Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * fs/fs-writeback.c | |
3 | * | |
4 | * Copyright (C) 2002, Linus Torvalds. | |
5 | * | |
6 | * Contains all the functions related to writing back and waiting | |
7 | * upon dirty inodes against superblocks, and writing back dirty | |
8 | * pages against inodes. ie: data writeback. Writeout of the | |
9 | * inode itself is not handled here. | |
10 | * | |
e1f8e874 | 11 | * 10Apr2002 Andrew Morton |
1da177e4 LT |
12 | * Split out of fs/inode.c |
13 | * Additions for address_space-based writeback | |
14 | */ | |
15 | ||
16 | #include <linux/kernel.h> | |
f5ff8422 | 17 | #include <linux/module.h> |
1da177e4 LT |
18 | #include <linux/spinlock.h> |
19 | #include <linux/sched.h> | |
20 | #include <linux/fs.h> | |
21 | #include <linux/mm.h> | |
03ba3782 JA |
22 | #include <linux/kthread.h> |
23 | #include <linux/freezer.h> | |
1da177e4 LT |
24 | #include <linux/writeback.h> |
25 | #include <linux/blkdev.h> | |
26 | #include <linux/backing-dev.h> | |
27 | #include <linux/buffer_head.h> | |
07f3f05c | 28 | #include "internal.h" |
1da177e4 | 29 | |
66f3b8e2 | 30 | #define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info) |
f11b00f3 | 31 | |
d0bceac7 JA |
32 | /* |
33 | * We don't actually have pdflush, but this one is exported though /proc... | |
34 | */ | |
35 | int nr_pdflush_threads; | |
36 | ||
03ba3782 JA |
37 | /* |
38 | * Work items for the bdi_writeback threads | |
f11b00f3 | 39 | */ |
03ba3782 JA |
40 | struct bdi_work { |
41 | struct list_head list; | |
42 | struct list_head wait_list; | |
43 | struct rcu_head rcu_head; | |
44 | ||
45 | unsigned long seen; | |
46 | atomic_t pending; | |
47 | ||
48 | struct super_block *sb; | |
49 | unsigned long nr_pages; | |
50 | enum writeback_sync_modes sync_mode; | |
51 | ||
52 | unsigned long state; | |
53 | }; | |
54 | ||
55 | enum { | |
56 | WS_USED_B = 0, | |
57 | WS_ONSTACK_B, | |
58 | }; | |
59 | ||
60 | #define WS_USED (1 << WS_USED_B) | |
61 | #define WS_ONSTACK (1 << WS_ONSTACK_B) | |
62 | ||
63 | static inline bool bdi_work_on_stack(struct bdi_work *work) | |
64 | { | |
65 | return test_bit(WS_ONSTACK_B, &work->state); | |
66 | } | |
67 | ||
68 | static inline void bdi_work_init(struct bdi_work *work, | |
69 | struct writeback_control *wbc) | |
70 | { | |
71 | INIT_RCU_HEAD(&work->rcu_head); | |
72 | work->sb = wbc->sb; | |
73 | work->nr_pages = wbc->nr_to_write; | |
74 | work->sync_mode = wbc->sync_mode; | |
75 | work->state = WS_USED; | |
76 | } | |
77 | ||
78 | static inline void bdi_work_init_on_stack(struct bdi_work *work, | |
79 | struct writeback_control *wbc) | |
f11b00f3 | 80 | { |
03ba3782 JA |
81 | bdi_work_init(work, wbc); |
82 | work->state |= WS_ONSTACK; | |
f11b00f3 AB |
83 | } |
84 | ||
85 | /** | |
86 | * writeback_in_progress - determine whether there is writeback in progress | |
87 | * @bdi: the device's backing_dev_info structure. | |
88 | * | |
03ba3782 JA |
89 | * Determine whether there is writeback waiting to be handled against a |
90 | * backing device. | |
f11b00f3 AB |
91 | */ |
92 | int writeback_in_progress(struct backing_dev_info *bdi) | |
93 | { | |
03ba3782 | 94 | return !list_empty(&bdi->work_list); |
f11b00f3 AB |
95 | } |
96 | ||
03ba3782 | 97 | static void bdi_work_clear(struct bdi_work *work) |
f11b00f3 | 98 | { |
03ba3782 JA |
99 | clear_bit(WS_USED_B, &work->state); |
100 | smp_mb__after_clear_bit(); | |
101 | wake_up_bit(&work->state, WS_USED_B); | |
f11b00f3 AB |
102 | } |
103 | ||
03ba3782 | 104 | static void bdi_work_free(struct rcu_head *head) |
4195f73d | 105 | { |
03ba3782 | 106 | struct bdi_work *work = container_of(head, struct bdi_work, rcu_head); |
4195f73d | 107 | |
03ba3782 JA |
108 | if (!bdi_work_on_stack(work)) |
109 | kfree(work); | |
110 | else | |
111 | bdi_work_clear(work); | |
4195f73d NP |
112 | } |
113 | ||
03ba3782 | 114 | static void wb_work_complete(struct bdi_work *work) |
1da177e4 | 115 | { |
03ba3782 | 116 | const enum writeback_sync_modes sync_mode = work->sync_mode; |
1da177e4 LT |
117 | |
118 | /* | |
03ba3782 JA |
119 | * For allocated work, we can clear the done/seen bit right here. |
120 | * For on-stack work, we need to postpone both the clear and free | |
121 | * to after the RCU grace period, since the stack could be invalidated | |
122 | * as soon as bdi_work_clear() has done the wakeup. | |
1da177e4 | 123 | */ |
03ba3782 JA |
124 | if (!bdi_work_on_stack(work)) |
125 | bdi_work_clear(work); | |
126 | if (sync_mode == WB_SYNC_NONE || bdi_work_on_stack(work)) | |
127 | call_rcu(&work->rcu_head, bdi_work_free); | |
128 | } | |
1da177e4 | 129 | |
03ba3782 JA |
130 | static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work) |
131 | { | |
1da177e4 | 132 | /* |
03ba3782 JA |
133 | * The caller has retrieved the work arguments from this work, |
134 | * drop our reference. If this is the last ref, delete and free it | |
1da177e4 | 135 | */ |
03ba3782 JA |
136 | if (atomic_dec_and_test(&work->pending)) { |
137 | struct backing_dev_info *bdi = wb->bdi; | |
1da177e4 | 138 | |
03ba3782 JA |
139 | spin_lock(&bdi->wb_lock); |
140 | list_del_rcu(&work->list); | |
141 | spin_unlock(&bdi->wb_lock); | |
1da177e4 | 142 | |
03ba3782 JA |
143 | wb_work_complete(work); |
144 | } | |
145 | } | |
1da177e4 | 146 | |
03ba3782 JA |
147 | static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work) |
148 | { | |
149 | if (work) { | |
150 | work->seen = bdi->wb_mask; | |
151 | BUG_ON(!work->seen); | |
152 | atomic_set(&work->pending, bdi->wb_cnt); | |
153 | BUG_ON(!bdi->wb_cnt); | |
1da177e4 LT |
154 | |
155 | /* | |
03ba3782 | 156 | * Make sure stores are seen before it appears on the list |
1da177e4 | 157 | */ |
03ba3782 | 158 | smp_mb(); |
1da177e4 | 159 | |
03ba3782 JA |
160 | spin_lock(&bdi->wb_lock); |
161 | list_add_tail_rcu(&work->list, &bdi->work_list); | |
162 | spin_unlock(&bdi->wb_lock); | |
163 | } | |
164 | ||
165 | /* | |
166 | * If the default thread isn't there, make sure we add it. When | |
167 | * it gets created and wakes up, we'll run this work. | |
168 | */ | |
169 | if (unlikely(list_empty_careful(&bdi->wb_list))) | |
170 | wake_up_process(default_backing_dev_info.wb.task); | |
171 | else { | |
172 | struct bdi_writeback *wb = &bdi->wb; | |
1da177e4 LT |
173 | |
174 | /* | |
03ba3782 JA |
175 | * If we failed allocating the bdi work item, wake up the wb |
176 | * thread always. As a safety precaution, it'll flush out | |
177 | * everything | |
1da177e4 | 178 | */ |
03ba3782 JA |
179 | if (!wb_has_dirty_io(wb)) { |
180 | if (work) | |
181 | wb_clear_pending(wb, work); | |
182 | } else if (wb->task) | |
183 | wake_up_process(wb->task); | |
1da177e4 | 184 | } |
1da177e4 LT |
185 | } |
186 | ||
03ba3782 JA |
187 | /* |
188 | * Used for on-stack allocated work items. The caller needs to wait until | |
189 | * the wb threads have acked the work before it's safe to continue. | |
190 | */ | |
191 | static void bdi_wait_on_work_clear(struct bdi_work *work) | |
192 | { | |
193 | wait_on_bit(&work->state, WS_USED_B, bdi_sched_wait, | |
194 | TASK_UNINTERRUPTIBLE); | |
195 | } | |
1da177e4 | 196 | |
03ba3782 | 197 | static struct bdi_work *bdi_alloc_work(struct writeback_control *wbc) |
1da177e4 | 198 | { |
03ba3782 JA |
199 | struct bdi_work *work; |
200 | ||
201 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
202 | if (work) | |
203 | bdi_work_init(work, wbc); | |
204 | ||
205 | return work; | |
206 | } | |
207 | ||
208 | void bdi_start_writeback(struct writeback_control *wbc) | |
209 | { | |
210 | const bool must_wait = wbc->sync_mode == WB_SYNC_ALL; | |
211 | struct bdi_work work_stack, *work = NULL; | |
212 | ||
213 | if (!must_wait) | |
214 | work = bdi_alloc_work(wbc); | |
215 | ||
216 | if (!work) { | |
217 | work = &work_stack; | |
218 | bdi_work_init_on_stack(work, wbc); | |
219 | } | |
220 | ||
221 | bdi_queue_work(wbc->bdi, work); | |
222 | ||
223 | /* | |
224 | * If the sync mode is WB_SYNC_ALL, block waiting for the work to | |
225 | * complete. If not, we only need to wait for the work to be started, | |
226 | * if we allocated it on-stack. We use the same mechanism, if the | |
227 | * wait bit is set in the bdi_work struct, then threads will not | |
228 | * clear pending until after they are done. | |
229 | * | |
230 | * Note that work == &work_stack if must_wait is true, so we don't | |
231 | * need to do call_rcu() here ever, since the completion path will | |
232 | * have done that for us. | |
233 | */ | |
234 | if (must_wait || work == &work_stack) { | |
235 | bdi_wait_on_work_clear(work); | |
236 | if (work != &work_stack) | |
237 | call_rcu(&work->rcu_head, bdi_work_free); | |
238 | } | |
1da177e4 LT |
239 | } |
240 | ||
6610a0bc AM |
241 | /* |
242 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
243 | * furthest end of its superblock's dirty-inode list. | |
244 | * | |
245 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 246 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
247 | * the case then the inode must have been redirtied while it was being written |
248 | * out and we don't reset its dirtied_when. | |
249 | */ | |
250 | static void redirty_tail(struct inode *inode) | |
251 | { | |
03ba3782 | 252 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
6610a0bc | 253 | |
03ba3782 | 254 | if (!list_empty(&wb->b_dirty)) { |
66f3b8e2 | 255 | struct inode *tail; |
6610a0bc | 256 | |
03ba3782 | 257 | tail = list_entry(wb->b_dirty.next, struct inode, i_list); |
66f3b8e2 | 258 | if (time_before(inode->dirtied_when, tail->dirtied_when)) |
6610a0bc AM |
259 | inode->dirtied_when = jiffies; |
260 | } | |
03ba3782 | 261 | list_move(&inode->i_list, &wb->b_dirty); |
6610a0bc AM |
262 | } |
263 | ||
c986d1e2 | 264 | /* |
66f3b8e2 | 265 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 266 | */ |
0e0f4fc2 | 267 | static void requeue_io(struct inode *inode) |
c986d1e2 | 268 | { |
03ba3782 JA |
269 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
270 | ||
271 | list_move(&inode->i_list, &wb->b_more_io); | |
c986d1e2 AM |
272 | } |
273 | ||
1c0eeaf5 JE |
274 | static void inode_sync_complete(struct inode *inode) |
275 | { | |
276 | /* | |
277 | * Prevent speculative execution through spin_unlock(&inode_lock); | |
278 | */ | |
279 | smp_mb(); | |
280 | wake_up_bit(&inode->i_state, __I_SYNC); | |
281 | } | |
282 | ||
d2caa3c5 JL |
283 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
284 | { | |
285 | bool ret = time_after(inode->dirtied_when, t); | |
286 | #ifndef CONFIG_64BIT | |
287 | /* | |
288 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
289 | * It _appears_ to be in the future, but is actually in distant past. | |
290 | * This test is necessary to prevent such wrapped-around relative times | |
291 | * from permanently stopping the whole pdflush writeback. | |
292 | */ | |
293 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
294 | #endif | |
295 | return ret; | |
296 | } | |
297 | ||
2c136579 FW |
298 | /* |
299 | * Move expired dirty inodes from @delaying_queue to @dispatch_queue. | |
300 | */ | |
301 | static void move_expired_inodes(struct list_head *delaying_queue, | |
302 | struct list_head *dispatch_queue, | |
303 | unsigned long *older_than_this) | |
304 | { | |
305 | while (!list_empty(delaying_queue)) { | |
306 | struct inode *inode = list_entry(delaying_queue->prev, | |
307 | struct inode, i_list); | |
308 | if (older_than_this && | |
d2caa3c5 | 309 | inode_dirtied_after(inode, *older_than_this)) |
2c136579 FW |
310 | break; |
311 | list_move(&inode->i_list, dispatch_queue); | |
312 | } | |
313 | } | |
314 | ||
315 | /* | |
316 | * Queue all expired dirty inodes for io, eldest first. | |
317 | */ | |
03ba3782 | 318 | static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) |
66f3b8e2 | 319 | { |
03ba3782 JA |
320 | list_splice_init(&wb->b_more_io, wb->b_io.prev); |
321 | move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); | |
66f3b8e2 JA |
322 | } |
323 | ||
03ba3782 | 324 | static int write_inode(struct inode *inode, int sync) |
08d8e974 | 325 | { |
03ba3782 JA |
326 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) |
327 | return inode->i_sb->s_op->write_inode(inode, sync); | |
328 | return 0; | |
08d8e974 | 329 | } |
08d8e974 | 330 | |
1da177e4 | 331 | /* |
01c03194 CH |
332 | * Wait for writeback on an inode to complete. |
333 | */ | |
334 | static void inode_wait_for_writeback(struct inode *inode) | |
335 | { | |
336 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
337 | wait_queue_head_t *wqh; | |
338 | ||
339 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
340 | do { | |
341 | spin_unlock(&inode_lock); | |
342 | __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); | |
343 | spin_lock(&inode_lock); | |
344 | } while (inode->i_state & I_SYNC); | |
345 | } | |
346 | ||
347 | /* | |
348 | * Write out an inode's dirty pages. Called under inode_lock. Either the | |
349 | * caller has ref on the inode (either via __iget or via syscall against an fd) | |
350 | * or the inode has I_WILL_FREE set (via generic_forget_inode) | |
351 | * | |
1da177e4 LT |
352 | * If `wait' is set, wait on the writeout. |
353 | * | |
354 | * The whole writeout design is quite complex and fragile. We want to avoid | |
355 | * starvation of particular inodes when others are being redirtied, prevent | |
356 | * livelocks, etc. | |
357 | * | |
358 | * Called under inode_lock. | |
359 | */ | |
360 | static int | |
01c03194 | 361 | writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 362 | { |
1da177e4 | 363 | struct address_space *mapping = inode->i_mapping; |
1da177e4 | 364 | int wait = wbc->sync_mode == WB_SYNC_ALL; |
01c03194 | 365 | unsigned dirty; |
1da177e4 LT |
366 | int ret; |
367 | ||
01c03194 CH |
368 | if (!atomic_read(&inode->i_count)) |
369 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
370 | else | |
371 | WARN_ON(inode->i_state & I_WILL_FREE); | |
372 | ||
373 | if (inode->i_state & I_SYNC) { | |
374 | /* | |
375 | * If this inode is locked for writeback and we are not doing | |
66f3b8e2 | 376 | * writeback-for-data-integrity, move it to b_more_io so that |
01c03194 CH |
377 | * writeback can proceed with the other inodes on s_io. |
378 | * | |
379 | * We'll have another go at writing back this inode when we | |
66f3b8e2 | 380 | * completed a full scan of b_io. |
01c03194 CH |
381 | */ |
382 | if (!wait) { | |
383 | requeue_io(inode); | |
384 | return 0; | |
385 | } | |
386 | ||
387 | /* | |
388 | * It's a data-integrity sync. We must wait. | |
389 | */ | |
390 | inode_wait_for_writeback(inode); | |
391 | } | |
392 | ||
1c0eeaf5 | 393 | BUG_ON(inode->i_state & I_SYNC); |
1da177e4 | 394 | |
1c0eeaf5 | 395 | /* Set I_SYNC, reset I_DIRTY */ |
1da177e4 | 396 | dirty = inode->i_state & I_DIRTY; |
1c0eeaf5 | 397 | inode->i_state |= I_SYNC; |
1da177e4 LT |
398 | inode->i_state &= ~I_DIRTY; |
399 | ||
400 | spin_unlock(&inode_lock); | |
401 | ||
402 | ret = do_writepages(mapping, wbc); | |
403 | ||
404 | /* Don't write the inode if only I_DIRTY_PAGES was set */ | |
405 | if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
406 | int err = write_inode(inode, wait); | |
407 | if (ret == 0) | |
408 | ret = err; | |
409 | } | |
410 | ||
411 | if (wait) { | |
412 | int err = filemap_fdatawait(mapping); | |
413 | if (ret == 0) | |
414 | ret = err; | |
415 | } | |
416 | ||
417 | spin_lock(&inode_lock); | |
1c0eeaf5 | 418 | inode->i_state &= ~I_SYNC; |
84a89245 | 419 | if (!(inode->i_state & (I_FREEING | I_CLEAR))) { |
1da177e4 LT |
420 | if (!(inode->i_state & I_DIRTY) && |
421 | mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { | |
422 | /* | |
423 | * We didn't write back all the pages. nfs_writepages() | |
424 | * sometimes bales out without doing anything. Redirty | |
66f3b8e2 | 425 | * the inode; Move it from b_io onto b_more_io/b_dirty. |
1b43ef91 AM |
426 | */ |
427 | /* | |
428 | * akpm: if the caller was the kupdate function we put | |
66f3b8e2 | 429 | * this inode at the head of b_dirty so it gets first |
1b43ef91 AM |
430 | * consideration. Otherwise, move it to the tail, for |
431 | * the reasons described there. I'm not really sure | |
432 | * how much sense this makes. Presumably I had a good | |
433 | * reasons for doing it this way, and I'd rather not | |
434 | * muck with it at present. | |
1da177e4 LT |
435 | */ |
436 | if (wbc->for_kupdate) { | |
437 | /* | |
2c136579 | 438 | * For the kupdate function we move the inode |
66f3b8e2 | 439 | * to b_more_io so it will get more writeout as |
2c136579 | 440 | * soon as the queue becomes uncongested. |
1da177e4 LT |
441 | */ |
442 | inode->i_state |= I_DIRTY_PAGES; | |
8bc3be27 FW |
443 | if (wbc->nr_to_write <= 0) { |
444 | /* | |
445 | * slice used up: queue for next turn | |
446 | */ | |
447 | requeue_io(inode); | |
448 | } else { | |
449 | /* | |
450 | * somehow blocked: retry later | |
451 | */ | |
452 | redirty_tail(inode); | |
453 | } | |
1da177e4 LT |
454 | } else { |
455 | /* | |
456 | * Otherwise fully redirty the inode so that | |
457 | * other inodes on this superblock will get some | |
458 | * writeout. Otherwise heavy writing to one | |
459 | * file would indefinitely suspend writeout of | |
460 | * all the other files. | |
461 | */ | |
462 | inode->i_state |= I_DIRTY_PAGES; | |
1b43ef91 | 463 | redirty_tail(inode); |
1da177e4 LT |
464 | } |
465 | } else if (inode->i_state & I_DIRTY) { | |
466 | /* | |
467 | * Someone redirtied the inode while were writing back | |
468 | * the pages. | |
469 | */ | |
6610a0bc | 470 | redirty_tail(inode); |
1da177e4 LT |
471 | } else if (atomic_read(&inode->i_count)) { |
472 | /* | |
473 | * The inode is clean, inuse | |
474 | */ | |
475 | list_move(&inode->i_list, &inode_in_use); | |
476 | } else { | |
477 | /* | |
478 | * The inode is clean, unused | |
479 | */ | |
480 | list_move(&inode->i_list, &inode_unused); | |
1da177e4 LT |
481 | } |
482 | } | |
1c0eeaf5 | 483 | inode_sync_complete(inode); |
1da177e4 LT |
484 | return ret; |
485 | } | |
486 | ||
03ba3782 JA |
487 | /* |
488 | * For WB_SYNC_NONE writeback, the caller does not have the sb pinned | |
489 | * before calling writeback. So make sure that we do pin it, so it doesn't | |
490 | * go away while we are writing inodes from it. | |
491 | * | |
492 | * Returns 0 if the super was successfully pinned (or pinning wasn't needed), | |
493 | * 1 if we failed. | |
494 | */ | |
495 | static int pin_sb_for_writeback(struct writeback_control *wbc, | |
496 | struct inode *inode) | |
497 | { | |
498 | struct super_block *sb = inode->i_sb; | |
499 | ||
500 | /* | |
501 | * Caller must already hold the ref for this | |
502 | */ | |
503 | if (wbc->sync_mode == WB_SYNC_ALL) { | |
504 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); | |
505 | return 0; | |
506 | } | |
507 | ||
508 | spin_lock(&sb_lock); | |
509 | sb->s_count++; | |
510 | if (down_read_trylock(&sb->s_umount)) { | |
511 | if (sb->s_root) { | |
512 | spin_unlock(&sb_lock); | |
513 | return 0; | |
514 | } | |
515 | /* | |
516 | * umounted, drop rwsem again and fall through to failure | |
517 | */ | |
518 | up_read(&sb->s_umount); | |
519 | } | |
520 | ||
521 | sb->s_count--; | |
522 | spin_unlock(&sb_lock); | |
523 | return 1; | |
524 | } | |
525 | ||
526 | static void unpin_sb_for_writeback(struct writeback_control *wbc, | |
527 | struct inode *inode) | |
528 | { | |
529 | struct super_block *sb = inode->i_sb; | |
530 | ||
531 | if (wbc->sync_mode == WB_SYNC_ALL) | |
532 | return; | |
533 | ||
534 | up_read(&sb->s_umount); | |
535 | put_super(sb); | |
536 | } | |
537 | ||
538 | static void writeback_inodes_wb(struct bdi_writeback *wb, | |
539 | struct writeback_control *wbc) | |
1da177e4 | 540 | { |
03ba3782 | 541 | struct super_block *sb = wbc->sb; |
66f3b8e2 | 542 | const int is_blkdev_sb = sb_is_blkdev_sb(sb); |
1da177e4 LT |
543 | const unsigned long start = jiffies; /* livelock avoidance */ |
544 | ||
ae8547b0 | 545 | spin_lock(&inode_lock); |
1da177e4 | 546 | |
03ba3782 JA |
547 | if (!wbc->for_kupdate || list_empty(&wb->b_io)) |
548 | queue_io(wb, wbc->older_than_this); | |
66f3b8e2 | 549 | |
03ba3782 JA |
550 | while (!list_empty(&wb->b_io)) { |
551 | struct inode *inode = list_entry(wb->b_io.prev, | |
1da177e4 | 552 | struct inode, i_list); |
1da177e4 LT |
553 | long pages_skipped; |
554 | ||
66f3b8e2 JA |
555 | /* |
556 | * super block given and doesn't match, skip this inode | |
557 | */ | |
558 | if (sb && sb != inode->i_sb) { | |
559 | redirty_tail(inode); | |
560 | continue; | |
561 | } | |
562 | ||
03ba3782 | 563 | if (!bdi_cap_writeback_dirty(wb->bdi)) { |
9852a0e7 | 564 | redirty_tail(inode); |
66f3b8e2 | 565 | if (is_blkdev_sb) { |
1da177e4 LT |
566 | /* |
567 | * Dirty memory-backed blockdev: the ramdisk | |
568 | * driver does this. Skip just this inode | |
569 | */ | |
570 | continue; | |
571 | } | |
572 | /* | |
573 | * Dirty memory-backed inode against a filesystem other | |
574 | * than the kernel-internal bdev filesystem. Skip the | |
575 | * entire superblock. | |
576 | */ | |
577 | break; | |
578 | } | |
579 | ||
84a89245 | 580 | if (inode->i_state & (I_NEW | I_WILL_FREE)) { |
7ef0d737 NP |
581 | requeue_io(inode); |
582 | continue; | |
583 | } | |
584 | ||
03ba3782 | 585 | if (wbc->nonblocking && bdi_write_congested(wb->bdi)) { |
1da177e4 | 586 | wbc->encountered_congestion = 1; |
66f3b8e2 | 587 | if (!is_blkdev_sb) |
1da177e4 | 588 | break; /* Skip a congested fs */ |
0e0f4fc2 | 589 | requeue_io(inode); |
1da177e4 LT |
590 | continue; /* Skip a congested blockdev */ |
591 | } | |
592 | ||
d2caa3c5 JL |
593 | /* |
594 | * Was this inode dirtied after sync_sb_inodes was called? | |
595 | * This keeps sync from extra jobs and livelock. | |
596 | */ | |
597 | if (inode_dirtied_after(inode, start)) | |
1da177e4 LT |
598 | break; |
599 | ||
03ba3782 JA |
600 | if (pin_sb_for_writeback(wbc, inode)) { |
601 | requeue_io(inode); | |
602 | continue; | |
603 | } | |
1da177e4 | 604 | |
84a89245 | 605 | BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); |
1da177e4 LT |
606 | __iget(inode); |
607 | pages_skipped = wbc->pages_skipped; | |
01c03194 | 608 | writeback_single_inode(inode, wbc); |
03ba3782 | 609 | unpin_sb_for_writeback(wbc, inode); |
1da177e4 LT |
610 | if (wbc->pages_skipped != pages_skipped) { |
611 | /* | |
612 | * writeback is not making progress due to locked | |
613 | * buffers. Skip this inode for now. | |
614 | */ | |
f57b9b7b | 615 | redirty_tail(inode); |
1da177e4 LT |
616 | } |
617 | spin_unlock(&inode_lock); | |
1da177e4 | 618 | iput(inode); |
4ffc8444 | 619 | cond_resched(); |
1da177e4 | 620 | spin_lock(&inode_lock); |
8bc3be27 FW |
621 | if (wbc->nr_to_write <= 0) { |
622 | wbc->more_io = 1; | |
1da177e4 | 623 | break; |
8bc3be27 | 624 | } |
03ba3782 | 625 | if (!list_empty(&wb->b_more_io)) |
8bc3be27 | 626 | wbc->more_io = 1; |
1da177e4 | 627 | } |
38f21977 | 628 | |
66f3b8e2 JA |
629 | spin_unlock(&inode_lock); |
630 | /* Leave any unwritten inodes on b_io */ | |
631 | } | |
632 | ||
03ba3782 JA |
633 | void writeback_inodes_wbc(struct writeback_control *wbc) |
634 | { | |
635 | struct backing_dev_info *bdi = wbc->bdi; | |
636 | ||
637 | writeback_inodes_wb(&bdi->wb, wbc); | |
638 | } | |
639 | ||
66f3b8e2 | 640 | /* |
03ba3782 JA |
641 | * The maximum number of pages to writeout in a single bdi flush/kupdate |
642 | * operation. We do this so we don't hold I_SYNC against an inode for | |
643 | * enormous amounts of time, which would block a userspace task which has | |
644 | * been forced to throttle against that inode. Also, the code reevaluates | |
645 | * the dirty each time it has written this many pages. | |
646 | */ | |
647 | #define MAX_WRITEBACK_PAGES 1024 | |
648 | ||
649 | static inline bool over_bground_thresh(void) | |
650 | { | |
651 | unsigned long background_thresh, dirty_thresh; | |
652 | ||
653 | get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); | |
654 | ||
655 | return (global_page_state(NR_FILE_DIRTY) + | |
656 | global_page_state(NR_UNSTABLE_NFS) >= background_thresh); | |
657 | } | |
658 | ||
659 | /* | |
660 | * Explicit flushing or periodic writeback of "old" data. | |
66f3b8e2 | 661 | * |
03ba3782 JA |
662 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
663 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
664 | * just walks the superblock inode list, writing back any inodes which are | |
665 | * older than a specific point in time. | |
66f3b8e2 | 666 | * |
03ba3782 JA |
667 | * Try to run once per dirty_writeback_interval. But if a writeback event |
668 | * takes longer than a dirty_writeback_interval interval, then leave a | |
669 | * one-second gap. | |
66f3b8e2 | 670 | * |
03ba3782 JA |
671 | * older_than_this takes precedence over nr_to_write. So we'll only write back |
672 | * all dirty pages if they are all attached to "old" mappings. | |
66f3b8e2 | 673 | */ |
03ba3782 JA |
674 | static long wb_writeback(struct bdi_writeback *wb, long nr_pages, |
675 | struct super_block *sb, | |
676 | enum writeback_sync_modes sync_mode, int for_kupdate) | |
66f3b8e2 | 677 | { |
03ba3782 JA |
678 | struct writeback_control wbc = { |
679 | .bdi = wb->bdi, | |
680 | .sb = sb, | |
681 | .sync_mode = sync_mode, | |
682 | .older_than_this = NULL, | |
683 | .for_kupdate = for_kupdate, | |
684 | .range_cyclic = 1, | |
685 | }; | |
686 | unsigned long oldest_jif; | |
687 | long wrote = 0; | |
66f3b8e2 | 688 | |
03ba3782 JA |
689 | if (wbc.for_kupdate) { |
690 | wbc.older_than_this = &oldest_jif; | |
691 | oldest_jif = jiffies - | |
692 | msecs_to_jiffies(dirty_expire_interval * 10); | |
693 | } | |
38f21977 | 694 | |
03ba3782 JA |
695 | for (;;) { |
696 | /* | |
697 | * Don't flush anything for non-integrity writeback where | |
698 | * no nr_pages was given | |
699 | */ | |
700 | if (!for_kupdate && nr_pages <= 0 && sync_mode == WB_SYNC_NONE) | |
701 | break; | |
66f3b8e2 | 702 | |
38f21977 | 703 | /* |
03ba3782 JA |
704 | * If no specific pages were given and this is just a |
705 | * periodic background writeout and we are below the | |
706 | * background dirty threshold, don't do anything | |
38f21977 | 707 | */ |
03ba3782 JA |
708 | if (for_kupdate && nr_pages <= 0 && !over_bground_thresh()) |
709 | break; | |
38f21977 | 710 | |
03ba3782 JA |
711 | wbc.more_io = 0; |
712 | wbc.encountered_congestion = 0; | |
713 | wbc.nr_to_write = MAX_WRITEBACK_PAGES; | |
714 | wbc.pages_skipped = 0; | |
715 | writeback_inodes_wb(wb, &wbc); | |
716 | nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; | |
717 | wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; | |
718 | ||
719 | /* | |
720 | * If we ran out of stuff to write, bail unless more_io got set | |
721 | */ | |
722 | if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) { | |
723 | if (wbc.more_io && !wbc.for_kupdate) | |
38f21977 | 724 | continue; |
03ba3782 JA |
725 | break; |
726 | } | |
727 | } | |
728 | ||
729 | return wrote; | |
730 | } | |
731 | ||
732 | /* | |
733 | * Return the next bdi_work struct that hasn't been processed by this | |
734 | * wb thread yet | |
735 | */ | |
736 | static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi, | |
737 | struct bdi_writeback *wb) | |
738 | { | |
739 | struct bdi_work *work, *ret = NULL; | |
740 | ||
741 | rcu_read_lock(); | |
742 | ||
743 | list_for_each_entry_rcu(work, &bdi->work_list, list) { | |
744 | if (!test_and_clear_bit(wb->nr, &work->seen)) | |
745 | continue; | |
746 | ||
747 | ret = work; | |
748 | break; | |
749 | } | |
750 | ||
751 | rcu_read_unlock(); | |
752 | return ret; | |
753 | } | |
754 | ||
755 | static long wb_check_old_data_flush(struct bdi_writeback *wb) | |
756 | { | |
757 | unsigned long expired; | |
758 | long nr_pages; | |
759 | ||
760 | expired = wb->last_old_flush + | |
761 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
762 | if (time_before(jiffies, expired)) | |
763 | return 0; | |
764 | ||
765 | wb->last_old_flush = jiffies; | |
766 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
767 | global_page_state(NR_UNSTABLE_NFS) + | |
768 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); | |
769 | ||
770 | if (nr_pages) | |
771 | return wb_writeback(wb, nr_pages, NULL, WB_SYNC_NONE, 1); | |
772 | ||
773 | return 0; | |
774 | } | |
775 | ||
776 | /* | |
777 | * Retrieve work items and do the writeback they describe | |
778 | */ | |
779 | long wb_do_writeback(struct bdi_writeback *wb, int force_wait) | |
780 | { | |
781 | struct backing_dev_info *bdi = wb->bdi; | |
782 | struct bdi_work *work; | |
783 | long nr_pages, wrote = 0; | |
784 | ||
785 | while ((work = get_next_work_item(bdi, wb)) != NULL) { | |
786 | enum writeback_sync_modes sync_mode; | |
787 | ||
788 | nr_pages = work->nr_pages; | |
789 | ||
790 | /* | |
791 | * Override sync mode, in case we must wait for completion | |
792 | */ | |
793 | if (force_wait) | |
794 | work->sync_mode = sync_mode = WB_SYNC_ALL; | |
795 | else | |
796 | sync_mode = work->sync_mode; | |
797 | ||
798 | /* | |
799 | * If this isn't a data integrity operation, just notify | |
800 | * that we have seen this work and we are now starting it. | |
801 | */ | |
802 | if (sync_mode == WB_SYNC_NONE) | |
803 | wb_clear_pending(wb, work); | |
804 | ||
805 | wrote += wb_writeback(wb, nr_pages, work->sb, sync_mode, 0); | |
806 | ||
807 | /* | |
808 | * This is a data integrity writeback, so only do the | |
809 | * notification when we have completed the work. | |
810 | */ | |
811 | if (sync_mode == WB_SYNC_ALL) | |
812 | wb_clear_pending(wb, work); | |
813 | } | |
814 | ||
815 | /* | |
816 | * Check for periodic writeback, kupdated() style | |
817 | */ | |
818 | wrote += wb_check_old_data_flush(wb); | |
819 | ||
820 | return wrote; | |
821 | } | |
822 | ||
823 | /* | |
824 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
825 | * wakes up periodically and does kupdated style flushing. | |
826 | */ | |
827 | int bdi_writeback_task(struct bdi_writeback *wb) | |
828 | { | |
829 | unsigned long last_active = jiffies; | |
830 | unsigned long wait_jiffies = -1UL; | |
831 | long pages_written; | |
832 | ||
833 | while (!kthread_should_stop()) { | |
834 | pages_written = wb_do_writeback(wb, 0); | |
835 | ||
836 | if (pages_written) | |
837 | last_active = jiffies; | |
838 | else if (wait_jiffies != -1UL) { | |
839 | unsigned long max_idle; | |
840 | ||
38f21977 | 841 | /* |
03ba3782 JA |
842 | * Longest period of inactivity that we tolerate. If we |
843 | * see dirty data again later, the task will get | |
844 | * recreated automatically. | |
38f21977 | 845 | */ |
03ba3782 JA |
846 | max_idle = max(5UL * 60 * HZ, wait_jiffies); |
847 | if (time_after(jiffies, max_idle + last_active)) | |
848 | break; | |
849 | } | |
850 | ||
851 | wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); | |
852 | set_current_state(TASK_INTERRUPTIBLE); | |
853 | schedule_timeout(wait_jiffies); | |
854 | try_to_freeze(); | |
855 | } | |
856 | ||
857 | return 0; | |
858 | } | |
859 | ||
860 | /* | |
861 | * Schedule writeback for all backing devices. Expensive! If this is a data | |
862 | * integrity operation, writeback will be complete when this returns. If | |
863 | * we are simply called for WB_SYNC_NONE, then writeback will merely be | |
864 | * scheduled to run. | |
865 | */ | |
866 | static void bdi_writeback_all(struct writeback_control *wbc) | |
867 | { | |
868 | const bool must_wait = wbc->sync_mode == WB_SYNC_ALL; | |
869 | struct backing_dev_info *bdi; | |
870 | struct bdi_work *work; | |
871 | LIST_HEAD(list); | |
872 | ||
873 | restart: | |
874 | spin_lock(&bdi_lock); | |
875 | ||
876 | list_for_each_entry(bdi, &bdi_list, bdi_list) { | |
877 | struct bdi_work *work; | |
878 | ||
879 | if (!bdi_has_dirty_io(bdi)) | |
880 | continue; | |
38f21977 | 881 | |
03ba3782 JA |
882 | /* |
883 | * If work allocation fails, do the writes inline. We drop | |
884 | * the lock and restart the list writeout. This should be OK, | |
885 | * since this happens rarely and because the writeout should | |
886 | * eventually make more free memory available. | |
887 | */ | |
888 | work = bdi_alloc_work(wbc); | |
889 | if (!work) { | |
890 | struct writeback_control __wbc; | |
38f21977 | 891 | |
03ba3782 JA |
892 | /* |
893 | * Not a data integrity writeout, just continue | |
894 | */ | |
895 | if (!must_wait) | |
896 | continue; | |
38f21977 | 897 | |
03ba3782 JA |
898 | spin_unlock(&bdi_lock); |
899 | __wbc = *wbc; | |
900 | __wbc.bdi = bdi; | |
901 | writeback_inodes_wbc(&__wbc); | |
902 | goto restart; | |
38f21977 | 903 | } |
03ba3782 JA |
904 | if (must_wait) |
905 | list_add_tail(&work->wait_list, &list); | |
906 | ||
907 | bdi_queue_work(bdi, work); | |
908 | } | |
909 | ||
910 | spin_unlock(&bdi_lock); | |
911 | ||
912 | /* | |
913 | * If this is for WB_SYNC_ALL, wait for pending work to complete | |
914 | * before returning. | |
915 | */ | |
916 | while (!list_empty(&list)) { | |
917 | work = list_entry(list.next, struct bdi_work, wait_list); | |
918 | list_del(&work->wait_list); | |
919 | bdi_wait_on_work_clear(work); | |
920 | call_rcu(&work->rcu_head, bdi_work_free); | |
66f3b8e2 | 921 | } |
1da177e4 LT |
922 | } |
923 | ||
924 | /* | |
03ba3782 JA |
925 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
926 | * the whole world. | |
927 | */ | |
928 | void wakeup_flusher_threads(long nr_pages) | |
929 | { | |
930 | struct writeback_control wbc = { | |
931 | .sync_mode = WB_SYNC_NONE, | |
932 | .older_than_this = NULL, | |
933 | .range_cyclic = 1, | |
934 | }; | |
935 | ||
936 | if (nr_pages == 0) | |
937 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
938 | global_page_state(NR_UNSTABLE_NFS); | |
939 | wbc.nr_to_write = nr_pages; | |
940 | bdi_writeback_all(&wbc); | |
941 | } | |
942 | ||
943 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) | |
944 | { | |
945 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
946 | struct dentry *dentry; | |
947 | const char *name = "?"; | |
948 | ||
949 | dentry = d_find_alias(inode); | |
950 | if (dentry) { | |
951 | spin_lock(&dentry->d_lock); | |
952 | name = (const char *) dentry->d_name.name; | |
953 | } | |
954 | printk(KERN_DEBUG | |
955 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
956 | current->comm, task_pid_nr(current), inode->i_ino, | |
957 | name, inode->i_sb->s_id); | |
958 | if (dentry) { | |
959 | spin_unlock(&dentry->d_lock); | |
960 | dput(dentry); | |
961 | } | |
962 | } | |
963 | } | |
964 | ||
965 | /** | |
966 | * __mark_inode_dirty - internal function | |
967 | * @inode: inode to mark | |
968 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
969 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
970 | * mark_inode_dirty_sync. | |
1da177e4 | 971 | * |
03ba3782 JA |
972 | * Put the inode on the super block's dirty list. |
973 | * | |
974 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
975 | * dirty list only if it is hashed or if it refers to a blockdev. | |
976 | * If it was not hashed, it will never be added to the dirty list | |
977 | * even if it is later hashed, as it will have been marked dirty already. | |
978 | * | |
979 | * In short, make sure you hash any inodes _before_ you start marking | |
980 | * them dirty. | |
1da177e4 | 981 | * |
03ba3782 JA |
982 | * This function *must* be atomic for the I_DIRTY_PAGES case - |
983 | * set_page_dirty() is called under spinlock in several places. | |
1da177e4 | 984 | * |
03ba3782 JA |
985 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
986 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
987 | * the kernel-internal blockdev inode represents the dirtying time of the | |
988 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
989 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
990 | * blockdev inode. | |
1da177e4 | 991 | */ |
03ba3782 | 992 | void __mark_inode_dirty(struct inode *inode, int flags) |
1da177e4 | 993 | { |
03ba3782 | 994 | struct super_block *sb = inode->i_sb; |
1da177e4 | 995 | |
03ba3782 JA |
996 | /* |
997 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
998 | * dirty the inode itself | |
999 | */ | |
1000 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
1001 | if (sb->s_op->dirty_inode) | |
1002 | sb->s_op->dirty_inode(inode); | |
1003 | } | |
1004 | ||
1005 | /* | |
1006 | * make sure that changes are seen by all cpus before we test i_state | |
1007 | * -- mikulas | |
1008 | */ | |
1009 | smp_mb(); | |
1010 | ||
1011 | /* avoid the locking if we can */ | |
1012 | if ((inode->i_state & flags) == flags) | |
1013 | return; | |
1014 | ||
1015 | if (unlikely(block_dump)) | |
1016 | block_dump___mark_inode_dirty(inode); | |
1017 | ||
1018 | spin_lock(&inode_lock); | |
1019 | if ((inode->i_state & flags) != flags) { | |
1020 | const int was_dirty = inode->i_state & I_DIRTY; | |
1021 | ||
1022 | inode->i_state |= flags; | |
1023 | ||
1024 | /* | |
1025 | * If the inode is being synced, just update its dirty state. | |
1026 | * The unlocker will place the inode on the appropriate | |
1027 | * superblock list, based upon its state. | |
1028 | */ | |
1029 | if (inode->i_state & I_SYNC) | |
1030 | goto out; | |
1031 | ||
1032 | /* | |
1033 | * Only add valid (hashed) inodes to the superblock's | |
1034 | * dirty list. Add blockdev inodes as well. | |
1035 | */ | |
1036 | if (!S_ISBLK(inode->i_mode)) { | |
1037 | if (hlist_unhashed(&inode->i_hash)) | |
1038 | goto out; | |
1039 | } | |
1040 | if (inode->i_state & (I_FREEING|I_CLEAR)) | |
1041 | goto out; | |
1042 | ||
1043 | /* | |
1044 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
1045 | * reposition it (that would break b_dirty time-ordering). | |
1046 | */ | |
1047 | if (!was_dirty) { | |
1048 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; | |
500b067c JA |
1049 | struct backing_dev_info *bdi = wb->bdi; |
1050 | ||
1051 | if (bdi_cap_writeback_dirty(bdi) && | |
1052 | !test_bit(BDI_registered, &bdi->state)) { | |
1053 | WARN_ON(1); | |
1054 | printk(KERN_ERR "bdi-%s not registered\n", | |
1055 | bdi->name); | |
1056 | } | |
03ba3782 JA |
1057 | |
1058 | inode->dirtied_when = jiffies; | |
1059 | list_move(&inode->i_list, &wb->b_dirty); | |
1da177e4 | 1060 | } |
1da177e4 | 1061 | } |
03ba3782 JA |
1062 | out: |
1063 | spin_unlock(&inode_lock); | |
1064 | } | |
1065 | EXPORT_SYMBOL(__mark_inode_dirty); | |
1066 | ||
1067 | /* | |
1068 | * Write out a superblock's list of dirty inodes. A wait will be performed | |
1069 | * upon no inodes, all inodes or the final one, depending upon sync_mode. | |
1070 | * | |
1071 | * If older_than_this is non-NULL, then only write out inodes which | |
1072 | * had their first dirtying at a time earlier than *older_than_this. | |
1073 | * | |
1074 | * If we're a pdlfush thread, then implement pdflush collision avoidance | |
1075 | * against the entire list. | |
1076 | * | |
1077 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. | |
1078 | * This function assumes that the blockdev superblock's inodes are backed by | |
1079 | * a variety of queues, so all inodes are searched. For other superblocks, | |
1080 | * assume that all inodes are backed by the same queue. | |
1081 | * | |
1082 | * The inodes to be written are parked on bdi->b_io. They are moved back onto | |
1083 | * bdi->b_dirty as they are selected for writing. This way, none can be missed | |
1084 | * on the writer throttling path, and we get decent balancing between many | |
1085 | * throttled threads: we don't want them all piling up on inode_sync_wait. | |
1086 | */ | |
1087 | static void wait_sb_inodes(struct writeback_control *wbc) | |
1088 | { | |
1089 | struct inode *inode, *old_inode = NULL; | |
1090 | ||
1091 | /* | |
1092 | * We need to be protected against the filesystem going from | |
1093 | * r/o to r/w or vice versa. | |
1094 | */ | |
1095 | WARN_ON(!rwsem_is_locked(&wbc->sb->s_umount)); | |
1096 | ||
1097 | spin_lock(&inode_lock); | |
1098 | ||
1099 | /* | |
1100 | * Data integrity sync. Must wait for all pages under writeback, | |
1101 | * because there may have been pages dirtied before our sync | |
1102 | * call, but which had writeout started before we write it out. | |
1103 | * In which case, the inode may not be on the dirty list, but | |
1104 | * we still have to wait for that writeout. | |
1105 | */ | |
1106 | list_for_each_entry(inode, &wbc->sb->s_inodes, i_sb_list) { | |
1107 | struct address_space *mapping; | |
1108 | ||
1109 | if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) | |
1110 | continue; | |
1111 | mapping = inode->i_mapping; | |
1112 | if (mapping->nrpages == 0) | |
1113 | continue; | |
1114 | __iget(inode); | |
1115 | spin_unlock(&inode_lock); | |
1116 | /* | |
1117 | * We hold a reference to 'inode' so it couldn't have | |
1118 | * been removed from s_inodes list while we dropped the | |
1119 | * inode_lock. We cannot iput the inode now as we can | |
1120 | * be holding the last reference and we cannot iput it | |
1121 | * under inode_lock. So we keep the reference and iput | |
1122 | * it later. | |
1123 | */ | |
1124 | iput(old_inode); | |
1125 | old_inode = inode; | |
1126 | ||
1127 | filemap_fdatawait(mapping); | |
1128 | ||
1129 | cond_resched(); | |
1130 | ||
1131 | spin_lock(&inode_lock); | |
1132 | } | |
1133 | spin_unlock(&inode_lock); | |
1134 | iput(old_inode); | |
1da177e4 LT |
1135 | } |
1136 | ||
d8a8559c JA |
1137 | /** |
1138 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
1139 | * @sb: the superblock | |
1da177e4 | 1140 | * |
d8a8559c JA |
1141 | * Start writeback on some inodes on this super_block. No guarantees are made |
1142 | * on how many (if any) will be written, and this function does not wait | |
1143 | * for IO completion of submitted IO. The number of pages submitted is | |
1144 | * returned. | |
1da177e4 | 1145 | */ |
d8a8559c | 1146 | long writeback_inodes_sb(struct super_block *sb) |
1da177e4 LT |
1147 | { |
1148 | struct writeback_control wbc = { | |
03ba3782 | 1149 | .sb = sb, |
d8a8559c | 1150 | .sync_mode = WB_SYNC_NONE, |
111ebb6e OH |
1151 | .range_start = 0, |
1152 | .range_end = LLONG_MAX, | |
1da177e4 | 1153 | }; |
d8a8559c JA |
1154 | unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); |
1155 | unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); | |
1156 | long nr_to_write; | |
1da177e4 | 1157 | |
d8a8559c | 1158 | nr_to_write = nr_dirty + nr_unstable + |
38f21977 | 1159 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); |
38f21977 | 1160 | |
d8a8559c | 1161 | wbc.nr_to_write = nr_to_write; |
03ba3782 | 1162 | bdi_writeback_all(&wbc); |
d8a8559c JA |
1163 | return nr_to_write - wbc.nr_to_write; |
1164 | } | |
1165 | EXPORT_SYMBOL(writeback_inodes_sb); | |
1166 | ||
1167 | /** | |
1168 | * sync_inodes_sb - sync sb inode pages | |
1169 | * @sb: the superblock | |
1170 | * | |
1171 | * This function writes and waits on any dirty inode belonging to this | |
1172 | * super_block. The number of pages synced is returned. | |
1173 | */ | |
1174 | long sync_inodes_sb(struct super_block *sb) | |
1175 | { | |
1176 | struct writeback_control wbc = { | |
03ba3782 | 1177 | .sb = sb, |
d8a8559c JA |
1178 | .sync_mode = WB_SYNC_ALL, |
1179 | .range_start = 0, | |
1180 | .range_end = LLONG_MAX, | |
1181 | }; | |
1182 | long nr_to_write = LONG_MAX; /* doesn't actually matter */ | |
1183 | ||
1184 | wbc.nr_to_write = nr_to_write; | |
03ba3782 JA |
1185 | bdi_writeback_all(&wbc); |
1186 | wait_sb_inodes(&wbc); | |
d8a8559c | 1187 | return nr_to_write - wbc.nr_to_write; |
1da177e4 | 1188 | } |
d8a8559c | 1189 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 1190 | |
1da177e4 | 1191 | /** |
7f04c26d AA |
1192 | * write_inode_now - write an inode to disk |
1193 | * @inode: inode to write to disk | |
1194 | * @sync: whether the write should be synchronous or not | |
1195 | * | |
1196 | * This function commits an inode to disk immediately if it is dirty. This is | |
1197 | * primarily needed by knfsd. | |
1da177e4 | 1198 | * |
7f04c26d | 1199 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 1200 | */ |
1da177e4 LT |
1201 | int write_inode_now(struct inode *inode, int sync) |
1202 | { | |
1203 | int ret; | |
1204 | struct writeback_control wbc = { | |
1205 | .nr_to_write = LONG_MAX, | |
18914b18 | 1206 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
1207 | .range_start = 0, |
1208 | .range_end = LLONG_MAX, | |
1da177e4 LT |
1209 | }; |
1210 | ||
1211 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 1212 | wbc.nr_to_write = 0; |
1da177e4 LT |
1213 | |
1214 | might_sleep(); | |
1215 | spin_lock(&inode_lock); | |
01c03194 | 1216 | ret = writeback_single_inode(inode, &wbc); |
1da177e4 LT |
1217 | spin_unlock(&inode_lock); |
1218 | if (sync) | |
1c0eeaf5 | 1219 | inode_sync_wait(inode); |
1da177e4 LT |
1220 | return ret; |
1221 | } | |
1222 | EXPORT_SYMBOL(write_inode_now); | |
1223 | ||
1224 | /** | |
1225 | * sync_inode - write an inode and its pages to disk. | |
1226 | * @inode: the inode to sync | |
1227 | * @wbc: controls the writeback mode | |
1228 | * | |
1229 | * sync_inode() will write an inode and its pages to disk. It will also | |
1230 | * correctly update the inode on its superblock's dirty inode lists and will | |
1231 | * update inode->i_state. | |
1232 | * | |
1233 | * The caller must have a ref on the inode. | |
1234 | */ | |
1235 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
1236 | { | |
1237 | int ret; | |
1238 | ||
1239 | spin_lock(&inode_lock); | |
01c03194 | 1240 | ret = writeback_single_inode(inode, wbc); |
1da177e4 LT |
1241 | spin_unlock(&inode_lock); |
1242 | return ret; | |
1243 | } | |
1244 | EXPORT_SYMBOL(sync_inode); | |
1245 | ||
1246 | /** | |
1247 | * generic_osync_inode - flush all dirty data for a given inode to disk | |
1248 | * @inode: inode to write | |
67be2dd1 | 1249 | * @mapping: the address_space that should be flushed |
1da177e4 LT |
1250 | * @what: what to write and wait upon |
1251 | * | |
1252 | * This can be called by file_write functions for files which have the | |
1253 | * O_SYNC flag set, to flush dirty writes to disk. | |
1254 | * | |
1255 | * @what is a bitmask, specifying which part of the inode's data should be | |
b8887e6e | 1256 | * written and waited upon. |
1da177e4 LT |
1257 | * |
1258 | * OSYNC_DATA: i_mapping's dirty data | |
1259 | * OSYNC_METADATA: the buffers at i_mapping->private_list | |
1260 | * OSYNC_INODE: the inode itself | |
1261 | */ | |
1262 | ||
1263 | int generic_osync_inode(struct inode *inode, struct address_space *mapping, int what) | |
1264 | { | |
1265 | int err = 0; | |
1266 | int need_write_inode_now = 0; | |
1267 | int err2; | |
1268 | ||
1da177e4 LT |
1269 | if (what & OSYNC_DATA) |
1270 | err = filemap_fdatawrite(mapping); | |
1271 | if (what & (OSYNC_METADATA|OSYNC_DATA)) { | |
1272 | err2 = sync_mapping_buffers(mapping); | |
1273 | if (!err) | |
1274 | err = err2; | |
1275 | } | |
1276 | if (what & OSYNC_DATA) { | |
1277 | err2 = filemap_fdatawait(mapping); | |
1278 | if (!err) | |
1279 | err = err2; | |
1280 | } | |
1da177e4 LT |
1281 | |
1282 | spin_lock(&inode_lock); | |
1283 | if ((inode->i_state & I_DIRTY) && | |
1284 | ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC))) | |
1285 | need_write_inode_now = 1; | |
1286 | spin_unlock(&inode_lock); | |
1287 | ||
1288 | if (need_write_inode_now) { | |
1289 | err2 = write_inode_now(inode, 1); | |
1290 | if (!err) | |
1291 | err = err2; | |
1292 | } | |
1293 | else | |
1c0eeaf5 | 1294 | inode_sync_wait(inode); |
1da177e4 LT |
1295 | |
1296 | return err; | |
1297 | } | |
1da177e4 | 1298 | EXPORT_SYMBOL(generic_osync_inode); |