5e6454 GK |
1020 | __getblk_slow(struct block_device *bdev, sector_t block, |
1021 | unsigned size, gfp_t gfp) | |
1da177e4 LT |
1022 | { |
1023 | /* Size must be multiple of hard sectorsize */ | |
e1defc4f | 1024 | if (unlikely(size & (bdev_logical_block_size(bdev)-1) || |
1da177e4 LT |
1025 | (size < 512 || size > PAGE_SIZE))) { |
1026 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", | |
1027 | size); | |
e1defc4f MP |
1028 | printk(KERN_ERR "logical block size: %d\n", |
1029 | bdev_logical_block_size(bdev)); | |
1da177e4 LT |
1030 | |
1031 | dump_stack(); | |
1032 | return NULL; | |
1033 | } | |
1034 | ||
676ce6d5 HD |
1035 | for (;;) { |
1036 | struct buffer_head *bh; | |
1037 | int ret; | |
1da177e4 LT |
1038 | |
1039 | bh = __find_get_block(bdev, block, size); | |
1040 | if (bh) | |
1041 | return bh; | |
676ce6d5 | 1042 | |
3b5e6454 | 1043 | ret = grow_buffers(bdev, block, size, gfp); |
676ce6d5 HD |
1044 | if (ret < 0) |
1045 | return NULL; | |
1da177e4 LT |
1046 | } |
1047 | } | |
1048 | ||
1049 | /* | |
1050 | * The relationship between dirty buffers and dirty pages: | |
1051 | * | |
1052 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and | |
ec82e1c1 | 1053 | * the page is tagged dirty in the page cache. |
1da177e4 LT |
1054 | * |
1055 | * At all times, the dirtiness of the buffers represents the dirtiness of | |
1056 | * subsections of the page. If the page has buffers, the page dirty bit is | |
1057 | * merely a hint about the true dirty state. | |
1058 | * | |
1059 | * When a page is set dirty in its entirety, all its buffers are marked dirty | |
1060 | * (if the page has buffers). | |
1061 | * | |
1062 | * When a buffer is marked dirty, its page is dirtied, but the page's other | |
1063 | * buffers are not. | |
1064 | * | |
1065 | * Also. When blockdev buffers are explicitly read with bread(), they | |
1066 | * individually become uptodate. But their backing page remains not | |
1067 | * uptodate - even if all of its buffers are uptodate. A subsequent | |
1068 | * block_read_full_page() against that page will discover all the uptodate | |
1069 | * buffers, will set the page uptodate and will perform no I/O. | |
1070 | */ | |
1071 | ||
1072 | /** | |
1073 | * mark_buffer_dirty - mark a buffer_head as needing writeout | |
67be2dd1 | 1074 | * @bh: the buffer_head to mark dirty |
1da177e4 | 1075 | * |
ec82e1c1 MW |
1076 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set |
1077 | * its backing page dirty, then tag the page as dirty in the page cache | |
1078 | * and then attach the address_space's inode to its superblock's dirty | |
1da177e4 LT |
1079 | * inode list. |
1080 | * | |
1081 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, | |
b93b0163 | 1082 | * i_pages lock and mapping->host->i_lock. |
1da177e4 | 1083 | */ |
fc9b52cd | 1084 | void mark_buffer_dirty(struct buffer_head *bh) |
1da177e4 | 1085 | { |
787d2214 | 1086 | WARN_ON_ONCE(!buffer_uptodate(bh)); |
1be62dc1 | 1087 | |
5305cb83 TH |
1088 | trace_block_dirty_buffer(bh); |
1089 | ||
1be62dc1 LT |
1090 | /* |
1091 | * Very *carefully* optimize the it-is-already-dirty case. | |
1092 | * | |
1093 | * Don't let the final "is it dirty" escape to before we | |
1094 | * perhaps modified the buffer. | |
1095 | */ | |
1096 | if (buffer_dirty(bh)) { | |
1097 | smp_mb(); | |
1098 | if (buffer_dirty(bh)) | |
1099 | return; | |
1100 | } | |
1101 | ||
a8e7d49a LT |
1102 | if (!test_set_buffer_dirty(bh)) { |
1103 | struct page *page = bh->b_page; | |
c4843a75 | 1104 | struct address_space *mapping = NULL; |
c4843a75 | 1105 | |
62cccb8c | 1106 | lock_page_memcg(page); |
8e9d78ed | 1107 | if (!TestSetPageDirty(page)) { |
c4843a75 | 1108 | mapping = page_mapping(page); |
8e9d78ed | 1109 | if (mapping) |
62cccb8c | 1110 | __set_page_dirty(page, mapping, 0); |
8e9d78ed | 1111 | } |
62cccb8c | 1112 | unlock_page_memcg(page); |
c4843a75 GT |
1113 | if (mapping) |
1114 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); | |
a8e7d49a | 1115 | } |
1da177e4 | 1116 | } |
1fe72eaa | 1117 | EXPORT_SYMBOL(mark_buffer_dirty); |
1da177e4 | 1118 | |
87354e5d JL |
1119 | void mark_buffer_write_io_error(struct buffer_head *bh) |
1120 | { | |
1121 | set_buffer_write_io_error(bh); | |
1122 | /* FIXME: do we need to set this in both places? */ | |
1123 | if (bh->b_page && bh->b_page->mapping) | |
1124 | mapping_set_error(bh->b_page->mapping, -EIO); | |
1125 | if (bh->b_assoc_map) | |
1126 | mapping_set_error(bh->b_assoc_map, -EIO); | |
1127 | } | |
1128 | EXPORT_SYMBOL(mark_buffer_write_io_error); | |
1129 | ||
1da177e4 LT |
1130 | /* |
1131 | * Decrement a buffer_head's reference count. If all buffers against a page | |
1132 | * have zero reference count, are clean and unlocked, and if the page is clean | |
1133 | * and unlocked then try_to_free_buffers() may strip the buffers from the page | |
1134 | * in preparation for freeing it (sometimes, rarely, buffers are removed from | |
1135 | * a page but it ends up not being freed, and buffers may later be reattached). | |
1136 | */ | |
1137 | void __brelse(struct buffer_head * buf) | |
1138 | { | |
1139 | if (atomic_read(&buf->b_count)) { | |
1140 | put_bh(buf); | |
1141 | return; | |
1142 | } | |
5c752ad9 | 1143 | WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); |
1da177e4 | 1144 | } |
1fe72eaa | 1145 | EXPORT_SYMBOL(__brelse); |
1da177e4 LT |
1146 | |
1147 | /* | |
1148 | * bforget() is like brelse(), except it discards any | |
1149 | * potentially dirty data. | |
1150 | */ | |
1151 | void __bforget(struct buffer_head *bh) | |
1152 | { | |
1153 | clear_buffer_dirty(bh); | |
535ee2fb | 1154 | if (bh->b_assoc_map) { |
1da177e4 LT |
1155 | struct address_space *buffer_mapping = bh->b_page->mapping; |
1156 | ||
1157 | spin_lock(&buffer_mapping->private_lock); | |
1158 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b | 1159 | bh->b_assoc_map = NULL; |
1da177e4 LT |
1160 | spin_unlock(&buffer_mapping->private_lock); |
1161 | } | |
1162 | __brelse(bh); | |
1163 | } | |
1fe72eaa | 1164 | EXPORT_SYMBOL(__bforget); |
1da177e4 LT |
1165 | |
1166 | static struct buffer_head *__bread_slow(struct buffer_head *bh) | |
1167 | { | |
1168 | lock_buffer(bh); | |
1169 | if (buffer_uptodate(bh)) { | |
1170 | unlock_buffer(bh); | |
1171 | return bh; | |
1172 | } else { | |
1173 | get_bh(bh); | |
1174 | bh->b_end_io = end_buffer_read_sync; | |
2a222ca9 | 1175 | submit_bh(REQ_OP_READ, 0, bh); |
1da177e4 LT |
1176 | wait_on_buffer(bh); |
1177 | if (buffer_uptodate(bh)) | |
1178 | return bh; | |
1179 | } | |
1180 | brelse(bh); | |
1181 | return NULL; | |
1182 | } | |
1183 | ||
1184 | /* | |
1185 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). | |
1186 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their | |
1187 | * refcount elevated by one when they're in an LRU. A buffer can only appear | |
1188 | * once in a particular CPU's LRU. A single buffer can be present in multiple | |
1189 | * CPU's LRUs at the same time. | |
1190 | * | |
1191 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and | |
1192 | * sb_find_get_block(). | |
1193 | * | |
1194 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use | |
1195 | * a local interrupt disable for that. | |
1196 | */ | |
1197 | ||
86cf78d7 | 1198 | #define BH_LRU_SIZE 16 |
1da177e4 LT |
1199 | |
1200 | struct bh_lru { | |
1201 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1202 | }; | |
1203 | ||
1204 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; | |
1205 | ||
1206 | #ifdef CONFIG_SMP | |
1207 | #define bh_lru_lock() local_irq_disable() | |
1208 | #define bh_lru_unlock() local_irq_enable() | |
1209 | #else | |
1210 | #define bh_lru_lock() preempt_disable() | |
1211 | #define bh_lru_unlock() preempt_enable() | |
1212 | #endif | |
1213 | ||
1214 | static inline void check_irqs_on(void) | |
1215 | { | |
1216 | #ifdef irqs_disabled | |
1217 | BUG_ON(irqs_disabled()); | |
1218 | #endif | |
1219 | } | |
1220 | ||
1221 | /* | |
241f01fb EB |
1222 | * Install a buffer_head into this cpu's LRU. If not already in the LRU, it is |
1223 | * inserted at the front, and the buffer_head at the back if any is evicted. | |
1224 | * Or, if already in the LRU it is moved to the front. | |
1da177e4 LT |
1225 | */ |
1226 | static void bh_lru_install(struct buffer_head *bh) | |
1227 | { | |
241f01fb EB |
1228 | struct buffer_head *evictee = bh; |
1229 | struct bh_lru *b; | |
1230 | int i; | |
1da177e4 LT |
1231 | |
1232 | check_irqs_on(); | |
1233 | bh_lru_lock(); | |
1da177e4 | 1234 | |
241f01fb EB |
1235 | b = this_cpu_ptr(&bh_lrus); |
1236 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1237 | swap(evictee, b->bhs[i]); | |
1238 | if (evictee == bh) { | |
1239 | bh_lru_unlock(); | |
1240 | return; | |
1da177e4 | 1241 | } |
1da177e4 | 1242 | } |
1da177e4 | 1243 | |
241f01fb EB |
1244 | get_bh(bh); |
1245 | bh_lru_unlock(); | |
1246 | brelse(evictee); | |
1da177e4 LT |
1247 | } |
1248 | ||
1249 | /* | |
1250 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. | |
1251 | */ | |
858119e1 | 1252 | static struct buffer_head * |
3991d3bd | 1253 | lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1254 | { |
1255 | struct buffer_head *ret = NULL; | |
3991d3bd | 1256 | unsigned int i; |
1da177e4 LT |
1257 | |
1258 | check_irqs_on(); | |
1259 | bh_lru_lock(); | |
1da177e4 | 1260 | for (i = 0; i < BH_LRU_SIZE; i++) { |
c7b92516 | 1261 | struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); |
1da177e4 | 1262 | |
9470dd5d ZB |
1263 | if (bh && bh->b_blocknr == block && bh->b_bdev == bdev && |
1264 | bh->b_size == size) { | |
1da177e4 LT |
1265 | if (i) { |
1266 | while (i) { | |
c7b92516 CL |
1267 | __this_cpu_write(bh_lrus.bhs[i], |
1268 | __this_cpu_read(bh_lrus.bhs[i - 1])); | |
1da177e4 LT |
1269 | i--; |
1270 | } | |
c7b92516 | 1271 | __this_cpu_write(bh_lrus.bhs[0], bh); |
1da177e4 LT |
1272 | } |
1273 | get_bh(bh); | |
1274 | ret = bh; | |
1275 | break; | |
1276 | } | |
1277 | } | |
1278 | bh_lru_unlock(); | |
1279 | return ret; | |
1280 | } | |
1281 | ||
1282 | /* | |
1283 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh | |
1284 | * it in the LRU and mark it as accessed. If it is not present then return | |
1285 | * NULL | |
1286 | */ | |
1287 | struct buffer_head * | |
3991d3bd | 1288 | __find_get_block(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1289 | { |
1290 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); | |
1291 | ||
1292 | if (bh == NULL) { | |
2457aec6 | 1293 | /* __find_get_block_slow will mark the page accessed */ |
385fd4c5 | 1294 | bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1295 | if (bh) |
1296 | bh_lru_install(bh); | |
2457aec6 | 1297 | } else |
1da177e4 | 1298 | touch_buffer(bh); |
2457aec6 | 1299 | |
1da177e4 LT |
1300 | return bh; |
1301 | } | |
1302 | EXPORT_SYMBOL(__find_get_block); | |
1303 | ||
1304 | /* | |
3b5e6454 | 1305 | * __getblk_gfp() will locate (and, if necessary, create) the buffer_head |
1da177e4 LT |
1306 | * which corresponds to the passed block_device, block and size. The |
1307 | * returned buffer has its reference count incremented. | |
1308 | * | |
3b5e6454 GK |
1309 | * __getblk_gfp() will lock up the machine if grow_dev_page's |
1310 | * try_to_free_buffers() attempt is failing. FIXME, perhaps? | |
1da177e4 LT |
1311 | */ |
1312 | struct buffer_head * | |
3b5e6454 GK |
1313 | __getblk_gfp(struct block_device *bdev, sector_t block, |
1314 | unsigned size, gfp_t gfp) | |
1da177e4 LT |
1315 | { |
1316 | struct buffer_head *bh = __find_get_block(bdev, block, size); | |
1317 | ||
1318 | might_sleep(); | |
1319 | if (bh == NULL) | |
3b5e6454 | 1320 | bh = __getblk_slow(bdev, block, size, gfp); |
1da177e4 LT |
1321 | return bh; |
1322 | } | |
3b5e6454 | 1323 | EXPORT_SYMBOL(__getblk_gfp); |
1da177e4 LT |
1324 | |
1325 | /* | |
1326 | * Do async read-ahead on a buffer.. | |
1327 | */ | |
3991d3bd | 1328 | void __breadahead(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1329 | { |
1330 | struct buffer_head *bh = __getblk(bdev, block, size); | |
a3e713b5 | 1331 | if (likely(bh)) { |
70246286 | 1332 | ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 1, &bh); |
a3e713b5 AM |
1333 | brelse(bh); |
1334 | } | |
1da177e4 LT |
1335 | } |
1336 | EXPORT_SYMBOL(__breadahead); | |
1337 | ||
1338 | /** | |
3b5e6454 | 1339 | * __bread_gfp() - reads a specified block and returns the bh |
67be2dd1 | 1340 | * @bdev: the block_device to read from |
1da177e4 LT |
1341 | * @block: number of block |
1342 | * @size: size (in bytes) to read | |
3b5e6454 GK |
1343 | * @gfp: page allocation flag |
1344 | * | |
1da177e4 | 1345 | * Reads a specified block, and returns buffer head that contains it. |
3b5e6454 GK |
1346 | * The page cache can be allocated from non-movable area |
1347 | * not to prevent page migration if you set gfp to zero. | |
1da177e4 LT |
1348 | * It returns NULL if the block was unreadable. |
1349 | */ | |
1350 | struct buffer_head * | |
3b5e6454 GK |
1351 | __bread_gfp(struct block_device *bdev, sector_t block, |
1352 | unsigned size, gfp_t gfp) | |
1da177e4 | 1353 | { |
3b5e6454 | 1354 | struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); |
1da177e4 | 1355 | |
a3e713b5 | 1356 | if (likely(bh) && !buffer_uptodate(bh)) |
1da177e4 LT |
1357 | bh = __bread_slow(bh); |
1358 | return bh; | |
1359 | } | |
3b5e6454 | 1360 | EXPORT_SYMBOL(__bread_gfp); |
1da177e4 LT |
1361 | |
1362 | /* | |
1363 | * invalidate_bh_lrus() is called rarely - but not only at unmount. | |
1364 | * This doesn't race because it runs in each cpu either in irq | |
1365 | * or with preempt disabled. | |
1366 | */ | |
1367 | static void invalidate_bh_lru(void *arg) | |
1368 | { | |
1369 | struct bh_lru *b = &get_cpu_var(bh_lrus); | |
1370 | int i; | |
1371 | ||
1372 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1373 | brelse(b->bhs[i]); | |
1374 | b->bhs[i] = NULL; | |
1375 | } | |
1376 | put_cpu_var(bh_lrus); | |
1377 | } | |
42be35d0 GBY |
1378 | |
1379 | static bool has_bh_in_lru(int cpu, void *dummy) | |
1380 | { | |
1381 | struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); | |
1382 | int i; | |
1da177e4 | 1383 | |
42be35d0 GBY |
1384 | for (i = 0; i < BH_LRU_SIZE; i++) { |
1385 | if (b->bhs[i]) | |
1386 | return 1; | |
1387 | } | |
1388 | ||
1389 | return 0; | |
1390 | } | |
1391 | ||
f9a14399 | 1392 | void invalidate_bh_lrus(void) |
1da177e4 | 1393 | { |
42be35d0 | 1394 | on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); |
1da177e4 | 1395 | } |
9db5579b | 1396 | EXPORT_SYMBOL_GPL(invalidate_bh_lrus); |
1da177e4 LT |
1397 | |
1398 | void set_bh_page(struct buffer_head *bh, | |
1399 | struct page *page, unsigned long offset) | |
1400 | { | |
1401 | bh->b_page = page; | |
e827f923 | 1402 | BUG_ON(offset >= PAGE_SIZE); |
1da177e4 LT |
1403 | if (PageHighMem(page)) |
1404 | /* | |
1405 | * This catches illegal uses and preserves the offset: | |
1406 | */ | |
1407 | bh->b_data = (char *)(0 + offset); | |
1408 | else | |
1409 | bh->b_data = page_address(page) + offset; | |
1410 | } | |
1411 | EXPORT_SYMBOL(set_bh_page); | |
1412 | ||
1413 | /* | |
1414 | * Called when truncating a buffer on a page completely. | |
1415 | */ | |
e7470ee8 MG |
1416 | |
1417 | /* Bits that are cleared during an invalidate */ | |
1418 | #define BUFFER_FLAGS_DISCARD \ | |
1419 | (1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \ | |
1420 | 1 << BH_Delay | 1 << BH_Unwritten) | |
1421 | ||
858119e1 | 1422 | static void discard_buffer(struct buffer_head * bh) |
1da177e4 | 1423 | { |
e7470ee8 MG |
1424 | unsigned long b_state, b_state_old; |
1425 | ||
1da177e4 LT |
1426 | lock_buffer(bh); |
1427 | clear_buffer_dirty(bh); | |
1428 | bh->b_bdev = NULL; | |
e7470ee8 MG |
1429 | b_state = bh->b_state; |
1430 | for (;;) { | |
1431 | b_state_old = cmpxchg(&bh->b_state, b_state, | |
1432 | (b_state & ~BUFFER_FLAGS_DISCARD)); | |
1433 | if (b_state_old == b_state) | |
1434 | break; | |
1435 | b_state = b_state_old; | |
1436 | } | |
1da177e4 LT |
1437 | unlock_buffer(bh); |
1438 | } | |
1439 | ||
1da177e4 | 1440 | /** |
814e1d25 | 1441 | * block_invalidatepage - invalidate part or all of a buffer-backed page |
1da177e4 LT |
1442 | * |
1443 | * @page: the page which is affected | |
d47992f8 LC |
1444 | * @offset: start of the range to invalidate |
1445 | * @length: length of the range to invalidate | |
1da177e4 LT |
1446 | * |
1447 | * block_invalidatepage() is called when all or part of the page has become | |
814e1d25 | 1448 | * invalidated by a truncate operation. |
1da177e4 LT |
1449 | * |
1450 | * block_invalidatepage() does not have to release all buffers, but it must | |
1451 | * ensure that no dirty buffer is left outside @offset and that no I/O | |
1452 | * is underway against any of the blocks which are outside the truncation | |
1453 | * point. Because the caller is about to free (and possibly reuse) those | |
1454 | * blocks on-disk. | |
1455 | */ | |
d47992f8 LC |
1456 | void block_invalidatepage(struct page *page, unsigned int offset, |
1457 | unsigned int length) | |
1da177e4 LT |
1458 | { |
1459 | struct buffer_head *head, *bh, *next; | |
1460 | unsigned int curr_off = 0; | |
d47992f8 | 1461 | unsigned int stop = length + offset; |
1da177e4 LT |
1462 | |
1463 | BUG_ON(!PageLocked(page)); | |
1464 | if (!page_has_buffers(page)) | |
1465 | goto out; | |
1466 | ||
d47992f8 LC |
1467 | /* |
1468 | * Check for overflow | |
1469 | */ | |
09cbfeaf | 1470 | BUG_ON(stop > PAGE_SIZE || stop < length); |
d47992f8 | 1471 | |
1da177e4 LT |
1472 | head = page_buffers(page); |
1473 | bh = head; | |
1474 | do { | |
1475 | unsigned int next_off = curr_off + bh->b_size; | |
1476 | next = bh->b_this_page; | |
1477 | ||
d47992f8 LC |
1478 | /* |
1479 | * Are we still fully in range ? | |
1480 | */ | |
1481 | if (next_off > stop) | |
1482 | goto out; | |
1483 | ||
1da177e4 LT |
1484 | /* |
1485 | * is this block fully invalidated? | |
1486 | */ | |
1487 | if (offset <= curr_off) | |
1488 | discard_buffer(bh); | |
1489 | curr_off = next_off; | |
1490 | bh = next; | |
1491 | } while (bh != head); | |
1492 | ||
1493 | /* | |
1494 | * We release buffers only if the entire page is being invalidated. | |
1495 | * The get_block cached value has been unconditionally invalidated, | |
1496 | * so real IO is not possible anymore. | |
1497 | */ | |
3172485f | 1498 | if (length == PAGE_SIZE) |
2ff28e22 | 1499 | try_to_release_page(page, 0); |
1da177e4 | 1500 | out: |
2ff28e22 | 1501 | return; |
1da177e4 LT |
1502 | } |
1503 | EXPORT_SYMBOL(block_invalidatepage); | |
1504 | ||
d47992f8 | 1505 | |
1da177e4 LT |
1506 | /* |
1507 | * We attach and possibly dirty the buffers atomically wrt | |
1508 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers | |
1509 | * is already excluded via the page lock. | |
1510 | */ | |
1511 | void create_empty_buffers(struct page *page, | |
1512 | unsigned long blocksize, unsigned long b_state) | |
1513 | { | |
1514 | struct buffer_head *bh, *head, *tail; | |
1515 | ||
640ab98f | 1516 | head = alloc_page_buffers(page, blocksize, true); |
1da177e4 LT |
1517 | bh = head; |
1518 | do { | |
1519 | bh->b_state |= b_state; | |
1520 | tail = bh; | |
1521 | bh = bh->b_this_page; | |
1522 | } while (bh); | |
1523 | tail->b_this_page = head; | |
1524 | ||
1525 | spin_lock(&page->mapping->private_lock); | |
1526 | if (PageUptodate(page) || PageDirty(page)) { | |
1527 | bh = head; | |
1528 | do { | |
1529 | if (PageDirty(page)) | |
1530 | set_buffer_dirty(bh); | |
1531 | if (PageUptodate(page)) | |
1532 | set_buffer_uptodate(bh); | |
1533 | bh = bh->b_this_page; | |
1534 | } while (bh != head); | |
1535 | } | |
1536 | attach_page_buffers(page, head); | |
1537 | spin_unlock(&page->mapping->private_lock); | |
1538 | } | |
1539 | EXPORT_SYMBOL(create_empty_buffers); | |
1540 | ||
29f3ad7d JK |
1541 | /** |
1542 | * clean_bdev_aliases: clean a range of buffers in block device | |
1543 | * @bdev: Block device to clean buffers in | |
1544 | * @block: Start of a range of blocks to clean | |
1545 | * @len: Number of blocks to clean | |
1da177e4 | 1546 | * |
29f3ad7d JK |
1547 | * We are taking a range of blocks for data and we don't want writeback of any |
1548 | * buffer-cache aliases starting from return from this function and until the | |
1549 | * moment when something will explicitly mark the buffer dirty (hopefully that | |
1550 | * will not happen until we will free that block ;-) We don't even need to mark | |
1551 | * it not-uptodate - nobody can expect anything from a newly allocated buffer | |
1552 | * anyway. We used to use unmap_buffer() for such invalidation, but that was | |
1553 | * wrong. We definitely don't want to mark the alias unmapped, for example - it | |
1554 | * would confuse anyone who might pick it with bread() afterwards... | |
1555 | * | |
1556 | * Also.. Note that bforget() doesn't lock the buffer. So there can be | |
1557 | * writeout I/O going on against recently-freed buffers. We don't wait on that | |
1558 | * I/O in bforget() - it's more efficient to wait on the I/O only if we really | |
1559 | * need to. That happens here. | |
1da177e4 | 1560 | */ |
29f3ad7d | 1561 | void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) |
1da177e4 | 1562 | { |
29f3ad7d JK |
1563 | struct inode *bd_inode = bdev->bd_inode; |
1564 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
1565 | struct pagevec pvec; | |
1566 | pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); | |
1567 | pgoff_t end; | |
c10f778d | 1568 | int i, count; |
29f3ad7d JK |
1569 | struct buffer_head *bh; |
1570 | struct buffer_head *head; | |
1da177e4 | 1571 | |
29f3ad7d | 1572 | end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits); |
86679820 | 1573 | pagevec_init(&pvec); |
397162ff | 1574 | while (pagevec_lookup_range(&pvec, bd_mapping, &index, end)) { |
c10f778d JK |
1575 | count = pagevec_count(&pvec); |
1576 | for (i = 0; i < count; i++) { | |
29f3ad7d | 1577 | struct page *page = pvec.pages[i]; |
1da177e4 | 1578 | |
29f3ad7d JK |
1579 | if (!page_has_buffers(page)) |
1580 | continue; | |
1581 | /* | |
1582 | * We use page lock instead of bd_mapping->private_lock | |
1583 | * to pin buffers here since we can afford to sleep and | |
1584 | * it scales better than a global spinlock lock. | |
1585 | */ | |
1586 | lock_page(page); | |
1587 | /* Recheck when the page is locked which pins bhs */ | |
1588 | if (!page_has_buffers(page)) | |
1589 | goto unlock_page; | |
1590 | head = page_buffers(page); | |
1591 | bh = head; | |
1592 | do { | |
6c006a9d | 1593 | if (!buffer_mapped(bh) || (bh->b_blocknr < block)) |
29f3ad7d JK |
1594 | goto next; |
1595 | if (bh->b_blocknr >= block + len) | |
1596 | break; | |
1597 | clear_buffer_dirty(bh); | |
1598 | wait_on_buffer(bh); | |
1599 | clear_buffer_req(bh); | |
1600 | next: | |
1601 | bh = bh->b_this_page; | |
1602 | } while (bh != head); | |
1603 | unlock_page: | |
1604 | unlock_page(page); | |
1605 | } | |
1606 | pagevec_release(&pvec); | |
1607 | cond_resched(); | |
c10f778d JK |
1608 | /* End of range already reached? */ |
1609 | if (index > end || !index) | |
1610 | break; | |
1da177e4 LT |
1611 | } |
1612 | } | |
29f3ad7d | 1613 | EXPORT_SYMBOL(clean_bdev_aliases); |
1da177e4 | 1614 | |
45bce8f3 LT |
1615 | /* |
1616 | * Size is a power-of-two in the range 512..PAGE_SIZE, | |
1617 | * and the case we care about most is PAGE_SIZE. | |
1618 | * | |
1619 | * So this *could* possibly be written with those | |
1620 | * constraints in mind (relevant mostly if some | |
1621 | * architecture has a slow bit-scan instruction) | |
1622 | */ | |
1623 | static inline int block_size_bits(unsigned int blocksize) | |
1624 | { | |
1625 | return ilog2(blocksize); | |
1626 | } | |
1627 | ||
1628 | static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) | |
1629 | { | |
1630 | BUG_ON(!PageLocked(page)); | |
1631 | ||
1632 | if (!page_has_buffers(page)) | |
6aa7de05 MR |
1633 | create_empty_buffers(page, 1 << READ_ONCE(inode->i_blkbits), |
1634 | b_state); | |
45bce8f3 LT |
1635 | return page_buffers(page); |
1636 | } | |
1637 | ||
1da177e4 LT |
1638 | /* |
1639 | * NOTE! All mapped/uptodate combinations are valid: | |
1640 | * | |
1641 | * Mapped Uptodate Meaning | |
1642 | * | |
1643 | * No No "unknown" - must do get_block() | |
1644 | * No Yes "hole" - zero-filled | |
1645 | * Yes No "allocated" - allocated on disk, not read in | |
1646 | * Yes Yes "valid" - allocated and up-to-date in memory. | |
1647 | * | |
1648 | * "Dirty" is valid only with the last case (mapped+uptodate). | |
1649 | */ | |
1650 | ||
1651 | /* | |
1652 | * While block_write_full_page is writing back the dirty buffers under | |
1653 | * the page lock, whoever dirtied the buffers may decide to clean them | |
1654 | * again at any time. We handle that by only looking at the buffer | |
1655 | * state inside lock_buffer(). | |
1656 | * | |
1657 | * If block_write_full_page() is called for regular writeback | |
1658 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a | |
1659 | * locked buffer. This only can happen if someone has written the buffer | |
1660 | * directly, with submit_bh(). At the address_space level PageWriteback | |
1661 | * prevents this contention from occurring. | |
6e34eedd TT |
1662 | * |
1663 | * If block_write_full_page() is called with wbc->sync_mode == | |
70fd7614 | 1664 | * WB_SYNC_ALL, the writes are posted using REQ_SYNC; this |
721a9602 | 1665 | * causes the writes to be flagged as synchronous writes. |
1da177e4 | 1666 | */ |
b4bba389 | 1667 | int __block_write_full_page(struct inode *inode, struct page *page, |
35c80d5f CM |
1668 | get_block_t *get_block, struct writeback_control *wbc, |
1669 | bh_end_io_t *handler) | |
1da177e4 LT |
1670 | { |
1671 | int err; | |
1672 | sector_t block; | |
1673 | sector_t last_block; | |
f0fbd5fc | 1674 | struct buffer_head *bh, *head; |
45bce8f3 | 1675 | unsigned int blocksize, bbits; |
1da177e4 | 1676 | int nr_underway = 0; |
7637241e | 1677 | int write_flags = wbc_to_write_flags(wbc); |
1da177e4 | 1678 | |
45bce8f3 | 1679 | head = create_page_buffers(page, inode, |
1da177e4 | 1680 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
1da177e4 LT |
1681 | |
1682 | /* | |
1683 | * Be very careful. We have no exclusion from __set_page_dirty_buffers | |
1684 | * here, and the (potentially unmapped) buffers may become dirty at | |
1685 | * any time. If a buffer becomes dirty here after we've inspected it | |
1686 | * then we just miss that fact, and the page stays dirty. | |
1687 | * | |
1688 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; | |
1689 | * handle that here by just cleaning them. | |
1690 | */ | |
1691 | ||
1da177e4 | 1692 | bh = head; |
45bce8f3 LT |
1693 | blocksize = bh->b_size; |
1694 | bbits = block_size_bits(blocksize); | |
1695 | ||
09cbfeaf | 1696 | block = (sector_t)page->index << (PAGE_SHIFT - bbits); |
45bce8f3 | 1697 | last_block = (i_size_read(inode) - 1) >> bbits; |
1da177e4 LT |
1698 | |
1699 | /* | |
1700 | * Get all the dirty buffers mapped to disk addresses and | |
1701 | * handle any aliases from the underlying blockdev's mapping. | |
1702 | */ | |
1703 | do { | |
1704 | if (block > last_block) { | |
1705 | /* | |
1706 | * mapped buffers outside i_size will occur, because | |
1707 | * this page can be outside i_size when there is a | |
1708 | * truncate in progress. | |
1709 | */ | |
1710 | /* | |
1711 | * The buffer was zeroed by block_write_full_page() | |
1712 | */ | |
1713 | clear_buffer_dirty(bh); | |
1714 | set_buffer_uptodate(bh); | |
29a814d2 AT |
1715 | } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && |
1716 | buffer_dirty(bh)) { | |
b0cf2321 | 1717 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1718 | err = get_block(inode, block, bh, 1); |
1719 | if (err) | |
1720 | goto recover; | |
29a814d2 | 1721 | clear_buffer_delay(bh); |
1da177e4 LT |
1722 | if (buffer_new(bh)) { |
1723 | /* blockdev mappings never come here */ | |
1724 | clear_buffer_new(bh); | |
e64855c6 | 1725 | clean_bdev_bh_alias(bh); |
1da177e4 LT |
1726 | } |
1727 | } | |
1728 | bh = bh->b_this_page; | |
1729 | block++; | |
1730 | } while (bh != head); | |
1731 | ||
1732 | do { | |
1da177e4 LT |
1733 | if (!buffer_mapped(bh)) |
1734 | continue; | |
1735 | /* | |
1736 | * If it's a fully non-blocking write attempt and we cannot | |
1737 | * lock the buffer then redirty the page. Note that this can | |
5b0830cb JA |
1738 | * potentially cause a busy-wait loop from writeback threads |
1739 | * and kswapd activity, but those code paths have their own | |
1740 | * higher-level throttling. | |
1da177e4 | 1741 | */ |
1b430bee | 1742 | if (wbc->sync_mode != WB_SYNC_NONE) { |
1da177e4 | 1743 | lock_buffer(bh); |
ca5de404 | 1744 | } else if (!trylock_buffer(bh)) { |
1da177e4 LT |
1745 | redirty_page_for_writepage(wbc, page); |
1746 | continue; | |
1747 | } | |
1748 | if (test_clear_buffer_dirty(bh)) { | |
35c80d5f | 1749 | mark_buffer_async_write_endio(bh, handler); |
1da177e4 LT |
1750 | } else { |
1751 | unlock_buffer(bh); | |
1752 | } | |
1753 | } while ((bh = bh->b_this_page) != head); | |
1754 | ||
1755 | /* | |
1756 | * The page and its buffers are protected by PageWriteback(), so we can | |
1757 | * drop the bh refcounts early. | |
1758 | */ | |
1759 | BUG_ON(PageWriteback(page)); | |
1760 | set_page_writeback(page); | |
1da177e4 LT |
1761 | |
1762 | do { | |
1763 | struct buffer_head *next = bh->b_this_page; | |
1764 | if (buffer_async_write(bh)) { | |
8e8f9298 JA |
1765 | submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, |
1766 | inode->i_write_hint, wbc); | |
1da177e4 LT |
1767 | nr_underway++; |
1768 | } | |
1da177e4 LT |
1769 | bh = next; |
1770 | } while (bh != head); | |
05937baa | 1771 | unlock_page(page); |
1da177e4 LT |
1772 | |
1773 | err = 0; | |
1774 | done: | |
1775 | if (nr_underway == 0) { | |
1776 | /* | |
1777 | * The page was marked dirty, but the buffers were | |
1778 | * clean. Someone wrote them back by hand with | |
1779 | * ll_rw_block/submit_bh. A rare case. | |
1780 | */ | |
1da177e4 | 1781 | end_page_writeback(page); |
3d67f2d7 | 1782 | |
1da177e4 LT |
1783 | /* |
1784 | * The page and buffer_heads can be released at any time from | |
1785 | * here on. | |
1786 | */ | |
1da177e4 LT |
1787 | } |
1788 | return err; | |
1789 | ||
1790 | recover: | |
1791 | /* | |
1792 | * ENOSPC, or some other error. We may already have added some | |
1793 | * blocks to the file, so we need to write these out to avoid | |
1794 | * exposing stale data. | |
1795 | * The page is currently locked and not marked for writeback | |
1796 | */ | |
1797 | bh = head; | |
1798 | /* Recovery: lock and submit the mapped buffers */ | |
1799 | do { | |
29a814d2 AT |
1800 | if (buffer_mapped(bh) && buffer_dirty(bh) && |
1801 | !buffer_delay(bh)) { | |
1da177e4 | 1802 | lock_buffer(bh); |
35c80d5f | 1803 | mark_buffer_async_write_endio(bh, handler); |
1da177e4 LT |
1804 | } else { |
1805 | /* | |
1806 | * The buffer may have been set dirty during | |
1807 | * attachment to a dirty page. | |
1808 | */ | |
1809 | clear_buffer_dirty(bh); | |
1810 | } | |
1811 | } while ((bh = bh->b_this_page) != head); | |
1812 | SetPageError(page); | |
1813 | BUG_ON(PageWriteback(page)); | |
7e4c3690 | 1814 | mapping_set_error(page->mapping, err); |
1da177e4 | 1815 | set_page_writeback(page); |
1da177e4 LT |
1816 | do { |
1817 | struct buffer_head *next = bh->b_this_page; | |
1818 | if (buffer_async_write(bh)) { | |
1819 | clear_buffer_dirty(bh); | |
8e8f9298 JA |
1820 | submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, |
1821 | inode->i_write_hint, wbc); | |
1da177e4 LT |
1822 | nr_underway++; |
1823 | } | |
1da177e4 LT |
1824 | bh = next; |
1825 | } while (bh != head); | |
ffda9d30 | 1826 | unlock_page(page); |
1da177e4 LT |
1827 | goto done; |
1828 | } | |
b4bba389 | 1829 | EXPORT_SYMBOL(__block_write_full_page); |
1da177e4 | 1830 | |
afddba49 NP |
1831 | /* |
1832 | * If a page has any new buffers, zero them out here, and mark them uptodate | |
1833 | * and dirty so they'll be written out (in order to prevent uninitialised | |
1834 | * block data from leaking). And clear the new bit. | |
1835 | */ | |
1836 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) | |
1837 | { | |
1838 | unsigned int block_start, block_end; | |
1839 | struct buffer_head *head, *bh; | |
1840 | ||
1841 | BUG_ON(!PageLocked(page)); | |
1842 | if (!page_has_buffers(page)) | |
1843 | return; | |
1844 | ||
1845 | bh = head = page_buffers(page); | |
1846 | block_start = 0; | |
1847 | do { | |
1848 | block_end = block_start + bh->b_size; | |
1849 | ||
1850 | if (buffer_new(bh)) { | |
1851 | if (block_end > from && block_start < to) { | |
1852 | if (!PageUptodate(page)) { | |
1853 | unsigned start, size; | |
1854 | ||
1855 | start = max(from, block_start); | |
1856 | size = min(to, block_end) - start; | |
1857 | ||
eebd2aa3 | 1858 | zero_user(page, start, size); |
afddba49 NP |
1859 | set_buffer_uptodate(bh); |
1860 | } | |
1861 | ||
1862 | clear_buffer_new(bh); | |
1863 | mark_buffer_dirty(bh); | |
1864 | } | |
1865 | } | |
1866 | ||
1867 | block_start = block_end; | |
1868 | bh = bh->b_this_page; | |
1869 | } while (bh != head); | |
1870 | } | |
1871 | EXPORT_SYMBOL(page_zero_new_buffers); | |
1872 | ||
ae259a9c CH |
1873 | static void |
1874 | iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, | |
1875 | struct iomap *iomap) | |
1876 | { | |
1877 | loff_t offset = block << inode->i_blkbits; | |
1878 | ||
1879 | bh->b_bdev = iomap->bdev; | |
1880 | ||
1881 | /* | |
1882 | * Block points to offset in file we need to map, iomap contains | |
1883 | * the offset at which the map starts. If the map ends before the | |
1884 | * current block, then do not map the buffer and let the caller | |
1885 | * handle it. | |
1886 | */ | |
1887 | BUG_ON(offset >= iomap->offset + iomap->length); | |
1888 | ||
1889 | switch (iomap->type) { | |
1890 | case IOMAP_HOLE: | |
1891 | /* | |
1892 | * If the buffer is not up to date or beyond the current EOF, | |
1893 | * we need to mark it as new to ensure sub-block zeroing is | |
1894 | * executed if necessary. | |
1895 | */ | |
1896 | if (!buffer_uptodate(bh) || | |
1897 | (offset >= i_size_read(inode))) | |
1898 | set_buffer_new(bh); | |
1899 | break; | |
1900 | case IOMAP_DELALLOC: | |
1901 | if (!buffer_uptodate(bh) || | |
1902 | (offset >= i_size_read(inode))) | |
1903 | set_buffer_new(bh); | |
1904 | set_buffer_uptodate(bh); | |
1905 | set_buffer_mapped(bh); | |
1906 | set_buffer_delay(bh); | |
1907 | break; | |
1908 | case IOMAP_UNWRITTEN: | |
1909 | /* | |
3d7b6b21 AG |
1910 | * For unwritten regions, we always need to ensure that regions |
1911 | * in the block we are not writing to are zeroed. Mark the | |
1912 | * buffer as new to ensure this. | |
ae259a9c CH |
1913 | */ |
1914 | set_buffer_new(bh); | |
1915 | set_buffer_unwritten(bh); | |
1916 | /* FALLTHRU */ | |
1917 | case IOMAP_MAPPED: | |
3d7b6b21 AG |
1918 | if ((iomap->flags & IOMAP_F_NEW) || |
1919 | offset >= i_size_read(inode)) | |
ae259a9c | 1920 | set_buffer_new(bh); |
19fe5f64 AG |
1921 | bh->b_blocknr = (iomap->addr + offset - iomap->offset) >> |
1922 | inode->i_blkbits; | |
ae259a9c CH |
1923 | set_buffer_mapped(bh); |
1924 | break; | |
1925 | } | |
1926 | } | |
1927 | ||
1928 | int __block_write_begin_int(struct page *page, loff_t pos, unsigned len, | |
1929 | get_block_t *get_block, struct iomap *iomap) | |
1da177e4 | 1930 | { |
09cbfeaf | 1931 | unsigned from = pos & (PAGE_SIZE - 1); |
ebdec241 | 1932 | unsigned to = from + len; |
6e1db88d | 1933 | struct inode *inode = page->mapping->host; |
1da177e4 LT |
1934 | unsigned block_start, block_end; |
1935 | sector_t block; | |
1936 | int err = 0; | |
1937 | unsigned blocksize, bbits; | |
1938 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1939 | ||
1940 | BUG_ON(!PageLocked(page)); | |
09cbfeaf KS |
1941 | BUG_ON(from > PAGE_SIZE); |
1942 | BUG_ON(to > PAGE_SIZE); | |
1da177e4 LT |
1943 | BUG_ON(from > to); |
1944 | ||
45bce8f3 LT |
1945 | head = create_page_buffers(page, inode, 0); |
1946 | blocksize = head->b_size; | |
1947 | bbits = block_size_bits(blocksize); | |
1da177e4 | 1948 | |
09cbfeaf | 1949 | block = (sector_t)page->index << (PAGE_SHIFT - bbits); |
1da177e4 LT |
1950 | |
1951 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1952 | block++, block_start=block_end, bh = bh->b_this_page) { | |
1953 | block_end = block_start + blocksize; | |
1954 | if (block_end <= from || block_start >= to) { | |
1955 | if (PageUptodate(page)) { | |
1956 | if (!buffer_uptodate(bh)) | |
1957 | set_buffer_uptodate(bh); | |
1958 | } | |
1959 | continue; | |
1960 | } | |
1961 | if (buffer_new(bh)) | |
1962 | clear_buffer_new(bh); | |
1963 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 1964 | WARN_ON(bh->b_size != blocksize); |
ae259a9c CH |
1965 | if (get_block) { |
1966 | err = get_block(inode, block, bh, 1); | |
1967 | if (err) | |
1968 | break; | |
1969 | } else { | |
1970 | iomap_to_bh(inode, block, bh, iomap); | |
1971 | } | |
1972 | ||
1da177e4 | 1973 | if (buffer_new(bh)) { |
e64855c6 | 1974 | clean_bdev_bh_alias(bh); |
1da177e4 | 1975 | if (PageUptodate(page)) { |
637aff46 | 1976 | clear_buffer_new(bh); |
1da177e4 | 1977 | set_buffer_uptodate(bh); |
637aff46 | 1978 | mark_buffer_dirty(bh); |
1da177e4 LT |
1979 | continue; |
1980 | } | |
eebd2aa3 CL |
1981 | if (block_end > to || block_start < from) |
1982 | zero_user_segments(page, | |
1983 | to, block_end, | |
1984 | block_start, from); | |
1da177e4 LT |
1985 | continue; |
1986 | } | |
1987 | } | |
1988 | if (PageUptodate(page)) { | |
1989 | if (!buffer_uptodate(bh)) | |
1990 | set_buffer_uptodate(bh); | |
1991 | continue; | |
1992 | } | |
1993 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
33a266dd | 1994 | !buffer_unwritten(bh) && |
1da177e4 | 1995 | (block_start < from || block_end > to)) { |
dfec8a14 | 1996 | ll_rw_block(REQ_OP_READ, 0, 1, &bh); |
1da177e4 LT |
1997 | *wait_bh++=bh; |
1998 | } | |
1999 | } | |
2000 | /* | |
2001 | * If we issued read requests - let them complete. | |
2002 | */ | |
2003 | while(wait_bh > wait) { | |
2004 | wait_on_buffer(*--wait_bh); | |
2005 | if (!buffer_uptodate(*wait_bh)) | |
f3ddbdc6 | 2006 | err = -EIO; |
1da177e4 | 2007 | } |
f9f07b6c | 2008 | if (unlikely(err)) |
afddba49 | 2009 | page_zero_new_buffers(page, from, to); |
1da177e4 LT |
2010 | return err; |
2011 | } | |
ae259a9c CH |
2012 | |
2013 | int __block_write_begin(struct page *page, loff_t pos, unsigned len, | |
2014 | get_block_t *get_block) | |
2015 | { | |
2016 | return __block_write_begin_int(page, pos, len, get_block, NULL); | |
2017 | } | |
ebdec241 | 2018 | EXPORT_SYMBOL(__block_write_begin); |
1da177e4 LT |
2019 | |
2020 | static int __block_commit_write(struct inode *inode, struct page *page, | |
2021 | unsigned from, unsigned to) | |
2022 | { | |
2023 | unsigned block_start, block_end; | |
2024 | int partial = 0; | |
2025 | unsigned blocksize; | |
2026 | struct buffer_head *bh, *head; | |
2027 | ||
45bce8f3 LT |
2028 | bh = head = page_buffers(page); |
2029 | blocksize = bh->b_size; | |
1da177e4 | 2030 | |
45bce8f3 LT |
2031 | block_start = 0; |
2032 | do { | |
1da177e4 LT |
2033 | block_end = block_start + blocksize; |
2034 | if (block_end <= from || block_start >= to) { | |
2035 | if (!buffer_uptodate(bh)) | |
2036 | partial = 1; | |
2037 | } else { | |
2038 | set_buffer_uptodate(bh); | |
2039 | mark_buffer_dirty(bh); | |
2040 | } | |
afddba49 | 2041 | clear_buffer_new(bh); |
45bce8f3 LT |
2042 | |
2043 | block_start = block_end; | |
2044 | bh = bh->b_this_page; | |
2045 | } while (bh != head); | |
1da177e4 LT |
2046 | |
2047 | /* | |
2048 | * If this is a partial write which happened to make all buffers | |
2049 | * uptodate then we can optimize away a bogus readpage() for | |
2050 | * the next read(). Here we 'discover' whether the page went | |
2051 | * uptodate as a result of this (potentially partial) write. | |
2052 | */ | |
2053 | if (!partial) | |
2054 | SetPageUptodate(page); | |
2055 | return 0; | |
2056 | } | |
2057 | ||
afddba49 | 2058 | /* |
155130a4 CH |
2059 | * block_write_begin takes care of the basic task of block allocation and |
2060 | * bringing partial write blocks uptodate first. | |
2061 | * | |
7bb46a67 | 2062 | * The filesystem needs to handle block truncation upon failure. |
afddba49 | 2063 | */ |
155130a4 CH |
2064 | int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, |
2065 | unsigned flags, struct page **pagep, get_block_t *get_block) | |
afddba49 | 2066 | { |
09cbfeaf | 2067 | pgoff_t index = pos >> PAGE_SHIFT; |
afddba49 | 2068 | struct page *page; |
6e1db88d | 2069 | int status; |
afddba49 | 2070 | |
6e1db88d CH |
2071 | page = grab_cache_page_write_begin(mapping, index, flags); |
2072 | if (!page) | |
2073 | return -ENOMEM; | |
afddba49 | 2074 | |
6e1db88d | 2075 | status = __block_write_begin(page, pos, len, get_block); |
afddba49 | 2076 | if (unlikely(status)) { |
6e1db88d | 2077 | unlock_page(page); |
09cbfeaf | 2078 | put_page(page); |
6e1db88d | 2079 | page = NULL; |
afddba49 NP |
2080 | } |
2081 | ||
6e1db88d | 2082 | *pagep = page; |
afddba49 NP |
2083 | return status; |
2084 | } | |
2085 | EXPORT_SYMBOL(block_write_begin); | |
2086 | ||
a6d639da CH |
2087 | int __generic_write_end(struct inode *inode, loff_t pos, unsigned copied, |
2088 | struct page *page) | |
2089 | { | |
2090 | loff_t old_size = inode->i_size; | |
2091 | bool i_size_changed = false; | |
2092 | ||
2093 | /* | |
2094 | * No need to use i_size_read() here, the i_size cannot change under us | |
2095 | * because we hold i_rwsem. | |
2096 | * | |
2097 | * But it's important to update i_size while still holding page lock: | |
2098 | * page writeout could otherwise come in and zero beyond i_size. | |
2099 | */ | |
2100 | if (pos + copied > inode->i_size) { | |
2101 | i_size_write(inode, pos + copied); | |
2102 | i_size_changed = true; | |
2103 | } | |
2104 | ||
2105 | unlock_page(page); | |
2106 | put_page(page); | |
2107 | ||
2108 | if (old_size < pos) | |
2109 | pagecache_isize_extended(inode, old_size, pos); | |
2110 | /* | |
2111 | * Don't mark the inode dirty under page lock. First, it unnecessarily | |
2112 | * makes the holding time of page lock longer. Second, it forces lock | |
2113 | * ordering of page lock and transaction start for journaling | |
2114 | * filesystems. | |
2115 | */ | |
2116 | if (i_size_changed) | |
2117 | mark_inode_dirty(inode); | |
2118 | return copied; | |
2119 | } | |
2120 | ||
afddba49 NP |
2121 | int block_write_end(struct file *file, struct address_space *mapping, |
2122 | loff_t pos, unsigned len, unsigned copied, | |
2123 | struct page *page, void *fsdata) | |
2124 | { | |
2125 | struct inode *inode = mapping->host; | |
2126 | unsigned start; | |
2127 | ||
09cbfeaf | 2128 | start = pos & (PAGE_SIZE - 1); |
afddba49 NP |
2129 | |
2130 | if (unlikely(copied < len)) { | |
2131 | /* | |
2132 | * The buffers that were written will now be uptodate, so we | |
2133 | * don't have to worry about a readpage reading them and | |
2134 | * overwriting a partial write. However if we have encountered | |
2135 | * a short write and only partially written into a buffer, it | |
2136 | * will not be marked uptodate, so a readpage might come in and | |
2137 | * destroy our partial write. | |
2138 | * | |
2139 | * Do the simplest thing, and just treat any short write to a | |
2140 | * non uptodate page as a zero-length write, and force the | |
2141 | * caller to redo the whole thing. | |
2142 | */ | |
2143 | if (!PageUptodate(page)) | |
2144 | copied = 0; | |
2145 | ||
2146 | page_zero_new_buffers(page, start+copied, start+len); | |
2147 | } | |
2148 | flush_dcache_page(page); | |
2149 | ||
2150 | /* This could be a short (even 0-length) commit */ | |
2151 | __block_commit_write(inode, page, start, start+copied); | |
2152 | ||
2153 | return copied; | |
2154 | } | |
2155 | EXPORT_SYMBOL(block_write_end); | |
2156 | ||
2157 | int generic_write_end(struct file *file, struct address_space *mapping, | |
2158 | loff_t pos, unsigned len, unsigned copied, | |
2159 | struct page *page, void *fsdata) | |
2160 | { | |
afddba49 | 2161 | copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); |
a6d639da | 2162 | return __generic_write_end(mapping->host, pos, copied, page); |
afddba49 NP |
2163 | } |
2164 | EXPORT_SYMBOL(generic_write_end); | |
2165 | ||
8ab22b9a HH |
2166 | /* |
2167 | * block_is_partially_uptodate checks whether buffers within a page are | |
2168 | * uptodate or not. | |
2169 | * | |
2170 | * Returns true if all buffers which correspond to a file portion | |
2171 | * we want to read are uptodate. | |
2172 | */ | |
c186afb4 AV |
2173 | int block_is_partially_uptodate(struct page *page, unsigned long from, |
2174 | unsigned long count) | |
8ab22b9a | 2175 | { |
8ab22b9a HH |
2176 | unsigned block_start, block_end, blocksize; |
2177 | unsigned to; | |
2178 | struct buffer_head *bh, *head; | |
2179 | int ret = 1; | |
2180 | ||
2181 | if (!page_has_buffers(page)) | |
2182 | return 0; | |
2183 | ||
45bce8f3 LT |
2184 | head = page_buffers(page); |
2185 | blocksize = head->b_size; | |
09cbfeaf | 2186 | to = min_t(unsigned, PAGE_SIZE - from, count); |
8ab22b9a | 2187 | to = from + to; |
09cbfeaf | 2188 | if (from < blocksize && to > PAGE_SIZE - blocksize) |
8ab22b9a HH |
2189 | return 0; |
2190 | ||
8ab22b9a HH |
2191 | bh = head; |
2192 | block_start = 0; | |
2193 | do { | |
2194 | block_end = block_start + blocksize; | |
2195 | if (block_end > from && block_start < to) { | |
2196 | if (!buffer_uptodate(bh)) { | |
2197 | ret = 0; | |
2198 | break; | |
2199 | } | |
2200 | if (block_end >= to) | |
2201 | break; | |
2202 | } | |
2203 | block_start = block_end; | |
2204 | bh = bh->b_this_page; | |
2205 | } while (bh != head); | |
2206 | ||
2207 | return ret; | |
2208 | } | |
2209 | EXPORT_SYMBOL(block_is_partially_uptodate); | |
2210 | ||
1da177e4 LT |
2211 | /* |
2212 | * Generic "read page" function for block devices that have the normal | |
2213 | * get_block functionality. This is most of the block device filesystems. | |
2214 | * Reads the page asynchronously --- the unlock_buffer() and | |
2215 | * set/clear_buffer_uptodate() functions propagate buffer state into the | |
2216 | * page struct once IO has completed. | |
2217 | */ | |
2218 | int block_read_full_page(struct page *page, get_block_t *get_block) | |
2219 | { | |
2220 | struct inode *inode = page->mapping->host; | |
2221 | sector_t iblock, lblock; | |
2222 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; | |
45bce8f3 | 2223 | unsigned int blocksize, bbits; |
1da177e4 LT |
2224 | int nr, i; |
2225 | int fully_mapped = 1; | |
2226 | ||
45bce8f3 LT |
2227 | head = create_page_buffers(page, inode, 0); |
2228 | blocksize = head->b_size; | |
2229 | bbits = block_size_bits(blocksize); | |
1da177e4 | 2230 | |
09cbfeaf | 2231 | iblock = (sector_t)page->index << (PAGE_SHIFT - bbits); |
45bce8f3 | 2232 | lblock = (i_size_read(inode)+blocksize-1) >> bbits; |
1da177e4 LT |
2233 | bh = head; |
2234 | nr = 0; | |
2235 | i = 0; | |
2236 | ||
2237 | do { | |
2238 | if (buffer_uptodate(bh)) | |
2239 | continue; | |
2240 | ||
2241 | if (!buffer_mapped(bh)) { | |
c64610ba AM |
2242 | int err = 0; |
2243 | ||
1da177e4 LT |
2244 | fully_mapped = 0; |
2245 | if (iblock < lblock) { | |
b0cf2321 | 2246 | WARN_ON(bh->b_size != blocksize); |
c64610ba AM |
2247 | err = get_block(inode, iblock, bh, 0); |
2248 | if (err) | |
1da177e4 LT |
2249 | SetPageError(page); |
2250 | } | |
2251 | if (!buffer_mapped(bh)) { | |
eebd2aa3 | 2252 | zero_user(page, i * blocksize, blocksize); |
c64610ba AM |
2253 | if (!err) |
2254 | set_buffer_uptodate(bh); | |
1da177e4 LT |
2255 | continue; |
2256 | } | |
2257 | /* | |
2258 | * get_block() might have updated the buffer | |
2259 | * synchronously | |
2260 | */ | |
2261 | if (buffer_uptodate(bh)) | |
2262 | continue; | |
2263 | } | |
2264 | arr[nr++] = bh; | |
2265 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
2266 | ||
2267 | if (fully_mapped) | |
2268 | SetPageMappedToDisk(page); | |
2269 | ||
2270 | if (!nr) { | |
2271 | /* | |
2272 | * All buffers are uptodate - we can set the page uptodate | |
2273 | * as well. But not if get_block() returned an error. | |
2274 | */ | |
2275 | if (!PageError(page)) | |
2276 | SetPageUptodate(page); | |
2277 | unlock_page(page); | |
2278 | return 0; | |
2279 | } | |
2280 | ||
2281 | /* Stage two: lock the buffers */ | |
2282 | for (i = 0; i < nr; i++) { | |
2283 | bh = arr[i]; | |
2284 | lock_buffer(bh); | |
2285 | mark_buffer_async_read(bh); | |
2286 | } | |
2287 | ||
2288 | /* | |
2289 | * Stage 3: start the IO. Check for uptodateness | |
2290 | * inside the buffer lock in case another process reading | |
2291 | * the underlying blockdev brought it uptodate (the sct fix). | |
2292 | */ | |
2293 | for (i = 0; i < nr; i++) { | |
2294 | bh = arr[i]; | |
2295 | if (buffer_uptodate(bh)) | |
2296 | end_buffer_async_read(bh, 1); | |
2297 | else | |
2a222ca9 | 2298 | submit_bh(REQ_OP_READ, 0, bh); |
1da177e4 LT |
2299 | } |
2300 | return 0; | |
2301 | } | |
1fe72eaa | 2302 | EXPORT_SYMBOL(block_read_full_page); |
1da177e4 LT |
2303 | |
2304 | /* utility function for filesystems that need to do work on expanding | |
89e10787 | 2305 | * truncates. Uses filesystem pagecache writes to allow the filesystem to |
1da177e4 LT |
2306 | * deal with the hole. |
2307 | */ | |
89e10787 | 2308 | int generic_cont_expand_simple(struct inode *inode, loff_t size) |
1da177e4 LT |
2309 | { |
2310 | struct address_space *mapping = inode->i_mapping; | |
2311 | struct page *page; | |
89e10787 | 2312 | void *fsdata; |
1da177e4 LT |
2313 | int err; |
2314 | ||
c08d3b0e | 2315 | err = inode_newsize_ok(inode, size); |
2316 | if (err) | |
1da177e4 LT |
2317 | goto out; |
2318 | ||
89e10787 | 2319 | err = pagecache_write_begin(NULL, mapping, size, 0, |
c718a975 | 2320 | AOP_FLAG_CONT_EXPAND, &page, &fsdata); |
89e10787 | 2321 | if (err) |
05eb0b51 | 2322 | goto out; |
05eb0b51 | 2323 | |
89e10787 NP |
2324 | err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); |
2325 | BUG_ON(err > 0); | |
05eb0b51 | 2326 | |
1da177e4 LT |
2327 | out: |
2328 | return err; | |
2329 | } | |
1fe72eaa | 2330 | EXPORT_SYMBOL(generic_cont_expand_simple); |
1da177e4 | 2331 | |
f1e3af72 AB |
2332 | static int cont_expand_zero(struct file *file, struct address_space *mapping, |
2333 | loff_t pos, loff_t *bytes) | |
1da177e4 | 2334 | { |
1da177e4 | 2335 | struct inode *inode = mapping->host; |
93407472 | 2336 | unsigned int blocksize = i_blocksize(inode); |
89e10787 NP |
2337 | struct page *page; |
2338 | void *fsdata; | |
2339 | pgoff_t index, curidx; | |
2340 | loff_t curpos; | |
2341 | unsigned zerofrom, offset, len; | |
2342 | int err = 0; | |
1da177e4 | 2343 | |
09cbfeaf KS |
2344 | index = pos >> PAGE_SHIFT; |
2345 | offset = pos & ~PAGE_MASK; | |
89e10787 | 2346 | |
09cbfeaf KS |
2347 | while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) { |
2348 | zerofrom = curpos & ~PAGE_MASK; | |
1da177e4 LT |
2349 | if (zerofrom & (blocksize-1)) { |
2350 | *bytes |= (blocksize-1); | |
2351 | (*bytes)++; | |
2352 | } | |
09cbfeaf | 2353 | len = PAGE_SIZE - zerofrom; |
1da177e4 | 2354 | |
c718a975 TH |
2355 | err = pagecache_write_begin(file, mapping, curpos, len, 0, |
2356 | &page, &fsdata); | |
89e10787 NP |
2357 | if (err) |
2358 | goto out; | |
eebd2aa3 | 2359 | zero_user(page, zerofrom, len); |
89e10787 NP |
2360 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2361 | page, fsdata); | |
2362 | if (err < 0) | |
2363 | goto out; | |
2364 | BUG_ON(err != len); | |
2365 | err = 0; | |
061e9746 OH |
2366 | |
2367 | balance_dirty_pages_ratelimited(mapping); | |
c2ca0fcd MP |
2368 | |
2369 | if (unlikely(fatal_signal_pending(current))) { | |
2370 | err = -EINTR; | |
2371 | goto out; | |
2372 | } | |
89e10787 | 2373 | } |
1da177e4 | 2374 | |
89e10787 NP |
2375 | /* page covers the boundary, find the boundary offset */ |
2376 | if (index == curidx) { | |
09cbfeaf | 2377 | zerofrom = curpos & ~PAGE_MASK; |
1da177e4 | 2378 | /* if we will expand the thing last block will be filled */ |
89e10787 NP |
2379 | if (offset <= zerofrom) { |
2380 | goto out; | |
2381 | } | |
2382 | if (zerofrom & (blocksize-1)) { | |
1da177e4 LT |
2383 | *bytes |= (blocksize-1); |
2384 | (*bytes)++; | |
2385 | } | |
89e10787 | 2386 | len = offset - zerofrom; |
1da177e4 | 2387 | |
c718a975 TH |
2388 | err = pagecache_write_begin(file, mapping, curpos, len, 0, |
2389 | &page, &fsdata); | |
89e10787 NP |
2390 | if (err) |
2391 | goto out; | |
eebd2aa3 | 2392 | zero_user(page, zerofrom, len); |
89e10787 NP |
2393 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2394 | page, fsdata); | |
2395 | if (err < 0) | |
2396 | goto out; | |
2397 | BUG_ON(err != len); | |
2398 | err = 0; | |
1da177e4 | 2399 | } |
89e10787 NP |
2400 | out: |
2401 | return err; | |
2402 | } | |
2403 | ||
2404 | /* | |
2405 | * For moronic filesystems that do not allow holes in file. | |
2406 | * We may have to extend the file. | |
2407 | */ | |
282dc178 | 2408 | int cont_write_begin(struct file *file, struct address_space *mapping, |
89e10787 NP |
2409 | loff_t pos, unsigned len, unsigned flags, |
2410 | struct page **pagep, void **fsdata, | |
2411 | get_block_t *get_block, loff_t *bytes) | |
2412 | { | |
2413 | struct inode *inode = mapping->host; | |
93407472 FF |
2414 | unsigned int blocksize = i_blocksize(inode); |
2415 | unsigned int zerofrom; | |
89e10787 NP |
2416 | int err; |
2417 | ||
2418 | err = cont_expand_zero(file, mapping, pos, bytes); | |
2419 | if (err) | |
155130a4 | 2420 | return err; |
89e10787 | 2421 | |
09cbfeaf | 2422 | zerofrom = *bytes & ~PAGE_MASK; |
89e10787 NP |
2423 | if (pos+len > *bytes && zerofrom & (blocksize-1)) { |
2424 | *bytes |= (blocksize-1); | |
2425 | (*bytes)++; | |
1da177e4 | 2426 | } |
1da177e4 | 2427 | |
155130a4 | 2428 | return block_write_begin(mapping, pos, len, flags, pagep, get_block); |
1da177e4 | 2429 | } |
1fe72eaa | 2430 | EXPORT_SYMBOL(cont_write_begin); |
1da177e4 | 2431 | |
1da177e4 LT |
2432 | int block_commit_write(struct page *page, unsigned from, unsigned to) |
2433 | { | |
2434 | struct inode *inode = page->mapping->host; | |
2435 | __block_commit_write(inode,page,from,to); | |
2436 | return 0; | |
2437 | } | |
1fe72eaa | 2438 | EXPORT_SYMBOL(block_commit_write); |
1da177e4 | 2439 | |
54171690 DC |
2440 | /* |
2441 | * block_page_mkwrite() is not allowed to change the file size as it gets | |
2442 | * called from a page fault handler when a page is first dirtied. Hence we must | |
2443 | * be careful to check for EOF conditions here. We set the page up correctly | |
2444 | * for a written page which means we get ENOSPC checking when writing into | |
2445 | * holes and correct delalloc and unwritten extent mapping on filesystems that | |
2446 | * support these features. | |
2447 | * | |
2448 | * We are not allowed to take the i_mutex here so we have to play games to | |
2449 | * protect against truncate races as the page could now be beyond EOF. Because | |
7bb46a67 | 2450 | * truncate writes the inode size before removing pages, once we have the |
54171690 DC |
2451 | * page lock we can determine safely if the page is beyond EOF. If it is not |
2452 | * beyond EOF, then the page is guaranteed safe against truncation until we | |
2453 | * unlock the page. | |
ea13a864 | 2454 | * |
14da9200 | 2455 | * Direct callers of this function should protect against filesystem freezing |
5c500029 | 2456 | * using sb_start_pagefault() - sb_end_pagefault() functions. |
54171690 | 2457 | */ |
5c500029 | 2458 | int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
24da4fab | 2459 | get_block_t get_block) |
54171690 | 2460 | { |
c2ec175c | 2461 | struct page *page = vmf->page; |
496ad9aa | 2462 | struct inode *inode = file_inode(vma->vm_file); |
54171690 DC |
2463 | unsigned long end; |
2464 | loff_t size; | |
24da4fab | 2465 | int ret; |
54171690 DC |
2466 | |
2467 | lock_page(page); | |
2468 | size = i_size_read(inode); | |
2469 | if ((page->mapping != inode->i_mapping) || | |
18336338 | 2470 | (page_offset(page) > size)) { |
24da4fab JK |
2471 | /* We overload EFAULT to mean page got truncated */ |
2472 | ret = -EFAULT; | |
2473 | goto out_unlock; | |
54171690 DC |
2474 | } |
2475 | ||
2476 | /* page is wholly or partially inside EOF */ | |
09cbfeaf KS |
2477 | if (((page->index + 1) << PAGE_SHIFT) > size) |
2478 | end = size & ~PAGE_MASK; | |
54171690 | 2479 | else |
09cbfeaf | 2480 | end = PAGE_SIZE; |
54171690 | 2481 | |
ebdec241 | 2482 | ret = __block_write_begin(page, 0, end, get_block); |
54171690 DC |
2483 | if (!ret) |
2484 | ret = block_commit_write(page, 0, end); | |
2485 | ||
24da4fab JK |
2486 | if (unlikely(ret < 0)) |
2487 | goto out_unlock; | |
ea13a864 | 2488 | set_page_dirty(page); |
1d1d1a76 | 2489 | wait_for_stable_page(page); |
24da4fab JK |
2490 | return 0; |
2491 | out_unlock: | |
2492 | unlock_page(page); | |
54171690 | 2493 | return ret; |
24da4fab | 2494 | } |
1fe72eaa | 2495 | EXPORT_SYMBOL(block_page_mkwrite); |
1da177e4 LT |
2496 | |
2497 | /* | |
03158cd7 | 2498 | * nobh_write_begin()'s prereads are special: the buffer_heads are freed |
1da177e4 LT |
2499 | * immediately, while under the page lock. So it needs a special end_io |
2500 | * handler which does not touch the bh after unlocking it. | |
1da177e4 LT |
2501 | */ |
2502 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2503 | { | |
68671f35 | 2504 | __end_buffer_read_notouch(bh, uptodate); |
1da177e4 LT |
2505 | } |
2506 | ||
03158cd7 NP |
2507 | /* |
2508 | * Attach the singly-linked list of buffers created by nobh_write_begin, to | |
2509 | * the page (converting it to circular linked list and taking care of page | |
2510 | * dirty races). | |
2511 | */ | |
2512 | static void attach_nobh_buffers(struct page *page, struct buffer_head *head) | |
2513 | { | |
2514 | struct buffer_head *bh; | |
2515 | ||
2516 | BUG_ON(!PageLocked(page)); | |
2517 | ||
2518 | spin_lock(&page->mapping->private_lock); | |
2519 | bh = head; | |
2520 | do { | |
2521 | if (PageDirty(page)) | |
2522 | set_buffer_dirty(bh); | |
2523 | if (!bh->b_this_page) | |
2524 | bh->b_this_page = head; | |
2525 | bh = bh->b_this_page; | |
2526 | } while (bh != head); | |
2527 | attach_page_buffers(page, head); | |
2528 | spin_unlock(&page->mapping->private_lock); | |
2529 | } | |
2530 | ||
1da177e4 | 2531 | /* |
ea0f04e5 CH |
2532 | * On entry, the page is fully not uptodate. |
2533 | * On exit the page is fully uptodate in the areas outside (from,to) | |
7bb46a67 | 2534 | * The filesystem needs to handle block truncation upon failure. |
1da177e4 | 2535 | */ |
ea0f04e5 | 2536 | int nobh_write_begin(struct address_space *mapping, |
03158cd7 NP |
2537 | loff_t pos, unsigned len, unsigned flags, |
2538 | struct page **pagep, void **fsdata, | |
1da177e4 LT |
2539 | get_block_t *get_block) |
2540 | { | |
03158cd7 | 2541 | struct inode *inode = mapping->host; |
1da177e4 LT |
2542 | const unsigned blkbits = inode->i_blkbits; |
2543 | const unsigned blocksize = 1 << blkbits; | |
a4b0672d | 2544 | struct buffer_head *head, *bh; |
03158cd7 NP |
2545 | struct page *page; |
2546 | pgoff_t index; | |
2547 | unsigned from, to; | |
1da177e4 | 2548 | unsigned block_in_page; |
a4b0672d | 2549 | unsigned block_start, block_end; |
1da177e4 | 2550 | sector_t block_in_file; |
1da177e4 | 2551 | int nr_reads = 0; |
1da177e4 LT |
2552 | int ret = 0; |
2553 | int is_mapped_to_disk = 1; | |
1da177e4 | 2554 | |
09cbfeaf KS |
2555 | index = pos >> PAGE_SHIFT; |
2556 | from = pos & (PAGE_SIZE - 1); | |
03158cd7 NP |
2557 | to = from + len; |
2558 | ||
54566b2c | 2559 | page = grab_cache_page_write_begin(mapping, index, flags); |
03158cd7 NP |
2560 | if (!page) |
2561 | return -ENOMEM; | |
2562 | *pagep = page; | |
2563 | *fsdata = NULL; | |
2564 | ||
2565 | if (page_has_buffers(page)) { | |
309f77ad NK |
2566 | ret = __block_write_begin(page, pos, len, get_block); |
2567 | if (unlikely(ret)) | |
2568 | goto out_release; | |
2569 | return ret; | |
03158cd7 | 2570 | } |
a4b0672d | 2571 | |
1da177e4 LT |
2572 | if (PageMappedToDisk(page)) |
2573 | return 0; | |
2574 | ||
a4b0672d NP |
2575 | /* |
2576 | * Allocate buffers so that we can keep track of state, and potentially | |
2577 | * attach them to the page if an error occurs. In the common case of | |
2578 | * no error, they will just be freed again without ever being attached | |
2579 | * to the page (which is all OK, because we're under the page lock). | |
2580 | * | |
2581 | * Be careful: the buffer linked list is a NULL terminated one, rather | |
2582 | * than the circular one we're used to. | |
2583 | */ | |
640ab98f | 2584 | head = alloc_page_buffers(page, blocksize, false); |
03158cd7 NP |
2585 | if (!head) { |
2586 | ret = -ENOMEM; | |
2587 | goto out_release; | |
2588 | } | |
a4b0672d | 2589 | |
09cbfeaf | 2590 | block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); |
1da177e4 LT |
2591 | |
2592 | /* | |
2593 | * We loop across all blocks in the page, whether or not they are | |
2594 | * part of the affected region. This is so we can discover if the | |
2595 | * page is fully mapped-to-disk. | |
2596 | */ | |
a4b0672d | 2597 | for (block_start = 0, block_in_page = 0, bh = head; |
09cbfeaf | 2598 | block_start < PAGE_SIZE; |
a4b0672d | 2599 | block_in_page++, block_start += blocksize, bh = bh->b_this_page) { |
1da177e4 LT |
2600 | int create; |
2601 | ||
a4b0672d NP |
2602 | block_end = block_start + blocksize; |
2603 | bh->b_state = 0; | |
1da177e4 LT |
2604 | create = 1; |
2605 | if (block_start >= to) | |
2606 | create = 0; | |
2607 | ret = get_block(inode, block_in_file + block_in_page, | |
a4b0672d | 2608 | bh, create); |
1da177e4 LT |
2609 | if (ret) |
2610 | goto failed; | |
a4b0672d | 2611 | if (!buffer_mapped(bh)) |
1da177e4 | 2612 | is_mapped_to_disk = 0; |
a4b0672d | 2613 | if (buffer_new(bh)) |
e64855c6 | 2614 | clean_bdev_bh_alias(bh); |
a4b0672d NP |
2615 | if (PageUptodate(page)) { |
2616 | set_buffer_uptodate(bh); | |
1da177e4 | 2617 | continue; |
a4b0672d NP |
2618 | } |
2619 | if (buffer_new(bh) || !buffer_mapped(bh)) { | |
eebd2aa3 CL |
2620 | zero_user_segments(page, block_start, from, |
2621 | to, block_end); | |
1da177e4 LT |
2622 | continue; |
2623 | } | |
a4b0672d | 2624 | if (buffer_uptodate(bh)) |
1da177e4 LT |
2625 | continue; /* reiserfs does this */ |
2626 | if (block_start < from || block_end > to) { | |
a4b0672d NP |
2627 | lock_buffer(bh); |
2628 | bh->b_end_io = end_buffer_read_nobh; | |
2a222ca9 | 2629 | submit_bh(REQ_OP_READ, 0, bh); |
a4b0672d | 2630 | nr_reads++; |
1da177e4 LT |
2631 | } |
2632 | } | |
2633 | ||
2634 | if (nr_reads) { | |
1da177e4 LT |
2635 | /* |
2636 | * The page is locked, so these buffers are protected from | |
2637 | * any VM or truncate activity. Hence we don't need to care | |
2638 | * for the buffer_head refcounts. | |
2639 | */ | |
a4b0672d | 2640 | for (bh = head; bh; bh = bh->b_this_page) { |
1da177e4 LT |
2641 | wait_on_buffer(bh); |
2642 | if (!buffer_uptodate(bh)) | |
2643 | ret = -EIO; | |
1da177e4 LT |
2644 | } |
2645 | if (ret) | |
2646 | goto failed; | |
2647 | } | |
2648 | ||
2649 | if (is_mapped_to_disk) | |
2650 | SetPageMappedToDisk(page); | |
1da177e4 | 2651 | |
03158cd7 | 2652 | *fsdata = head; /* to be released by nobh_write_end */ |
a4b0672d | 2653 | |
1da177e4 LT |
2654 | return 0; |
2655 | ||
2656 | failed: | |
03158cd7 | 2657 | BUG_ON(!ret); |
1da177e4 | 2658 | /* |
a4b0672d NP |
2659 | * Error recovery is a bit difficult. We need to zero out blocks that |
2660 | * were newly allocated, and dirty them to ensure they get written out. | |
2661 | * Buffers need to be attached to the page at this point, otherwise | |
2662 | * the handling of potential IO errors during writeout would be hard | |
2663 | * (could try doing synchronous writeout, but what if that fails too?) | |
1da177e4 | 2664 | */ |
03158cd7 NP |
2665 | attach_nobh_buffers(page, head); |
2666 | page_zero_new_buffers(page, from, to); | |
a4b0672d | 2667 | |
03158cd7 NP |
2668 | out_release: |
2669 | unlock_page(page); | |
09cbfeaf | 2670 | put_page(page); |
03158cd7 | 2671 | *pagep = NULL; |
a4b0672d | 2672 | |
7bb46a67 | 2673 | return ret; |
2674 | } | |
03158cd7 | 2675 | EXPORT_SYMBOL(nobh_write_begin); |
1da177e4 | 2676 | |
03158cd7 NP |
2677 | int nobh_write_end(struct file *file, struct address_space *mapping, |
2678 | loff_t pos, unsigned len, unsigned copied, | |
2679 | struct page *page, void *fsdata) | |
1da177e4 LT |
2680 | { |
2681 | struct inode *inode = page->mapping->host; | |
efdc3131 | 2682 | struct buffer_head *head = fsdata; |
03158cd7 | 2683 | struct buffer_head *bh; |
5b41e74a | 2684 | BUG_ON(fsdata != NULL && page_has_buffers(page)); |
1da177e4 | 2685 | |
d4cf109f | 2686 | if (unlikely(copied < len) && head) |
5b41e74a DM |
2687 | attach_nobh_buffers(page, head); |
2688 | if (page_has_buffers(page)) | |
2689 | return generic_write_end(file, mapping, pos, len, | |
2690 | copied, page, fsdata); | |
a4b0672d | 2691 | |
22c8ca78 | 2692 | SetPageUptodate(page); |
1da177e4 | 2693 | set_page_dirty(page); |
03158cd7 NP |
2694 | if (pos+copied > inode->i_size) { |
2695 | i_size_write(inode, pos+copied); | |
1da177e4 LT |
2696 | mark_inode_dirty(inode); |
2697 | } | |
03158cd7 NP |
2698 | |
2699 | unlock_page(page); | |
09cbfeaf | 2700 | put_page(page); |
03158cd7 | 2701 | |
03158cd7 NP |
2702 | while (head) { |
2703 | bh = head; | |
2704 | head = head->b_this_page; | |
2705 | free_buffer_head(bh); | |
2706 | } | |
2707 | ||
2708 | return copied; | |
1da177e4 | 2709 | } |
03158cd7 | 2710 | EXPORT_SYMBOL(nobh_write_end); |
1da177e4 LT |
2711 | |
2712 | /* | |
2713 | * nobh_writepage() - based on block_full_write_page() except | |
2714 | * that it tries to operate without attaching bufferheads to | |
2715 | * the page. | |
2716 | */ | |
2717 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2718 | struct writeback_control *wbc) | |
2719 | { | |
2720 | struct inode * const inode = page->mapping->host; | |
2721 | loff_t i_size = i_size_read(inode); | |
09cbfeaf | 2722 | const pgoff_t end_index = i_size >> PAGE_SHIFT; |
1da177e4 | 2723 | unsigned offset; |
1da177e4 LT |
2724 | int ret; |
2725 | ||
2726 | /* Is the page fully inside i_size? */ | |
2727 | if (page->index < end_index) | |
2728 | goto out; | |
2729 | ||
2730 | /* Is the page fully outside i_size? (truncate in progress) */ | |
09cbfeaf | 2731 | offset = i_size & (PAGE_SIZE-1); |
1da177e4 LT |
2732 | if (page->index >= end_index+1 || !offset) { |
2733 | /* | |
2734 | * The page may have dirty, unmapped buffers. For example, | |
2735 | * they may have been added in ext3_writepage(). Make them | |
2736 | * freeable here, so the page does not leak. | |
2737 | */ | |
2738 | #if 0 | |
2739 | /* Not really sure about this - do we need this ? */ | |
2740 | if (page->mapping->a_ops->invalidatepage) | |
2741 | page->mapping->a_ops->invalidatepage(page, offset); | |
2742 | #endif | |
2743 | unlock_page(page); | |
2744 | return 0; /* don't care */ | |
2745 | } | |
2746 | ||
2747 | /* | |
2748 | * The page straddles i_size. It must be zeroed out on each and every | |
2749 | * writepage invocation because it may be mmapped. "A file is mapped | |
2750 | * in multiples of the page size. For a file that is not a multiple of | |
2751 | * the page size, the remaining memory is zeroed when mapped, and | |
2752 | * writes to that region are not written out to the file." | |
2753 | */ | |
09cbfeaf | 2754 | zero_user_segment(page, offset, PAGE_SIZE); |
1da177e4 LT |
2755 | out: |
2756 | ret = mpage_writepage(page, get_block, wbc); | |
2757 | if (ret == -EAGAIN) | |
35c80d5f CM |
2758 | ret = __block_write_full_page(inode, page, get_block, wbc, |
2759 | end_buffer_async_write); | |
1da177e4 LT |
2760 | return ret; |
2761 | } | |
2762 | EXPORT_SYMBOL(nobh_writepage); | |
2763 | ||
03158cd7 NP |
2764 | int nobh_truncate_page(struct address_space *mapping, |
2765 | loff_t from, get_block_t *get_block) | |
1da177e4 | 2766 | { |
09cbfeaf KS |
2767 | pgoff_t index = from >> PAGE_SHIFT; |
2768 | unsigned offset = from & (PAGE_SIZE-1); | |
03158cd7 NP |
2769 | unsigned blocksize; |
2770 | sector_t iblock; | |
2771 | unsigned length, pos; | |
2772 | struct inode *inode = mapping->host; | |
1da177e4 | 2773 | struct page *page; |
03158cd7 NP |
2774 | struct buffer_head map_bh; |
2775 | int err; | |
1da177e4 | 2776 | |
93407472 | 2777 | blocksize = i_blocksize(inode); |
03158cd7 NP |
2778 | length = offset & (blocksize - 1); |
2779 | ||
2780 | /* Block boundary? Nothing to do */ | |
2781 | if (!length) | |
2782 | return 0; | |
2783 | ||
2784 | length = blocksize - length; | |
09cbfeaf | 2785 | iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); |
1da177e4 | 2786 | |
1da177e4 | 2787 | page = grab_cache_page(mapping, index); |
03158cd7 | 2788 | err = -ENOMEM; |
1da177e4 LT |
2789 | if (!page) |
2790 | goto out; | |
2791 | ||
03158cd7 NP |
2792 | if (page_has_buffers(page)) { |
2793 | has_buffers: | |
2794 | unlock_page(page); | |
09cbfeaf | 2795 | put_page(page); |
03158cd7 NP |
2796 | return block_truncate_page(mapping, from, get_block); |
2797 | } | |
2798 | ||
2799 | /* Find the buffer that contains "offset" */ | |
2800 | pos = blocksize; | |
2801 | while (offset >= pos) { | |
2802 | iblock++; | |
2803 | pos += blocksize; | |
2804 | } | |
2805 | ||
460bcf57 TT |
2806 | map_bh.b_size = blocksize; |
2807 | map_bh.b_state = 0; | |
03158cd7 NP |
2808 | err = get_block(inode, iblock, &map_bh, 0); |
2809 | if (err) | |
2810 | goto unlock; | |
2811 | /* unmapped? It's a hole - nothing to do */ | |
2812 | if (!buffer_mapped(&map_bh)) | |
2813 | goto unlock; | |
2814 | ||
2815 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2816 | if (!PageUptodate(page)) { | |
2817 | err = mapping->a_ops->readpage(NULL, page); | |
2818 | if (err) { | |
09cbfeaf | 2819 | put_page(page); |
03158cd7 NP |
2820 | goto out; |
2821 | } | |
2822 | lock_page(page); | |
2823 | if (!PageUptodate(page)) { | |
2824 | err = -EIO; | |
2825 | goto unlock; | |
2826 | } | |
2827 | if (page_has_buffers(page)) | |
2828 | goto has_buffers; | |
1da177e4 | 2829 | } |
eebd2aa3 | 2830 | zero_user(page, offset, length); |
03158cd7 NP |
2831 | set_page_dirty(page); |
2832 | err = 0; | |
2833 | ||
2834 | unlock: | |
1da177e4 | 2835 | unlock_page(page); |
09cbfeaf | 2836 | put_page(page); |
1da177e4 | 2837 | out: |
03158cd7 | 2838 | return err; |
1da177e4 LT |
2839 | } |
2840 | EXPORT_SYMBOL(nobh_truncate_page); | |
2841 | ||
2842 | int block_truncate_page(struct address_space *mapping, | |
2843 | loff_t from, get_block_t *get_block) | |
2844 | { | |
09cbfeaf KS |
2845 | pgoff_t index = from >> PAGE_SHIFT; |
2846 | unsigned offset = from & (PAGE_SIZE-1); | |
1da177e4 | 2847 | unsigned blocksize; |
54b21a79 | 2848 | sector_t iblock; |
1da177e4 LT |
2849 | unsigned length, pos; |
2850 | struct inode *inode = mapping->host; | |
2851 | struct page *page; | |
2852 | struct buffer_head *bh; | |
1da177e4 LT |
2853 | int err; |
2854 | ||
93407472 | 2855 | blocksize = i_blocksize(inode); |
1da177e4 LT |
2856 | length = offset & (blocksize - 1); |
2857 | ||
2858 | /* Block boundary? Nothing to do */ | |
2859 | if (!length) | |
2860 | return 0; | |
2861 | ||
2862 | length = blocksize - length; | |
09cbfeaf | 2863 | iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
2864 | |
2865 | page = grab_cache_page(mapping, index); | |
2866 | err = -ENOMEM; | |
2867 | if (!page) | |
2868 | goto out; | |
2869 | ||
2870 | if (!page_has_buffers(page)) | |
2871 | create_empty_buffers(page, blocksize, 0); | |
2872 | ||
2873 | /* Find the buffer that contains "offset" */ | |
2874 | bh = page_buffers(page); | |
2875 | pos = blocksize; | |
2876 | while (offset >= pos) { | |
2877 | bh = bh->b_this_page; | |
2878 | iblock++; | |
2879 | pos += blocksize; | |
2880 | } | |
2881 | ||
2882 | err = 0; | |
2883 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 2884 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
2885 | err = get_block(inode, iblock, bh, 0); |
2886 | if (err) | |
2887 | goto unlock; | |
2888 | /* unmapped? It's a hole - nothing to do */ | |
2889 | if (!buffer_mapped(bh)) | |
2890 | goto unlock; | |
2891 | } | |
2892 | ||
2893 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2894 | if (PageUptodate(page)) | |
2895 | set_buffer_uptodate(bh); | |
2896 | ||
33a266dd | 2897 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { |
1da177e4 | 2898 | err = -EIO; |
dfec8a14 | 2899 | ll_rw_block(REQ_OP_READ, 0, 1, &bh); |
1da177e4 LT |
2900 | wait_on_buffer(bh); |
2901 | /* Uhhuh. Read error. Complain and punt. */ | |
2902 | if (!buffer_uptodate(bh)) | |
2903 | goto unlock; | |
2904 | } | |
2905 | ||
eebd2aa3 | 2906 | zero_user(page, offset, length); |
1da177e4 LT |
2907 | mark_buffer_dirty(bh); |
2908 | err = 0; | |
2909 | ||
2910 | unlock: | |
2911 | unlock_page(page); | |
09cbfeaf | 2912 | put_page(page); |
1da177e4 LT |
2913 | out: |
2914 | return err; | |
2915 | } | |
1fe72eaa | 2916 | EXPORT_SYMBOL(block_truncate_page); |
1da177e4 LT |
2917 | |
2918 | /* | |
2919 | * The generic ->writepage function for buffer-backed address_spaces | |
2920 | */ | |
1b938c08 MW |
2921 | int block_write_full_page(struct page *page, get_block_t *get_block, |
2922 | struct writeback_control *wbc) | |
1da177e4 LT |
2923 | { |
2924 | struct inode * const inode = page->mapping->host; | |
2925 | loff_t i_size = i_size_read(inode); | |
09cbfeaf | 2926 | const pgoff_t end_index = i_size >> PAGE_SHIFT; |
1da177e4 | 2927 | unsigned offset; |
1da177e4 LT |
2928 | |
2929 | /* Is the page fully inside i_size? */ | |
2930 | if (page->index < end_index) | |
35c80d5f | 2931 | return __block_write_full_page(inode, page, get_block, wbc, |
1b938c08 | 2932 | end_buffer_async_write); |
1da177e4 LT |
2933 | |
2934 | /* Is the page fully outside i_size? (truncate in progress) */ | |
09cbfeaf | 2935 | offset = i_size & (PAGE_SIZE-1); |
1da177e4 LT |
2936 | if (page->index >= end_index+1 || !offset) { |
2937 | /* | |
2938 | * The page may have dirty, unmapped buffers. For example, | |
2939 | * they may have been added in ext3_writepage(). Make them | |
2940 | * freeable here, so the page does not leak. | |
2941 | */ | |
09cbfeaf | 2942 | do_invalidatepage(page, 0, PAGE_SIZE); |
1da177e4 LT |
2943 | unlock_page(page); |
2944 | return 0; /* don't care */ | |
2945 | } | |
2946 | ||
2947 | /* | |
2948 | * The page straddles i_size. It must be zeroed out on each and every | |
2a61aa40 | 2949 | * writepage invocation because it may be mmapped. "A file is mapped |
1da177e4 LT |
2950 | * in multiples of the page size. For a file that is not a multiple of |
2951 | * the page size, the remaining memory is zeroed when mapped, and | |
2952 | * writes to that region are not written out to the file." | |
2953 | */ | |
09cbfeaf | 2954 | zero_user_segment(page, offset, PAGE_SIZE); |
1b938c08 MW |
2955 | return __block_write_full_page(inode, page, get_block, wbc, |
2956 | end_buffer_async_write); | |
35c80d5f | 2957 | } |
1fe72eaa | 2958 | EXPORT_SYMBOL(block_write_full_page); |
35c80d5f | 2959 | |
1da177e4 LT |
2960 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, |
2961 | get_block_t *get_block) | |
2962 | { | |
1da177e4 | 2963 | struct inode *inode = mapping->host; |
2a527d68 AP |
2964 | struct buffer_head tmp = { |
2965 | .b_size = i_blocksize(inode), | |
2966 | }; | |
2967 | ||
1da177e4 LT |
2968 | get_block(inode, block, &tmp, 0); |
2969 | return tmp.b_blocknr; | |
2970 | } | |
1fe72eaa | 2971 | EXPORT_SYMBOL(generic_block_bmap); |
1da177e4 | 2972 | |
4246a0b6 | 2973 | static void end_bio_bh_io_sync(struct bio *bio) |
1da177e4 LT |
2974 | { |
2975 | struct buffer_head *bh = bio->bi_private; | |
2976 | ||
b7c44ed9 | 2977 | if (unlikely(bio_flagged(bio, BIO_QUIET))) |
08bafc03 KM |
2978 | set_bit(BH_Quiet, &bh->b_state); |
2979 | ||
4e4cbee9 | 2980 | bh->b_end_io(bh, !bio->bi_status); |
1da177e4 | 2981 | bio_put(bio); |
1da177e4 LT |
2982 | } |
2983 | ||
57302e0d LT |
2984 | /* |
2985 | * This allows us to do IO even on the odd last sectors | |
59d43914 | 2986 | * of a device, even if the block size is some multiple |
57302e0d LT |
2987 | * of the physical sector size. |
2988 | * | |
2989 | * We'll just truncate the bio to the size of the device, | |
2990 | * and clear the end of the buffer head manually. | |
2991 | * | |
2992 | * Truly out-of-range accesses will turn into actual IO | |
2993 | * errors, this only handles the "we need to be able to | |
2994 | * do IO at the final sector" case. | |
2995 | */ | |
2a222ca9 | 2996 | void guard_bio_eod(int op, struct bio *bio) |
57302e0d LT |
2997 | { |
2998 | sector_t maxsector; | |
c45a8f2d | 2999 | struct bio_vec *bvec = bio_last_bvec_all(bio); |
59d43914 | 3000 | unsigned truncated_bytes; |
67f2519f GE |
3001 | struct hd_struct *part; |
3002 | ||
3003 | rcu_read_lock(); | |
3004 | part = __disk_get_part(bio->bi_disk, bio->bi_partno); | |
3005 | if (part) | |
3006 | maxsector = part_nr_sects_read(part); | |
3007 | else | |
3008 | maxsector = get_capacity(bio->bi_disk); | |
3009 | rcu_read_unlock(); | |
57302e0d | 3010 | |
57302e0d LT |
3011 | if (!maxsector) |
3012 | return; | |
3013 | ||
3014 | /* | |
3015 | * If the *whole* IO is past the end of the device, | |
3016 | * let it through, and the IO layer will turn it into | |
3017 | * an EIO. | |
3018 | */ | |
4f024f37 | 3019 | if (unlikely(bio->bi_iter.bi_sector >= maxsector)) |
57302e0d LT |
3020 | return; |
3021 | ||
4f024f37 | 3022 | maxsector -= bio->bi_iter.bi_sector; |
59d43914 | 3023 | if (likely((bio->bi_iter.bi_size >> 9) <= maxsector)) |
57302e0d LT |
3024 | return; |
3025 | ||
59d43914 AM |
3026 | /* Uhhuh. We've got a bio that straddles the device size! */ |
3027 | truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9); | |
57302e0d LT |
3028 | |
3029 | /* Truncate the bio.. */ | |
59d43914 AM |
3030 | bio->bi_iter.bi_size -= truncated_bytes; |
3031 | bvec->bv_len -= truncated_bytes; | |
57302e0d LT |
3032 | |
3033 | /* ..and clear the end of the buffer for reads */ | |
2a222ca9 | 3034 | if (op == REQ_OP_READ) { |
59d43914 AM |
3035 | zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len, |
3036 | truncated_bytes); | |
57302e0d LT |
3037 | } |
3038 | } | |
3039 | ||
2a222ca9 | 3040 | static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, |
8e8f9298 | 3041 | enum rw_hint write_hint, struct writeback_control *wbc) |
1da177e4 LT |
3042 | { |
3043 | struct bio *bio; | |
1da177e4 LT |
3044 | |
3045 | BUG_ON(!buffer_locked(bh)); | |
3046 | BUG_ON(!buffer_mapped(bh)); | |
3047 | BUG_ON(!bh->b_end_io); | |
8fb0e342 AK |
3048 | BUG_ON(buffer_delay(bh)); |
3049 | BUG_ON(buffer_unwritten(bh)); | |
1da177e4 | 3050 | |
1da177e4 | 3051 | /* |
48fd4f93 | 3052 | * Only clear out a write error when rewriting |
1da177e4 | 3053 | */ |
2a222ca9 | 3054 | if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE)) |
1da177e4 LT |
3055 | clear_buffer_write_io_error(bh); |
3056 | ||
3057 | /* | |
3058 | * from here on down, it's all bio -- do the initial mapping, | |
3059 | * submit_bio -> generic_make_request may further map this bio around | |
3060 | */ | |
3061 | bio = bio_alloc(GFP_NOIO, 1); | |
3062 | ||
b5f2954d DZ |
3063 | if (wbc) { |
3064 | wbc_init_bio(wbc, bio); | |
3065 | wbc_account_io(wbc, bh->b_page, bh->b_size); | |
3066 | } | |
3067 | ||
4f024f37 | 3068 | bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); |
74d46992 | 3069 | bio_set_dev(bio, bh->b_bdev); |
8e8f9298 | 3070 | bio->bi_write_hint = write_hint; |
1da177e4 | 3071 | |
6cf66b4c KO |
3072 | bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh)); |
3073 | BUG_ON(bio->bi_iter.bi_size != bh->b_size); | |
1da177e4 LT |
3074 | |
3075 | bio->bi_end_io = end_bio_bh_io_sync; | |
3076 | bio->bi_private = bh; | |
3077 | ||
57302e0d | 3078 | /* Take care of bh's that straddle the end of the device */ |
2a222ca9 | 3079 | guard_bio_eod(op, bio); |
57302e0d | 3080 | |
877f962c | 3081 | if (buffer_meta(bh)) |
2a222ca9 | 3082 | op_flags |= REQ_META; |
877f962c | 3083 | if (buffer_prio(bh)) |
2a222ca9 MC |
3084 | op_flags |= REQ_PRIO; |
3085 | bio_set_op_attrs(bio, op, op_flags); | |
877f962c | 3086 | |
4e49ea4a | 3087 | submit_bio(bio); |
f6454b04 | 3088 | return 0; |
1da177e4 | 3089 | } |
bafc0dba | 3090 | |
020c2833 | 3091 | int submit_bh(int op, int op_flags, struct buffer_head *bh) |
bafc0dba | 3092 | { |
8e8f9298 | 3093 | return submit_bh_wbc(op, op_flags, bh, 0, NULL); |
71368511 | 3094 | } |
1fe72eaa | 3095 | EXPORT_SYMBOL(submit_bh); |
1da177e4 LT |
3096 | |
3097 | /** | |
3098 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
dfec8a14 | 3099 | * @op: whether to %READ or %WRITE |
ef295ecf | 3100 | * @op_flags: req_flag_bits |
1da177e4 LT |
3101 | * @nr: number of &struct buffer_heads in the array |
3102 | * @bhs: array of pointers to &struct buffer_head | |
3103 | * | |
a7662236 | 3104 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
70246286 CH |
3105 | * requests an I/O operation on them, either a %REQ_OP_READ or a %REQ_OP_WRITE. |
3106 | * @op_flags contains flags modifying the detailed I/O behavior, most notably | |
3107 | * %REQ_RAHEAD. | |
1da177e4 LT |
3108 | * |
3109 | * This function drops any buffer that it cannot get a lock on (with the | |
9cb569d6 CH |
3110 | * BH_Lock state bit), any buffer that appears to be clean when doing a write |
3111 | * request, and any buffer that appears to be up-to-date when doing read | |
3112 | * request. Further it marks as clean buffers that are processed for | |
3113 | * writing (the buffer cache won't assume that they are actually clean | |
3114 | * until the buffer gets unlocked). | |
1da177e4 LT |
3115 | * |
3116 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
e227867f | 3117 | * the buffer up-to-date (if appropriate), unlocks the buffer and wakes |
1da177e4 LT |
3118 | * any waiters. |
3119 | * | |
3120 | * All of the buffers must be for the same device, and must also be a | |
3121 | * multiple of the current approved size for the device. | |
3122 | */ | |
dfec8a14 | 3123 | void ll_rw_block(int op, int op_flags, int nr, struct buffer_head *bhs[]) |
1da177e4 LT |
3124 | { |
3125 | int i; | |
3126 | ||
3127 | for (i = 0; i < nr; i++) { | |
3128 | struct buffer_head *bh = bhs[i]; | |
3129 | ||
9cb569d6 | 3130 | if (!trylock_buffer(bh)) |
1da177e4 | 3131 | continue; |
dfec8a14 | 3132 | if (op == WRITE) { |
1da177e4 | 3133 | if (test_clear_buffer_dirty(bh)) { |
76c3073a | 3134 | bh->b_end_io = end_buffer_write_sync; |
e60e5c50 | 3135 | get_bh(bh); |
dfec8a14 | 3136 | submit_bh(op, op_flags, bh); |
1da177e4 LT |
3137 | continue; |
3138 | } | |
3139 | } else { | |
1da177e4 | 3140 | if (!buffer_uptodate(bh)) { |
76c3073a | 3141 | bh->b_end_io = end_buffer_read_sync; |
e60e5c50 | 3142 | get_bh(bh); |
dfec8a14 | 3143 | submit_bh(op, op_flags, bh); |
1da177e4 LT |
3144 | continue; |
3145 | } | |
3146 | } | |
3147 | unlock_buffer(bh); | |
1da177e4 LT |
3148 | } |
3149 | } | |
1fe72eaa | 3150 | EXPORT_SYMBOL(ll_rw_block); |
1da177e4 | 3151 | |
2a222ca9 | 3152 | void write_dirty_buffer(struct buffer_head *bh, int op_flags) |
9cb569d6 CH |
3153 | { |
3154 | lock_buffer(bh); | |
3155 | if (!test_clear_buffer_dirty(bh)) { | |
3156 | unlock_buffer(bh); | |
3157 | return; | |
3158 | } | |
3159 | bh->b_end_io = end_buffer_write_sync; | |
3160 | get_bh(bh); | |
2a222ca9 | 3161 | submit_bh(REQ_OP_WRITE, op_flags, bh); |
9cb569d6 CH |
3162 | } |
3163 | EXPORT_SYMBOL(write_dirty_buffer); | |
3164 | ||
1da177e4 LT |
3165 | /* |
3166 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
3167 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
3168 | * the buffer_head. | |
3169 | */ | |
2a222ca9 | 3170 | int __sync_dirty_buffer(struct buffer_head *bh, int op_flags) |
1da177e4 LT |
3171 | { |
3172 | int ret = 0; | |
3173 | ||
3174 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
3175 | lock_buffer(bh); | |
3176 | if (test_clear_buffer_dirty(bh)) { | |
3177 | get_bh(bh); | |
3178 | bh->b_end_io = end_buffer_write_sync; | |
2a222ca9 | 3179 | ret = submit_bh(REQ_OP_WRITE, op_flags, bh); |
1da177e4 | 3180 | wait_on_buffer(bh); |
1da177e4 LT |
3181 | if (!ret && !buffer_uptodate(bh)) |
3182 | ret = -EIO; | |
3183 | } else { | |
3184 | unlock_buffer(bh); | |
3185 | } | |
3186 | return ret; | |
3187 | } | |
87e99511 CH |
3188 | EXPORT_SYMBOL(__sync_dirty_buffer); |
3189 | ||
3190 | int sync_dirty_buffer(struct buffer_head *bh) | |
3191 | { | |
70fd7614 | 3192 | return __sync_dirty_buffer(bh, REQ_SYNC); |
87e99511 | 3193 | } |
1fe72eaa | 3194 | EXPORT_SYMBOL(sync_dirty_buffer); |
1da177e4 LT |
3195 | |
3196 | /* | |
3197 | * try_to_free_buffers() checks if all the buffers on this particular page | |
3198 | * are unused, and releases them if so. | |
3199 | * | |
3200 | * Exclusion against try_to_free_buffers may be obtained by either | |
3201 | * locking the page or by holding its mapping's private_lock. | |
3202 | * | |
3203 | * If the page is dirty but all the buffers are clean then we need to | |
3204 | * be sure to mark the page clean as well. This is because the page | |
3205 | * may be against a block device, and a later reattachment of buffers | |
3206 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
3207 | * filesystem data on the same device. | |
3208 | * | |
3209 | * The same applies to regular filesystem pages: if all the buffers are | |
3210 | * clean then we set the page clean and proceed. To do that, we require | |
3211 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
3212 | * private_lock. | |
3213 | * | |
3214 | * try_to_free_buffers() is non-blocking. | |
3215 | */ | |
3216 | static inline int buffer_busy(struct buffer_head *bh) | |
3217 | { | |
3218 | return atomic_read(&bh->b_count) | | |
3219 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
3220 | } | |
3221 | ||
3222 | static int | |
3223 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
3224 | { | |
3225 | struct buffer_head *head = page_buffers(page); | |
3226 | struct buffer_head *bh; | |
3227 | ||
3228 | bh = head; | |
3229 | do { | |
1da177e4 LT |
3230 | if (buffer_busy(bh)) |
3231 | goto failed; | |
3232 | bh = bh->b_this_page; | |
3233 | } while (bh != head); | |
3234 | ||
3235 | do { | |
3236 | struct buffer_head *next = bh->b_this_page; | |
3237 | ||
535ee2fb | 3238 | if (bh->b_assoc_map) |
1da177e4 LT |
3239 | __remove_assoc_queue(bh); |
3240 | bh = next; | |
3241 | } while (bh != head); | |
3242 | *buffers_to_free = head; | |
3243 | __clear_page_buffers(page); | |
3244 | return 1; | |
3245 | failed: | |
3246 | return 0; | |
3247 | } | |
3248 | ||
3249 | int try_to_free_buffers(struct page *page) | |
3250 | { | |
3251 | struct address_space * const mapping = page->mapping; | |
3252 | struct buffer_head *buffers_to_free = NULL; | |
3253 | int ret = 0; | |
3254 | ||
3255 | BUG_ON(!PageLocked(page)); | |
ecdfc978 | 3256 | if (PageWriteback(page)) |
1da177e4 LT |
3257 | return 0; |
3258 | ||
3259 | if (mapping == NULL) { /* can this still happen? */ | |
3260 | ret = drop_buffers(page, &buffers_to_free); | |
3261 | goto out; | |
3262 | } | |
3263 | ||
3264 | spin_lock(&mapping->private_lock); | |
3265 | ret = drop_buffers(page, &buffers_to_free); | |
ecdfc978 LT |
3266 | |
3267 | /* | |
3268 | * If the filesystem writes its buffers by hand (eg ext3) | |
3269 | * then we can have clean buffers against a dirty page. We | |
3270 | * clean the page here; otherwise the VM will never notice | |
3271 | * that the filesystem did any IO at all. | |
3272 | * | |
3273 | * Also, during truncate, discard_buffer will have marked all | |
3274 | * the page's buffers clean. We discover that here and clean | |
3275 | * the page also. | |
87df7241 NP |
3276 | * |
3277 | * private_lock must be held over this entire operation in order | |
3278 | * to synchronise against __set_page_dirty_buffers and prevent the | |
3279 | * dirty bit from being lost. | |
ecdfc978 | 3280 | */ |
11f81bec TH |
3281 | if (ret) |
3282 | cancel_dirty_page(page); | |
87df7241 | 3283 | spin_unlock(&mapping->private_lock); |
1da177e4 LT |
3284 | out: |
3285 | if (buffers_to_free) { | |
3286 | struct buffer_head *bh = buffers_to_free; | |
3287 | ||
3288 | do { | |
3289 | struct buffer_head *next = bh->b_this_page; | |
3290 | free_buffer_head(bh); | |
3291 | bh = next; | |
3292 | } while (bh != buffers_to_free); | |
3293 | } | |
3294 | return ret; | |
3295 | } | |
3296 | EXPORT_SYMBOL(try_to_free_buffers); | |
3297 | ||
1da177e4 LT |
3298 | /* |
3299 | * There are no bdflush tunables left. But distributions are | |
3300 | * still running obsolete flush daemons, so we terminate them here. | |
3301 | * | |
3302 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
5b0830cb | 3303 | * The `flush-X' kernel threads fully replace bdflush daemons and this call. |
1da177e4 | 3304 | */ |
bdc480e3 | 3305 | SYSCALL_DEFINE2(bdflush, int, func, long, data) |
1da177e4 LT |
3306 | { |
3307 | static int msg_count; | |
3308 | ||
3309 | if (!capable(CAP_SYS_ADMIN)) | |
3310 | return -EPERM; | |
3311 | ||
3312 | if (msg_count < 5) { | |
3313 | msg_count++; | |
3314 | printk(KERN_INFO | |
3315 | "warning: process `%s' used the obsolete bdflush" | |
3316 | " system call\n", current->comm); | |
3317 | printk(KERN_INFO "Fix your initscripts?\n"); | |
3318 | } | |
3319 | ||
3320 | if (func == 1) | |
3321 | do_exit(0); | |
3322 | return 0; | |
3323 | } | |
3324 | ||
3325 | /* | |
3326 | * Buffer-head allocation | |
3327 | */ | |
a0a9b043 | 3328 | static struct kmem_cache *bh_cachep __read_mostly; |
1da177e4 LT |
3329 | |
3330 | /* | |
3331 | * Once the number of bh's in the machine exceeds this level, we start | |
3332 | * stripping them in writeback. | |
3333 | */ | |
43be594a | 3334 | static unsigned long max_buffer_heads; |
1da177e4 LT |
3335 | |
3336 | int buffer_heads_over_limit; | |
3337 | ||
3338 | struct bh_accounting { | |
3339 | int nr; /* Number of live bh's */ | |
3340 | int ratelimit; /* Limit cacheline bouncing */ | |
3341 | }; | |
3342 | ||
3343 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
3344 | ||
3345 | static void recalc_bh_state(void) | |
3346 | { | |
3347 | int i; | |
3348 | int tot = 0; | |
3349 | ||
ee1be862 | 3350 | if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) |
1da177e4 | 3351 | return; |
c7b92516 | 3352 | __this_cpu_write(bh_accounting.ratelimit, 0); |
8a143426 | 3353 | for_each_online_cpu(i) |
1da177e4 LT |
3354 | tot += per_cpu(bh_accounting, i).nr; |
3355 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
3356 | } | |
c7b92516 | 3357 | |
dd0fc66f | 3358 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
1da177e4 | 3359 | { |
019b4d12 | 3360 | struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); |
1da177e4 | 3361 | if (ret) { |
a35afb83 | 3362 | INIT_LIST_HEAD(&ret->b_assoc_buffers); |
c7b92516 CL |
3363 | preempt_disable(); |
3364 | __this_cpu_inc(bh_accounting.nr); | |
1da177e4 | 3365 | recalc_bh_state(); |
c7b92516 | 3366 | preempt_enable(); |
1da177e4 LT |
3367 | } |
3368 | return ret; | |
3369 | } | |
3370 | EXPORT_SYMBOL(alloc_buffer_head); | |
3371 | ||
3372 | void free_buffer_head(struct buffer_head *bh) | |
3373 | { | |
3374 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
3375 | kmem_cache_free(bh_cachep, bh); | |
c7b92516 CL |
3376 | preempt_disable(); |
3377 | __this_cpu_dec(bh_accounting.nr); | |
1da177e4 | 3378 | recalc_bh_state(); |
c7b92516 | 3379 | preempt_enable(); |
1da177e4 LT |
3380 | } |
3381 | EXPORT_SYMBOL(free_buffer_head); | |
3382 | ||
fc4d24c9 | 3383 | static int buffer_exit_cpu_dead(unsigned int cpu) |
1da177e4 LT |
3384 | { |
3385 | int i; | |
3386 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
3387 | ||
3388 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
3389 | brelse(b->bhs[i]); | |
3390 | b->bhs[i] = NULL; | |
3391 | } | |
c7b92516 | 3392 | this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); |
8a143426 | 3393 | per_cpu(bh_accounting, cpu).nr = 0; |
fc4d24c9 | 3394 | return 0; |
1da177e4 | 3395 | } |
1da177e4 | 3396 | |
389d1b08 | 3397 | /** |
a6b91919 | 3398 | * bh_uptodate_or_lock - Test whether the buffer is uptodate |
389d1b08 AK |
3399 | * @bh: struct buffer_head |
3400 | * | |
3401 | * Return true if the buffer is up-to-date and false, | |
3402 | * with the buffer locked, if not. | |
3403 | */ | |
3404 | int bh_uptodate_or_lock(struct buffer_head *bh) | |
3405 | { | |
3406 | if (!buffer_uptodate(bh)) { | |
3407 | lock_buffer(bh); | |
3408 | if (!buffer_uptodate(bh)) | |
3409 | return 0; | |
3410 | unlock_buffer(bh); | |
3411 | } | |
3412 | return 1; | |
3413 | } | |
3414 | EXPORT_SYMBOL(bh_uptodate_or_lock); | |
3415 | ||
3416 | /** | |
a6b91919 | 3417 | * bh_submit_read - Submit a locked buffer for reading |
389d1b08 AK |
3418 | * @bh: struct buffer_head |
3419 | * | |
3420 | * Returns zero on success and -EIO on error. | |
3421 | */ | |
3422 | int bh_submit_read(struct buffer_head *bh) | |
3423 | { | |
3424 | BUG_ON(!buffer_locked(bh)); | |
3425 | ||
3426 | if (buffer_uptodate(bh)) { | |
3427 | unlock_buffer(bh); | |
3428 | return 0; | |
3429 | } | |
3430 | ||
3431 | get_bh(bh); | |
3432 | bh->b_end_io = end_buffer_read_sync; | |
2a222ca9 | 3433 | submit_bh(REQ_OP_READ, 0, bh); |
389d1b08 AK |
3434 | wait_on_buffer(bh); |
3435 | if (buffer_uptodate(bh)) | |
3436 | return 0; | |
3437 | return -EIO; | |
3438 | } | |
3439 | EXPORT_SYMBOL(bh_submit_read); | |
3440 | ||
1da177e4 LT |
3441 | void __init buffer_init(void) |
3442 | { | |
43be594a | 3443 | unsigned long nrpages; |
fc4d24c9 | 3444 | int ret; |
1da177e4 | 3445 | |
b98938c3 CL |
3446 | bh_cachep = kmem_cache_create("buffer_head", |
3447 | sizeof(struct buffer_head), 0, | |
3448 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| | |
3449 | SLAB_MEM_SPREAD), | |
019b4d12 | 3450 | NULL); |
1da177e4 LT |
3451 | |
3452 | /* | |
3453 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3454 | */ | |
3455 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3456 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
fc4d24c9 SAS |
3457 | ret = cpuhp_setup_state_nocalls(CPUHP_FS_BUFF_DEAD, "fs/buffer:dead", |
3458 | NULL, buffer_exit_cpu_dead); | |
3459 | WARN_ON(ret < 0); | |
1da177e4 | 3460 | } |