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Commit | Line | Data |
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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; | |
52957fe1 HS |
45 | unsigned int for_kupdate:1; |
46 | unsigned int range_cyclic:1; | |
47 | unsigned 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 { | |
7f0e7bed CH |
66 | WS_INPROGRESS = 0, |
67 | WS_ONSTACK, | |
03ba3782 JA |
68 | }; |
69 | ||
03ba3782 | 70 | static inline void bdi_work_init(struct bdi_work *work, |
b6e51316 | 71 | struct wb_writeback_args *args) |
03ba3782 JA |
72 | { |
73 | INIT_RCU_HEAD(&work->rcu_head); | |
b6e51316 | 74 | work->args = *args; |
7f0e7bed | 75 | __set_bit(WS_INPROGRESS, &work->state); |
03ba3782 JA |
76 | } |
77 | ||
f11b00f3 AB |
78 | /** |
79 | * writeback_in_progress - determine whether there is writeback in progress | |
80 | * @bdi: the device's backing_dev_info structure. | |
81 | * | |
03ba3782 JA |
82 | * Determine whether there is writeback waiting to be handled against a |
83 | * backing device. | |
f11b00f3 AB |
84 | */ |
85 | int writeback_in_progress(struct backing_dev_info *bdi) | |
86 | { | |
03ba3782 | 87 | return !list_empty(&bdi->work_list); |
f11b00f3 AB |
88 | } |
89 | ||
03ba3782 | 90 | static void bdi_work_free(struct rcu_head *head) |
4195f73d | 91 | { |
03ba3782 | 92 | struct bdi_work *work = container_of(head, struct bdi_work, rcu_head); |
4195f73d | 93 | |
7f0e7bed CH |
94 | clear_bit(WS_INPROGRESS, &work->state); |
95 | smp_mb__after_clear_bit(); | |
96 | wake_up_bit(&work->state, WS_INPROGRESS); | |
1da177e4 | 97 | |
7f0e7bed CH |
98 | if (!test_bit(WS_ONSTACK, &work->state)) |
99 | kfree(work); | |
03ba3782 | 100 | } |
1da177e4 | 101 | |
03ba3782 JA |
102 | static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work) |
103 | { | |
1da177e4 | 104 | /* |
03ba3782 JA |
105 | * The caller has retrieved the work arguments from this work, |
106 | * drop our reference. If this is the last ref, delete and free it | |
1da177e4 | 107 | */ |
03ba3782 JA |
108 | if (atomic_dec_and_test(&work->pending)) { |
109 | struct backing_dev_info *bdi = wb->bdi; | |
1da177e4 | 110 | |
03ba3782 JA |
111 | spin_lock(&bdi->wb_lock); |
112 | list_del_rcu(&work->list); | |
113 | spin_unlock(&bdi->wb_lock); | |
1da177e4 | 114 | |
7f0e7bed | 115 | call_rcu(&work->rcu_head, bdi_work_free); |
03ba3782 JA |
116 | } |
117 | } | |
1da177e4 | 118 | |
03ba3782 JA |
119 | static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work) |
120 | { | |
bcddc3f0 JA |
121 | work->seen = bdi->wb_mask; |
122 | BUG_ON(!work->seen); | |
123 | atomic_set(&work->pending, bdi->wb_cnt); | |
124 | BUG_ON(!bdi->wb_cnt); | |
1da177e4 | 125 | |
bcddc3f0 | 126 | /* |
deed62ed NP |
127 | * list_add_tail_rcu() contains the necessary barriers to |
128 | * make sure the above stores are seen before the item is | |
129 | * noticed on the list | |
bcddc3f0 | 130 | */ |
bcddc3f0 JA |
131 | spin_lock(&bdi->wb_lock); |
132 | list_add_tail_rcu(&work->list, &bdi->work_list); | |
133 | spin_unlock(&bdi->wb_lock); | |
03ba3782 JA |
134 | |
135 | /* | |
136 | * If the default thread isn't there, make sure we add it. When | |
137 | * it gets created and wakes up, we'll run this work. | |
138 | */ | |
139 | if (unlikely(list_empty_careful(&bdi->wb_list))) | |
140 | wake_up_process(default_backing_dev_info.wb.task); | |
141 | else { | |
142 | struct bdi_writeback *wb = &bdi->wb; | |
1da177e4 | 143 | |
1ef7d9aa | 144 | if (wb->task) |
03ba3782 | 145 | wake_up_process(wb->task); |
1da177e4 | 146 | } |
1da177e4 LT |
147 | } |
148 | ||
03ba3782 JA |
149 | /* |
150 | * Used for on-stack allocated work items. The caller needs to wait until | |
151 | * the wb threads have acked the work before it's safe to continue. | |
152 | */ | |
7f0e7bed | 153 | static void bdi_wait_on_work_done(struct bdi_work *work) |
03ba3782 | 154 | { |
7f0e7bed | 155 | wait_on_bit(&work->state, WS_INPROGRESS, bdi_sched_wait, |
03ba3782 JA |
156 | TASK_UNINTERRUPTIBLE); |
157 | } | |
1da177e4 | 158 | |
f11fcae8 | 159 | static void bdi_alloc_queue_work(struct backing_dev_info *bdi, |
f17625b3 | 160 | struct wb_writeback_args *args) |
1da177e4 | 161 | { |
03ba3782 JA |
162 | struct bdi_work *work; |
163 | ||
bcddc3f0 JA |
164 | /* |
165 | * This is WB_SYNC_NONE writeback, so if allocation fails just | |
166 | * wakeup the thread for old dirty data writeback | |
167 | */ | |
03ba3782 | 168 | work = kmalloc(sizeof(*work), GFP_ATOMIC); |
bcddc3f0 | 169 | if (work) { |
b6e51316 | 170 | bdi_work_init(work, args); |
bcddc3f0 JA |
171 | bdi_queue_work(bdi, work); |
172 | } else { | |
173 | struct bdi_writeback *wb = &bdi->wb; | |
03ba3782 | 174 | |
bcddc3f0 JA |
175 | if (wb->task) |
176 | wake_up_process(wb->task); | |
177 | } | |
03ba3782 JA |
178 | } |
179 | ||
b6e51316 | 180 | /** |
3c4d7165 | 181 | * bdi_queue_work_onstack - start and wait for writeback |
b6e51316 JA |
182 | * @sb: write inodes from this super_block |
183 | * | |
184 | * Description: | |
3c4d7165 CH |
185 | * This function initiates writeback and waits for the operation to |
186 | * complete. Callers must hold the sb s_umount semaphore for | |
b6e51316 JA |
187 | * reading, to avoid having the super disappear before we are done. |
188 | */ | |
3c4d7165 | 189 | static void bdi_queue_work_onstack(struct wb_writeback_args *args) |
03ba3782 | 190 | { |
b6e51316 | 191 | struct bdi_work work; |
03ba3782 | 192 | |
3c4d7165 | 193 | bdi_work_init(&work, args); |
7f0e7bed | 194 | __set_bit(WS_ONSTACK, &work.state); |
03ba3782 | 195 | |
3c4d7165 | 196 | bdi_queue_work(args->sb->s_bdi, &work); |
7f0e7bed | 197 | bdi_wait_on_work_done(&work); |
b6e51316 JA |
198 | } |
199 | ||
200 | /** | |
201 | * bdi_start_writeback - start writeback | |
202 | * @bdi: the backing device to write from | |
203 | * @nr_pages: the number of pages to write | |
204 | * | |
205 | * Description: | |
206 | * This does WB_SYNC_NONE opportunistic writeback. The IO is only | |
207 | * started when this function returns, we make no guarentees on | |
0e3c9a22 | 208 | * completion. Caller need not hold sb s_umount semaphore. |
b6e51316 JA |
209 | * |
210 | */ | |
c5444198 | 211 | void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages) |
b6e51316 JA |
212 | { |
213 | struct wb_writeback_args args = { | |
214 | .sync_mode = WB_SYNC_NONE, | |
215 | .nr_pages = nr_pages, | |
216 | .range_cyclic = 1, | |
217 | }; | |
218 | ||
c5444198 CH |
219 | bdi_alloc_queue_work(bdi, &args); |
220 | } | |
d3ddec76 | 221 | |
c5444198 CH |
222 | /** |
223 | * bdi_start_background_writeback - start background writeback | |
224 | * @bdi: the backing device to write from | |
225 | * | |
226 | * Description: | |
227 | * This does WB_SYNC_NONE background writeback. The IO is only | |
228 | * started when this function returns, we make no guarentees on | |
229 | * completion. Caller need not hold sb s_umount semaphore. | |
230 | */ | |
231 | void bdi_start_background_writeback(struct backing_dev_info *bdi) | |
232 | { | |
233 | struct wb_writeback_args args = { | |
234 | .sync_mode = WB_SYNC_NONE, | |
235 | .nr_pages = LONG_MAX, | |
236 | .for_background = 1, | |
237 | .range_cyclic = 1, | |
238 | }; | |
f17625b3 | 239 | bdi_alloc_queue_work(bdi, &args); |
1da177e4 LT |
240 | } |
241 | ||
6610a0bc AM |
242 | /* |
243 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
244 | * furthest end of its superblock's dirty-inode list. | |
245 | * | |
246 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 247 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
248 | * the case then the inode must have been redirtied while it was being written |
249 | * out and we don't reset its dirtied_when. | |
250 | */ | |
251 | static void redirty_tail(struct inode *inode) | |
252 | { | |
03ba3782 | 253 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
6610a0bc | 254 | |
03ba3782 | 255 | if (!list_empty(&wb->b_dirty)) { |
66f3b8e2 | 256 | struct inode *tail; |
6610a0bc | 257 | |
03ba3782 | 258 | tail = list_entry(wb->b_dirty.next, struct inode, i_list); |
66f3b8e2 | 259 | if (time_before(inode->dirtied_when, tail->dirtied_when)) |
6610a0bc AM |
260 | inode->dirtied_when = jiffies; |
261 | } | |
03ba3782 | 262 | list_move(&inode->i_list, &wb->b_dirty); |
6610a0bc AM |
263 | } |
264 | ||
c986d1e2 | 265 | /* |
66f3b8e2 | 266 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 267 | */ |
0e0f4fc2 | 268 | static void requeue_io(struct inode *inode) |
c986d1e2 | 269 | { |
03ba3782 JA |
270 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
271 | ||
272 | list_move(&inode->i_list, &wb->b_more_io); | |
c986d1e2 AM |
273 | } |
274 | ||
1c0eeaf5 JE |
275 | static void inode_sync_complete(struct inode *inode) |
276 | { | |
277 | /* | |
278 | * Prevent speculative execution through spin_unlock(&inode_lock); | |
279 | */ | |
280 | smp_mb(); | |
281 | wake_up_bit(&inode->i_state, __I_SYNC); | |
282 | } | |
283 | ||
d2caa3c5 JL |
284 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
285 | { | |
286 | bool ret = time_after(inode->dirtied_when, t); | |
287 | #ifndef CONFIG_64BIT | |
288 | /* | |
289 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
290 | * It _appears_ to be in the future, but is actually in distant past. | |
291 | * This test is necessary to prevent such wrapped-around relative times | |
5b0830cb | 292 | * from permanently stopping the whole bdi writeback. |
d2caa3c5 JL |
293 | */ |
294 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
295 | #endif | |
296 | return ret; | |
297 | } | |
298 | ||
2c136579 FW |
299 | /* |
300 | * Move expired dirty inodes from @delaying_queue to @dispatch_queue. | |
301 | */ | |
302 | static void move_expired_inodes(struct list_head *delaying_queue, | |
303 | struct list_head *dispatch_queue, | |
304 | unsigned long *older_than_this) | |
305 | { | |
5c03449d SL |
306 | LIST_HEAD(tmp); |
307 | struct list_head *pos, *node; | |
cf137307 | 308 | struct super_block *sb = NULL; |
5c03449d | 309 | struct inode *inode; |
cf137307 | 310 | int do_sb_sort = 0; |
5c03449d | 311 | |
2c136579 | 312 | while (!list_empty(delaying_queue)) { |
5c03449d | 313 | inode = list_entry(delaying_queue->prev, struct inode, i_list); |
2c136579 | 314 | if (older_than_this && |
d2caa3c5 | 315 | inode_dirtied_after(inode, *older_than_this)) |
2c136579 | 316 | break; |
cf137307 JA |
317 | if (sb && sb != inode->i_sb) |
318 | do_sb_sort = 1; | |
319 | sb = inode->i_sb; | |
5c03449d SL |
320 | list_move(&inode->i_list, &tmp); |
321 | } | |
322 | ||
cf137307 JA |
323 | /* just one sb in list, splice to dispatch_queue and we're done */ |
324 | if (!do_sb_sort) { | |
325 | list_splice(&tmp, dispatch_queue); | |
326 | return; | |
327 | } | |
328 | ||
5c03449d SL |
329 | /* Move inodes from one superblock together */ |
330 | while (!list_empty(&tmp)) { | |
331 | inode = list_entry(tmp.prev, struct inode, i_list); | |
332 | sb = inode->i_sb; | |
333 | list_for_each_prev_safe(pos, node, &tmp) { | |
334 | inode = list_entry(pos, struct inode, i_list); | |
335 | if (inode->i_sb == sb) | |
336 | list_move(&inode->i_list, dispatch_queue); | |
337 | } | |
2c136579 FW |
338 | } |
339 | } | |
340 | ||
341 | /* | |
342 | * Queue all expired dirty inodes for io, eldest first. | |
343 | */ | |
03ba3782 | 344 | static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) |
66f3b8e2 | 345 | { |
03ba3782 JA |
346 | list_splice_init(&wb->b_more_io, wb->b_io.prev); |
347 | move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); | |
66f3b8e2 JA |
348 | } |
349 | ||
a9185b41 | 350 | static int write_inode(struct inode *inode, struct writeback_control *wbc) |
08d8e974 | 351 | { |
03ba3782 | 352 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) |
a9185b41 | 353 | return inode->i_sb->s_op->write_inode(inode, wbc); |
03ba3782 | 354 | return 0; |
08d8e974 | 355 | } |
08d8e974 | 356 | |
1da177e4 | 357 | /* |
01c03194 CH |
358 | * Wait for writeback on an inode to complete. |
359 | */ | |
360 | static void inode_wait_for_writeback(struct inode *inode) | |
361 | { | |
362 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
363 | wait_queue_head_t *wqh; | |
364 | ||
365 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
58a9d3d8 | 366 | while (inode->i_state & I_SYNC) { |
01c03194 CH |
367 | spin_unlock(&inode_lock); |
368 | __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); | |
369 | spin_lock(&inode_lock); | |
58a9d3d8 | 370 | } |
01c03194 CH |
371 | } |
372 | ||
373 | /* | |
374 | * Write out an inode's dirty pages. Called under inode_lock. Either the | |
375 | * caller has ref on the inode (either via __iget or via syscall against an fd) | |
376 | * or the inode has I_WILL_FREE set (via generic_forget_inode) | |
377 | * | |
1da177e4 LT |
378 | * If `wait' is set, wait on the writeout. |
379 | * | |
380 | * The whole writeout design is quite complex and fragile. We want to avoid | |
381 | * starvation of particular inodes when others are being redirtied, prevent | |
382 | * livelocks, etc. | |
383 | * | |
384 | * Called under inode_lock. | |
385 | */ | |
386 | static int | |
01c03194 | 387 | writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 388 | { |
1da177e4 | 389 | struct address_space *mapping = inode->i_mapping; |
01c03194 | 390 | unsigned dirty; |
1da177e4 LT |
391 | int ret; |
392 | ||
01c03194 CH |
393 | if (!atomic_read(&inode->i_count)) |
394 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
395 | else | |
396 | WARN_ON(inode->i_state & I_WILL_FREE); | |
397 | ||
398 | if (inode->i_state & I_SYNC) { | |
399 | /* | |
400 | * If this inode is locked for writeback and we are not doing | |
66f3b8e2 | 401 | * writeback-for-data-integrity, move it to b_more_io so that |
01c03194 CH |
402 | * writeback can proceed with the other inodes on s_io. |
403 | * | |
404 | * We'll have another go at writing back this inode when we | |
66f3b8e2 | 405 | * completed a full scan of b_io. |
01c03194 | 406 | */ |
a9185b41 | 407 | if (wbc->sync_mode != WB_SYNC_ALL) { |
01c03194 CH |
408 | requeue_io(inode); |
409 | return 0; | |
410 | } | |
411 | ||
412 | /* | |
413 | * It's a data-integrity sync. We must wait. | |
414 | */ | |
415 | inode_wait_for_writeback(inode); | |
416 | } | |
417 | ||
1c0eeaf5 | 418 | BUG_ON(inode->i_state & I_SYNC); |
1da177e4 | 419 | |
5547e8aa | 420 | /* Set I_SYNC, reset I_DIRTY_PAGES */ |
1c0eeaf5 | 421 | inode->i_state |= I_SYNC; |
5547e8aa | 422 | inode->i_state &= ~I_DIRTY_PAGES; |
1da177e4 LT |
423 | spin_unlock(&inode_lock); |
424 | ||
425 | ret = do_writepages(mapping, wbc); | |
426 | ||
26821ed4 CH |
427 | /* |
428 | * Make sure to wait on the data before writing out the metadata. | |
429 | * This is important for filesystems that modify metadata on data | |
430 | * I/O completion. | |
431 | */ | |
a9185b41 | 432 | if (wbc->sync_mode == WB_SYNC_ALL) { |
26821ed4 | 433 | int err = filemap_fdatawait(mapping); |
1da177e4 LT |
434 | if (ret == 0) |
435 | ret = err; | |
436 | } | |
437 | ||
5547e8aa DM |
438 | /* |
439 | * Some filesystems may redirty the inode during the writeback | |
440 | * due to delalloc, clear dirty metadata flags right before | |
441 | * write_inode() | |
442 | */ | |
443 | spin_lock(&inode_lock); | |
444 | dirty = inode->i_state & I_DIRTY; | |
445 | inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC); | |
446 | spin_unlock(&inode_lock); | |
26821ed4 CH |
447 | /* Don't write the inode if only I_DIRTY_PAGES was set */ |
448 | if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
a9185b41 | 449 | int err = write_inode(inode, wbc); |
1da177e4 LT |
450 | if (ret == 0) |
451 | ret = err; | |
452 | } | |
453 | ||
454 | spin_lock(&inode_lock); | |
1c0eeaf5 | 455 | inode->i_state &= ~I_SYNC; |
84a89245 | 456 | if (!(inode->i_state & (I_FREEING | I_CLEAR))) { |
b3af9468 | 457 | if ((inode->i_state & I_DIRTY_PAGES) && wbc->for_kupdate) { |
ae1b7f7d | 458 | /* |
b3af9468 WF |
459 | * More pages get dirtied by a fast dirtier. |
460 | */ | |
461 | goto select_queue; | |
462 | } else if (inode->i_state & I_DIRTY) { | |
463 | /* | |
464 | * At least XFS will redirty the inode during the | |
465 | * writeback (delalloc) and on io completion (isize). | |
ae1b7f7d WF |
466 | */ |
467 | redirty_tail(inode); | |
468 | } else if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { | |
1da177e4 LT |
469 | /* |
470 | * We didn't write back all the pages. nfs_writepages() | |
471 | * sometimes bales out without doing anything. Redirty | |
66f3b8e2 | 472 | * the inode; Move it from b_io onto b_more_io/b_dirty. |
1b43ef91 AM |
473 | */ |
474 | /* | |
475 | * akpm: if the caller was the kupdate function we put | |
66f3b8e2 | 476 | * this inode at the head of b_dirty so it gets first |
1b43ef91 AM |
477 | * consideration. Otherwise, move it to the tail, for |
478 | * the reasons described there. I'm not really sure | |
479 | * how much sense this makes. Presumably I had a good | |
480 | * reasons for doing it this way, and I'd rather not | |
481 | * muck with it at present. | |
1da177e4 LT |
482 | */ |
483 | if (wbc->for_kupdate) { | |
484 | /* | |
2c136579 | 485 | * For the kupdate function we move the inode |
66f3b8e2 | 486 | * to b_more_io so it will get more writeout as |
2c136579 | 487 | * soon as the queue becomes uncongested. |
1da177e4 LT |
488 | */ |
489 | inode->i_state |= I_DIRTY_PAGES; | |
b3af9468 | 490 | select_queue: |
8bc3be27 FW |
491 | if (wbc->nr_to_write <= 0) { |
492 | /* | |
493 | * slice used up: queue for next turn | |
494 | */ | |
495 | requeue_io(inode); | |
496 | } else { | |
497 | /* | |
498 | * somehow blocked: retry later | |
499 | */ | |
500 | redirty_tail(inode); | |
501 | } | |
1da177e4 LT |
502 | } else { |
503 | /* | |
504 | * Otherwise fully redirty the inode so that | |
505 | * other inodes on this superblock will get some | |
506 | * writeout. Otherwise heavy writing to one | |
507 | * file would indefinitely suspend writeout of | |
508 | * all the other files. | |
509 | */ | |
510 | inode->i_state |= I_DIRTY_PAGES; | |
1b43ef91 | 511 | redirty_tail(inode); |
1da177e4 | 512 | } |
1da177e4 LT |
513 | } else if (atomic_read(&inode->i_count)) { |
514 | /* | |
515 | * The inode is clean, inuse | |
516 | */ | |
517 | list_move(&inode->i_list, &inode_in_use); | |
518 | } else { | |
519 | /* | |
520 | * The inode is clean, unused | |
521 | */ | |
522 | list_move(&inode->i_list, &inode_unused); | |
1da177e4 LT |
523 | } |
524 | } | |
1c0eeaf5 | 525 | inode_sync_complete(inode); |
1da177e4 LT |
526 | return ret; |
527 | } | |
528 | ||
03ba3782 | 529 | /* |
d19de7ed | 530 | * For background writeback the caller does not have the sb pinned |
03ba3782 JA |
531 | * before calling writeback. So make sure that we do pin it, so it doesn't |
532 | * go away while we are writing inodes from it. | |
03ba3782 | 533 | */ |
d19de7ed | 534 | static bool pin_sb_for_writeback(struct super_block *sb) |
03ba3782 | 535 | { |
03ba3782 JA |
536 | spin_lock(&sb_lock); |
537 | sb->s_count++; | |
538 | if (down_read_trylock(&sb->s_umount)) { | |
539 | if (sb->s_root) { | |
540 | spin_unlock(&sb_lock); | |
d19de7ed | 541 | return true; |
03ba3782 JA |
542 | } |
543 | /* | |
544 | * umounted, drop rwsem again and fall through to failure | |
545 | */ | |
546 | up_read(&sb->s_umount); | |
547 | } | |
03ba3782 JA |
548 | sb->s_count--; |
549 | spin_unlock(&sb_lock); | |
d19de7ed | 550 | return false; |
03ba3782 JA |
551 | } |
552 | ||
f11c9c5c ES |
553 | /* |
554 | * Write a portion of b_io inodes which belong to @sb. | |
555 | * If @wbc->sb != NULL, then find and write all such | |
556 | * inodes. Otherwise write only ones which go sequentially | |
557 | * in reverse order. | |
558 | * Return 1, if the caller writeback routine should be | |
559 | * interrupted. Otherwise return 0. | |
560 | */ | |
561 | static int writeback_sb_inodes(struct super_block *sb, | |
562 | struct bdi_writeback *wb, | |
563 | struct writeback_control *wbc) | |
1da177e4 | 564 | { |
03ba3782 | 565 | while (!list_empty(&wb->b_io)) { |
1da177e4 | 566 | long pages_skipped; |
f11c9c5c ES |
567 | struct inode *inode = list_entry(wb->b_io.prev, |
568 | struct inode, i_list); | |
569 | if (wbc->sb && sb != inode->i_sb) { | |
570 | /* super block given and doesn't | |
571 | match, skip this inode */ | |
66f3b8e2 JA |
572 | redirty_tail(inode); |
573 | continue; | |
574 | } | |
f11c9c5c ES |
575 | if (sb != inode->i_sb) |
576 | /* finish with this superblock */ | |
577 | return 0; | |
84a89245 | 578 | if (inode->i_state & (I_NEW | I_WILL_FREE)) { |
7ef0d737 NP |
579 | requeue_io(inode); |
580 | continue; | |
581 | } | |
d2caa3c5 JL |
582 | /* |
583 | * Was this inode dirtied after sync_sb_inodes was called? | |
584 | * This keeps sync from extra jobs and livelock. | |
585 | */ | |
f11c9c5c ES |
586 | if (inode_dirtied_after(inode, wbc->wb_start)) |
587 | return 1; | |
1da177e4 | 588 | |
84a89245 | 589 | BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); |
1da177e4 LT |
590 | __iget(inode); |
591 | pages_skipped = wbc->pages_skipped; | |
01c03194 | 592 | writeback_single_inode(inode, wbc); |
1da177e4 LT |
593 | if (wbc->pages_skipped != pages_skipped) { |
594 | /* | |
595 | * writeback is not making progress due to locked | |
596 | * buffers. Skip this inode for now. | |
597 | */ | |
f57b9b7b | 598 | redirty_tail(inode); |
1da177e4 LT |
599 | } |
600 | spin_unlock(&inode_lock); | |
1da177e4 | 601 | iput(inode); |
4ffc8444 | 602 | cond_resched(); |
1da177e4 | 603 | spin_lock(&inode_lock); |
8bc3be27 FW |
604 | if (wbc->nr_to_write <= 0) { |
605 | wbc->more_io = 1; | |
f11c9c5c | 606 | return 1; |
8bc3be27 | 607 | } |
03ba3782 | 608 | if (!list_empty(&wb->b_more_io)) |
8bc3be27 | 609 | wbc->more_io = 1; |
1da177e4 | 610 | } |
f11c9c5c ES |
611 | /* b_io is empty */ |
612 | return 1; | |
613 | } | |
614 | ||
615 | static void writeback_inodes_wb(struct bdi_writeback *wb, | |
616 | struct writeback_control *wbc) | |
617 | { | |
618 | int ret = 0; | |
619 | ||
620 | wbc->wb_start = jiffies; /* livelock avoidance */ | |
621 | spin_lock(&inode_lock); | |
622 | if (!wbc->for_kupdate || list_empty(&wb->b_io)) | |
623 | queue_io(wb, wbc->older_than_this); | |
38f21977 | 624 | |
f11c9c5c ES |
625 | while (!list_empty(&wb->b_io)) { |
626 | struct inode *inode = list_entry(wb->b_io.prev, | |
627 | struct inode, i_list); | |
628 | struct super_block *sb = inode->i_sb; | |
9ecc2738 | 629 | |
d19de7ed CH |
630 | if (wbc->sb) { |
631 | /* | |
632 | * We are requested to write out inodes for a specific | |
633 | * superblock. This means we already have s_umount | |
634 | * taken by the caller which also waits for us to | |
635 | * complete the writeout. | |
636 | */ | |
637 | if (sb != wbc->sb) { | |
638 | redirty_tail(inode); | |
639 | continue; | |
640 | } | |
f11c9c5c | 641 | |
d19de7ed CH |
642 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
643 | ||
644 | ret = writeback_sb_inodes(sb, wb, wbc); | |
645 | } else { | |
334132ae CH |
646 | if (!pin_sb_for_writeback(sb)) { |
647 | requeue_io(inode); | |
d19de7ed | 648 | continue; |
334132ae | 649 | } |
d19de7ed CH |
650 | ret = writeback_sb_inodes(sb, wb, wbc); |
651 | drop_super(sb); | |
f11c9c5c | 652 | } |
f11c9c5c | 653 | |
f11c9c5c ES |
654 | if (ret) |
655 | break; | |
656 | } | |
66f3b8e2 JA |
657 | spin_unlock(&inode_lock); |
658 | /* Leave any unwritten inodes on b_io */ | |
659 | } | |
660 | ||
03ba3782 JA |
661 | void writeback_inodes_wbc(struct writeback_control *wbc) |
662 | { | |
663 | struct backing_dev_info *bdi = wbc->bdi; | |
664 | ||
665 | writeback_inodes_wb(&bdi->wb, wbc); | |
666 | } | |
667 | ||
66f3b8e2 | 668 | /* |
03ba3782 JA |
669 | * The maximum number of pages to writeout in a single bdi flush/kupdate |
670 | * operation. We do this so we don't hold I_SYNC against an inode for | |
671 | * enormous amounts of time, which would block a userspace task which has | |
672 | * been forced to throttle against that inode. Also, the code reevaluates | |
673 | * the dirty each time it has written this many pages. | |
674 | */ | |
675 | #define MAX_WRITEBACK_PAGES 1024 | |
676 | ||
677 | static inline bool over_bground_thresh(void) | |
678 | { | |
679 | unsigned long background_thresh, dirty_thresh; | |
680 | ||
681 | get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); | |
682 | ||
683 | return (global_page_state(NR_FILE_DIRTY) + | |
684 | global_page_state(NR_UNSTABLE_NFS) >= background_thresh); | |
685 | } | |
686 | ||
687 | /* | |
688 | * Explicit flushing or periodic writeback of "old" data. | |
66f3b8e2 | 689 | * |
03ba3782 JA |
690 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
691 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
692 | * just walks the superblock inode list, writing back any inodes which are | |
693 | * older than a specific point in time. | |
66f3b8e2 | 694 | * |
03ba3782 JA |
695 | * Try to run once per dirty_writeback_interval. But if a writeback event |
696 | * takes longer than a dirty_writeback_interval interval, then leave a | |
697 | * one-second gap. | |
66f3b8e2 | 698 | * |
03ba3782 JA |
699 | * older_than_this takes precedence over nr_to_write. So we'll only write back |
700 | * all dirty pages if they are all attached to "old" mappings. | |
66f3b8e2 | 701 | */ |
c4a77a6c JA |
702 | static long wb_writeback(struct bdi_writeback *wb, |
703 | struct wb_writeback_args *args) | |
66f3b8e2 | 704 | { |
03ba3782 JA |
705 | struct writeback_control wbc = { |
706 | .bdi = wb->bdi, | |
c4a77a6c JA |
707 | .sb = args->sb, |
708 | .sync_mode = args->sync_mode, | |
03ba3782 | 709 | .older_than_this = NULL, |
c4a77a6c | 710 | .for_kupdate = args->for_kupdate, |
b17621fe | 711 | .for_background = args->for_background, |
c4a77a6c | 712 | .range_cyclic = args->range_cyclic, |
03ba3782 JA |
713 | }; |
714 | unsigned long oldest_jif; | |
715 | long wrote = 0; | |
a5989bdc | 716 | struct inode *inode; |
66f3b8e2 | 717 | |
03ba3782 JA |
718 | if (wbc.for_kupdate) { |
719 | wbc.older_than_this = &oldest_jif; | |
720 | oldest_jif = jiffies - | |
721 | msecs_to_jiffies(dirty_expire_interval * 10); | |
722 | } | |
c4a77a6c JA |
723 | if (!wbc.range_cyclic) { |
724 | wbc.range_start = 0; | |
725 | wbc.range_end = LLONG_MAX; | |
726 | } | |
38f21977 | 727 | |
03ba3782 JA |
728 | for (;;) { |
729 | /* | |
d3ddec76 | 730 | * Stop writeback when nr_pages has been consumed |
03ba3782 | 731 | */ |
d3ddec76 | 732 | if (args->nr_pages <= 0) |
03ba3782 | 733 | break; |
66f3b8e2 | 734 | |
38f21977 | 735 | /* |
d3ddec76 WF |
736 | * For background writeout, stop when we are below the |
737 | * background dirty threshold | |
38f21977 | 738 | */ |
d3ddec76 | 739 | if (args->for_background && !over_bground_thresh()) |
03ba3782 | 740 | break; |
38f21977 | 741 | |
03ba3782 | 742 | wbc.more_io = 0; |
03ba3782 JA |
743 | wbc.nr_to_write = MAX_WRITEBACK_PAGES; |
744 | wbc.pages_skipped = 0; | |
745 | writeback_inodes_wb(wb, &wbc); | |
c4a77a6c | 746 | args->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
03ba3782 JA |
747 | wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
748 | ||
749 | /* | |
71fd05a8 | 750 | * If we consumed everything, see if we have more |
03ba3782 | 751 | */ |
71fd05a8 JA |
752 | if (wbc.nr_to_write <= 0) |
753 | continue; | |
754 | /* | |
755 | * Didn't write everything and we don't have more IO, bail | |
756 | */ | |
757 | if (!wbc.more_io) | |
03ba3782 | 758 | break; |
71fd05a8 JA |
759 | /* |
760 | * Did we write something? Try for more | |
761 | */ | |
762 | if (wbc.nr_to_write < MAX_WRITEBACK_PAGES) | |
763 | continue; | |
764 | /* | |
765 | * Nothing written. Wait for some inode to | |
766 | * become available for writeback. Otherwise | |
767 | * we'll just busyloop. | |
768 | */ | |
769 | spin_lock(&inode_lock); | |
770 | if (!list_empty(&wb->b_more_io)) { | |
771 | inode = list_entry(wb->b_more_io.prev, | |
772 | struct inode, i_list); | |
773 | inode_wait_for_writeback(inode); | |
03ba3782 | 774 | } |
71fd05a8 | 775 | spin_unlock(&inode_lock); |
03ba3782 JA |
776 | } |
777 | ||
778 | return wrote; | |
779 | } | |
780 | ||
781 | /* | |
782 | * Return the next bdi_work struct that hasn't been processed by this | |
8010c3b6 JA |
783 | * wb thread yet. ->seen is initially set for each thread that exists |
784 | * for this device, when a thread first notices a piece of work it | |
785 | * clears its bit. Depending on writeback type, the thread will notify | |
786 | * completion on either receiving the work (WB_SYNC_NONE) or after | |
787 | * it is done (WB_SYNC_ALL). | |
03ba3782 JA |
788 | */ |
789 | static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi, | |
790 | struct bdi_writeback *wb) | |
791 | { | |
792 | struct bdi_work *work, *ret = NULL; | |
793 | ||
794 | rcu_read_lock(); | |
795 | ||
796 | list_for_each_entry_rcu(work, &bdi->work_list, list) { | |
77fad5e6 | 797 | if (!test_bit(wb->nr, &work->seen)) |
03ba3782 | 798 | continue; |
77fad5e6 | 799 | clear_bit(wb->nr, &work->seen); |
03ba3782 JA |
800 | |
801 | ret = work; | |
802 | break; | |
803 | } | |
804 | ||
805 | rcu_read_unlock(); | |
806 | return ret; | |
807 | } | |
808 | ||
809 | static long wb_check_old_data_flush(struct bdi_writeback *wb) | |
810 | { | |
811 | unsigned long expired; | |
812 | long nr_pages; | |
813 | ||
69b62d01 JA |
814 | /* |
815 | * When set to zero, disable periodic writeback | |
816 | */ | |
817 | if (!dirty_writeback_interval) | |
818 | return 0; | |
819 | ||
03ba3782 JA |
820 | expired = wb->last_old_flush + |
821 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
822 | if (time_before(jiffies, expired)) | |
823 | return 0; | |
824 | ||
825 | wb->last_old_flush = jiffies; | |
826 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
827 | global_page_state(NR_UNSTABLE_NFS) + | |
828 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); | |
829 | ||
c4a77a6c JA |
830 | if (nr_pages) { |
831 | struct wb_writeback_args args = { | |
832 | .nr_pages = nr_pages, | |
833 | .sync_mode = WB_SYNC_NONE, | |
834 | .for_kupdate = 1, | |
835 | .range_cyclic = 1, | |
836 | }; | |
837 | ||
838 | return wb_writeback(wb, &args); | |
839 | } | |
03ba3782 JA |
840 | |
841 | return 0; | |
842 | } | |
843 | ||
844 | /* | |
845 | * Retrieve work items and do the writeback they describe | |
846 | */ | |
847 | long wb_do_writeback(struct bdi_writeback *wb, int force_wait) | |
848 | { | |
849 | struct backing_dev_info *bdi = wb->bdi; | |
850 | struct bdi_work *work; | |
c4a77a6c | 851 | long wrote = 0; |
03ba3782 JA |
852 | |
853 | while ((work = get_next_work_item(bdi, wb)) != NULL) { | |
c4a77a6c | 854 | struct wb_writeback_args args = work->args; |
03ba3782 JA |
855 | |
856 | /* | |
857 | * Override sync mode, in case we must wait for completion | |
858 | */ | |
859 | if (force_wait) | |
c4a77a6c | 860 | work->args.sync_mode = args.sync_mode = WB_SYNC_ALL; |
03ba3782 JA |
861 | |
862 | /* | |
863 | * If this isn't a data integrity operation, just notify | |
864 | * that we have seen this work and we are now starting it. | |
865 | */ | |
7f0e7bed | 866 | if (!test_bit(WS_ONSTACK, &work->state)) |
03ba3782 JA |
867 | wb_clear_pending(wb, work); |
868 | ||
c4a77a6c | 869 | wrote += wb_writeback(wb, &args); |
03ba3782 JA |
870 | |
871 | /* | |
872 | * This is a data integrity writeback, so only do the | |
873 | * notification when we have completed the work. | |
874 | */ | |
7f0e7bed | 875 | if (test_bit(WS_ONSTACK, &work->state)) |
03ba3782 JA |
876 | wb_clear_pending(wb, work); |
877 | } | |
878 | ||
879 | /* | |
880 | * Check for periodic writeback, kupdated() style | |
881 | */ | |
882 | wrote += wb_check_old_data_flush(wb); | |
883 | ||
884 | return wrote; | |
885 | } | |
886 | ||
887 | /* | |
888 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
889 | * wakes up periodically and does kupdated style flushing. | |
890 | */ | |
891 | int bdi_writeback_task(struct bdi_writeback *wb) | |
892 | { | |
893 | unsigned long last_active = jiffies; | |
894 | unsigned long wait_jiffies = -1UL; | |
895 | long pages_written; | |
896 | ||
897 | while (!kthread_should_stop()) { | |
898 | pages_written = wb_do_writeback(wb, 0); | |
899 | ||
900 | if (pages_written) | |
901 | last_active = jiffies; | |
902 | else if (wait_jiffies != -1UL) { | |
903 | unsigned long max_idle; | |
904 | ||
38f21977 | 905 | /* |
03ba3782 JA |
906 | * Longest period of inactivity that we tolerate. If we |
907 | * see dirty data again later, the task will get | |
908 | * recreated automatically. | |
38f21977 | 909 | */ |
03ba3782 JA |
910 | max_idle = max(5UL * 60 * HZ, wait_jiffies); |
911 | if (time_after(jiffies, max_idle + last_active)) | |
912 | break; | |
913 | } | |
914 | ||
69b62d01 JA |
915 | if (dirty_writeback_interval) { |
916 | wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); | |
917 | schedule_timeout_interruptible(wait_jiffies); | |
f9eadbbd JA |
918 | } else { |
919 | set_current_state(TASK_INTERRUPTIBLE); | |
920 | if (list_empty_careful(&wb->bdi->work_list) && | |
921 | !kthread_should_stop()) | |
922 | schedule(); | |
923 | __set_current_state(TASK_RUNNING); | |
924 | } | |
69b62d01 | 925 | |
03ba3782 JA |
926 | try_to_freeze(); |
927 | } | |
928 | ||
929 | return 0; | |
930 | } | |
931 | ||
932 | /* | |
b8c2f347 CH |
933 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
934 | * the whole world. | |
03ba3782 | 935 | */ |
b8c2f347 | 936 | void wakeup_flusher_threads(long nr_pages) |
03ba3782 | 937 | { |
b8c2f347 | 938 | struct backing_dev_info *bdi; |
b6e51316 | 939 | struct wb_writeback_args args = { |
b6e51316 JA |
940 | .sync_mode = WB_SYNC_NONE, |
941 | }; | |
03ba3782 | 942 | |
b8c2f347 CH |
943 | if (nr_pages) { |
944 | args.nr_pages = nr_pages; | |
945 | } else { | |
946 | args.nr_pages = global_page_state(NR_FILE_DIRTY) + | |
947 | global_page_state(NR_UNSTABLE_NFS); | |
948 | } | |
03ba3782 | 949 | |
b8c2f347 | 950 | rcu_read_lock(); |
cfc4ba53 | 951 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { |
03ba3782 JA |
952 | if (!bdi_has_dirty_io(bdi)) |
953 | continue; | |
f17625b3 | 954 | bdi_alloc_queue_work(bdi, &args); |
03ba3782 | 955 | } |
cfc4ba53 | 956 | rcu_read_unlock(); |
1da177e4 LT |
957 | } |
958 | ||
03ba3782 JA |
959 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) |
960 | { | |
961 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
962 | struct dentry *dentry; | |
963 | const char *name = "?"; | |
964 | ||
965 | dentry = d_find_alias(inode); | |
966 | if (dentry) { | |
967 | spin_lock(&dentry->d_lock); | |
968 | name = (const char *) dentry->d_name.name; | |
969 | } | |
970 | printk(KERN_DEBUG | |
971 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
972 | current->comm, task_pid_nr(current), inode->i_ino, | |
973 | name, inode->i_sb->s_id); | |
974 | if (dentry) { | |
975 | spin_unlock(&dentry->d_lock); | |
976 | dput(dentry); | |
977 | } | |
978 | } | |
979 | } | |
980 | ||
981 | /** | |
982 | * __mark_inode_dirty - internal function | |
983 | * @inode: inode to mark | |
984 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
985 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
986 | * mark_inode_dirty_sync. | |
1da177e4 | 987 | * |
03ba3782 JA |
988 | * Put the inode on the super block's dirty list. |
989 | * | |
990 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
991 | * dirty list only if it is hashed or if it refers to a blockdev. | |
992 | * If it was not hashed, it will never be added to the dirty list | |
993 | * even if it is later hashed, as it will have been marked dirty already. | |
994 | * | |
995 | * In short, make sure you hash any inodes _before_ you start marking | |
996 | * them dirty. | |
1da177e4 | 997 | * |
03ba3782 JA |
998 | * This function *must* be atomic for the I_DIRTY_PAGES case - |
999 | * set_page_dirty() is called under spinlock in several places. | |
1da177e4 | 1000 | * |
03ba3782 JA |
1001 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
1002 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
1003 | * the kernel-internal blockdev inode represents the dirtying time of the | |
1004 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
1005 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
1006 | * blockdev inode. | |
1da177e4 | 1007 | */ |
03ba3782 | 1008 | void __mark_inode_dirty(struct inode *inode, int flags) |
1da177e4 | 1009 | { |
03ba3782 | 1010 | struct super_block *sb = inode->i_sb; |
1da177e4 | 1011 | |
03ba3782 JA |
1012 | /* |
1013 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
1014 | * dirty the inode itself | |
1015 | */ | |
1016 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
1017 | if (sb->s_op->dirty_inode) | |
1018 | sb->s_op->dirty_inode(inode); | |
1019 | } | |
1020 | ||
1021 | /* | |
1022 | * make sure that changes are seen by all cpus before we test i_state | |
1023 | * -- mikulas | |
1024 | */ | |
1025 | smp_mb(); | |
1026 | ||
1027 | /* avoid the locking if we can */ | |
1028 | if ((inode->i_state & flags) == flags) | |
1029 | return; | |
1030 | ||
1031 | if (unlikely(block_dump)) | |
1032 | block_dump___mark_inode_dirty(inode); | |
1033 | ||
1034 | spin_lock(&inode_lock); | |
1035 | if ((inode->i_state & flags) != flags) { | |
1036 | const int was_dirty = inode->i_state & I_DIRTY; | |
1037 | ||
1038 | inode->i_state |= flags; | |
1039 | ||
1040 | /* | |
1041 | * If the inode is being synced, just update its dirty state. | |
1042 | * The unlocker will place the inode on the appropriate | |
1043 | * superblock list, based upon its state. | |
1044 | */ | |
1045 | if (inode->i_state & I_SYNC) | |
1046 | goto out; | |
1047 | ||
1048 | /* | |
1049 | * Only add valid (hashed) inodes to the superblock's | |
1050 | * dirty list. Add blockdev inodes as well. | |
1051 | */ | |
1052 | if (!S_ISBLK(inode->i_mode)) { | |
1053 | if (hlist_unhashed(&inode->i_hash)) | |
1054 | goto out; | |
1055 | } | |
1056 | if (inode->i_state & (I_FREEING|I_CLEAR)) | |
1057 | goto out; | |
1058 | ||
1059 | /* | |
1060 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
1061 | * reposition it (that would break b_dirty time-ordering). | |
1062 | */ | |
1063 | if (!was_dirty) { | |
1064 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; | |
500b067c JA |
1065 | struct backing_dev_info *bdi = wb->bdi; |
1066 | ||
1067 | if (bdi_cap_writeback_dirty(bdi) && | |
1068 | !test_bit(BDI_registered, &bdi->state)) { | |
1069 | WARN_ON(1); | |
1070 | printk(KERN_ERR "bdi-%s not registered\n", | |
1071 | bdi->name); | |
1072 | } | |
03ba3782 JA |
1073 | |
1074 | inode->dirtied_when = jiffies; | |
1075 | list_move(&inode->i_list, &wb->b_dirty); | |
1da177e4 | 1076 | } |
1da177e4 | 1077 | } |
03ba3782 JA |
1078 | out: |
1079 | spin_unlock(&inode_lock); | |
1080 | } | |
1081 | EXPORT_SYMBOL(__mark_inode_dirty); | |
1082 | ||
1083 | /* | |
1084 | * Write out a superblock's list of dirty inodes. A wait will be performed | |
1085 | * upon no inodes, all inodes or the final one, depending upon sync_mode. | |
1086 | * | |
1087 | * If older_than_this is non-NULL, then only write out inodes which | |
1088 | * had their first dirtying at a time earlier than *older_than_this. | |
1089 | * | |
03ba3782 JA |
1090 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. |
1091 | * This function assumes that the blockdev superblock's inodes are backed by | |
1092 | * a variety of queues, so all inodes are searched. For other superblocks, | |
1093 | * assume that all inodes are backed by the same queue. | |
1094 | * | |
1095 | * The inodes to be written are parked on bdi->b_io. They are moved back onto | |
1096 | * bdi->b_dirty as they are selected for writing. This way, none can be missed | |
1097 | * on the writer throttling path, and we get decent balancing between many | |
1098 | * throttled threads: we don't want them all piling up on inode_sync_wait. | |
1099 | */ | |
b6e51316 | 1100 | static void wait_sb_inodes(struct super_block *sb) |
03ba3782 JA |
1101 | { |
1102 | struct inode *inode, *old_inode = NULL; | |
1103 | ||
1104 | /* | |
1105 | * We need to be protected against the filesystem going from | |
1106 | * r/o to r/w or vice versa. | |
1107 | */ | |
b6e51316 | 1108 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
03ba3782 JA |
1109 | |
1110 | spin_lock(&inode_lock); | |
1111 | ||
1112 | /* | |
1113 | * Data integrity sync. Must wait for all pages under writeback, | |
1114 | * because there may have been pages dirtied before our sync | |
1115 | * call, but which had writeout started before we write it out. | |
1116 | * In which case, the inode may not be on the dirty list, but | |
1117 | * we still have to wait for that writeout. | |
1118 | */ | |
b6e51316 | 1119 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
03ba3782 JA |
1120 | struct address_space *mapping; |
1121 | ||
1122 | if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) | |
1123 | continue; | |
1124 | mapping = inode->i_mapping; | |
1125 | if (mapping->nrpages == 0) | |
1126 | continue; | |
1127 | __iget(inode); | |
1128 | spin_unlock(&inode_lock); | |
1129 | /* | |
1130 | * We hold a reference to 'inode' so it couldn't have | |
1131 | * been removed from s_inodes list while we dropped the | |
1132 | * inode_lock. We cannot iput the inode now as we can | |
1133 | * be holding the last reference and we cannot iput it | |
1134 | * under inode_lock. So we keep the reference and iput | |
1135 | * it later. | |
1136 | */ | |
1137 | iput(old_inode); | |
1138 | old_inode = inode; | |
1139 | ||
1140 | filemap_fdatawait(mapping); | |
1141 | ||
1142 | cond_resched(); | |
1143 | ||
1144 | spin_lock(&inode_lock); | |
1145 | } | |
1146 | spin_unlock(&inode_lock); | |
1147 | iput(old_inode); | |
1da177e4 LT |
1148 | } |
1149 | ||
d8a8559c JA |
1150 | /** |
1151 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
1152 | * @sb: the superblock | |
1da177e4 | 1153 | * |
d8a8559c JA |
1154 | * Start writeback on some inodes on this super_block. No guarantees are made |
1155 | * on how many (if any) will be written, and this function does not wait | |
1156 | * for IO completion of submitted IO. The number of pages submitted is | |
1157 | * returned. | |
1da177e4 | 1158 | */ |
b6e51316 | 1159 | void writeback_inodes_sb(struct super_block *sb) |
1da177e4 | 1160 | { |
0e3c9a22 JA |
1161 | unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); |
1162 | unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); | |
3c4d7165 CH |
1163 | struct wb_writeback_args args = { |
1164 | .sb = sb, | |
1165 | .sync_mode = WB_SYNC_NONE, | |
1166 | }; | |
d8a8559c | 1167 | |
cf37e972 CH |
1168 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
1169 | ||
3c4d7165 | 1170 | args.nr_pages = nr_dirty + nr_unstable + |
0e3c9a22 JA |
1171 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); |
1172 | ||
3c4d7165 | 1173 | bdi_queue_work_onstack(&args); |
e913fc82 | 1174 | } |
0e3c9a22 | 1175 | EXPORT_SYMBOL(writeback_inodes_sb); |
e913fc82 | 1176 | |
17bd55d0 ES |
1177 | /** |
1178 | * writeback_inodes_sb_if_idle - start writeback if none underway | |
1179 | * @sb: the superblock | |
1180 | * | |
1181 | * Invoke writeback_inodes_sb if no writeback is currently underway. | |
1182 | * Returns 1 if writeback was started, 0 if not. | |
1183 | */ | |
1184 | int writeback_inodes_sb_if_idle(struct super_block *sb) | |
1185 | { | |
1186 | if (!writeback_in_progress(sb->s_bdi)) { | |
cf37e972 | 1187 | down_read(&sb->s_umount); |
17bd55d0 | 1188 | writeback_inodes_sb(sb); |
cf37e972 | 1189 | up_read(&sb->s_umount); |
17bd55d0 ES |
1190 | return 1; |
1191 | } else | |
1192 | return 0; | |
1193 | } | |
1194 | EXPORT_SYMBOL(writeback_inodes_sb_if_idle); | |
1195 | ||
d8a8559c JA |
1196 | /** |
1197 | * sync_inodes_sb - sync sb inode pages | |
1198 | * @sb: the superblock | |
1199 | * | |
1200 | * This function writes and waits on any dirty inode belonging to this | |
1201 | * super_block. The number of pages synced is returned. | |
1202 | */ | |
b6e51316 | 1203 | void sync_inodes_sb(struct super_block *sb) |
d8a8559c | 1204 | { |
3c4d7165 CH |
1205 | struct wb_writeback_args args = { |
1206 | .sb = sb, | |
1207 | .sync_mode = WB_SYNC_ALL, | |
1208 | .nr_pages = LONG_MAX, | |
1209 | .range_cyclic = 0, | |
1210 | }; | |
1211 | ||
cf37e972 CH |
1212 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
1213 | ||
3c4d7165 | 1214 | bdi_queue_work_onstack(&args); |
b6e51316 | 1215 | wait_sb_inodes(sb); |
1da177e4 | 1216 | } |
d8a8559c | 1217 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 1218 | |
1da177e4 | 1219 | /** |
7f04c26d AA |
1220 | * write_inode_now - write an inode to disk |
1221 | * @inode: inode to write to disk | |
1222 | * @sync: whether the write should be synchronous or not | |
1223 | * | |
1224 | * This function commits an inode to disk immediately if it is dirty. This is | |
1225 | * primarily needed by knfsd. | |
1da177e4 | 1226 | * |
7f04c26d | 1227 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 1228 | */ |
1da177e4 LT |
1229 | int write_inode_now(struct inode *inode, int sync) |
1230 | { | |
1231 | int ret; | |
1232 | struct writeback_control wbc = { | |
1233 | .nr_to_write = LONG_MAX, | |
18914b18 | 1234 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
1235 | .range_start = 0, |
1236 | .range_end = LLONG_MAX, | |
1da177e4 LT |
1237 | }; |
1238 | ||
1239 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 1240 | wbc.nr_to_write = 0; |
1da177e4 LT |
1241 | |
1242 | might_sleep(); | |
1243 | spin_lock(&inode_lock); | |
01c03194 | 1244 | ret = writeback_single_inode(inode, &wbc); |
1da177e4 LT |
1245 | spin_unlock(&inode_lock); |
1246 | if (sync) | |
1c0eeaf5 | 1247 | inode_sync_wait(inode); |
1da177e4 LT |
1248 | return ret; |
1249 | } | |
1250 | EXPORT_SYMBOL(write_inode_now); | |
1251 | ||
1252 | /** | |
1253 | * sync_inode - write an inode and its pages to disk. | |
1254 | * @inode: the inode to sync | |
1255 | * @wbc: controls the writeback mode | |
1256 | * | |
1257 | * sync_inode() will write an inode and its pages to disk. It will also | |
1258 | * correctly update the inode on its superblock's dirty inode lists and will | |
1259 | * update inode->i_state. | |
1260 | * | |
1261 | * The caller must have a ref on the inode. | |
1262 | */ | |
1263 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
1264 | { | |
1265 | int ret; | |
1266 | ||
1267 | spin_lock(&inode_lock); | |
01c03194 | 1268 | ret = writeback_single_inode(inode, wbc); |
1da177e4 LT |
1269 | spin_unlock(&inode_lock); |
1270 | return ret; | |
1271 | } | |
1272 | EXPORT_SYMBOL(sync_inode); |