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; | |
e913fc82 | 48 | int sb_pinned:1; |
c4a77a6c JA |
49 | }; |
50 | ||
03ba3782 JA |
51 | /* |
52 | * Work items for the bdi_writeback threads | |
f11b00f3 | 53 | */ |
03ba3782 | 54 | struct bdi_work { |
8010c3b6 JA |
55 | struct list_head list; /* pending work list */ |
56 | struct rcu_head rcu_head; /* for RCU free/clear of work */ | |
03ba3782 | 57 | |
8010c3b6 JA |
58 | unsigned long seen; /* threads that have seen this work */ |
59 | atomic_t pending; /* number of threads still to do work */ | |
03ba3782 | 60 | |
8010c3b6 | 61 | struct wb_writeback_args args; /* writeback arguments */ |
03ba3782 | 62 | |
8010c3b6 | 63 | unsigned long state; /* flag bits, see WS_* */ |
03ba3782 JA |
64 | }; |
65 | ||
66 | enum { | |
67 | WS_USED_B = 0, | |
68 | WS_ONSTACK_B, | |
69 | }; | |
70 | ||
71 | #define WS_USED (1 << WS_USED_B) | |
72 | #define WS_ONSTACK (1 << WS_ONSTACK_B) | |
73 | ||
74 | static inline bool bdi_work_on_stack(struct bdi_work *work) | |
75 | { | |
76 | return test_bit(WS_ONSTACK_B, &work->state); | |
77 | } | |
78 | ||
79 | static inline void bdi_work_init(struct bdi_work *work, | |
b6e51316 | 80 | struct wb_writeback_args *args) |
03ba3782 JA |
81 | { |
82 | INIT_RCU_HEAD(&work->rcu_head); | |
b6e51316 | 83 | work->args = *args; |
03ba3782 JA |
84 | work->state = WS_USED; |
85 | } | |
86 | ||
f11b00f3 AB |
87 | /** |
88 | * writeback_in_progress - determine whether there is writeback in progress | |
89 | * @bdi: the device's backing_dev_info structure. | |
90 | * | |
03ba3782 JA |
91 | * Determine whether there is writeback waiting to be handled against a |
92 | * backing device. | |
f11b00f3 AB |
93 | */ |
94 | int writeback_in_progress(struct backing_dev_info *bdi) | |
95 | { | |
03ba3782 | 96 | return !list_empty(&bdi->work_list); |
f11b00f3 AB |
97 | } |
98 | ||
03ba3782 | 99 | static void bdi_work_clear(struct bdi_work *work) |
f11b00f3 | 100 | { |
03ba3782 JA |
101 | clear_bit(WS_USED_B, &work->state); |
102 | smp_mb__after_clear_bit(); | |
1ef7d9aa NP |
103 | /* |
104 | * work can have disappeared at this point. bit waitq functions | |
105 | * should be able to tolerate this, provided bdi_sched_wait does | |
106 | * not dereference it's pointer argument. | |
107 | */ | |
03ba3782 | 108 | wake_up_bit(&work->state, WS_USED_B); |
f11b00f3 AB |
109 | } |
110 | ||
03ba3782 | 111 | static void bdi_work_free(struct rcu_head *head) |
4195f73d | 112 | { |
03ba3782 | 113 | struct bdi_work *work = container_of(head, struct bdi_work, rcu_head); |
4195f73d | 114 | |
03ba3782 JA |
115 | if (!bdi_work_on_stack(work)) |
116 | kfree(work); | |
117 | else | |
118 | bdi_work_clear(work); | |
4195f73d NP |
119 | } |
120 | ||
03ba3782 | 121 | static void wb_work_complete(struct bdi_work *work) |
1da177e4 | 122 | { |
c4a77a6c | 123 | const enum writeback_sync_modes sync_mode = work->args.sync_mode; |
77b9d059 | 124 | int onstack = bdi_work_on_stack(work); |
1da177e4 LT |
125 | |
126 | /* | |
03ba3782 JA |
127 | * For allocated work, we can clear the done/seen bit right here. |
128 | * For on-stack work, we need to postpone both the clear and free | |
129 | * to after the RCU grace period, since the stack could be invalidated | |
130 | * as soon as bdi_work_clear() has done the wakeup. | |
1da177e4 | 131 | */ |
77b9d059 | 132 | if (!onstack) |
03ba3782 | 133 | bdi_work_clear(work); |
77b9d059 | 134 | if (sync_mode == WB_SYNC_NONE || onstack) |
03ba3782 JA |
135 | call_rcu(&work->rcu_head, bdi_work_free); |
136 | } | |
1da177e4 | 137 | |
03ba3782 JA |
138 | static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work) |
139 | { | |
1da177e4 | 140 | /* |
03ba3782 JA |
141 | * The caller has retrieved the work arguments from this work, |
142 | * drop our reference. If this is the last ref, delete and free it | |
1da177e4 | 143 | */ |
03ba3782 JA |
144 | if (atomic_dec_and_test(&work->pending)) { |
145 | struct backing_dev_info *bdi = wb->bdi; | |
1da177e4 | 146 | |
03ba3782 JA |
147 | spin_lock(&bdi->wb_lock); |
148 | list_del_rcu(&work->list); | |
149 | spin_unlock(&bdi->wb_lock); | |
1da177e4 | 150 | |
03ba3782 JA |
151 | wb_work_complete(work); |
152 | } | |
153 | } | |
1da177e4 | 154 | |
03ba3782 JA |
155 | static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work) |
156 | { | |
bcddc3f0 JA |
157 | work->seen = bdi->wb_mask; |
158 | BUG_ON(!work->seen); | |
159 | atomic_set(&work->pending, bdi->wb_cnt); | |
160 | BUG_ON(!bdi->wb_cnt); | |
1da177e4 | 161 | |
bcddc3f0 | 162 | /* |
deed62ed NP |
163 | * list_add_tail_rcu() contains the necessary barriers to |
164 | * make sure the above stores are seen before the item is | |
165 | * noticed on the list | |
bcddc3f0 | 166 | */ |
bcddc3f0 JA |
167 | spin_lock(&bdi->wb_lock); |
168 | list_add_tail_rcu(&work->list, &bdi->work_list); | |
169 | spin_unlock(&bdi->wb_lock); | |
03ba3782 JA |
170 | |
171 | /* | |
172 | * If the default thread isn't there, make sure we add it. When | |
173 | * it gets created and wakes up, we'll run this work. | |
174 | */ | |
175 | if (unlikely(list_empty_careful(&bdi->wb_list))) | |
176 | wake_up_process(default_backing_dev_info.wb.task); | |
177 | else { | |
178 | struct bdi_writeback *wb = &bdi->wb; | |
1da177e4 | 179 | |
1ef7d9aa | 180 | if (wb->task) |
03ba3782 | 181 | wake_up_process(wb->task); |
1da177e4 | 182 | } |
1da177e4 LT |
183 | } |
184 | ||
03ba3782 JA |
185 | /* |
186 | * Used for on-stack allocated work items. The caller needs to wait until | |
187 | * the wb threads have acked the work before it's safe to continue. | |
188 | */ | |
189 | static void bdi_wait_on_work_clear(struct bdi_work *work) | |
190 | { | |
191 | wait_on_bit(&work->state, WS_USED_B, bdi_sched_wait, | |
192 | TASK_UNINTERRUPTIBLE); | |
193 | } | |
1da177e4 | 194 | |
f11fcae8 | 195 | static void bdi_alloc_queue_work(struct backing_dev_info *bdi, |
b6e51316 | 196 | struct wb_writeback_args *args) |
1da177e4 | 197 | { |
03ba3782 JA |
198 | struct bdi_work *work; |
199 | ||
bcddc3f0 JA |
200 | /* |
201 | * This is WB_SYNC_NONE writeback, so if allocation fails just | |
202 | * wakeup the thread for old dirty data writeback | |
203 | */ | |
03ba3782 | 204 | work = kmalloc(sizeof(*work), GFP_ATOMIC); |
bcddc3f0 | 205 | if (work) { |
b6e51316 | 206 | bdi_work_init(work, args); |
bcddc3f0 JA |
207 | bdi_queue_work(bdi, work); |
208 | } else { | |
209 | struct bdi_writeback *wb = &bdi->wb; | |
03ba3782 | 210 | |
bcddc3f0 JA |
211 | if (wb->task) |
212 | wake_up_process(wb->task); | |
213 | } | |
03ba3782 JA |
214 | } |
215 | ||
b6e51316 JA |
216 | /** |
217 | * bdi_sync_writeback - start and wait for writeback | |
218 | * @bdi: the backing device to write from | |
219 | * @sb: write inodes from this super_block | |
220 | * | |
221 | * Description: | |
222 | * This does WB_SYNC_ALL data integrity writeback and waits for the | |
223 | * IO to complete. Callers must hold the sb s_umount semaphore for | |
224 | * reading, to avoid having the super disappear before we are done. | |
225 | */ | |
226 | static void bdi_sync_writeback(struct backing_dev_info *bdi, | |
227 | struct super_block *sb) | |
03ba3782 | 228 | { |
b6e51316 JA |
229 | struct wb_writeback_args args = { |
230 | .sb = sb, | |
231 | .sync_mode = WB_SYNC_ALL, | |
232 | .nr_pages = LONG_MAX, | |
233 | .range_cyclic = 0, | |
e913fc82 JA |
234 | /* |
235 | * Setting sb_pinned is not necessary for WB_SYNC_ALL, but | |
236 | * lets make it explicitly clear. | |
237 | */ | |
238 | .sb_pinned = 1, | |
b6e51316 JA |
239 | }; |
240 | struct bdi_work work; | |
03ba3782 | 241 | |
b6e51316 JA |
242 | bdi_work_init(&work, &args); |
243 | work.state |= WS_ONSTACK; | |
03ba3782 | 244 | |
b6e51316 JA |
245 | bdi_queue_work(bdi, &work); |
246 | bdi_wait_on_work_clear(&work); | |
247 | } | |
248 | ||
249 | /** | |
250 | * bdi_start_writeback - start writeback | |
251 | * @bdi: the backing device to write from | |
4b6764fa | 252 | * @sb: write inodes from this super_block |
b6e51316 | 253 | * @nr_pages: the number of pages to write |
e913fc82 | 254 | * @sb_locked: caller already holds sb umount sem. |
b6e51316 JA |
255 | * |
256 | * Description: | |
257 | * This does WB_SYNC_NONE opportunistic writeback. The IO is only | |
258 | * started when this function returns, we make no guarentees on | |
e913fc82 | 259 | * completion. Caller specifies whether sb umount sem is held already or not. |
b6e51316 JA |
260 | * |
261 | */ | |
a72bfd4d | 262 | void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb, |
e913fc82 | 263 | long nr_pages, int sb_locked) |
b6e51316 JA |
264 | { |
265 | struct wb_writeback_args args = { | |
a72bfd4d | 266 | .sb = sb, |
b6e51316 JA |
267 | .sync_mode = WB_SYNC_NONE, |
268 | .nr_pages = nr_pages, | |
269 | .range_cyclic = 1, | |
e913fc82 | 270 | .sb_pinned = sb_locked, |
b6e51316 JA |
271 | }; |
272 | ||
d3ddec76 WF |
273 | /* |
274 | * We treat @nr_pages=0 as the special case to do background writeback, | |
275 | * ie. to sync pages until the background dirty threshold is reached. | |
276 | */ | |
277 | if (!nr_pages) { | |
278 | args.nr_pages = LONG_MAX; | |
279 | args.for_background = 1; | |
280 | } | |
281 | ||
b6e51316 | 282 | bdi_alloc_queue_work(bdi, &args); |
1da177e4 LT |
283 | } |
284 | ||
6610a0bc AM |
285 | /* |
286 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
287 | * furthest end of its superblock's dirty-inode list. | |
288 | * | |
289 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 290 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
291 | * the case then the inode must have been redirtied while it was being written |
292 | * out and we don't reset its dirtied_when. | |
293 | */ | |
294 | static void redirty_tail(struct inode *inode) | |
295 | { | |
03ba3782 | 296 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
6610a0bc | 297 | |
03ba3782 | 298 | if (!list_empty(&wb->b_dirty)) { |
66f3b8e2 | 299 | struct inode *tail; |
6610a0bc | 300 | |
03ba3782 | 301 | tail = list_entry(wb->b_dirty.next, struct inode, i_list); |
66f3b8e2 | 302 | if (time_before(inode->dirtied_when, tail->dirtied_when)) |
6610a0bc AM |
303 | inode->dirtied_when = jiffies; |
304 | } | |
03ba3782 | 305 | list_move(&inode->i_list, &wb->b_dirty); |
6610a0bc AM |
306 | } |
307 | ||
c986d1e2 | 308 | /* |
66f3b8e2 | 309 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 310 | */ |
0e0f4fc2 | 311 | static void requeue_io(struct inode *inode) |
c986d1e2 | 312 | { |
03ba3782 JA |
313 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
314 | ||
315 | list_move(&inode->i_list, &wb->b_more_io); | |
c986d1e2 AM |
316 | } |
317 | ||
1c0eeaf5 JE |
318 | static void inode_sync_complete(struct inode *inode) |
319 | { | |
320 | /* | |
321 | * Prevent speculative execution through spin_unlock(&inode_lock); | |
322 | */ | |
323 | smp_mb(); | |
324 | wake_up_bit(&inode->i_state, __I_SYNC); | |
325 | } | |
326 | ||
d2caa3c5 JL |
327 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
328 | { | |
329 | bool ret = time_after(inode->dirtied_when, t); | |
330 | #ifndef CONFIG_64BIT | |
331 | /* | |
332 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
333 | * It _appears_ to be in the future, but is actually in distant past. | |
334 | * This test is necessary to prevent such wrapped-around relative times | |
5b0830cb | 335 | * from permanently stopping the whole bdi writeback. |
d2caa3c5 JL |
336 | */ |
337 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
338 | #endif | |
339 | return ret; | |
340 | } | |
341 | ||
2c136579 FW |
342 | /* |
343 | * Move expired dirty inodes from @delaying_queue to @dispatch_queue. | |
344 | */ | |
345 | static void move_expired_inodes(struct list_head *delaying_queue, | |
346 | struct list_head *dispatch_queue, | |
347 | unsigned long *older_than_this) | |
348 | { | |
5c03449d SL |
349 | LIST_HEAD(tmp); |
350 | struct list_head *pos, *node; | |
cf137307 | 351 | struct super_block *sb = NULL; |
5c03449d | 352 | struct inode *inode; |
cf137307 | 353 | int do_sb_sort = 0; |
5c03449d | 354 | |
2c136579 | 355 | while (!list_empty(delaying_queue)) { |
5c03449d | 356 | inode = list_entry(delaying_queue->prev, struct inode, i_list); |
2c136579 | 357 | if (older_than_this && |
d2caa3c5 | 358 | inode_dirtied_after(inode, *older_than_this)) |
2c136579 | 359 | break; |
cf137307 JA |
360 | if (sb && sb != inode->i_sb) |
361 | do_sb_sort = 1; | |
362 | sb = inode->i_sb; | |
5c03449d SL |
363 | list_move(&inode->i_list, &tmp); |
364 | } | |
365 | ||
cf137307 JA |
366 | /* just one sb in list, splice to dispatch_queue and we're done */ |
367 | if (!do_sb_sort) { | |
368 | list_splice(&tmp, dispatch_queue); | |
369 | return; | |
370 | } | |
371 | ||
5c03449d SL |
372 | /* Move inodes from one superblock together */ |
373 | while (!list_empty(&tmp)) { | |
374 | inode = list_entry(tmp.prev, struct inode, i_list); | |
375 | sb = inode->i_sb; | |
376 | list_for_each_prev_safe(pos, node, &tmp) { | |
377 | inode = list_entry(pos, struct inode, i_list); | |
378 | if (inode->i_sb == sb) | |
379 | list_move(&inode->i_list, dispatch_queue); | |
380 | } | |
2c136579 FW |
381 | } |
382 | } | |
383 | ||
384 | /* | |
385 | * Queue all expired dirty inodes for io, eldest first. | |
386 | */ | |
03ba3782 | 387 | static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) |
66f3b8e2 | 388 | { |
03ba3782 JA |
389 | list_splice_init(&wb->b_more_io, wb->b_io.prev); |
390 | move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); | |
66f3b8e2 JA |
391 | } |
392 | ||
a9185b41 | 393 | static int write_inode(struct inode *inode, struct writeback_control *wbc) |
08d8e974 | 394 | { |
03ba3782 | 395 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) |
a9185b41 | 396 | return inode->i_sb->s_op->write_inode(inode, wbc); |
03ba3782 | 397 | return 0; |
08d8e974 | 398 | } |
08d8e974 | 399 | |
1da177e4 | 400 | /* |
01c03194 CH |
401 | * Wait for writeback on an inode to complete. |
402 | */ | |
403 | static void inode_wait_for_writeback(struct inode *inode) | |
404 | { | |
405 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
406 | wait_queue_head_t *wqh; | |
407 | ||
408 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
409 | do { | |
410 | spin_unlock(&inode_lock); | |
411 | __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); | |
412 | spin_lock(&inode_lock); | |
413 | } while (inode->i_state & I_SYNC); | |
414 | } | |
415 | ||
416 | /* | |
417 | * Write out an inode's dirty pages. Called under inode_lock. Either the | |
418 | * caller has ref on the inode (either via __iget or via syscall against an fd) | |
419 | * or the inode has I_WILL_FREE set (via generic_forget_inode) | |
420 | * | |
1da177e4 LT |
421 | * If `wait' is set, wait on the writeout. |
422 | * | |
423 | * The whole writeout design is quite complex and fragile. We want to avoid | |
424 | * starvation of particular inodes when others are being redirtied, prevent | |
425 | * livelocks, etc. | |
426 | * | |
427 | * Called under inode_lock. | |
428 | */ | |
429 | static int | |
01c03194 | 430 | writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 431 | { |
1da177e4 | 432 | struct address_space *mapping = inode->i_mapping; |
01c03194 | 433 | unsigned dirty; |
1da177e4 LT |
434 | int ret; |
435 | ||
01c03194 CH |
436 | if (!atomic_read(&inode->i_count)) |
437 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
438 | else | |
439 | WARN_ON(inode->i_state & I_WILL_FREE); | |
440 | ||
441 | if (inode->i_state & I_SYNC) { | |
442 | /* | |
443 | * If this inode is locked for writeback and we are not doing | |
66f3b8e2 | 444 | * writeback-for-data-integrity, move it to b_more_io so that |
01c03194 CH |
445 | * writeback can proceed with the other inodes on s_io. |
446 | * | |
447 | * We'll have another go at writing back this inode when we | |
66f3b8e2 | 448 | * completed a full scan of b_io. |
01c03194 | 449 | */ |
a9185b41 | 450 | if (wbc->sync_mode != WB_SYNC_ALL) { |
01c03194 CH |
451 | requeue_io(inode); |
452 | return 0; | |
453 | } | |
454 | ||
455 | /* | |
456 | * It's a data-integrity sync. We must wait. | |
457 | */ | |
458 | inode_wait_for_writeback(inode); | |
459 | } | |
460 | ||
1c0eeaf5 | 461 | BUG_ON(inode->i_state & I_SYNC); |
1da177e4 | 462 | |
1c0eeaf5 | 463 | /* Set I_SYNC, reset I_DIRTY */ |
1da177e4 | 464 | dirty = inode->i_state & I_DIRTY; |
1c0eeaf5 | 465 | inode->i_state |= I_SYNC; |
1da177e4 LT |
466 | inode->i_state &= ~I_DIRTY; |
467 | ||
468 | spin_unlock(&inode_lock); | |
469 | ||
470 | ret = do_writepages(mapping, wbc); | |
471 | ||
26821ed4 CH |
472 | /* |
473 | * Make sure to wait on the data before writing out the metadata. | |
474 | * This is important for filesystems that modify metadata on data | |
475 | * I/O completion. | |
476 | */ | |
a9185b41 | 477 | if (wbc->sync_mode == WB_SYNC_ALL) { |
26821ed4 | 478 | int err = filemap_fdatawait(mapping); |
1da177e4 LT |
479 | if (ret == 0) |
480 | ret = err; | |
481 | } | |
482 | ||
26821ed4 CH |
483 | /* Don't write the inode if only I_DIRTY_PAGES was set */ |
484 | if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
a9185b41 | 485 | int err = write_inode(inode, wbc); |
1da177e4 LT |
486 | if (ret == 0) |
487 | ret = err; | |
488 | } | |
489 | ||
490 | spin_lock(&inode_lock); | |
1c0eeaf5 | 491 | inode->i_state &= ~I_SYNC; |
84a89245 | 492 | if (!(inode->i_state & (I_FREEING | I_CLEAR))) { |
b3af9468 | 493 | if ((inode->i_state & I_DIRTY_PAGES) && wbc->for_kupdate) { |
ae1b7f7d | 494 | /* |
b3af9468 WF |
495 | * More pages get dirtied by a fast dirtier. |
496 | */ | |
497 | goto select_queue; | |
498 | } else if (inode->i_state & I_DIRTY) { | |
499 | /* | |
500 | * At least XFS will redirty the inode during the | |
501 | * writeback (delalloc) and on io completion (isize). | |
ae1b7f7d WF |
502 | */ |
503 | redirty_tail(inode); | |
504 | } else if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { | |
1da177e4 LT |
505 | /* |
506 | * We didn't write back all the pages. nfs_writepages() | |
507 | * sometimes bales out without doing anything. Redirty | |
66f3b8e2 | 508 | * the inode; Move it from b_io onto b_more_io/b_dirty. |
1b43ef91 AM |
509 | */ |
510 | /* | |
511 | * akpm: if the caller was the kupdate function we put | |
66f3b8e2 | 512 | * this inode at the head of b_dirty so it gets first |
1b43ef91 AM |
513 | * consideration. Otherwise, move it to the tail, for |
514 | * the reasons described there. I'm not really sure | |
515 | * how much sense this makes. Presumably I had a good | |
516 | * reasons for doing it this way, and I'd rather not | |
517 | * muck with it at present. | |
1da177e4 LT |
518 | */ |
519 | if (wbc->for_kupdate) { | |
520 | /* | |
2c136579 | 521 | * For the kupdate function we move the inode |
66f3b8e2 | 522 | * to b_more_io so it will get more writeout as |
2c136579 | 523 | * soon as the queue becomes uncongested. |
1da177e4 LT |
524 | */ |
525 | inode->i_state |= I_DIRTY_PAGES; | |
b3af9468 | 526 | select_queue: |
8bc3be27 FW |
527 | if (wbc->nr_to_write <= 0) { |
528 | /* | |
529 | * slice used up: queue for next turn | |
530 | */ | |
531 | requeue_io(inode); | |
532 | } else { | |
533 | /* | |
534 | * somehow blocked: retry later | |
535 | */ | |
536 | redirty_tail(inode); | |
537 | } | |
1da177e4 LT |
538 | } else { |
539 | /* | |
540 | * Otherwise fully redirty the inode so that | |
541 | * other inodes on this superblock will get some | |
542 | * writeout. Otherwise heavy writing to one | |
543 | * file would indefinitely suspend writeout of | |
544 | * all the other files. | |
545 | */ | |
546 | inode->i_state |= I_DIRTY_PAGES; | |
1b43ef91 | 547 | redirty_tail(inode); |
1da177e4 | 548 | } |
1da177e4 LT |
549 | } else if (atomic_read(&inode->i_count)) { |
550 | /* | |
551 | * The inode is clean, inuse | |
552 | */ | |
553 | list_move(&inode->i_list, &inode_in_use); | |
554 | } else { | |
555 | /* | |
556 | * The inode is clean, unused | |
557 | */ | |
558 | list_move(&inode->i_list, &inode_unused); | |
1da177e4 LT |
559 | } |
560 | } | |
1c0eeaf5 | 561 | inode_sync_complete(inode); |
1da177e4 LT |
562 | return ret; |
563 | } | |
564 | ||
f11c9c5c | 565 | static void unpin_sb_for_writeback(struct super_block *sb) |
9ecc2738 | 566 | { |
f11c9c5c ES |
567 | up_read(&sb->s_umount); |
568 | put_super(sb); | |
9ecc2738 JA |
569 | } |
570 | ||
f11c9c5c ES |
571 | enum sb_pin_state { |
572 | SB_PINNED, | |
573 | SB_NOT_PINNED, | |
574 | SB_PIN_FAILED | |
575 | }; | |
576 | ||
03ba3782 JA |
577 | /* |
578 | * For WB_SYNC_NONE writeback, the caller does not have the sb pinned | |
579 | * before calling writeback. So make sure that we do pin it, so it doesn't | |
580 | * go away while we are writing inodes from it. | |
03ba3782 | 581 | */ |
f11c9c5c ES |
582 | static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc, |
583 | struct super_block *sb) | |
03ba3782 | 584 | { |
03ba3782 JA |
585 | /* |
586 | * Caller must already hold the ref for this | |
587 | */ | |
e913fc82 | 588 | if (wbc->sync_mode == WB_SYNC_ALL || wbc->sb_pinned) { |
03ba3782 | 589 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
f11c9c5c | 590 | return SB_NOT_PINNED; |
03ba3782 | 591 | } |
03ba3782 JA |
592 | spin_lock(&sb_lock); |
593 | sb->s_count++; | |
594 | if (down_read_trylock(&sb->s_umount)) { | |
595 | if (sb->s_root) { | |
596 | spin_unlock(&sb_lock); | |
f11c9c5c | 597 | return SB_PINNED; |
03ba3782 JA |
598 | } |
599 | /* | |
600 | * umounted, drop rwsem again and fall through to failure | |
601 | */ | |
602 | up_read(&sb->s_umount); | |
603 | } | |
03ba3782 JA |
604 | sb->s_count--; |
605 | spin_unlock(&sb_lock); | |
f11c9c5c | 606 | return SB_PIN_FAILED; |
03ba3782 JA |
607 | } |
608 | ||
f11c9c5c ES |
609 | /* |
610 | * Write a portion of b_io inodes which belong to @sb. | |
611 | * If @wbc->sb != NULL, then find and write all such | |
612 | * inodes. Otherwise write only ones which go sequentially | |
613 | * in reverse order. | |
614 | * Return 1, if the caller writeback routine should be | |
615 | * interrupted. Otherwise return 0. | |
616 | */ | |
617 | static int writeback_sb_inodes(struct super_block *sb, | |
618 | struct bdi_writeback *wb, | |
619 | struct writeback_control *wbc) | |
1da177e4 | 620 | { |
03ba3782 | 621 | while (!list_empty(&wb->b_io)) { |
1da177e4 | 622 | long pages_skipped; |
f11c9c5c ES |
623 | struct inode *inode = list_entry(wb->b_io.prev, |
624 | struct inode, i_list); | |
625 | if (wbc->sb && sb != inode->i_sb) { | |
626 | /* super block given and doesn't | |
627 | match, skip this inode */ | |
66f3b8e2 JA |
628 | redirty_tail(inode); |
629 | continue; | |
630 | } | |
f11c9c5c ES |
631 | if (sb != inode->i_sb) |
632 | /* finish with this superblock */ | |
633 | return 0; | |
84a89245 | 634 | if (inode->i_state & (I_NEW | I_WILL_FREE)) { |
7ef0d737 NP |
635 | requeue_io(inode); |
636 | continue; | |
637 | } | |
d2caa3c5 JL |
638 | /* |
639 | * Was this inode dirtied after sync_sb_inodes was called? | |
640 | * This keeps sync from extra jobs and livelock. | |
641 | */ | |
f11c9c5c ES |
642 | if (inode_dirtied_after(inode, wbc->wb_start)) |
643 | return 1; | |
1da177e4 | 644 | |
84a89245 | 645 | BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); |
1da177e4 LT |
646 | __iget(inode); |
647 | pages_skipped = wbc->pages_skipped; | |
01c03194 | 648 | writeback_single_inode(inode, wbc); |
1da177e4 LT |
649 | if (wbc->pages_skipped != pages_skipped) { |
650 | /* | |
651 | * writeback is not making progress due to locked | |
652 | * buffers. Skip this inode for now. | |
653 | */ | |
f57b9b7b | 654 | redirty_tail(inode); |
1da177e4 LT |
655 | } |
656 | spin_unlock(&inode_lock); | |
1da177e4 | 657 | iput(inode); |
4ffc8444 | 658 | cond_resched(); |
1da177e4 | 659 | spin_lock(&inode_lock); |
8bc3be27 FW |
660 | if (wbc->nr_to_write <= 0) { |
661 | wbc->more_io = 1; | |
f11c9c5c | 662 | return 1; |
8bc3be27 | 663 | } |
03ba3782 | 664 | if (!list_empty(&wb->b_more_io)) |
8bc3be27 | 665 | wbc->more_io = 1; |
1da177e4 | 666 | } |
f11c9c5c ES |
667 | /* b_io is empty */ |
668 | return 1; | |
669 | } | |
670 | ||
671 | static void writeback_inodes_wb(struct bdi_writeback *wb, | |
672 | struct writeback_control *wbc) | |
673 | { | |
674 | int ret = 0; | |
675 | ||
676 | wbc->wb_start = jiffies; /* livelock avoidance */ | |
677 | spin_lock(&inode_lock); | |
678 | if (!wbc->for_kupdate || list_empty(&wb->b_io)) | |
679 | queue_io(wb, wbc->older_than_this); | |
38f21977 | 680 | |
f11c9c5c ES |
681 | while (!list_empty(&wb->b_io)) { |
682 | struct inode *inode = list_entry(wb->b_io.prev, | |
683 | struct inode, i_list); | |
684 | struct super_block *sb = inode->i_sb; | |
685 | enum sb_pin_state state; | |
9ecc2738 | 686 | |
f11c9c5c ES |
687 | if (wbc->sb && sb != wbc->sb) { |
688 | /* super block given and doesn't | |
689 | match, skip this inode */ | |
690 | redirty_tail(inode); | |
691 | continue; | |
692 | } | |
693 | state = pin_sb_for_writeback(wbc, sb); | |
694 | ||
695 | if (state == SB_PIN_FAILED) { | |
696 | requeue_io(inode); | |
697 | continue; | |
698 | } | |
699 | ret = writeback_sb_inodes(sb, wb, wbc); | |
700 | ||
701 | if (state == SB_PINNED) | |
702 | unpin_sb_for_writeback(sb); | |
703 | if (ret) | |
704 | break; | |
705 | } | |
66f3b8e2 JA |
706 | spin_unlock(&inode_lock); |
707 | /* Leave any unwritten inodes on b_io */ | |
708 | } | |
709 | ||
03ba3782 JA |
710 | void writeback_inodes_wbc(struct writeback_control *wbc) |
711 | { | |
712 | struct backing_dev_info *bdi = wbc->bdi; | |
713 | ||
714 | writeback_inodes_wb(&bdi->wb, wbc); | |
715 | } | |
716 | ||
66f3b8e2 | 717 | /* |
03ba3782 JA |
718 | * The maximum number of pages to writeout in a single bdi flush/kupdate |
719 | * operation. We do this so we don't hold I_SYNC against an inode for | |
720 | * enormous amounts of time, which would block a userspace task which has | |
721 | * been forced to throttle against that inode. Also, the code reevaluates | |
722 | * the dirty each time it has written this many pages. | |
723 | */ | |
724 | #define MAX_WRITEBACK_PAGES 1024 | |
725 | ||
726 | static inline bool over_bground_thresh(void) | |
727 | { | |
728 | unsigned long background_thresh, dirty_thresh; | |
729 | ||
730 | get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); | |
731 | ||
732 | return (global_page_state(NR_FILE_DIRTY) + | |
733 | global_page_state(NR_UNSTABLE_NFS) >= background_thresh); | |
734 | } | |
735 | ||
736 | /* | |
737 | * Explicit flushing or periodic writeback of "old" data. | |
66f3b8e2 | 738 | * |
03ba3782 JA |
739 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
740 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
741 | * just walks the superblock inode list, writing back any inodes which are | |
742 | * older than a specific point in time. | |
66f3b8e2 | 743 | * |
03ba3782 JA |
744 | * Try to run once per dirty_writeback_interval. But if a writeback event |
745 | * takes longer than a dirty_writeback_interval interval, then leave a | |
746 | * one-second gap. | |
66f3b8e2 | 747 | * |
03ba3782 JA |
748 | * older_than_this takes precedence over nr_to_write. So we'll only write back |
749 | * all dirty pages if they are all attached to "old" mappings. | |
66f3b8e2 | 750 | */ |
c4a77a6c JA |
751 | static long wb_writeback(struct bdi_writeback *wb, |
752 | struct wb_writeback_args *args) | |
66f3b8e2 | 753 | { |
03ba3782 JA |
754 | struct writeback_control wbc = { |
755 | .bdi = wb->bdi, | |
c4a77a6c JA |
756 | .sb = args->sb, |
757 | .sync_mode = args->sync_mode, | |
03ba3782 | 758 | .older_than_this = NULL, |
c4a77a6c | 759 | .for_kupdate = args->for_kupdate, |
b17621fe | 760 | .for_background = args->for_background, |
c4a77a6c | 761 | .range_cyclic = args->range_cyclic, |
e913fc82 | 762 | .sb_pinned = args->sb_pinned, |
03ba3782 JA |
763 | }; |
764 | unsigned long oldest_jif; | |
765 | long wrote = 0; | |
a5989bdc | 766 | struct inode *inode; |
66f3b8e2 | 767 | |
03ba3782 JA |
768 | if (wbc.for_kupdate) { |
769 | wbc.older_than_this = &oldest_jif; | |
770 | oldest_jif = jiffies - | |
771 | msecs_to_jiffies(dirty_expire_interval * 10); | |
772 | } | |
c4a77a6c JA |
773 | if (!wbc.range_cyclic) { |
774 | wbc.range_start = 0; | |
775 | wbc.range_end = LLONG_MAX; | |
776 | } | |
38f21977 | 777 | |
03ba3782 JA |
778 | for (;;) { |
779 | /* | |
d3ddec76 | 780 | * Stop writeback when nr_pages has been consumed |
03ba3782 | 781 | */ |
d3ddec76 | 782 | if (args->nr_pages <= 0) |
03ba3782 | 783 | break; |
66f3b8e2 | 784 | |
38f21977 | 785 | /* |
d3ddec76 WF |
786 | * For background writeout, stop when we are below the |
787 | * background dirty threshold | |
38f21977 | 788 | */ |
d3ddec76 | 789 | if (args->for_background && !over_bground_thresh()) |
03ba3782 | 790 | break; |
38f21977 | 791 | |
03ba3782 | 792 | wbc.more_io = 0; |
03ba3782 JA |
793 | wbc.nr_to_write = MAX_WRITEBACK_PAGES; |
794 | wbc.pages_skipped = 0; | |
795 | writeback_inodes_wb(wb, &wbc); | |
c4a77a6c | 796 | args->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
03ba3782 JA |
797 | wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
798 | ||
799 | /* | |
71fd05a8 | 800 | * If we consumed everything, see if we have more |
03ba3782 | 801 | */ |
71fd05a8 JA |
802 | if (wbc.nr_to_write <= 0) |
803 | continue; | |
804 | /* | |
805 | * Didn't write everything and we don't have more IO, bail | |
806 | */ | |
807 | if (!wbc.more_io) | |
03ba3782 | 808 | break; |
71fd05a8 JA |
809 | /* |
810 | * Did we write something? Try for more | |
811 | */ | |
812 | if (wbc.nr_to_write < MAX_WRITEBACK_PAGES) | |
813 | continue; | |
814 | /* | |
815 | * Nothing written. Wait for some inode to | |
816 | * become available for writeback. Otherwise | |
817 | * we'll just busyloop. | |
818 | */ | |
819 | spin_lock(&inode_lock); | |
820 | if (!list_empty(&wb->b_more_io)) { | |
821 | inode = list_entry(wb->b_more_io.prev, | |
822 | struct inode, i_list); | |
823 | inode_wait_for_writeback(inode); | |
03ba3782 | 824 | } |
71fd05a8 | 825 | spin_unlock(&inode_lock); |
03ba3782 JA |
826 | } |
827 | ||
828 | return wrote; | |
829 | } | |
830 | ||
831 | /* | |
832 | * Return the next bdi_work struct that hasn't been processed by this | |
8010c3b6 JA |
833 | * wb thread yet. ->seen is initially set for each thread that exists |
834 | * for this device, when a thread first notices a piece of work it | |
835 | * clears its bit. Depending on writeback type, the thread will notify | |
836 | * completion on either receiving the work (WB_SYNC_NONE) or after | |
837 | * it is done (WB_SYNC_ALL). | |
03ba3782 JA |
838 | */ |
839 | static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi, | |
840 | struct bdi_writeback *wb) | |
841 | { | |
842 | struct bdi_work *work, *ret = NULL; | |
843 | ||
844 | rcu_read_lock(); | |
845 | ||
846 | list_for_each_entry_rcu(work, &bdi->work_list, list) { | |
77fad5e6 | 847 | if (!test_bit(wb->nr, &work->seen)) |
03ba3782 | 848 | continue; |
77fad5e6 | 849 | clear_bit(wb->nr, &work->seen); |
03ba3782 JA |
850 | |
851 | ret = work; | |
852 | break; | |
853 | } | |
854 | ||
855 | rcu_read_unlock(); | |
856 | return ret; | |
857 | } | |
858 | ||
859 | static long wb_check_old_data_flush(struct bdi_writeback *wb) | |
860 | { | |
861 | unsigned long expired; | |
862 | long nr_pages; | |
863 | ||
69b62d01 JA |
864 | /* |
865 | * When set to zero, disable periodic writeback | |
866 | */ | |
867 | if (!dirty_writeback_interval) | |
868 | return 0; | |
869 | ||
03ba3782 JA |
870 | expired = wb->last_old_flush + |
871 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
872 | if (time_before(jiffies, expired)) | |
873 | return 0; | |
874 | ||
875 | wb->last_old_flush = jiffies; | |
876 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
877 | global_page_state(NR_UNSTABLE_NFS) + | |
878 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); | |
879 | ||
c4a77a6c JA |
880 | if (nr_pages) { |
881 | struct wb_writeback_args args = { | |
882 | .nr_pages = nr_pages, | |
883 | .sync_mode = WB_SYNC_NONE, | |
884 | .for_kupdate = 1, | |
885 | .range_cyclic = 1, | |
886 | }; | |
887 | ||
888 | return wb_writeback(wb, &args); | |
889 | } | |
03ba3782 JA |
890 | |
891 | return 0; | |
892 | } | |
893 | ||
894 | /* | |
895 | * Retrieve work items and do the writeback they describe | |
896 | */ | |
897 | long wb_do_writeback(struct bdi_writeback *wb, int force_wait) | |
898 | { | |
899 | struct backing_dev_info *bdi = wb->bdi; | |
900 | struct bdi_work *work; | |
c4a77a6c | 901 | long wrote = 0; |
03ba3782 JA |
902 | |
903 | while ((work = get_next_work_item(bdi, wb)) != NULL) { | |
c4a77a6c | 904 | struct wb_writeback_args args = work->args; |
03ba3782 JA |
905 | |
906 | /* | |
907 | * Override sync mode, in case we must wait for completion | |
908 | */ | |
909 | if (force_wait) | |
c4a77a6c | 910 | work->args.sync_mode = args.sync_mode = WB_SYNC_ALL; |
03ba3782 JA |
911 | |
912 | /* | |
913 | * If this isn't a data integrity operation, just notify | |
914 | * that we have seen this work and we are now starting it. | |
915 | */ | |
c4a77a6c | 916 | if (args.sync_mode == WB_SYNC_NONE) |
03ba3782 JA |
917 | wb_clear_pending(wb, work); |
918 | ||
c4a77a6c | 919 | wrote += wb_writeback(wb, &args); |
03ba3782 JA |
920 | |
921 | /* | |
922 | * This is a data integrity writeback, so only do the | |
923 | * notification when we have completed the work. | |
924 | */ | |
c4a77a6c | 925 | if (args.sync_mode == WB_SYNC_ALL) |
03ba3782 JA |
926 | wb_clear_pending(wb, work); |
927 | } | |
928 | ||
929 | /* | |
930 | * Check for periodic writeback, kupdated() style | |
931 | */ | |
932 | wrote += wb_check_old_data_flush(wb); | |
933 | ||
934 | return wrote; | |
935 | } | |
936 | ||
937 | /* | |
938 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
939 | * wakes up periodically and does kupdated style flushing. | |
940 | */ | |
941 | int bdi_writeback_task(struct bdi_writeback *wb) | |
942 | { | |
943 | unsigned long last_active = jiffies; | |
944 | unsigned long wait_jiffies = -1UL; | |
945 | long pages_written; | |
946 | ||
947 | while (!kthread_should_stop()) { | |
948 | pages_written = wb_do_writeback(wb, 0); | |
949 | ||
950 | if (pages_written) | |
951 | last_active = jiffies; | |
952 | else if (wait_jiffies != -1UL) { | |
953 | unsigned long max_idle; | |
954 | ||
38f21977 | 955 | /* |
03ba3782 JA |
956 | * Longest period of inactivity that we tolerate. If we |
957 | * see dirty data again later, the task will get | |
958 | * recreated automatically. | |
38f21977 | 959 | */ |
03ba3782 JA |
960 | max_idle = max(5UL * 60 * HZ, wait_jiffies); |
961 | if (time_after(jiffies, max_idle + last_active)) | |
962 | break; | |
963 | } | |
964 | ||
69b62d01 JA |
965 | if (dirty_writeback_interval) { |
966 | wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); | |
967 | schedule_timeout_interruptible(wait_jiffies); | |
968 | } else | |
969 | schedule(); | |
970 | ||
03ba3782 JA |
971 | try_to_freeze(); |
972 | } | |
973 | ||
974 | return 0; | |
975 | } | |
976 | ||
977 | /* | |
b6e51316 JA |
978 | * Schedule writeback for all backing devices. This does WB_SYNC_NONE |
979 | * writeback, for integrity writeback see bdi_sync_writeback(). | |
03ba3782 | 980 | */ |
b6e51316 | 981 | static void bdi_writeback_all(struct super_block *sb, long nr_pages) |
03ba3782 | 982 | { |
b6e51316 JA |
983 | struct wb_writeback_args args = { |
984 | .sb = sb, | |
985 | .nr_pages = nr_pages, | |
986 | .sync_mode = WB_SYNC_NONE, | |
987 | }; | |
03ba3782 | 988 | struct backing_dev_info *bdi; |
03ba3782 | 989 | |
cfc4ba53 | 990 | rcu_read_lock(); |
03ba3782 | 991 | |
cfc4ba53 | 992 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { |
03ba3782 JA |
993 | if (!bdi_has_dirty_io(bdi)) |
994 | continue; | |
38f21977 | 995 | |
b6e51316 | 996 | bdi_alloc_queue_work(bdi, &args); |
03ba3782 JA |
997 | } |
998 | ||
cfc4ba53 | 999 | rcu_read_unlock(); |
1da177e4 LT |
1000 | } |
1001 | ||
1002 | /* | |
03ba3782 JA |
1003 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
1004 | * the whole world. | |
1005 | */ | |
1006 | void wakeup_flusher_threads(long nr_pages) | |
1007 | { | |
03ba3782 JA |
1008 | if (nr_pages == 0) |
1009 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
1010 | global_page_state(NR_UNSTABLE_NFS); | |
b6e51316 | 1011 | bdi_writeback_all(NULL, nr_pages); |
03ba3782 JA |
1012 | } |
1013 | ||
1014 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) | |
1015 | { | |
1016 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
1017 | struct dentry *dentry; | |
1018 | const char *name = "?"; | |
1019 | ||
1020 | dentry = d_find_alias(inode); | |
1021 | if (dentry) { | |
1022 | spin_lock(&dentry->d_lock); | |
1023 | name = (const char *) dentry->d_name.name; | |
1024 | } | |
1025 | printk(KERN_DEBUG | |
1026 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
1027 | current->comm, task_pid_nr(current), inode->i_ino, | |
1028 | name, inode->i_sb->s_id); | |
1029 | if (dentry) { | |
1030 | spin_unlock(&dentry->d_lock); | |
1031 | dput(dentry); | |
1032 | } | |
1033 | } | |
1034 | } | |
1035 | ||
1036 | /** | |
1037 | * __mark_inode_dirty - internal function | |
1038 | * @inode: inode to mark | |
1039 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
1040 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
1041 | * mark_inode_dirty_sync. | |
1da177e4 | 1042 | * |
03ba3782 JA |
1043 | * Put the inode on the super block's dirty list. |
1044 | * | |
1045 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
1046 | * dirty list only if it is hashed or if it refers to a blockdev. | |
1047 | * If it was not hashed, it will never be added to the dirty list | |
1048 | * even if it is later hashed, as it will have been marked dirty already. | |
1049 | * | |
1050 | * In short, make sure you hash any inodes _before_ you start marking | |
1051 | * them dirty. | |
1da177e4 | 1052 | * |
03ba3782 JA |
1053 | * This function *must* be atomic for the I_DIRTY_PAGES case - |
1054 | * set_page_dirty() is called under spinlock in several places. | |
1da177e4 | 1055 | * |
03ba3782 JA |
1056 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
1057 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
1058 | * the kernel-internal blockdev inode represents the dirtying time of the | |
1059 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
1060 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
1061 | * blockdev inode. | |
1da177e4 | 1062 | */ |
03ba3782 | 1063 | void __mark_inode_dirty(struct inode *inode, int flags) |
1da177e4 | 1064 | { |
03ba3782 | 1065 | struct super_block *sb = inode->i_sb; |
1da177e4 | 1066 | |
03ba3782 JA |
1067 | /* |
1068 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
1069 | * dirty the inode itself | |
1070 | */ | |
1071 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
1072 | if (sb->s_op->dirty_inode) | |
1073 | sb->s_op->dirty_inode(inode); | |
1074 | } | |
1075 | ||
1076 | /* | |
1077 | * make sure that changes are seen by all cpus before we test i_state | |
1078 | * -- mikulas | |
1079 | */ | |
1080 | smp_mb(); | |
1081 | ||
1082 | /* avoid the locking if we can */ | |
1083 | if ((inode->i_state & flags) == flags) | |
1084 | return; | |
1085 | ||
1086 | if (unlikely(block_dump)) | |
1087 | block_dump___mark_inode_dirty(inode); | |
1088 | ||
1089 | spin_lock(&inode_lock); | |
1090 | if ((inode->i_state & flags) != flags) { | |
1091 | const int was_dirty = inode->i_state & I_DIRTY; | |
1092 | ||
1093 | inode->i_state |= flags; | |
1094 | ||
1095 | /* | |
1096 | * If the inode is being synced, just update its dirty state. | |
1097 | * The unlocker will place the inode on the appropriate | |
1098 | * superblock list, based upon its state. | |
1099 | */ | |
1100 | if (inode->i_state & I_SYNC) | |
1101 | goto out; | |
1102 | ||
1103 | /* | |
1104 | * Only add valid (hashed) inodes to the superblock's | |
1105 | * dirty list. Add blockdev inodes as well. | |
1106 | */ | |
1107 | if (!S_ISBLK(inode->i_mode)) { | |
1108 | if (hlist_unhashed(&inode->i_hash)) | |
1109 | goto out; | |
1110 | } | |
1111 | if (inode->i_state & (I_FREEING|I_CLEAR)) | |
1112 | goto out; | |
1113 | ||
1114 | /* | |
1115 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
1116 | * reposition it (that would break b_dirty time-ordering). | |
1117 | */ | |
1118 | if (!was_dirty) { | |
1119 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; | |
500b067c JA |
1120 | struct backing_dev_info *bdi = wb->bdi; |
1121 | ||
1122 | if (bdi_cap_writeback_dirty(bdi) && | |
1123 | !test_bit(BDI_registered, &bdi->state)) { | |
1124 | WARN_ON(1); | |
1125 | printk(KERN_ERR "bdi-%s not registered\n", | |
1126 | bdi->name); | |
1127 | } | |
03ba3782 JA |
1128 | |
1129 | inode->dirtied_when = jiffies; | |
1130 | list_move(&inode->i_list, &wb->b_dirty); | |
1da177e4 | 1131 | } |
1da177e4 | 1132 | } |
03ba3782 JA |
1133 | out: |
1134 | spin_unlock(&inode_lock); | |
1135 | } | |
1136 | EXPORT_SYMBOL(__mark_inode_dirty); | |
1137 | ||
1138 | /* | |
1139 | * Write out a superblock's list of dirty inodes. A wait will be performed | |
1140 | * upon no inodes, all inodes or the final one, depending upon sync_mode. | |
1141 | * | |
1142 | * If older_than_this is non-NULL, then only write out inodes which | |
1143 | * had their first dirtying at a time earlier than *older_than_this. | |
1144 | * | |
03ba3782 JA |
1145 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. |
1146 | * This function assumes that the blockdev superblock's inodes are backed by | |
1147 | * a variety of queues, so all inodes are searched. For other superblocks, | |
1148 | * assume that all inodes are backed by the same queue. | |
1149 | * | |
1150 | * The inodes to be written are parked on bdi->b_io. They are moved back onto | |
1151 | * bdi->b_dirty as they are selected for writing. This way, none can be missed | |
1152 | * on the writer throttling path, and we get decent balancing between many | |
1153 | * throttled threads: we don't want them all piling up on inode_sync_wait. | |
1154 | */ | |
b6e51316 | 1155 | static void wait_sb_inodes(struct super_block *sb) |
03ba3782 JA |
1156 | { |
1157 | struct inode *inode, *old_inode = NULL; | |
1158 | ||
1159 | /* | |
1160 | * We need to be protected against the filesystem going from | |
1161 | * r/o to r/w or vice versa. | |
1162 | */ | |
b6e51316 | 1163 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
03ba3782 JA |
1164 | |
1165 | spin_lock(&inode_lock); | |
1166 | ||
1167 | /* | |
1168 | * Data integrity sync. Must wait for all pages under writeback, | |
1169 | * because there may have been pages dirtied before our sync | |
1170 | * call, but which had writeout started before we write it out. | |
1171 | * In which case, the inode may not be on the dirty list, but | |
1172 | * we still have to wait for that writeout. | |
1173 | */ | |
b6e51316 | 1174 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
03ba3782 JA |
1175 | struct address_space *mapping; |
1176 | ||
1177 | if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) | |
1178 | continue; | |
1179 | mapping = inode->i_mapping; | |
1180 | if (mapping->nrpages == 0) | |
1181 | continue; | |
1182 | __iget(inode); | |
1183 | spin_unlock(&inode_lock); | |
1184 | /* | |
1185 | * We hold a reference to 'inode' so it couldn't have | |
1186 | * been removed from s_inodes list while we dropped the | |
1187 | * inode_lock. We cannot iput the inode now as we can | |
1188 | * be holding the last reference and we cannot iput it | |
1189 | * under inode_lock. So we keep the reference and iput | |
1190 | * it later. | |
1191 | */ | |
1192 | iput(old_inode); | |
1193 | old_inode = inode; | |
1194 | ||
1195 | filemap_fdatawait(mapping); | |
1196 | ||
1197 | cond_resched(); | |
1198 | ||
1199 | spin_lock(&inode_lock); | |
1200 | } | |
1201 | spin_unlock(&inode_lock); | |
1202 | iput(old_inode); | |
1da177e4 LT |
1203 | } |
1204 | ||
e913fc82 JA |
1205 | static void __writeback_inodes_sb(struct super_block *sb, int sb_locked) |
1206 | { | |
1207 | unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); | |
1208 | unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); | |
1209 | long nr_to_write; | |
1210 | ||
1211 | nr_to_write = nr_dirty + nr_unstable + | |
1212 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); | |
1213 | ||
1214 | bdi_start_writeback(sb->s_bdi, sb, nr_to_write, sb_locked); | |
1215 | } | |
1216 | ||
d8a8559c JA |
1217 | /** |
1218 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
1219 | * @sb: the superblock | |
1da177e4 | 1220 | * |
d8a8559c JA |
1221 | * Start writeback on some inodes on this super_block. No guarantees are made |
1222 | * on how many (if any) will be written, and this function does not wait | |
1223 | * for IO completion of submitted IO. The number of pages submitted is | |
1224 | * returned. | |
1da177e4 | 1225 | */ |
b6e51316 | 1226 | void writeback_inodes_sb(struct super_block *sb) |
1da177e4 | 1227 | { |
e913fc82 | 1228 | __writeback_inodes_sb(sb, 0); |
d8a8559c JA |
1229 | } |
1230 | EXPORT_SYMBOL(writeback_inodes_sb); | |
1231 | ||
e913fc82 JA |
1232 | /** |
1233 | * writeback_inodes_sb_locked - writeback dirty inodes from given super_block | |
1234 | * @sb: the superblock | |
1235 | * | |
1236 | * Like writeback_inodes_sb(), except the caller already holds the | |
1237 | * sb umount sem. | |
1238 | */ | |
1239 | void writeback_inodes_sb_locked(struct super_block *sb) | |
1240 | { | |
1241 | __writeback_inodes_sb(sb, 1); | |
1242 | } | |
1243 | ||
17bd55d0 ES |
1244 | /** |
1245 | * writeback_inodes_sb_if_idle - start writeback if none underway | |
1246 | * @sb: the superblock | |
1247 | * | |
1248 | * Invoke writeback_inodes_sb if no writeback is currently underway. | |
1249 | * Returns 1 if writeback was started, 0 if not. | |
1250 | */ | |
1251 | int writeback_inodes_sb_if_idle(struct super_block *sb) | |
1252 | { | |
1253 | if (!writeback_in_progress(sb->s_bdi)) { | |
1254 | writeback_inodes_sb(sb); | |
1255 | return 1; | |
1256 | } else | |
1257 | return 0; | |
1258 | } | |
1259 | EXPORT_SYMBOL(writeback_inodes_sb_if_idle); | |
1260 | ||
d8a8559c JA |
1261 | /** |
1262 | * sync_inodes_sb - sync sb inode pages | |
1263 | * @sb: the superblock | |
1264 | * | |
1265 | * This function writes and waits on any dirty inode belonging to this | |
1266 | * super_block. The number of pages synced is returned. | |
1267 | */ | |
b6e51316 | 1268 | void sync_inodes_sb(struct super_block *sb) |
d8a8559c | 1269 | { |
b6e51316 JA |
1270 | bdi_sync_writeback(sb->s_bdi, sb); |
1271 | wait_sb_inodes(sb); | |
1da177e4 | 1272 | } |
d8a8559c | 1273 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 1274 | |
1da177e4 | 1275 | /** |
7f04c26d AA |
1276 | * write_inode_now - write an inode to disk |
1277 | * @inode: inode to write to disk | |
1278 | * @sync: whether the write should be synchronous or not | |
1279 | * | |
1280 | * This function commits an inode to disk immediately if it is dirty. This is | |
1281 | * primarily needed by knfsd. | |
1da177e4 | 1282 | * |
7f04c26d | 1283 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 1284 | */ |
1da177e4 LT |
1285 | int write_inode_now(struct inode *inode, int sync) |
1286 | { | |
1287 | int ret; | |
1288 | struct writeback_control wbc = { | |
1289 | .nr_to_write = LONG_MAX, | |
18914b18 | 1290 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
1291 | .range_start = 0, |
1292 | .range_end = LLONG_MAX, | |
1da177e4 LT |
1293 | }; |
1294 | ||
1295 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 1296 | wbc.nr_to_write = 0; |
1da177e4 LT |
1297 | |
1298 | might_sleep(); | |
1299 | spin_lock(&inode_lock); | |
01c03194 | 1300 | ret = writeback_single_inode(inode, &wbc); |
1da177e4 LT |
1301 | spin_unlock(&inode_lock); |
1302 | if (sync) | |
1c0eeaf5 | 1303 | inode_sync_wait(inode); |
1da177e4 LT |
1304 | return ret; |
1305 | } | |
1306 | EXPORT_SYMBOL(write_inode_now); | |
1307 | ||
1308 | /** | |
1309 | * sync_inode - write an inode and its pages to disk. | |
1310 | * @inode: the inode to sync | |
1311 | * @wbc: controls the writeback mode | |
1312 | * | |
1313 | * sync_inode() will write an inode and its pages to disk. It will also | |
1314 | * correctly update the inode on its superblock's dirty inode lists and will | |
1315 | * update inode->i_state. | |
1316 | * | |
1317 | * The caller must have a ref on the inode. | |
1318 | */ | |
1319 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
1320 | { | |
1321 | int ret; | |
1322 | ||
1323 | spin_lock(&inode_lock); | |
01c03194 | 1324 | ret = writeback_single_inode(inode, wbc); |
1da177e4 LT |
1325 | spin_unlock(&inode_lock); |
1326 | return ret; | |
1327 | } | |
1328 | EXPORT_SYMBOL(sync_inode); |