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 | 18 | #include <linux/spinlock.h> |
5a0e3ad6 | 19 | #include <linux/slab.h> |
1da177e4 LT |
20 | #include <linux/sched.h> |
21 | #include <linux/fs.h> | |
22 | #include <linux/mm.h> | |
03ba3782 JA |
23 | #include <linux/kthread.h> |
24 | #include <linux/freezer.h> | |
1da177e4 LT |
25 | #include <linux/writeback.h> |
26 | #include <linux/blkdev.h> | |
27 | #include <linux/backing-dev.h> | |
28 | #include <linux/buffer_head.h> | |
07f3f05c | 29 | #include "internal.h" |
1da177e4 | 30 | |
66f3b8e2 | 31 | #define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info) |
f11b00f3 | 32 | |
d0bceac7 JA |
33 | /* |
34 | * We don't actually have pdflush, but this one is exported though /proc... | |
35 | */ | |
36 | int nr_pdflush_threads; | |
37 | ||
c4a77a6c JA |
38 | /* |
39 | * Passed into wb_writeback(), essentially a subset of writeback_control | |
40 | */ | |
41 | struct wb_writeback_args { | |
42 | long nr_pages; | |
43 | struct super_block *sb; | |
44 | enum writeback_sync_modes sync_mode; | |
d3ddec76 WF |
45 | int for_kupdate:1; |
46 | int range_cyclic:1; | |
47 | int for_background:1; | |
c4a77a6c JA |
48 | }; |
49 | ||
03ba3782 JA |
50 | /* |
51 | * Work items for the bdi_writeback threads | |
f11b00f3 | 52 | */ |
03ba3782 | 53 | struct bdi_work { |
8010c3b6 JA |
54 | struct list_head list; /* pending work list */ |
55 | struct rcu_head rcu_head; /* for RCU free/clear of work */ | |
03ba3782 | 56 | |
8010c3b6 JA |
57 | unsigned long seen; /* threads that have seen this work */ |
58 | atomic_t pending; /* number of threads still to do work */ | |
03ba3782 | 59 | |
8010c3b6 | 60 | struct wb_writeback_args args; /* writeback arguments */ |
03ba3782 | 61 | |
8010c3b6 | 62 | unsigned long state; /* flag bits, see WS_* */ |
03ba3782 JA |
63 | }; |
64 | ||
65 | enum { | |
66 | WS_USED_B = 0, | |
67 | WS_ONSTACK_B, | |
68 | }; | |
69 | ||
70 | #define WS_USED (1 << WS_USED_B) | |
71 | #define WS_ONSTACK (1 << WS_ONSTACK_B) | |
72 | ||
73 | static inline bool bdi_work_on_stack(struct bdi_work *work) | |
74 | { | |
75 | return test_bit(WS_ONSTACK_B, &work->state); | |
76 | } | |
77 | ||
78 | static inline void bdi_work_init(struct bdi_work *work, | |
b6e51316 | 79 | struct wb_writeback_args *args) |
03ba3782 JA |
80 | { |
81 | INIT_RCU_HEAD(&work->rcu_head); | |
b6e51316 | 82 | work->args = *args; |
03ba3782 JA |
83 | work->state = WS_USED; |
84 | } | |
85 | ||
f11b00f3 AB |
86 | /** |
87 | * writeback_in_progress - determine whether there is writeback in progress | |
88 | * @bdi: the device's backing_dev_info structure. | |
89 | * | |
03ba3782 JA |
90 | * Determine whether there is writeback waiting to be handled against a |
91 | * backing device. | |
f11b00f3 AB |
92 | */ |
93 | int writeback_in_progress(struct backing_dev_info *bdi) | |
94 | { | |
03ba3782 | 95 | return !list_empty(&bdi->work_list); |
f11b00f3 AB |
96 | } |
97 | ||
03ba3782 | 98 | static void bdi_work_clear(struct bdi_work *work) |
f11b00f3 | 99 | { |
03ba3782 JA |
100 | clear_bit(WS_USED_B, &work->state); |
101 | smp_mb__after_clear_bit(); | |
1ef7d9aa NP |
102 | /* |
103 | * work can have disappeared at this point. bit waitq functions | |
104 | * should be able to tolerate this, provided bdi_sched_wait does | |
105 | * not dereference it's pointer argument. | |
106 | */ | |
03ba3782 | 107 | wake_up_bit(&work->state, WS_USED_B); |
f11b00f3 AB |
108 | } |
109 | ||
03ba3782 | 110 | static void bdi_work_free(struct rcu_head *head) |
4195f73d | 111 | { |
03ba3782 | 112 | struct bdi_work *work = container_of(head, struct bdi_work, rcu_head); |
4195f73d | 113 | |
03ba3782 JA |
114 | if (!bdi_work_on_stack(work)) |
115 | kfree(work); | |
116 | else | |
117 | bdi_work_clear(work); | |
4195f73d NP |
118 | } |
119 | ||
03ba3782 | 120 | static void wb_work_complete(struct bdi_work *work) |
1da177e4 | 121 | { |
c4a77a6c | 122 | const enum writeback_sync_modes sync_mode = work->args.sync_mode; |
77b9d059 | 123 | int onstack = bdi_work_on_stack(work); |
1da177e4 LT |
124 | |
125 | /* | |
03ba3782 JA |
126 | * For allocated work, we can clear the done/seen bit right here. |
127 | * For on-stack work, we need to postpone both the clear and free | |
128 | * to after the RCU grace period, since the stack could be invalidated | |
129 | * as soon as bdi_work_clear() has done the wakeup. | |
1da177e4 | 130 | */ |
77b9d059 | 131 | if (!onstack) |
03ba3782 | 132 | bdi_work_clear(work); |
77b9d059 | 133 | if (sync_mode == WB_SYNC_NONE || onstack) |
03ba3782 JA |
134 | call_rcu(&work->rcu_head, bdi_work_free); |
135 | } | |
1da177e4 | 136 | |
03ba3782 JA |
137 | static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work) |
138 | { | |
1da177e4 | 139 | /* |
03ba3782 JA |
140 | * The caller has retrieved the work arguments from this work, |
141 | * drop our reference. If this is the last ref, delete and free it | |
1da177e4 | 142 | */ |
03ba3782 JA |
143 | if (atomic_dec_and_test(&work->pending)) { |
144 | struct backing_dev_info *bdi = wb->bdi; | |
1da177e4 | 145 | |
03ba3782 JA |
146 | spin_lock(&bdi->wb_lock); |
147 | list_del_rcu(&work->list); | |
148 | spin_unlock(&bdi->wb_lock); | |
1da177e4 | 149 | |
03ba3782 JA |
150 | wb_work_complete(work); |
151 | } | |
152 | } | |
1da177e4 | 153 | |
03ba3782 JA |
154 | static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work) |
155 | { | |
bcddc3f0 JA |
156 | work->seen = bdi->wb_mask; |
157 | BUG_ON(!work->seen); | |
158 | atomic_set(&work->pending, bdi->wb_cnt); | |
159 | BUG_ON(!bdi->wb_cnt); | |
1da177e4 | 160 | |
bcddc3f0 | 161 | /* |
deed62ed NP |
162 | * list_add_tail_rcu() contains the necessary barriers to |
163 | * make sure the above stores are seen before the item is | |
164 | * noticed on the list | |
bcddc3f0 | 165 | */ |
bcddc3f0 JA |
166 | spin_lock(&bdi->wb_lock); |
167 | list_add_tail_rcu(&work->list, &bdi->work_list); | |
168 | spin_unlock(&bdi->wb_lock); | |
03ba3782 JA |
169 | |
170 | /* | |
171 | * If the default thread isn't there, make sure we add it. When | |
172 | * it gets created and wakes up, we'll run this work. | |
173 | */ | |
174 | if (unlikely(list_empty_careful(&bdi->wb_list))) | |
175 | wake_up_process(default_backing_dev_info.wb.task); | |
176 | else { | |
177 | struct bdi_writeback *wb = &bdi->wb; | |
1da177e4 | 178 | |
1ef7d9aa | 179 | if (wb->task) |
03ba3782 | 180 | wake_up_process(wb->task); |
1da177e4 | 181 | } |
1da177e4 LT |
182 | } |
183 | ||
03ba3782 JA |
184 | /* |
185 | * Used for on-stack allocated work items. The caller needs to wait until | |
186 | * the wb threads have acked the work before it's safe to continue. | |
187 | */ | |
188 | static void bdi_wait_on_work_clear(struct bdi_work *work) | |
189 | { | |
190 | wait_on_bit(&work->state, WS_USED_B, bdi_sched_wait, | |
191 | TASK_UNINTERRUPTIBLE); | |
192 | } | |
1da177e4 | 193 | |
f11fcae8 | 194 | static void bdi_alloc_queue_work(struct backing_dev_info *bdi, |
b6e51316 | 195 | struct wb_writeback_args *args) |
1da177e4 | 196 | { |
03ba3782 JA |
197 | struct bdi_work *work; |
198 | ||
bcddc3f0 JA |
199 | /* |
200 | * This is WB_SYNC_NONE writeback, so if allocation fails just | |
201 | * wakeup the thread for old dirty data writeback | |
202 | */ | |
03ba3782 | 203 | work = kmalloc(sizeof(*work), GFP_ATOMIC); |
bcddc3f0 | 204 | if (work) { |
b6e51316 | 205 | bdi_work_init(work, args); |
bcddc3f0 JA |
206 | bdi_queue_work(bdi, work); |
207 | } else { | |
208 | struct bdi_writeback *wb = &bdi->wb; | |
03ba3782 | 209 | |
bcddc3f0 JA |
210 | if (wb->task) |
211 | wake_up_process(wb->task); | |
212 | } | |
03ba3782 JA |
213 | } |
214 | ||
b6e51316 JA |
215 | /** |
216 | * bdi_sync_writeback - start and wait for writeback | |
217 | * @bdi: the backing device to write from | |
218 | * @sb: write inodes from this super_block | |
219 | * | |
220 | * Description: | |
221 | * This does WB_SYNC_ALL data integrity writeback and waits for the | |
222 | * IO to complete. Callers must hold the sb s_umount semaphore for | |
223 | * reading, to avoid having the super disappear before we are done. | |
224 | */ | |
225 | static void bdi_sync_writeback(struct backing_dev_info *bdi, | |
226 | struct super_block *sb) | |
03ba3782 | 227 | { |
b6e51316 JA |
228 | struct wb_writeback_args args = { |
229 | .sb = sb, | |
230 | .sync_mode = WB_SYNC_ALL, | |
231 | .nr_pages = LONG_MAX, | |
232 | .range_cyclic = 0, | |
233 | }; | |
234 | struct bdi_work work; | |
03ba3782 | 235 | |
b6e51316 JA |
236 | bdi_work_init(&work, &args); |
237 | work.state |= WS_ONSTACK; | |
03ba3782 | 238 | |
b6e51316 JA |
239 | bdi_queue_work(bdi, &work); |
240 | bdi_wait_on_work_clear(&work); | |
241 | } | |
242 | ||
243 | /** | |
244 | * bdi_start_writeback - start writeback | |
245 | * @bdi: the backing device to write from | |
4b6764fa | 246 | * @sb: write inodes from this super_block |
b6e51316 JA |
247 | * @nr_pages: the number of pages to write |
248 | * | |
249 | * Description: | |
250 | * This does WB_SYNC_NONE opportunistic writeback. The IO is only | |
251 | * started when this function returns, we make no guarentees on | |
252 | * completion. Caller need not hold sb s_umount semaphore. | |
253 | * | |
254 | */ | |
a72bfd4d JA |
255 | void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb, |
256 | long nr_pages) | |
b6e51316 JA |
257 | { |
258 | struct wb_writeback_args args = { | |
a72bfd4d | 259 | .sb = sb, |
b6e51316 JA |
260 | .sync_mode = WB_SYNC_NONE, |
261 | .nr_pages = nr_pages, | |
262 | .range_cyclic = 1, | |
263 | }; | |
264 | ||
d3ddec76 WF |
265 | /* |
266 | * We treat @nr_pages=0 as the special case to do background writeback, | |
267 | * ie. to sync pages until the background dirty threshold is reached. | |
268 | */ | |
269 | if (!nr_pages) { | |
270 | args.nr_pages = LONG_MAX; | |
271 | args.for_background = 1; | |
272 | } | |
273 | ||
b6e51316 | 274 | bdi_alloc_queue_work(bdi, &args); |
1da177e4 LT |
275 | } |
276 | ||
6610a0bc AM |
277 | /* |
278 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
279 | * furthest end of its superblock's dirty-inode list. | |
280 | * | |
281 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 282 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
283 | * the case then the inode must have been redirtied while it was being written |
284 | * out and we don't reset its dirtied_when. | |
285 | */ | |
286 | static void redirty_tail(struct inode *inode) | |
287 | { | |
03ba3782 | 288 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
6610a0bc | 289 | |
03ba3782 | 290 | if (!list_empty(&wb->b_dirty)) { |
66f3b8e2 | 291 | struct inode *tail; |
6610a0bc | 292 | |
03ba3782 | 293 | tail = list_entry(wb->b_dirty.next, struct inode, i_list); |
66f3b8e2 | 294 | if (time_before(inode->dirtied_when, tail->dirtied_when)) |
6610a0bc AM |
295 | inode->dirtied_when = jiffies; |
296 | } | |
03ba3782 | 297 | list_move(&inode->i_list, &wb->b_dirty); |
6610a0bc AM |
298 | } |
299 | ||
c986d1e2 | 300 | /* |
66f3b8e2 | 301 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 302 | */ |
0e0f4fc2 | 303 | static void requeue_io(struct inode *inode) |
c986d1e2 | 304 | { |
03ba3782 JA |
305 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
306 | ||
307 | list_move(&inode->i_list, &wb->b_more_io); | |
c986d1e2 AM |
308 | } |
309 | ||
1c0eeaf5 JE |
310 | static void inode_sync_complete(struct inode *inode) |
311 | { | |
312 | /* | |
313 | * Prevent speculative execution through spin_unlock(&inode_lock); | |
314 | */ | |
315 | smp_mb(); | |
316 | wake_up_bit(&inode->i_state, __I_SYNC); | |
317 | } | |
318 | ||
d2caa3c5 JL |
319 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
320 | { | |
321 | bool ret = time_after(inode->dirtied_when, t); | |
322 | #ifndef CONFIG_64BIT | |
323 | /* | |
324 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
325 | * It _appears_ to be in the future, but is actually in distant past. | |
326 | * This test is necessary to prevent such wrapped-around relative times | |
5b0830cb | 327 | * from permanently stopping the whole bdi writeback. |
d2caa3c5 JL |
328 | */ |
329 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
330 | #endif | |
331 | return ret; | |
332 | } | |
333 | ||
2c136579 FW |
334 | /* |
335 | * Move expired dirty inodes from @delaying_queue to @dispatch_queue. | |
336 | */ | |
337 | static void move_expired_inodes(struct list_head *delaying_queue, | |
338 | struct list_head *dispatch_queue, | |
339 | unsigned long *older_than_this) | |
340 | { | |
5c03449d SL |
341 | LIST_HEAD(tmp); |
342 | struct list_head *pos, *node; | |
cf137307 | 343 | struct super_block *sb = NULL; |
5c03449d | 344 | struct inode *inode; |
cf137307 | 345 | int do_sb_sort = 0; |
5c03449d | 346 | |
2c136579 | 347 | while (!list_empty(delaying_queue)) { |
5c03449d | 348 | inode = list_entry(delaying_queue->prev, struct inode, i_list); |
2c136579 | 349 | if (older_than_this && |
d2caa3c5 | 350 | inode_dirtied_after(inode, *older_than_this)) |
2c136579 | 351 | break; |
cf137307 JA |
352 | if (sb && sb != inode->i_sb) |
353 | do_sb_sort = 1; | |
354 | sb = inode->i_sb; | |
5c03449d SL |
355 | list_move(&inode->i_list, &tmp); |
356 | } | |
357 | ||
cf137307 JA |
358 | /* just one sb in list, splice to dispatch_queue and we're done */ |
359 | if (!do_sb_sort) { | |
360 | list_splice(&tmp, dispatch_queue); | |
361 | return; | |
362 | } | |
363 | ||
5c03449d SL |
364 | /* Move inodes from one superblock together */ |
365 | while (!list_empty(&tmp)) { | |
366 | inode = list_entry(tmp.prev, struct inode, i_list); | |
367 | sb = inode->i_sb; | |
368 | list_for_each_prev_safe(pos, node, &tmp) { | |
369 | inode = list_entry(pos, struct inode, i_list); | |
370 | if (inode->i_sb == sb) | |
371 | list_move(&inode->i_list, dispatch_queue); | |
372 | } | |
2c136579 FW |
373 | } |
374 | } | |
375 | ||
376 | /* | |
377 | * Queue all expired dirty inodes for io, eldest first. | |
378 | */ | |
03ba3782 | 379 | static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) |
66f3b8e2 | 380 | { |
03ba3782 JA |
381 | list_splice_init(&wb->b_more_io, wb->b_io.prev); |
382 | move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); | |
66f3b8e2 JA |
383 | } |
384 | ||
a9185b41 | 385 | static int write_inode(struct inode *inode, struct writeback_control *wbc) |
08d8e974 | 386 | { |
03ba3782 | 387 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) |
a9185b41 | 388 | return inode->i_sb->s_op->write_inode(inode, wbc); |
03ba3782 | 389 | return 0; |
08d8e974 | 390 | } |
08d8e974 | 391 | |
1da177e4 | 392 | /* |
01c03194 CH |
393 | * Wait for writeback on an inode to complete. |
394 | */ | |
395 | static void inode_wait_for_writeback(struct inode *inode) | |
396 | { | |
397 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
398 | wait_queue_head_t *wqh; | |
399 | ||
400 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
401 | do { | |
402 | spin_unlock(&inode_lock); | |
403 | __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); | |
404 | spin_lock(&inode_lock); | |
405 | } while (inode->i_state & I_SYNC); | |
406 | } | |
407 | ||
408 | /* | |
409 | * Write out an inode's dirty pages. Called under inode_lock. Either the | |
410 | * caller has ref on the inode (either via __iget or via syscall against an fd) | |
411 | * or the inode has I_WILL_FREE set (via generic_forget_inode) | |
412 | * | |
1da177e4 LT |
413 | * If `wait' is set, wait on the writeout. |
414 | * | |
415 | * The whole writeout design is quite complex and fragile. We want to avoid | |
416 | * starvation of particular inodes when others are being redirtied, prevent | |
417 | * livelocks, etc. | |
418 | * | |
419 | * Called under inode_lock. | |
420 | */ | |
421 | static int | |
01c03194 | 422 | writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 423 | { |
1da177e4 | 424 | struct address_space *mapping = inode->i_mapping; |
01c03194 | 425 | unsigned dirty; |
1da177e4 LT |
426 | int ret; |
427 | ||
01c03194 CH |
428 | if (!atomic_read(&inode->i_count)) |
429 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
430 | else | |
431 | WARN_ON(inode->i_state & I_WILL_FREE); | |
432 | ||
433 | if (inode->i_state & I_SYNC) { | |
434 | /* | |
435 | * If this inode is locked for writeback and we are not doing | |
66f3b8e2 | 436 | * writeback-for-data-integrity, move it to b_more_io so that |
01c03194 CH |
437 | * writeback can proceed with the other inodes on s_io. |
438 | * | |
439 | * We'll have another go at writing back this inode when we | |
66f3b8e2 | 440 | * completed a full scan of b_io. |
01c03194 | 441 | */ |
a9185b41 | 442 | if (wbc->sync_mode != WB_SYNC_ALL) { |
01c03194 CH |
443 | requeue_io(inode); |
444 | return 0; | |
445 | } | |
446 | ||
447 | /* | |
448 | * It's a data-integrity sync. We must wait. | |
449 | */ | |
450 | inode_wait_for_writeback(inode); | |
451 | } | |
452 | ||
1c0eeaf5 | 453 | BUG_ON(inode->i_state & I_SYNC); |
1da177e4 | 454 | |
1c0eeaf5 | 455 | /* Set I_SYNC, reset I_DIRTY */ |
1da177e4 | 456 | dirty = inode->i_state & I_DIRTY; |
1c0eeaf5 | 457 | inode->i_state |= I_SYNC; |
1da177e4 LT |
458 | inode->i_state &= ~I_DIRTY; |
459 | ||
460 | spin_unlock(&inode_lock); | |
461 | ||
462 | ret = do_writepages(mapping, wbc); | |
463 | ||
26821ed4 CH |
464 | /* |
465 | * Make sure to wait on the data before writing out the metadata. | |
466 | * This is important for filesystems that modify metadata on data | |
467 | * I/O completion. | |
468 | */ | |
a9185b41 | 469 | if (wbc->sync_mode == WB_SYNC_ALL) { |
26821ed4 | 470 | int err = filemap_fdatawait(mapping); |
1da177e4 LT |
471 | if (ret == 0) |
472 | ret = err; | |
473 | } | |
474 | ||
26821ed4 CH |
475 | /* Don't write the inode if only I_DIRTY_PAGES was set */ |
476 | if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
a9185b41 | 477 | int err = write_inode(inode, wbc); |
1da177e4 LT |
478 | if (ret == 0) |
479 | ret = err; | |
480 | } | |
481 | ||
482 | spin_lock(&inode_lock); | |
1c0eeaf5 | 483 | inode->i_state &= ~I_SYNC; |
84a89245 | 484 | if (!(inode->i_state & (I_FREEING | I_CLEAR))) { |
b3af9468 | 485 | if ((inode->i_state & I_DIRTY_PAGES) && wbc->for_kupdate) { |
ae1b7f7d | 486 | /* |
b3af9468 WF |
487 | * More pages get dirtied by a fast dirtier. |
488 | */ | |
489 | goto select_queue; | |
490 | } else if (inode->i_state & I_DIRTY) { | |
491 | /* | |
492 | * At least XFS will redirty the inode during the | |
493 | * writeback (delalloc) and on io completion (isize). | |
ae1b7f7d WF |
494 | */ |
495 | redirty_tail(inode); | |
496 | } else if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { | |
1da177e4 LT |
497 | /* |
498 | * We didn't write back all the pages. nfs_writepages() | |
499 | * sometimes bales out without doing anything. Redirty | |
66f3b8e2 | 500 | * the inode; Move it from b_io onto b_more_io/b_dirty. |
1b43ef91 AM |
501 | */ |
502 | /* | |
503 | * akpm: if the caller was the kupdate function we put | |
66f3b8e2 | 504 | * this inode at the head of b_dirty so it gets first |
1b43ef91 AM |
505 | * consideration. Otherwise, move it to the tail, for |
506 | * the reasons described there. I'm not really sure | |
507 | * how much sense this makes. Presumably I had a good | |
508 | * reasons for doing it this way, and I'd rather not | |
509 | * muck with it at present. | |
1da177e4 LT |
510 | */ |
511 | if (wbc->for_kupdate) { | |
512 | /* | |
2c136579 | 513 | * For the kupdate function we move the inode |
66f3b8e2 | 514 | * to b_more_io so it will get more writeout as |
2c136579 | 515 | * soon as the queue becomes uncongested. |
1da177e4 LT |
516 | */ |
517 | inode->i_state |= I_DIRTY_PAGES; | |
b3af9468 | 518 | select_queue: |
8bc3be27 FW |
519 | if (wbc->nr_to_write <= 0) { |
520 | /* | |
521 | * slice used up: queue for next turn | |
522 | */ | |
523 | requeue_io(inode); | |
524 | } else { | |
525 | /* | |
526 | * somehow blocked: retry later | |
527 | */ | |
528 | redirty_tail(inode); | |
529 | } | |
1da177e4 LT |
530 | } else { |
531 | /* | |
532 | * Otherwise fully redirty the inode so that | |
533 | * other inodes on this superblock will get some | |
534 | * writeout. Otherwise heavy writing to one | |
535 | * file would indefinitely suspend writeout of | |
536 | * all the other files. | |
537 | */ | |
538 | inode->i_state |= I_DIRTY_PAGES; | |
1b43ef91 | 539 | redirty_tail(inode); |
1da177e4 | 540 | } |
1da177e4 LT |
541 | } else if (atomic_read(&inode->i_count)) { |
542 | /* | |
543 | * The inode is clean, inuse | |
544 | */ | |
545 | list_move(&inode->i_list, &inode_in_use); | |
546 | } else { | |
547 | /* | |
548 | * The inode is clean, unused | |
549 | */ | |
550 | list_move(&inode->i_list, &inode_unused); | |
1da177e4 LT |
551 | } |
552 | } | |
1c0eeaf5 | 553 | inode_sync_complete(inode); |
1da177e4 LT |
554 | return ret; |
555 | } | |
556 | ||
f11c9c5c | 557 | static void unpin_sb_for_writeback(struct super_block *sb) |
9ecc2738 | 558 | { |
f11c9c5c ES |
559 | up_read(&sb->s_umount); |
560 | put_super(sb); | |
9ecc2738 JA |
561 | } |
562 | ||
f11c9c5c ES |
563 | enum sb_pin_state { |
564 | SB_PINNED, | |
565 | SB_NOT_PINNED, | |
566 | SB_PIN_FAILED | |
567 | }; | |
568 | ||
03ba3782 JA |
569 | /* |
570 | * For WB_SYNC_NONE writeback, the caller does not have the sb pinned | |
571 | * before calling writeback. So make sure that we do pin it, so it doesn't | |
572 | * go away while we are writing inodes from it. | |
03ba3782 | 573 | */ |
f11c9c5c ES |
574 | static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc, |
575 | struct super_block *sb) | |
03ba3782 | 576 | { |
03ba3782 JA |
577 | /* |
578 | * Caller must already hold the ref for this | |
579 | */ | |
580 | if (wbc->sync_mode == WB_SYNC_ALL) { | |
581 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); | |
f11c9c5c | 582 | return SB_NOT_PINNED; |
03ba3782 | 583 | } |
03ba3782 JA |
584 | spin_lock(&sb_lock); |
585 | sb->s_count++; | |
586 | if (down_read_trylock(&sb->s_umount)) { | |
587 | if (sb->s_root) { | |
588 | spin_unlock(&sb_lock); | |
f11c9c5c | 589 | return SB_PINNED; |
03ba3782 JA |
590 | } |
591 | /* | |
592 | * umounted, drop rwsem again and fall through to failure | |
593 | */ | |
594 | up_read(&sb->s_umount); | |
595 | } | |
03ba3782 JA |
596 | sb->s_count--; |
597 | spin_unlock(&sb_lock); | |
f11c9c5c | 598 | return SB_PIN_FAILED; |
03ba3782 JA |
599 | } |
600 | ||
f11c9c5c ES |
601 | /* |
602 | * Write a portion of b_io inodes which belong to @sb. | |
603 | * If @wbc->sb != NULL, then find and write all such | |
604 | * inodes. Otherwise write only ones which go sequentially | |
605 | * in reverse order. | |
606 | * Return 1, if the caller writeback routine should be | |
607 | * interrupted. Otherwise return 0. | |
608 | */ | |
609 | static int writeback_sb_inodes(struct super_block *sb, | |
610 | struct bdi_writeback *wb, | |
611 | struct writeback_control *wbc) | |
1da177e4 | 612 | { |
03ba3782 | 613 | while (!list_empty(&wb->b_io)) { |
1da177e4 | 614 | long pages_skipped; |
f11c9c5c ES |
615 | struct inode *inode = list_entry(wb->b_io.prev, |
616 | struct inode, i_list); | |
617 | if (wbc->sb && sb != inode->i_sb) { | |
618 | /* super block given and doesn't | |
619 | match, skip this inode */ | |
66f3b8e2 JA |
620 | redirty_tail(inode); |
621 | continue; | |
622 | } | |
f11c9c5c ES |
623 | if (sb != inode->i_sb) |
624 | /* finish with this superblock */ | |
625 | return 0; | |
84a89245 | 626 | if (inode->i_state & (I_NEW | I_WILL_FREE)) { |
7ef0d737 NP |
627 | requeue_io(inode); |
628 | continue; | |
629 | } | |
d2caa3c5 JL |
630 | /* |
631 | * Was this inode dirtied after sync_sb_inodes was called? | |
632 | * This keeps sync from extra jobs and livelock. | |
633 | */ | |
f11c9c5c ES |
634 | if (inode_dirtied_after(inode, wbc->wb_start)) |
635 | return 1; | |
1da177e4 | 636 | |
84a89245 | 637 | BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); |
1da177e4 LT |
638 | __iget(inode); |
639 | pages_skipped = wbc->pages_skipped; | |
01c03194 | 640 | writeback_single_inode(inode, wbc); |
1da177e4 LT |
641 | if (wbc->pages_skipped != pages_skipped) { |
642 | /* | |
643 | * writeback is not making progress due to locked | |
644 | * buffers. Skip this inode for now. | |
645 | */ | |
f57b9b7b | 646 | redirty_tail(inode); |
1da177e4 LT |
647 | } |
648 | spin_unlock(&inode_lock); | |
1da177e4 | 649 | iput(inode); |
4ffc8444 | 650 | cond_resched(); |
1da177e4 | 651 | spin_lock(&inode_lock); |
8bc3be27 FW |
652 | if (wbc->nr_to_write <= 0) { |
653 | wbc->more_io = 1; | |
f11c9c5c | 654 | return 1; |
8bc3be27 | 655 | } |
03ba3782 | 656 | if (!list_empty(&wb->b_more_io)) |
8bc3be27 | 657 | wbc->more_io = 1; |
1da177e4 | 658 | } |
f11c9c5c ES |
659 | /* b_io is empty */ |
660 | return 1; | |
661 | } | |
662 | ||
663 | static void writeback_inodes_wb(struct bdi_writeback *wb, | |
664 | struct writeback_control *wbc) | |
665 | { | |
666 | int ret = 0; | |
667 | ||
668 | wbc->wb_start = jiffies; /* livelock avoidance */ | |
669 | spin_lock(&inode_lock); | |
670 | if (!wbc->for_kupdate || list_empty(&wb->b_io)) | |
671 | queue_io(wb, wbc->older_than_this); | |
38f21977 | 672 | |
f11c9c5c ES |
673 | while (!list_empty(&wb->b_io)) { |
674 | struct inode *inode = list_entry(wb->b_io.prev, | |
675 | struct inode, i_list); | |
676 | struct super_block *sb = inode->i_sb; | |
677 | enum sb_pin_state state; | |
9ecc2738 | 678 | |
f11c9c5c ES |
679 | if (wbc->sb && sb != wbc->sb) { |
680 | /* super block given and doesn't | |
681 | match, skip this inode */ | |
682 | redirty_tail(inode); | |
683 | continue; | |
684 | } | |
685 | state = pin_sb_for_writeback(wbc, sb); | |
686 | ||
687 | if (state == SB_PIN_FAILED) { | |
688 | requeue_io(inode); | |
689 | continue; | |
690 | } | |
691 | ret = writeback_sb_inodes(sb, wb, wbc); | |
692 | ||
693 | if (state == SB_PINNED) | |
694 | unpin_sb_for_writeback(sb); | |
695 | if (ret) | |
696 | break; | |
697 | } | |
66f3b8e2 JA |
698 | spin_unlock(&inode_lock); |
699 | /* Leave any unwritten inodes on b_io */ | |
700 | } | |
701 | ||
03ba3782 JA |
702 | void writeback_inodes_wbc(struct writeback_control *wbc) |
703 | { | |
704 | struct backing_dev_info *bdi = wbc->bdi; | |
705 | ||
706 | writeback_inodes_wb(&bdi->wb, wbc); | |
707 | } | |
708 | ||
66f3b8e2 | 709 | /* |
03ba3782 JA |
710 | * The maximum number of pages to writeout in a single bdi flush/kupdate |
711 | * operation. We do this so we don't hold I_SYNC against an inode for | |
712 | * enormous amounts of time, which would block a userspace task which has | |
713 | * been forced to throttle against that inode. Also, the code reevaluates | |
714 | * the dirty each time it has written this many pages. | |
715 | */ | |
716 | #define MAX_WRITEBACK_PAGES 1024 | |
717 | ||
718 | static inline bool over_bground_thresh(void) | |
719 | { | |
720 | unsigned long background_thresh, dirty_thresh; | |
721 | ||
722 | get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); | |
723 | ||
724 | return (global_page_state(NR_FILE_DIRTY) + | |
725 | global_page_state(NR_UNSTABLE_NFS) >= background_thresh); | |
726 | } | |
727 | ||
728 | /* | |
729 | * Explicit flushing or periodic writeback of "old" data. | |
66f3b8e2 | 730 | * |
03ba3782 JA |
731 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
732 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
733 | * just walks the superblock inode list, writing back any inodes which are | |
734 | * older than a specific point in time. | |
66f3b8e2 | 735 | * |
03ba3782 JA |
736 | * Try to run once per dirty_writeback_interval. But if a writeback event |
737 | * takes longer than a dirty_writeback_interval interval, then leave a | |
738 | * one-second gap. | |
66f3b8e2 | 739 | * |
03ba3782 JA |
740 | * older_than_this takes precedence over nr_to_write. So we'll only write back |
741 | * all dirty pages if they are all attached to "old" mappings. | |
66f3b8e2 | 742 | */ |
c4a77a6c JA |
743 | static long wb_writeback(struct bdi_writeback *wb, |
744 | struct wb_writeback_args *args) | |
66f3b8e2 | 745 | { |
03ba3782 JA |
746 | struct writeback_control wbc = { |
747 | .bdi = wb->bdi, | |
c4a77a6c JA |
748 | .sb = args->sb, |
749 | .sync_mode = args->sync_mode, | |
03ba3782 | 750 | .older_than_this = NULL, |
c4a77a6c | 751 | .for_kupdate = args->for_kupdate, |
b17621fe | 752 | .for_background = args->for_background, |
c4a77a6c | 753 | .range_cyclic = args->range_cyclic, |
03ba3782 JA |
754 | }; |
755 | unsigned long oldest_jif; | |
756 | long wrote = 0; | |
a5989bdc | 757 | struct inode *inode; |
66f3b8e2 | 758 | |
03ba3782 JA |
759 | if (wbc.for_kupdate) { |
760 | wbc.older_than_this = &oldest_jif; | |
761 | oldest_jif = jiffies - | |
762 | msecs_to_jiffies(dirty_expire_interval * 10); | |
763 | } | |
c4a77a6c JA |
764 | if (!wbc.range_cyclic) { |
765 | wbc.range_start = 0; | |
766 | wbc.range_end = LLONG_MAX; | |
767 | } | |
38f21977 | 768 | |
03ba3782 JA |
769 | for (;;) { |
770 | /* | |
d3ddec76 | 771 | * Stop writeback when nr_pages has been consumed |
03ba3782 | 772 | */ |
d3ddec76 | 773 | if (args->nr_pages <= 0) |
03ba3782 | 774 | break; |
66f3b8e2 | 775 | |
38f21977 | 776 | /* |
d3ddec76 WF |
777 | * For background writeout, stop when we are below the |
778 | * background dirty threshold | |
38f21977 | 779 | */ |
d3ddec76 | 780 | if (args->for_background && !over_bground_thresh()) |
03ba3782 | 781 | break; |
38f21977 | 782 | |
03ba3782 | 783 | wbc.more_io = 0; |
03ba3782 JA |
784 | wbc.nr_to_write = MAX_WRITEBACK_PAGES; |
785 | wbc.pages_skipped = 0; | |
786 | writeback_inodes_wb(wb, &wbc); | |
c4a77a6c | 787 | args->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
03ba3782 JA |
788 | wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
789 | ||
790 | /* | |
71fd05a8 | 791 | * If we consumed everything, see if we have more |
03ba3782 | 792 | */ |
71fd05a8 JA |
793 | if (wbc.nr_to_write <= 0) |
794 | continue; | |
795 | /* | |
796 | * Didn't write everything and we don't have more IO, bail | |
797 | */ | |
798 | if (!wbc.more_io) | |
03ba3782 | 799 | break; |
71fd05a8 JA |
800 | /* |
801 | * Did we write something? Try for more | |
802 | */ | |
803 | if (wbc.nr_to_write < MAX_WRITEBACK_PAGES) | |
804 | continue; | |
805 | /* | |
806 | * Nothing written. Wait for some inode to | |
807 | * become available for writeback. Otherwise | |
808 | * we'll just busyloop. | |
809 | */ | |
810 | spin_lock(&inode_lock); | |
811 | if (!list_empty(&wb->b_more_io)) { | |
812 | inode = list_entry(wb->b_more_io.prev, | |
813 | struct inode, i_list); | |
814 | inode_wait_for_writeback(inode); | |
03ba3782 | 815 | } |
71fd05a8 | 816 | spin_unlock(&inode_lock); |
03ba3782 JA |
817 | } |
818 | ||
819 | return wrote; | |
820 | } | |
821 | ||
822 | /* | |
823 | * Return the next bdi_work struct that hasn't been processed by this | |
8010c3b6 JA |
824 | * wb thread yet. ->seen is initially set for each thread that exists |
825 | * for this device, when a thread first notices a piece of work it | |
826 | * clears its bit. Depending on writeback type, the thread will notify | |
827 | * completion on either receiving the work (WB_SYNC_NONE) or after | |
828 | * it is done (WB_SYNC_ALL). | |
03ba3782 JA |
829 | */ |
830 | static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi, | |
831 | struct bdi_writeback *wb) | |
832 | { | |
833 | struct bdi_work *work, *ret = NULL; | |
834 | ||
835 | rcu_read_lock(); | |
836 | ||
837 | list_for_each_entry_rcu(work, &bdi->work_list, list) { | |
77fad5e6 | 838 | if (!test_bit(wb->nr, &work->seen)) |
03ba3782 | 839 | continue; |
77fad5e6 | 840 | clear_bit(wb->nr, &work->seen); |
03ba3782 JA |
841 | |
842 | ret = work; | |
843 | break; | |
844 | } | |
845 | ||
846 | rcu_read_unlock(); | |
847 | return ret; | |
848 | } | |
849 | ||
850 | static long wb_check_old_data_flush(struct bdi_writeback *wb) | |
851 | { | |
852 | unsigned long expired; | |
853 | long nr_pages; | |
854 | ||
855 | expired = wb->last_old_flush + | |
856 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
857 | if (time_before(jiffies, expired)) | |
858 | return 0; | |
859 | ||
860 | wb->last_old_flush = jiffies; | |
861 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
862 | global_page_state(NR_UNSTABLE_NFS) + | |
863 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); | |
864 | ||
c4a77a6c JA |
865 | if (nr_pages) { |
866 | struct wb_writeback_args args = { | |
867 | .nr_pages = nr_pages, | |
868 | .sync_mode = WB_SYNC_NONE, | |
869 | .for_kupdate = 1, | |
870 | .range_cyclic = 1, | |
871 | }; | |
872 | ||
873 | return wb_writeback(wb, &args); | |
874 | } | |
03ba3782 JA |
875 | |
876 | return 0; | |
877 | } | |
878 | ||
879 | /* | |
880 | * Retrieve work items and do the writeback they describe | |
881 | */ | |
882 | long wb_do_writeback(struct bdi_writeback *wb, int force_wait) | |
883 | { | |
884 | struct backing_dev_info *bdi = wb->bdi; | |
885 | struct bdi_work *work; | |
c4a77a6c | 886 | long wrote = 0; |
03ba3782 JA |
887 | |
888 | while ((work = get_next_work_item(bdi, wb)) != NULL) { | |
c4a77a6c | 889 | struct wb_writeback_args args = work->args; |
03ba3782 JA |
890 | |
891 | /* | |
892 | * Override sync mode, in case we must wait for completion | |
893 | */ | |
894 | if (force_wait) | |
c4a77a6c | 895 | work->args.sync_mode = args.sync_mode = WB_SYNC_ALL; |
03ba3782 JA |
896 | |
897 | /* | |
898 | * If this isn't a data integrity operation, just notify | |
899 | * that we have seen this work and we are now starting it. | |
900 | */ | |
c4a77a6c | 901 | if (args.sync_mode == WB_SYNC_NONE) |
03ba3782 JA |
902 | wb_clear_pending(wb, work); |
903 | ||
c4a77a6c | 904 | wrote += wb_writeback(wb, &args); |
03ba3782 JA |
905 | |
906 | /* | |
907 | * This is a data integrity writeback, so only do the | |
908 | * notification when we have completed the work. | |
909 | */ | |
c4a77a6c | 910 | if (args.sync_mode == WB_SYNC_ALL) |
03ba3782 JA |
911 | wb_clear_pending(wb, work); |
912 | } | |
913 | ||
914 | /* | |
915 | * Check for periodic writeback, kupdated() style | |
916 | */ | |
917 | wrote += wb_check_old_data_flush(wb); | |
918 | ||
919 | return wrote; | |
920 | } | |
921 | ||
922 | /* | |
923 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
924 | * wakes up periodically and does kupdated style flushing. | |
925 | */ | |
926 | int bdi_writeback_task(struct bdi_writeback *wb) | |
927 | { | |
928 | unsigned long last_active = jiffies; | |
929 | unsigned long wait_jiffies = -1UL; | |
930 | long pages_written; | |
931 | ||
932 | while (!kthread_should_stop()) { | |
933 | pages_written = wb_do_writeback(wb, 0); | |
934 | ||
935 | if (pages_written) | |
936 | last_active = jiffies; | |
937 | else if (wait_jiffies != -1UL) { | |
938 | unsigned long max_idle; | |
939 | ||
38f21977 | 940 | /* |
03ba3782 JA |
941 | * Longest period of inactivity that we tolerate. If we |
942 | * see dirty data again later, the task will get | |
943 | * recreated automatically. | |
38f21977 | 944 | */ |
03ba3782 JA |
945 | max_idle = max(5UL * 60 * HZ, wait_jiffies); |
946 | if (time_after(jiffies, max_idle + last_active)) | |
947 | break; | |
948 | } | |
949 | ||
950 | wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); | |
49db0414 | 951 | schedule_timeout_interruptible(wait_jiffies); |
03ba3782 JA |
952 | try_to_freeze(); |
953 | } | |
954 | ||
955 | return 0; | |
956 | } | |
957 | ||
958 | /* | |
b6e51316 JA |
959 | * Schedule writeback for all backing devices. This does WB_SYNC_NONE |
960 | * writeback, for integrity writeback see bdi_sync_writeback(). | |
03ba3782 | 961 | */ |
b6e51316 | 962 | static void bdi_writeback_all(struct super_block *sb, long nr_pages) |
03ba3782 | 963 | { |
b6e51316 JA |
964 | struct wb_writeback_args args = { |
965 | .sb = sb, | |
966 | .nr_pages = nr_pages, | |
967 | .sync_mode = WB_SYNC_NONE, | |
968 | }; | |
03ba3782 | 969 | struct backing_dev_info *bdi; |
03ba3782 | 970 | |
cfc4ba53 | 971 | rcu_read_lock(); |
03ba3782 | 972 | |
cfc4ba53 | 973 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { |
03ba3782 JA |
974 | if (!bdi_has_dirty_io(bdi)) |
975 | continue; | |
38f21977 | 976 | |
b6e51316 | 977 | bdi_alloc_queue_work(bdi, &args); |
03ba3782 JA |
978 | } |
979 | ||
cfc4ba53 | 980 | rcu_read_unlock(); |
1da177e4 LT |
981 | } |
982 | ||
983 | /* | |
03ba3782 JA |
984 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
985 | * the whole world. | |
986 | */ | |
987 | void wakeup_flusher_threads(long nr_pages) | |
988 | { | |
03ba3782 JA |
989 | if (nr_pages == 0) |
990 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
991 | global_page_state(NR_UNSTABLE_NFS); | |
b6e51316 | 992 | bdi_writeback_all(NULL, nr_pages); |
03ba3782 JA |
993 | } |
994 | ||
995 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) | |
996 | { | |
997 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
998 | struct dentry *dentry; | |
999 | const char *name = "?"; | |
1000 | ||
1001 | dentry = d_find_alias(inode); | |
1002 | if (dentry) { | |
1003 | spin_lock(&dentry->d_lock); | |
1004 | name = (const char *) dentry->d_name.name; | |
1005 | } | |
1006 | printk(KERN_DEBUG | |
1007 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
1008 | current->comm, task_pid_nr(current), inode->i_ino, | |
1009 | name, inode->i_sb->s_id); | |
1010 | if (dentry) { | |
1011 | spin_unlock(&dentry->d_lock); | |
1012 | dput(dentry); | |
1013 | } | |
1014 | } | |
1015 | } | |
1016 | ||
1017 | /** | |
1018 | * __mark_inode_dirty - internal function | |
1019 | * @inode: inode to mark | |
1020 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
1021 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
1022 | * mark_inode_dirty_sync. | |
1da177e4 | 1023 | * |
03ba3782 JA |
1024 | * Put the inode on the super block's dirty list. |
1025 | * | |
1026 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
1027 | * dirty list only if it is hashed or if it refers to a blockdev. | |
1028 | * If it was not hashed, it will never be added to the dirty list | |
1029 | * even if it is later hashed, as it will have been marked dirty already. | |
1030 | * | |
1031 | * In short, make sure you hash any inodes _before_ you start marking | |
1032 | * them dirty. | |
1da177e4 | 1033 | * |
03ba3782 JA |
1034 | * This function *must* be atomic for the I_DIRTY_PAGES case - |
1035 | * set_page_dirty() is called under spinlock in several places. | |
1da177e4 | 1036 | * |
03ba3782 JA |
1037 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
1038 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
1039 | * the kernel-internal blockdev inode represents the dirtying time of the | |
1040 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
1041 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
1042 | * blockdev inode. | |
1da177e4 | 1043 | */ |
03ba3782 | 1044 | void __mark_inode_dirty(struct inode *inode, int flags) |
1da177e4 | 1045 | { |
03ba3782 | 1046 | struct super_block *sb = inode->i_sb; |
1da177e4 | 1047 | |
03ba3782 JA |
1048 | /* |
1049 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
1050 | * dirty the inode itself | |
1051 | */ | |
1052 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
1053 | if (sb->s_op->dirty_inode) | |
1054 | sb->s_op->dirty_inode(inode); | |
1055 | } | |
1056 | ||
1057 | /* | |
1058 | * make sure that changes are seen by all cpus before we test i_state | |
1059 | * -- mikulas | |
1060 | */ | |
1061 | smp_mb(); | |
1062 | ||
1063 | /* avoid the locking if we can */ | |
1064 | if ((inode->i_state & flags) == flags) | |
1065 | return; | |
1066 | ||
1067 | if (unlikely(block_dump)) | |
1068 | block_dump___mark_inode_dirty(inode); | |
1069 | ||
1070 | spin_lock(&inode_lock); | |
1071 | if ((inode->i_state & flags) != flags) { | |
1072 | const int was_dirty = inode->i_state & I_DIRTY; | |
1073 | ||
1074 | inode->i_state |= flags; | |
1075 | ||
1076 | /* | |
1077 | * If the inode is being synced, just update its dirty state. | |
1078 | * The unlocker will place the inode on the appropriate | |
1079 | * superblock list, based upon its state. | |
1080 | */ | |
1081 | if (inode->i_state & I_SYNC) | |
1082 | goto out; | |
1083 | ||
1084 | /* | |
1085 | * Only add valid (hashed) inodes to the superblock's | |
1086 | * dirty list. Add blockdev inodes as well. | |
1087 | */ | |
1088 | if (!S_ISBLK(inode->i_mode)) { | |
1089 | if (hlist_unhashed(&inode->i_hash)) | |
1090 | goto out; | |
1091 | } | |
1092 | if (inode->i_state & (I_FREEING|I_CLEAR)) | |
1093 | goto out; | |
1094 | ||
1095 | /* | |
1096 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
1097 | * reposition it (that would break b_dirty time-ordering). | |
1098 | */ | |
1099 | if (!was_dirty) { | |
1100 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; | |
500b067c JA |
1101 | struct backing_dev_info *bdi = wb->bdi; |
1102 | ||
1103 | if (bdi_cap_writeback_dirty(bdi) && | |
1104 | !test_bit(BDI_registered, &bdi->state)) { | |
1105 | WARN_ON(1); | |
1106 | printk(KERN_ERR "bdi-%s not registered\n", | |
1107 | bdi->name); | |
1108 | } | |
03ba3782 JA |
1109 | |
1110 | inode->dirtied_when = jiffies; | |
1111 | list_move(&inode->i_list, &wb->b_dirty); | |
1da177e4 | 1112 | } |
1da177e4 | 1113 | } |
03ba3782 JA |
1114 | out: |
1115 | spin_unlock(&inode_lock); | |
1116 | } | |
1117 | EXPORT_SYMBOL(__mark_inode_dirty); | |
1118 | ||
1119 | /* | |
1120 | * Write out a superblock's list of dirty inodes. A wait will be performed | |
1121 | * upon no inodes, all inodes or the final one, depending upon sync_mode. | |
1122 | * | |
1123 | * If older_than_this is non-NULL, then only write out inodes which | |
1124 | * had their first dirtying at a time earlier than *older_than_this. | |
1125 | * | |
03ba3782 JA |
1126 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. |
1127 | * This function assumes that the blockdev superblock's inodes are backed by | |
1128 | * a variety of queues, so all inodes are searched. For other superblocks, | |
1129 | * assume that all inodes are backed by the same queue. | |
1130 | * | |
1131 | * The inodes to be written are parked on bdi->b_io. They are moved back onto | |
1132 | * bdi->b_dirty as they are selected for writing. This way, none can be missed | |
1133 | * on the writer throttling path, and we get decent balancing between many | |
1134 | * throttled threads: we don't want them all piling up on inode_sync_wait. | |
1135 | */ | |
b6e51316 | 1136 | static void wait_sb_inodes(struct super_block *sb) |
03ba3782 JA |
1137 | { |
1138 | struct inode *inode, *old_inode = NULL; | |
1139 | ||
1140 | /* | |
1141 | * We need to be protected against the filesystem going from | |
1142 | * r/o to r/w or vice versa. | |
1143 | */ | |
b6e51316 | 1144 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
03ba3782 JA |
1145 | |
1146 | spin_lock(&inode_lock); | |
1147 | ||
1148 | /* | |
1149 | * Data integrity sync. Must wait for all pages under writeback, | |
1150 | * because there may have been pages dirtied before our sync | |
1151 | * call, but which had writeout started before we write it out. | |
1152 | * In which case, the inode may not be on the dirty list, but | |
1153 | * we still have to wait for that writeout. | |
1154 | */ | |
b6e51316 | 1155 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
03ba3782 JA |
1156 | struct address_space *mapping; |
1157 | ||
1158 | if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) | |
1159 | continue; | |
1160 | mapping = inode->i_mapping; | |
1161 | if (mapping->nrpages == 0) | |
1162 | continue; | |
1163 | __iget(inode); | |
1164 | spin_unlock(&inode_lock); | |
1165 | /* | |
1166 | * We hold a reference to 'inode' so it couldn't have | |
1167 | * been removed from s_inodes list while we dropped the | |
1168 | * inode_lock. We cannot iput the inode now as we can | |
1169 | * be holding the last reference and we cannot iput it | |
1170 | * under inode_lock. So we keep the reference and iput | |
1171 | * it later. | |
1172 | */ | |
1173 | iput(old_inode); | |
1174 | old_inode = inode; | |
1175 | ||
1176 | filemap_fdatawait(mapping); | |
1177 | ||
1178 | cond_resched(); | |
1179 | ||
1180 | spin_lock(&inode_lock); | |
1181 | } | |
1182 | spin_unlock(&inode_lock); | |
1183 | iput(old_inode); | |
1da177e4 LT |
1184 | } |
1185 | ||
d8a8559c JA |
1186 | /** |
1187 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
1188 | * @sb: the superblock | |
1da177e4 | 1189 | * |
d8a8559c JA |
1190 | * Start writeback on some inodes on this super_block. No guarantees are made |
1191 | * on how many (if any) will be written, and this function does not wait | |
1192 | * for IO completion of submitted IO. The number of pages submitted is | |
1193 | * returned. | |
1da177e4 | 1194 | */ |
b6e51316 | 1195 | void writeback_inodes_sb(struct super_block *sb) |
1da177e4 | 1196 | { |
d8a8559c JA |
1197 | unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); |
1198 | unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); | |
1199 | long nr_to_write; | |
1da177e4 | 1200 | |
d8a8559c | 1201 | nr_to_write = nr_dirty + nr_unstable + |
38f21977 | 1202 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); |
38f21977 | 1203 | |
a72bfd4d | 1204 | bdi_start_writeback(sb->s_bdi, sb, nr_to_write); |
d8a8559c JA |
1205 | } |
1206 | EXPORT_SYMBOL(writeback_inodes_sb); | |
1207 | ||
17bd55d0 ES |
1208 | /** |
1209 | * writeback_inodes_sb_if_idle - start writeback if none underway | |
1210 | * @sb: the superblock | |
1211 | * | |
1212 | * Invoke writeback_inodes_sb if no writeback is currently underway. | |
1213 | * Returns 1 if writeback was started, 0 if not. | |
1214 | */ | |
1215 | int writeback_inodes_sb_if_idle(struct super_block *sb) | |
1216 | { | |
1217 | if (!writeback_in_progress(sb->s_bdi)) { | |
1218 | writeback_inodes_sb(sb); | |
1219 | return 1; | |
1220 | } else | |
1221 | return 0; | |
1222 | } | |
1223 | EXPORT_SYMBOL(writeback_inodes_sb_if_idle); | |
1224 | ||
d8a8559c JA |
1225 | /** |
1226 | * sync_inodes_sb - sync sb inode pages | |
1227 | * @sb: the superblock | |
1228 | * | |
1229 | * This function writes and waits on any dirty inode belonging to this | |
1230 | * super_block. The number of pages synced is returned. | |
1231 | */ | |
b6e51316 | 1232 | void sync_inodes_sb(struct super_block *sb) |
d8a8559c | 1233 | { |
b6e51316 JA |
1234 | bdi_sync_writeback(sb->s_bdi, sb); |
1235 | wait_sb_inodes(sb); | |
1da177e4 | 1236 | } |
d8a8559c | 1237 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 1238 | |
1da177e4 | 1239 | /** |
7f04c26d AA |
1240 | * write_inode_now - write an inode to disk |
1241 | * @inode: inode to write to disk | |
1242 | * @sync: whether the write should be synchronous or not | |
1243 | * | |
1244 | * This function commits an inode to disk immediately if it is dirty. This is | |
1245 | * primarily needed by knfsd. | |
1da177e4 | 1246 | * |
7f04c26d | 1247 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 1248 | */ |
1da177e4 LT |
1249 | int write_inode_now(struct inode *inode, int sync) |
1250 | { | |
1251 | int ret; | |
1252 | struct writeback_control wbc = { | |
1253 | .nr_to_write = LONG_MAX, | |
18914b18 | 1254 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
1255 | .range_start = 0, |
1256 | .range_end = LLONG_MAX, | |
1da177e4 LT |
1257 | }; |
1258 | ||
1259 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 1260 | wbc.nr_to_write = 0; |
1da177e4 LT |
1261 | |
1262 | might_sleep(); | |
1263 | spin_lock(&inode_lock); | |
01c03194 | 1264 | ret = writeback_single_inode(inode, &wbc); |
1da177e4 LT |
1265 | spin_unlock(&inode_lock); |
1266 | if (sync) | |
1c0eeaf5 | 1267 | inode_sync_wait(inode); |
1da177e4 LT |
1268 | return ret; |
1269 | } | |
1270 | EXPORT_SYMBOL(write_inode_now); | |
1271 | ||
1272 | /** | |
1273 | * sync_inode - write an inode and its pages to disk. | |
1274 | * @inode: the inode to sync | |
1275 | * @wbc: controls the writeback mode | |
1276 | * | |
1277 | * sync_inode() will write an inode and its pages to disk. It will also | |
1278 | * correctly update the inode on its superblock's dirty inode lists and will | |
1279 | * update inode->i_state. | |
1280 | * | |
1281 | * The caller must have a ref on the inode. | |
1282 | */ | |
1283 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
1284 | { | |
1285 | int ret; | |
1286 | ||
1287 | spin_lock(&inode_lock); | |
01c03194 | 1288 | ret = writeback_single_inode(inode, wbc); |
1da177e4 LT |
1289 | spin_unlock(&inode_lock); |
1290 | return ret; | |
1291 | } | |
1292 | EXPORT_SYMBOL(sync_inode); |