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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 | |
4b6764fa | 203 | * @sb: write inodes from this super_block |
b6e51316 JA |
204 | * @nr_pages: the number of pages to write |
205 | * | |
206 | * Description: | |
207 | * This does WB_SYNC_NONE opportunistic writeback. The IO is only | |
208 | * started when this function returns, we make no guarentees on | |
0e3c9a22 | 209 | * completion. Caller need not hold sb s_umount semaphore. |
b6e51316 JA |
210 | * |
211 | */ | |
a72bfd4d | 212 | void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb, |
0e3c9a22 | 213 | long nr_pages) |
b6e51316 JA |
214 | { |
215 | struct wb_writeback_args args = { | |
a72bfd4d | 216 | .sb = sb, |
b6e51316 JA |
217 | .sync_mode = WB_SYNC_NONE, |
218 | .nr_pages = nr_pages, | |
219 | .range_cyclic = 1, | |
220 | }; | |
221 | ||
d3ddec76 WF |
222 | /* |
223 | * We treat @nr_pages=0 as the special case to do background writeback, | |
224 | * ie. to sync pages until the background dirty threshold is reached. | |
225 | */ | |
226 | if (!nr_pages) { | |
227 | args.nr_pages = LONG_MAX; | |
228 | args.for_background = 1; | |
229 | } | |
230 | ||
f17625b3 | 231 | bdi_alloc_queue_work(bdi, &args); |
1da177e4 LT |
232 | } |
233 | ||
6610a0bc AM |
234 | /* |
235 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
236 | * furthest end of its superblock's dirty-inode list. | |
237 | * | |
238 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 239 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
240 | * the case then the inode must have been redirtied while it was being written |
241 | * out and we don't reset its dirtied_when. | |
242 | */ | |
243 | static void redirty_tail(struct inode *inode) | |
244 | { | |
03ba3782 | 245 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
6610a0bc | 246 | |
03ba3782 | 247 | if (!list_empty(&wb->b_dirty)) { |
66f3b8e2 | 248 | struct inode *tail; |
6610a0bc | 249 | |
03ba3782 | 250 | tail = list_entry(wb->b_dirty.next, struct inode, i_list); |
66f3b8e2 | 251 | if (time_before(inode->dirtied_when, tail->dirtied_when)) |
6610a0bc AM |
252 | inode->dirtied_when = jiffies; |
253 | } | |
03ba3782 | 254 | list_move(&inode->i_list, &wb->b_dirty); |
6610a0bc AM |
255 | } |
256 | ||
c986d1e2 | 257 | /* |
66f3b8e2 | 258 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 259 | */ |
0e0f4fc2 | 260 | static void requeue_io(struct inode *inode) |
c986d1e2 | 261 | { |
03ba3782 JA |
262 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
263 | ||
264 | list_move(&inode->i_list, &wb->b_more_io); | |
c986d1e2 AM |
265 | } |
266 | ||
1c0eeaf5 JE |
267 | static void inode_sync_complete(struct inode *inode) |
268 | { | |
269 | /* | |
270 | * Prevent speculative execution through spin_unlock(&inode_lock); | |
271 | */ | |
272 | smp_mb(); | |
273 | wake_up_bit(&inode->i_state, __I_SYNC); | |
274 | } | |
275 | ||
d2caa3c5 JL |
276 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
277 | { | |
278 | bool ret = time_after(inode->dirtied_when, t); | |
279 | #ifndef CONFIG_64BIT | |
280 | /* | |
281 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
282 | * It _appears_ to be in the future, but is actually in distant past. | |
283 | * This test is necessary to prevent such wrapped-around relative times | |
5b0830cb | 284 | * from permanently stopping the whole bdi writeback. |
d2caa3c5 JL |
285 | */ |
286 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
287 | #endif | |
288 | return ret; | |
289 | } | |
290 | ||
2c136579 FW |
291 | /* |
292 | * Move expired dirty inodes from @delaying_queue to @dispatch_queue. | |
293 | */ | |
294 | static void move_expired_inodes(struct list_head *delaying_queue, | |
295 | struct list_head *dispatch_queue, | |
296 | unsigned long *older_than_this) | |
297 | { | |
5c03449d SL |
298 | LIST_HEAD(tmp); |
299 | struct list_head *pos, *node; | |
cf137307 | 300 | struct super_block *sb = NULL; |
5c03449d | 301 | struct inode *inode; |
cf137307 | 302 | int do_sb_sort = 0; |
5c03449d | 303 | |
2c136579 | 304 | while (!list_empty(delaying_queue)) { |
5c03449d | 305 | inode = list_entry(delaying_queue->prev, struct inode, i_list); |
2c136579 | 306 | if (older_than_this && |
d2caa3c5 | 307 | inode_dirtied_after(inode, *older_than_this)) |
2c136579 | 308 | break; |
cf137307 JA |
309 | if (sb && sb != inode->i_sb) |
310 | do_sb_sort = 1; | |
311 | sb = inode->i_sb; | |
5c03449d SL |
312 | list_move(&inode->i_list, &tmp); |
313 | } | |
314 | ||
cf137307 JA |
315 | /* just one sb in list, splice to dispatch_queue and we're done */ |
316 | if (!do_sb_sort) { | |
317 | list_splice(&tmp, dispatch_queue); | |
318 | return; | |
319 | } | |
320 | ||
5c03449d SL |
321 | /* Move inodes from one superblock together */ |
322 | while (!list_empty(&tmp)) { | |
323 | inode = list_entry(tmp.prev, struct inode, i_list); | |
324 | sb = inode->i_sb; | |
325 | list_for_each_prev_safe(pos, node, &tmp) { | |
326 | inode = list_entry(pos, struct inode, i_list); | |
327 | if (inode->i_sb == sb) | |
328 | list_move(&inode->i_list, dispatch_queue); | |
329 | } | |
2c136579 FW |
330 | } |
331 | } | |
332 | ||
333 | /* | |
334 | * Queue all expired dirty inodes for io, eldest first. | |
335 | */ | |
03ba3782 | 336 | static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) |
66f3b8e2 | 337 | { |
03ba3782 JA |
338 | list_splice_init(&wb->b_more_io, wb->b_io.prev); |
339 | move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); | |
66f3b8e2 JA |
340 | } |
341 | ||
a9185b41 | 342 | static int write_inode(struct inode *inode, struct writeback_control *wbc) |
08d8e974 | 343 | { |
03ba3782 | 344 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) |
a9185b41 | 345 | return inode->i_sb->s_op->write_inode(inode, wbc); |
03ba3782 | 346 | return 0; |
08d8e974 | 347 | } |
08d8e974 | 348 | |
1da177e4 | 349 | /* |
01c03194 CH |
350 | * Wait for writeback on an inode to complete. |
351 | */ | |
352 | static void inode_wait_for_writeback(struct inode *inode) | |
353 | { | |
354 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
355 | wait_queue_head_t *wqh; | |
356 | ||
357 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
58a9d3d8 | 358 | while (inode->i_state & I_SYNC) { |
01c03194 CH |
359 | spin_unlock(&inode_lock); |
360 | __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); | |
361 | spin_lock(&inode_lock); | |
58a9d3d8 | 362 | } |
01c03194 CH |
363 | } |
364 | ||
365 | /* | |
366 | * Write out an inode's dirty pages. Called under inode_lock. Either the | |
367 | * caller has ref on the inode (either via __iget or via syscall against an fd) | |
368 | * or the inode has I_WILL_FREE set (via generic_forget_inode) | |
369 | * | |
1da177e4 LT |
370 | * If `wait' is set, wait on the writeout. |
371 | * | |
372 | * The whole writeout design is quite complex and fragile. We want to avoid | |
373 | * starvation of particular inodes when others are being redirtied, prevent | |
374 | * livelocks, etc. | |
375 | * | |
376 | * Called under inode_lock. | |
377 | */ | |
378 | static int | |
01c03194 | 379 | writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 380 | { |
1da177e4 | 381 | struct address_space *mapping = inode->i_mapping; |
01c03194 | 382 | unsigned dirty; |
1da177e4 LT |
383 | int ret; |
384 | ||
01c03194 CH |
385 | if (!atomic_read(&inode->i_count)) |
386 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
387 | else | |
388 | WARN_ON(inode->i_state & I_WILL_FREE); | |
389 | ||
390 | if (inode->i_state & I_SYNC) { | |
391 | /* | |
392 | * If this inode is locked for writeback and we are not doing | |
66f3b8e2 | 393 | * writeback-for-data-integrity, move it to b_more_io so that |
01c03194 CH |
394 | * writeback can proceed with the other inodes on s_io. |
395 | * | |
396 | * We'll have another go at writing back this inode when we | |
66f3b8e2 | 397 | * completed a full scan of b_io. |
01c03194 | 398 | */ |
a9185b41 | 399 | if (wbc->sync_mode != WB_SYNC_ALL) { |
01c03194 CH |
400 | requeue_io(inode); |
401 | return 0; | |
402 | } | |
403 | ||
404 | /* | |
405 | * It's a data-integrity sync. We must wait. | |
406 | */ | |
407 | inode_wait_for_writeback(inode); | |
408 | } | |
409 | ||
1c0eeaf5 | 410 | BUG_ON(inode->i_state & I_SYNC); |
1da177e4 | 411 | |
5547e8aa | 412 | /* Set I_SYNC, reset I_DIRTY_PAGES */ |
1c0eeaf5 | 413 | inode->i_state |= I_SYNC; |
5547e8aa | 414 | inode->i_state &= ~I_DIRTY_PAGES; |
1da177e4 LT |
415 | spin_unlock(&inode_lock); |
416 | ||
417 | ret = do_writepages(mapping, wbc); | |
418 | ||
26821ed4 CH |
419 | /* |
420 | * Make sure to wait on the data before writing out the metadata. | |
421 | * This is important for filesystems that modify metadata on data | |
422 | * I/O completion. | |
423 | */ | |
a9185b41 | 424 | if (wbc->sync_mode == WB_SYNC_ALL) { |
26821ed4 | 425 | int err = filemap_fdatawait(mapping); |
1da177e4 LT |
426 | if (ret == 0) |
427 | ret = err; | |
428 | } | |
429 | ||
5547e8aa DM |
430 | /* |
431 | * Some filesystems may redirty the inode during the writeback | |
432 | * due to delalloc, clear dirty metadata flags right before | |
433 | * write_inode() | |
434 | */ | |
435 | spin_lock(&inode_lock); | |
436 | dirty = inode->i_state & I_DIRTY; | |
437 | inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC); | |
438 | spin_unlock(&inode_lock); | |
26821ed4 CH |
439 | /* Don't write the inode if only I_DIRTY_PAGES was set */ |
440 | if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
a9185b41 | 441 | int err = write_inode(inode, wbc); |
1da177e4 LT |
442 | if (ret == 0) |
443 | ret = err; | |
444 | } | |
445 | ||
446 | spin_lock(&inode_lock); | |
1c0eeaf5 | 447 | inode->i_state &= ~I_SYNC; |
84a89245 | 448 | if (!(inode->i_state & (I_FREEING | I_CLEAR))) { |
b3af9468 | 449 | if ((inode->i_state & I_DIRTY_PAGES) && wbc->for_kupdate) { |
ae1b7f7d | 450 | /* |
b3af9468 WF |
451 | * More pages get dirtied by a fast dirtier. |
452 | */ | |
453 | goto select_queue; | |
454 | } else if (inode->i_state & I_DIRTY) { | |
455 | /* | |
456 | * At least XFS will redirty the inode during the | |
457 | * writeback (delalloc) and on io completion (isize). | |
ae1b7f7d WF |
458 | */ |
459 | redirty_tail(inode); | |
460 | } else if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { | |
1da177e4 LT |
461 | /* |
462 | * We didn't write back all the pages. nfs_writepages() | |
463 | * sometimes bales out without doing anything. Redirty | |
66f3b8e2 | 464 | * the inode; Move it from b_io onto b_more_io/b_dirty. |
1b43ef91 AM |
465 | */ |
466 | /* | |
467 | * akpm: if the caller was the kupdate function we put | |
66f3b8e2 | 468 | * this inode at the head of b_dirty so it gets first |
1b43ef91 AM |
469 | * consideration. Otherwise, move it to the tail, for |
470 | * the reasons described there. I'm not really sure | |
471 | * how much sense this makes. Presumably I had a good | |
472 | * reasons for doing it this way, and I'd rather not | |
473 | * muck with it at present. | |
1da177e4 LT |
474 | */ |
475 | if (wbc->for_kupdate) { | |
476 | /* | |
2c136579 | 477 | * For the kupdate function we move the inode |
66f3b8e2 | 478 | * to b_more_io so it will get more writeout as |
2c136579 | 479 | * soon as the queue becomes uncongested. |
1da177e4 LT |
480 | */ |
481 | inode->i_state |= I_DIRTY_PAGES; | |
b3af9468 | 482 | select_queue: |
8bc3be27 FW |
483 | if (wbc->nr_to_write <= 0) { |
484 | /* | |
485 | * slice used up: queue for next turn | |
486 | */ | |
487 | requeue_io(inode); | |
488 | } else { | |
489 | /* | |
490 | * somehow blocked: retry later | |
491 | */ | |
492 | redirty_tail(inode); | |
493 | } | |
1da177e4 LT |
494 | } else { |
495 | /* | |
496 | * Otherwise fully redirty the inode so that | |
497 | * other inodes on this superblock will get some | |
498 | * writeout. Otherwise heavy writing to one | |
499 | * file would indefinitely suspend writeout of | |
500 | * all the other files. | |
501 | */ | |
502 | inode->i_state |= I_DIRTY_PAGES; | |
1b43ef91 | 503 | redirty_tail(inode); |
1da177e4 | 504 | } |
1da177e4 LT |
505 | } else if (atomic_read(&inode->i_count)) { |
506 | /* | |
507 | * The inode is clean, inuse | |
508 | */ | |
509 | list_move(&inode->i_list, &inode_in_use); | |
510 | } else { | |
511 | /* | |
512 | * The inode is clean, unused | |
513 | */ | |
514 | list_move(&inode->i_list, &inode_unused); | |
1da177e4 LT |
515 | } |
516 | } | |
1c0eeaf5 | 517 | inode_sync_complete(inode); |
1da177e4 LT |
518 | return ret; |
519 | } | |
520 | ||
f11c9c5c | 521 | static void unpin_sb_for_writeback(struct super_block *sb) |
9ecc2738 | 522 | { |
f11c9c5c ES |
523 | up_read(&sb->s_umount); |
524 | put_super(sb); | |
9ecc2738 JA |
525 | } |
526 | ||
f11c9c5c ES |
527 | enum sb_pin_state { |
528 | SB_PINNED, | |
529 | SB_NOT_PINNED, | |
530 | SB_PIN_FAILED | |
531 | }; | |
532 | ||
03ba3782 JA |
533 | /* |
534 | * For WB_SYNC_NONE writeback, the caller does not have the sb pinned | |
535 | * before calling writeback. So make sure that we do pin it, so it doesn't | |
536 | * go away while we are writing inodes from it. | |
03ba3782 | 537 | */ |
f11c9c5c ES |
538 | static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc, |
539 | struct super_block *sb) | |
03ba3782 | 540 | { |
03ba3782 JA |
541 | /* |
542 | * Caller must already hold the ref for this | |
543 | */ | |
0e3c9a22 | 544 | if (wbc->sync_mode == WB_SYNC_ALL) { |
03ba3782 | 545 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
f11c9c5c | 546 | return SB_NOT_PINNED; |
03ba3782 | 547 | } |
03ba3782 JA |
548 | spin_lock(&sb_lock); |
549 | sb->s_count++; | |
550 | if (down_read_trylock(&sb->s_umount)) { | |
551 | if (sb->s_root) { | |
552 | spin_unlock(&sb_lock); | |
f11c9c5c | 553 | return SB_PINNED; |
03ba3782 JA |
554 | } |
555 | /* | |
556 | * umounted, drop rwsem again and fall through to failure | |
557 | */ | |
558 | up_read(&sb->s_umount); | |
559 | } | |
03ba3782 JA |
560 | sb->s_count--; |
561 | spin_unlock(&sb_lock); | |
f11c9c5c | 562 | return SB_PIN_FAILED; |
03ba3782 JA |
563 | } |
564 | ||
f11c9c5c ES |
565 | /* |
566 | * Write a portion of b_io inodes which belong to @sb. | |
567 | * If @wbc->sb != NULL, then find and write all such | |
568 | * inodes. Otherwise write only ones which go sequentially | |
569 | * in reverse order. | |
570 | * Return 1, if the caller writeback routine should be | |
571 | * interrupted. Otherwise return 0. | |
572 | */ | |
573 | static int writeback_sb_inodes(struct super_block *sb, | |
574 | struct bdi_writeback *wb, | |
575 | struct writeback_control *wbc) | |
1da177e4 | 576 | { |
03ba3782 | 577 | while (!list_empty(&wb->b_io)) { |
1da177e4 | 578 | long pages_skipped; |
f11c9c5c ES |
579 | struct inode *inode = list_entry(wb->b_io.prev, |
580 | struct inode, i_list); | |
581 | if (wbc->sb && sb != inode->i_sb) { | |
582 | /* super block given and doesn't | |
583 | match, skip this inode */ | |
66f3b8e2 JA |
584 | redirty_tail(inode); |
585 | continue; | |
586 | } | |
f11c9c5c ES |
587 | if (sb != inode->i_sb) |
588 | /* finish with this superblock */ | |
589 | return 0; | |
84a89245 | 590 | if (inode->i_state & (I_NEW | I_WILL_FREE)) { |
7ef0d737 NP |
591 | requeue_io(inode); |
592 | continue; | |
593 | } | |
d2caa3c5 JL |
594 | /* |
595 | * Was this inode dirtied after sync_sb_inodes was called? | |
596 | * This keeps sync from extra jobs and livelock. | |
597 | */ | |
f11c9c5c ES |
598 | if (inode_dirtied_after(inode, wbc->wb_start)) |
599 | return 1; | |
1da177e4 | 600 | |
84a89245 | 601 | BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); |
1da177e4 LT |
602 | __iget(inode); |
603 | pages_skipped = wbc->pages_skipped; | |
01c03194 | 604 | writeback_single_inode(inode, wbc); |
1da177e4 LT |
605 | if (wbc->pages_skipped != pages_skipped) { |
606 | /* | |
607 | * writeback is not making progress due to locked | |
608 | * buffers. Skip this inode for now. | |
609 | */ | |
f57b9b7b | 610 | redirty_tail(inode); |
1da177e4 LT |
611 | } |
612 | spin_unlock(&inode_lock); | |
1da177e4 | 613 | iput(inode); |
4ffc8444 | 614 | cond_resched(); |
1da177e4 | 615 | spin_lock(&inode_lock); |
8bc3be27 FW |
616 | if (wbc->nr_to_write <= 0) { |
617 | wbc->more_io = 1; | |
f11c9c5c | 618 | return 1; |
8bc3be27 | 619 | } |
03ba3782 | 620 | if (!list_empty(&wb->b_more_io)) |
8bc3be27 | 621 | wbc->more_io = 1; |
1da177e4 | 622 | } |
f11c9c5c ES |
623 | /* b_io is empty */ |
624 | return 1; | |
625 | } | |
626 | ||
627 | static void writeback_inodes_wb(struct bdi_writeback *wb, | |
628 | struct writeback_control *wbc) | |
629 | { | |
630 | int ret = 0; | |
631 | ||
632 | wbc->wb_start = jiffies; /* livelock avoidance */ | |
633 | spin_lock(&inode_lock); | |
634 | if (!wbc->for_kupdate || list_empty(&wb->b_io)) | |
635 | queue_io(wb, wbc->older_than_this); | |
38f21977 | 636 | |
f11c9c5c ES |
637 | while (!list_empty(&wb->b_io)) { |
638 | struct inode *inode = list_entry(wb->b_io.prev, | |
639 | struct inode, i_list); | |
640 | struct super_block *sb = inode->i_sb; | |
641 | enum sb_pin_state state; | |
9ecc2738 | 642 | |
f11c9c5c ES |
643 | if (wbc->sb && sb != wbc->sb) { |
644 | /* super block given and doesn't | |
645 | match, skip this inode */ | |
646 | redirty_tail(inode); | |
647 | continue; | |
648 | } | |
649 | state = pin_sb_for_writeback(wbc, sb); | |
650 | ||
651 | if (state == SB_PIN_FAILED) { | |
652 | requeue_io(inode); | |
653 | continue; | |
654 | } | |
655 | ret = writeback_sb_inodes(sb, wb, wbc); | |
656 | ||
657 | if (state == SB_PINNED) | |
658 | unpin_sb_for_writeback(sb); | |
659 | if (ret) | |
660 | break; | |
661 | } | |
66f3b8e2 JA |
662 | spin_unlock(&inode_lock); |
663 | /* Leave any unwritten inodes on b_io */ | |
664 | } | |
665 | ||
03ba3782 JA |
666 | void writeback_inodes_wbc(struct writeback_control *wbc) |
667 | { | |
668 | struct backing_dev_info *bdi = wbc->bdi; | |
669 | ||
670 | writeback_inodes_wb(&bdi->wb, wbc); | |
671 | } | |
672 | ||
66f3b8e2 | 673 | /* |
03ba3782 JA |
674 | * The maximum number of pages to writeout in a single bdi flush/kupdate |
675 | * operation. We do this so we don't hold I_SYNC against an inode for | |
676 | * enormous amounts of time, which would block a userspace task which has | |
677 | * been forced to throttle against that inode. Also, the code reevaluates | |
678 | * the dirty each time it has written this many pages. | |
679 | */ | |
680 | #define MAX_WRITEBACK_PAGES 1024 | |
681 | ||
682 | static inline bool over_bground_thresh(void) | |
683 | { | |
684 | unsigned long background_thresh, dirty_thresh; | |
685 | ||
686 | get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); | |
687 | ||
688 | return (global_page_state(NR_FILE_DIRTY) + | |
689 | global_page_state(NR_UNSTABLE_NFS) >= background_thresh); | |
690 | } | |
691 | ||
692 | /* | |
693 | * Explicit flushing or periodic writeback of "old" data. | |
66f3b8e2 | 694 | * |
03ba3782 JA |
695 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
696 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
697 | * just walks the superblock inode list, writing back any inodes which are | |
698 | * older than a specific point in time. | |
66f3b8e2 | 699 | * |
03ba3782 JA |
700 | * Try to run once per dirty_writeback_interval. But if a writeback event |
701 | * takes longer than a dirty_writeback_interval interval, then leave a | |
702 | * one-second gap. | |
66f3b8e2 | 703 | * |
03ba3782 JA |
704 | * older_than_this takes precedence over nr_to_write. So we'll only write back |
705 | * all dirty pages if they are all attached to "old" mappings. | |
66f3b8e2 | 706 | */ |
c4a77a6c JA |
707 | static long wb_writeback(struct bdi_writeback *wb, |
708 | struct wb_writeback_args *args) | |
66f3b8e2 | 709 | { |
03ba3782 JA |
710 | struct writeback_control wbc = { |
711 | .bdi = wb->bdi, | |
c4a77a6c JA |
712 | .sb = args->sb, |
713 | .sync_mode = args->sync_mode, | |
03ba3782 | 714 | .older_than_this = NULL, |
c4a77a6c | 715 | .for_kupdate = args->for_kupdate, |
b17621fe | 716 | .for_background = args->for_background, |
c4a77a6c | 717 | .range_cyclic = args->range_cyclic, |
03ba3782 JA |
718 | }; |
719 | unsigned long oldest_jif; | |
720 | long wrote = 0; | |
a5989bdc | 721 | struct inode *inode; |
66f3b8e2 | 722 | |
03ba3782 JA |
723 | if (wbc.for_kupdate) { |
724 | wbc.older_than_this = &oldest_jif; | |
725 | oldest_jif = jiffies - | |
726 | msecs_to_jiffies(dirty_expire_interval * 10); | |
727 | } | |
c4a77a6c JA |
728 | if (!wbc.range_cyclic) { |
729 | wbc.range_start = 0; | |
730 | wbc.range_end = LLONG_MAX; | |
731 | } | |
38f21977 | 732 | |
03ba3782 JA |
733 | for (;;) { |
734 | /* | |
d3ddec76 | 735 | * Stop writeback when nr_pages has been consumed |
03ba3782 | 736 | */ |
d3ddec76 | 737 | if (args->nr_pages <= 0) |
03ba3782 | 738 | break; |
66f3b8e2 | 739 | |
38f21977 | 740 | /* |
d3ddec76 WF |
741 | * For background writeout, stop when we are below the |
742 | * background dirty threshold | |
38f21977 | 743 | */ |
d3ddec76 | 744 | if (args->for_background && !over_bground_thresh()) |
03ba3782 | 745 | break; |
38f21977 | 746 | |
03ba3782 | 747 | wbc.more_io = 0; |
03ba3782 JA |
748 | wbc.nr_to_write = MAX_WRITEBACK_PAGES; |
749 | wbc.pages_skipped = 0; | |
750 | writeback_inodes_wb(wb, &wbc); | |
c4a77a6c | 751 | args->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
03ba3782 JA |
752 | wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; |
753 | ||
754 | /* | |
71fd05a8 | 755 | * If we consumed everything, see if we have more |
03ba3782 | 756 | */ |
71fd05a8 JA |
757 | if (wbc.nr_to_write <= 0) |
758 | continue; | |
759 | /* | |
760 | * Didn't write everything and we don't have more IO, bail | |
761 | */ | |
762 | if (!wbc.more_io) | |
03ba3782 | 763 | break; |
71fd05a8 JA |
764 | /* |
765 | * Did we write something? Try for more | |
766 | */ | |
767 | if (wbc.nr_to_write < MAX_WRITEBACK_PAGES) | |
768 | continue; | |
769 | /* | |
770 | * Nothing written. Wait for some inode to | |
771 | * become available for writeback. Otherwise | |
772 | * we'll just busyloop. | |
773 | */ | |
774 | spin_lock(&inode_lock); | |
775 | if (!list_empty(&wb->b_more_io)) { | |
776 | inode = list_entry(wb->b_more_io.prev, | |
777 | struct inode, i_list); | |
778 | inode_wait_for_writeback(inode); | |
03ba3782 | 779 | } |
71fd05a8 | 780 | spin_unlock(&inode_lock); |
03ba3782 JA |
781 | } |
782 | ||
783 | return wrote; | |
784 | } | |
785 | ||
786 | /* | |
787 | * Return the next bdi_work struct that hasn't been processed by this | |
8010c3b6 JA |
788 | * wb thread yet. ->seen is initially set for each thread that exists |
789 | * for this device, when a thread first notices a piece of work it | |
790 | * clears its bit. Depending on writeback type, the thread will notify | |
791 | * completion on either receiving the work (WB_SYNC_NONE) or after | |
792 | * it is done (WB_SYNC_ALL). | |
03ba3782 JA |
793 | */ |
794 | static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi, | |
795 | struct bdi_writeback *wb) | |
796 | { | |
797 | struct bdi_work *work, *ret = NULL; | |
798 | ||
799 | rcu_read_lock(); | |
800 | ||
801 | list_for_each_entry_rcu(work, &bdi->work_list, list) { | |
77fad5e6 | 802 | if (!test_bit(wb->nr, &work->seen)) |
03ba3782 | 803 | continue; |
77fad5e6 | 804 | clear_bit(wb->nr, &work->seen); |
03ba3782 JA |
805 | |
806 | ret = work; | |
807 | break; | |
808 | } | |
809 | ||
810 | rcu_read_unlock(); | |
811 | return ret; | |
812 | } | |
813 | ||
814 | static long wb_check_old_data_flush(struct bdi_writeback *wb) | |
815 | { | |
816 | unsigned long expired; | |
817 | long nr_pages; | |
818 | ||
69b62d01 JA |
819 | /* |
820 | * When set to zero, disable periodic writeback | |
821 | */ | |
822 | if (!dirty_writeback_interval) | |
823 | return 0; | |
824 | ||
03ba3782 JA |
825 | expired = wb->last_old_flush + |
826 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
827 | if (time_before(jiffies, expired)) | |
828 | return 0; | |
829 | ||
830 | wb->last_old_flush = jiffies; | |
831 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
832 | global_page_state(NR_UNSTABLE_NFS) + | |
833 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); | |
834 | ||
c4a77a6c JA |
835 | if (nr_pages) { |
836 | struct wb_writeback_args args = { | |
837 | .nr_pages = nr_pages, | |
838 | .sync_mode = WB_SYNC_NONE, | |
839 | .for_kupdate = 1, | |
840 | .range_cyclic = 1, | |
841 | }; | |
842 | ||
843 | return wb_writeback(wb, &args); | |
844 | } | |
03ba3782 JA |
845 | |
846 | return 0; | |
847 | } | |
848 | ||
849 | /* | |
850 | * Retrieve work items and do the writeback they describe | |
851 | */ | |
852 | long wb_do_writeback(struct bdi_writeback *wb, int force_wait) | |
853 | { | |
854 | struct backing_dev_info *bdi = wb->bdi; | |
855 | struct bdi_work *work; | |
c4a77a6c | 856 | long wrote = 0; |
03ba3782 JA |
857 | |
858 | while ((work = get_next_work_item(bdi, wb)) != NULL) { | |
c4a77a6c | 859 | struct wb_writeback_args args = work->args; |
03ba3782 JA |
860 | |
861 | /* | |
862 | * Override sync mode, in case we must wait for completion | |
863 | */ | |
864 | if (force_wait) | |
c4a77a6c | 865 | work->args.sync_mode = args.sync_mode = WB_SYNC_ALL; |
03ba3782 JA |
866 | |
867 | /* | |
868 | * If this isn't a data integrity operation, just notify | |
869 | * that we have seen this work and we are now starting it. | |
870 | */ | |
7f0e7bed | 871 | if (!test_bit(WS_ONSTACK, &work->state)) |
03ba3782 JA |
872 | wb_clear_pending(wb, work); |
873 | ||
c4a77a6c | 874 | wrote += wb_writeback(wb, &args); |
03ba3782 JA |
875 | |
876 | /* | |
877 | * This is a data integrity writeback, so only do the | |
878 | * notification when we have completed the work. | |
879 | */ | |
7f0e7bed | 880 | if (test_bit(WS_ONSTACK, &work->state)) |
03ba3782 JA |
881 | wb_clear_pending(wb, work); |
882 | } | |
883 | ||
884 | /* | |
885 | * Check for periodic writeback, kupdated() style | |
886 | */ | |
887 | wrote += wb_check_old_data_flush(wb); | |
888 | ||
889 | return wrote; | |
890 | } | |
891 | ||
892 | /* | |
893 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
894 | * wakes up periodically and does kupdated style flushing. | |
895 | */ | |
896 | int bdi_writeback_task(struct bdi_writeback *wb) | |
897 | { | |
898 | unsigned long last_active = jiffies; | |
899 | unsigned long wait_jiffies = -1UL; | |
900 | long pages_written; | |
901 | ||
902 | while (!kthread_should_stop()) { | |
903 | pages_written = wb_do_writeback(wb, 0); | |
904 | ||
905 | if (pages_written) | |
906 | last_active = jiffies; | |
907 | else if (wait_jiffies != -1UL) { | |
908 | unsigned long max_idle; | |
909 | ||
38f21977 | 910 | /* |
03ba3782 JA |
911 | * Longest period of inactivity that we tolerate. If we |
912 | * see dirty data again later, the task will get | |
913 | * recreated automatically. | |
38f21977 | 914 | */ |
03ba3782 JA |
915 | max_idle = max(5UL * 60 * HZ, wait_jiffies); |
916 | if (time_after(jiffies, max_idle + last_active)) | |
917 | break; | |
918 | } | |
919 | ||
69b62d01 JA |
920 | if (dirty_writeback_interval) { |
921 | wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); | |
922 | schedule_timeout_interruptible(wait_jiffies); | |
f9eadbbd JA |
923 | } else { |
924 | set_current_state(TASK_INTERRUPTIBLE); | |
925 | if (list_empty_careful(&wb->bdi->work_list) && | |
926 | !kthread_should_stop()) | |
927 | schedule(); | |
928 | __set_current_state(TASK_RUNNING); | |
929 | } | |
69b62d01 | 930 | |
03ba3782 JA |
931 | try_to_freeze(); |
932 | } | |
933 | ||
934 | return 0; | |
935 | } | |
936 | ||
937 | /* | |
b6e51316 | 938 | * Schedule writeback for all backing devices. This does WB_SYNC_NONE |
3c4d7165 | 939 | * writeback, for integrity writeback see bdi_queue_work_onstack(). |
03ba3782 | 940 | */ |
b6e51316 | 941 | static void bdi_writeback_all(struct super_block *sb, long nr_pages) |
03ba3782 | 942 | { |
b6e51316 JA |
943 | struct wb_writeback_args args = { |
944 | .sb = sb, | |
945 | .nr_pages = nr_pages, | |
946 | .sync_mode = WB_SYNC_NONE, | |
947 | }; | |
03ba3782 | 948 | struct backing_dev_info *bdi; |
03ba3782 | 949 | |
cfc4ba53 | 950 | rcu_read_lock(); |
03ba3782 | 951 | |
cfc4ba53 | 952 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { |
03ba3782 JA |
953 | if (!bdi_has_dirty_io(bdi)) |
954 | continue; | |
38f21977 | 955 | |
f17625b3 | 956 | bdi_alloc_queue_work(bdi, &args); |
03ba3782 JA |
957 | } |
958 | ||
cfc4ba53 | 959 | rcu_read_unlock(); |
1da177e4 LT |
960 | } |
961 | ||
962 | /* | |
03ba3782 JA |
963 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
964 | * the whole world. | |
965 | */ | |
966 | void wakeup_flusher_threads(long nr_pages) | |
967 | { | |
03ba3782 JA |
968 | if (nr_pages == 0) |
969 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
970 | global_page_state(NR_UNSTABLE_NFS); | |
b6e51316 | 971 | bdi_writeback_all(NULL, nr_pages); |
03ba3782 JA |
972 | } |
973 | ||
974 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) | |
975 | { | |
976 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
977 | struct dentry *dentry; | |
978 | const char *name = "?"; | |
979 | ||
980 | dentry = d_find_alias(inode); | |
981 | if (dentry) { | |
982 | spin_lock(&dentry->d_lock); | |
983 | name = (const char *) dentry->d_name.name; | |
984 | } | |
985 | printk(KERN_DEBUG | |
986 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
987 | current->comm, task_pid_nr(current), inode->i_ino, | |
988 | name, inode->i_sb->s_id); | |
989 | if (dentry) { | |
990 | spin_unlock(&dentry->d_lock); | |
991 | dput(dentry); | |
992 | } | |
993 | } | |
994 | } | |
995 | ||
996 | /** | |
997 | * __mark_inode_dirty - internal function | |
998 | * @inode: inode to mark | |
999 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
1000 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
1001 | * mark_inode_dirty_sync. | |
1da177e4 | 1002 | * |
03ba3782 JA |
1003 | * Put the inode on the super block's dirty list. |
1004 | * | |
1005 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
1006 | * dirty list only if it is hashed or if it refers to a blockdev. | |
1007 | * If it was not hashed, it will never be added to the dirty list | |
1008 | * even if it is later hashed, as it will have been marked dirty already. | |
1009 | * | |
1010 | * In short, make sure you hash any inodes _before_ you start marking | |
1011 | * them dirty. | |
1da177e4 | 1012 | * |
03ba3782 JA |
1013 | * This function *must* be atomic for the I_DIRTY_PAGES case - |
1014 | * set_page_dirty() is called under spinlock in several places. | |
1da177e4 | 1015 | * |
03ba3782 JA |
1016 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
1017 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
1018 | * the kernel-internal blockdev inode represents the dirtying time of the | |
1019 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
1020 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
1021 | * blockdev inode. | |
1da177e4 | 1022 | */ |
03ba3782 | 1023 | void __mark_inode_dirty(struct inode *inode, int flags) |
1da177e4 | 1024 | { |
03ba3782 | 1025 | struct super_block *sb = inode->i_sb; |
1da177e4 | 1026 | |
03ba3782 JA |
1027 | /* |
1028 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
1029 | * dirty the inode itself | |
1030 | */ | |
1031 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
1032 | if (sb->s_op->dirty_inode) | |
1033 | sb->s_op->dirty_inode(inode); | |
1034 | } | |
1035 | ||
1036 | /* | |
1037 | * make sure that changes are seen by all cpus before we test i_state | |
1038 | * -- mikulas | |
1039 | */ | |
1040 | smp_mb(); | |
1041 | ||
1042 | /* avoid the locking if we can */ | |
1043 | if ((inode->i_state & flags) == flags) | |
1044 | return; | |
1045 | ||
1046 | if (unlikely(block_dump)) | |
1047 | block_dump___mark_inode_dirty(inode); | |
1048 | ||
1049 | spin_lock(&inode_lock); | |
1050 | if ((inode->i_state & flags) != flags) { | |
1051 | const int was_dirty = inode->i_state & I_DIRTY; | |
1052 | ||
1053 | inode->i_state |= flags; | |
1054 | ||
1055 | /* | |
1056 | * If the inode is being synced, just update its dirty state. | |
1057 | * The unlocker will place the inode on the appropriate | |
1058 | * superblock list, based upon its state. | |
1059 | */ | |
1060 | if (inode->i_state & I_SYNC) | |
1061 | goto out; | |
1062 | ||
1063 | /* | |
1064 | * Only add valid (hashed) inodes to the superblock's | |
1065 | * dirty list. Add blockdev inodes as well. | |
1066 | */ | |
1067 | if (!S_ISBLK(inode->i_mode)) { | |
1068 | if (hlist_unhashed(&inode->i_hash)) | |
1069 | goto out; | |
1070 | } | |
1071 | if (inode->i_state & (I_FREEING|I_CLEAR)) | |
1072 | goto out; | |
1073 | ||
1074 | /* | |
1075 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
1076 | * reposition it (that would break b_dirty time-ordering). | |
1077 | */ | |
1078 | if (!was_dirty) { | |
1079 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; | |
500b067c JA |
1080 | struct backing_dev_info *bdi = wb->bdi; |
1081 | ||
1082 | if (bdi_cap_writeback_dirty(bdi) && | |
1083 | !test_bit(BDI_registered, &bdi->state)) { | |
1084 | WARN_ON(1); | |
1085 | printk(KERN_ERR "bdi-%s not registered\n", | |
1086 | bdi->name); | |
1087 | } | |
03ba3782 JA |
1088 | |
1089 | inode->dirtied_when = jiffies; | |
1090 | list_move(&inode->i_list, &wb->b_dirty); | |
1da177e4 | 1091 | } |
1da177e4 | 1092 | } |
03ba3782 JA |
1093 | out: |
1094 | spin_unlock(&inode_lock); | |
1095 | } | |
1096 | EXPORT_SYMBOL(__mark_inode_dirty); | |
1097 | ||
1098 | /* | |
1099 | * Write out a superblock's list of dirty inodes. A wait will be performed | |
1100 | * upon no inodes, all inodes or the final one, depending upon sync_mode. | |
1101 | * | |
1102 | * If older_than_this is non-NULL, then only write out inodes which | |
1103 | * had their first dirtying at a time earlier than *older_than_this. | |
1104 | * | |
03ba3782 JA |
1105 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. |
1106 | * This function assumes that the blockdev superblock's inodes are backed by | |
1107 | * a variety of queues, so all inodes are searched. For other superblocks, | |
1108 | * assume that all inodes are backed by the same queue. | |
1109 | * | |
1110 | * The inodes to be written are parked on bdi->b_io. They are moved back onto | |
1111 | * bdi->b_dirty as they are selected for writing. This way, none can be missed | |
1112 | * on the writer throttling path, and we get decent balancing between many | |
1113 | * throttled threads: we don't want them all piling up on inode_sync_wait. | |
1114 | */ | |
b6e51316 | 1115 | static void wait_sb_inodes(struct super_block *sb) |
03ba3782 JA |
1116 | { |
1117 | struct inode *inode, *old_inode = NULL; | |
1118 | ||
1119 | /* | |
1120 | * We need to be protected against the filesystem going from | |
1121 | * r/o to r/w or vice versa. | |
1122 | */ | |
b6e51316 | 1123 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
03ba3782 JA |
1124 | |
1125 | spin_lock(&inode_lock); | |
1126 | ||
1127 | /* | |
1128 | * Data integrity sync. Must wait for all pages under writeback, | |
1129 | * because there may have been pages dirtied before our sync | |
1130 | * call, but which had writeout started before we write it out. | |
1131 | * In which case, the inode may not be on the dirty list, but | |
1132 | * we still have to wait for that writeout. | |
1133 | */ | |
b6e51316 | 1134 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
03ba3782 JA |
1135 | struct address_space *mapping; |
1136 | ||
1137 | if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) | |
1138 | continue; | |
1139 | mapping = inode->i_mapping; | |
1140 | if (mapping->nrpages == 0) | |
1141 | continue; | |
1142 | __iget(inode); | |
1143 | spin_unlock(&inode_lock); | |
1144 | /* | |
1145 | * We hold a reference to 'inode' so it couldn't have | |
1146 | * been removed from s_inodes list while we dropped the | |
1147 | * inode_lock. We cannot iput the inode now as we can | |
1148 | * be holding the last reference and we cannot iput it | |
1149 | * under inode_lock. So we keep the reference and iput | |
1150 | * it later. | |
1151 | */ | |
1152 | iput(old_inode); | |
1153 | old_inode = inode; | |
1154 | ||
1155 | filemap_fdatawait(mapping); | |
1156 | ||
1157 | cond_resched(); | |
1158 | ||
1159 | spin_lock(&inode_lock); | |
1160 | } | |
1161 | spin_unlock(&inode_lock); | |
1162 | iput(old_inode); | |
1da177e4 LT |
1163 | } |
1164 | ||
d8a8559c JA |
1165 | /** |
1166 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
1167 | * @sb: the superblock | |
1da177e4 | 1168 | * |
d8a8559c JA |
1169 | * Start writeback on some inodes on this super_block. No guarantees are made |
1170 | * on how many (if any) will be written, and this function does not wait | |
1171 | * for IO completion of submitted IO. The number of pages submitted is | |
1172 | * returned. | |
1da177e4 | 1173 | */ |
b6e51316 | 1174 | void writeback_inodes_sb(struct super_block *sb) |
1da177e4 | 1175 | { |
0e3c9a22 JA |
1176 | unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); |
1177 | unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); | |
3c4d7165 CH |
1178 | struct wb_writeback_args args = { |
1179 | .sb = sb, | |
1180 | .sync_mode = WB_SYNC_NONE, | |
1181 | }; | |
d8a8559c | 1182 | |
cf37e972 CH |
1183 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
1184 | ||
3c4d7165 | 1185 | args.nr_pages = nr_dirty + nr_unstable + |
0e3c9a22 JA |
1186 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); |
1187 | ||
3c4d7165 | 1188 | bdi_queue_work_onstack(&args); |
e913fc82 | 1189 | } |
0e3c9a22 | 1190 | EXPORT_SYMBOL(writeback_inodes_sb); |
e913fc82 | 1191 | |
17bd55d0 ES |
1192 | /** |
1193 | * writeback_inodes_sb_if_idle - start writeback if none underway | |
1194 | * @sb: the superblock | |
1195 | * | |
1196 | * Invoke writeback_inodes_sb if no writeback is currently underway. | |
1197 | * Returns 1 if writeback was started, 0 if not. | |
1198 | */ | |
1199 | int writeback_inodes_sb_if_idle(struct super_block *sb) | |
1200 | { | |
1201 | if (!writeback_in_progress(sb->s_bdi)) { | |
cf37e972 | 1202 | down_read(&sb->s_umount); |
17bd55d0 | 1203 | writeback_inodes_sb(sb); |
cf37e972 | 1204 | up_read(&sb->s_umount); |
17bd55d0 ES |
1205 | return 1; |
1206 | } else | |
1207 | return 0; | |
1208 | } | |
1209 | EXPORT_SYMBOL(writeback_inodes_sb_if_idle); | |
1210 | ||
d8a8559c JA |
1211 | /** |
1212 | * sync_inodes_sb - sync sb inode pages | |
1213 | * @sb: the superblock | |
1214 | * | |
1215 | * This function writes and waits on any dirty inode belonging to this | |
1216 | * super_block. The number of pages synced is returned. | |
1217 | */ | |
b6e51316 | 1218 | void sync_inodes_sb(struct super_block *sb) |
d8a8559c | 1219 | { |
3c4d7165 CH |
1220 | struct wb_writeback_args args = { |
1221 | .sb = sb, | |
1222 | .sync_mode = WB_SYNC_ALL, | |
1223 | .nr_pages = LONG_MAX, | |
1224 | .range_cyclic = 0, | |
1225 | }; | |
1226 | ||
cf37e972 CH |
1227 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
1228 | ||
3c4d7165 | 1229 | bdi_queue_work_onstack(&args); |
b6e51316 | 1230 | wait_sb_inodes(sb); |
1da177e4 | 1231 | } |
d8a8559c | 1232 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 1233 | |
1da177e4 | 1234 | /** |
7f04c26d AA |
1235 | * write_inode_now - write an inode to disk |
1236 | * @inode: inode to write to disk | |
1237 | * @sync: whether the write should be synchronous or not | |
1238 | * | |
1239 | * This function commits an inode to disk immediately if it is dirty. This is | |
1240 | * primarily needed by knfsd. | |
1da177e4 | 1241 | * |
7f04c26d | 1242 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 1243 | */ |
1da177e4 LT |
1244 | int write_inode_now(struct inode *inode, int sync) |
1245 | { | |
1246 | int ret; | |
1247 | struct writeback_control wbc = { | |
1248 | .nr_to_write = LONG_MAX, | |
18914b18 | 1249 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
1250 | .range_start = 0, |
1251 | .range_end = LLONG_MAX, | |
1da177e4 LT |
1252 | }; |
1253 | ||
1254 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 1255 | wbc.nr_to_write = 0; |
1da177e4 LT |
1256 | |
1257 | might_sleep(); | |
1258 | spin_lock(&inode_lock); | |
01c03194 | 1259 | ret = writeback_single_inode(inode, &wbc); |
1da177e4 LT |
1260 | spin_unlock(&inode_lock); |
1261 | if (sync) | |
1c0eeaf5 | 1262 | inode_sync_wait(inode); |
1da177e4 LT |
1263 | return ret; |
1264 | } | |
1265 | EXPORT_SYMBOL(write_inode_now); | |
1266 | ||
1267 | /** | |
1268 | * sync_inode - write an inode and its pages to disk. | |
1269 | * @inode: the inode to sync | |
1270 | * @wbc: controls the writeback mode | |
1271 | * | |
1272 | * sync_inode() will write an inode and its pages to disk. It will also | |
1273 | * correctly update the inode on its superblock's dirty inode lists and will | |
1274 | * update inode->i_state. | |
1275 | * | |
1276 | * The caller must have a ref on the inode. | |
1277 | */ | |
1278 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
1279 | { | |
1280 | int ret; | |
1281 | ||
1282 | spin_lock(&inode_lock); | |
01c03194 | 1283 | ret = writeback_single_inode(inode, wbc); |
1da177e4 LT |
1284 | spin_unlock(&inode_lock); |
1285 | return ret; | |
1286 | } | |
1287 | EXPORT_SYMBOL(sync_inode); |