Commit | Line | Data |
---|---|---|
cafe5635 KO |
1 | /* |
2 | * background writeback - scan btree for dirty data and write it to the backing | |
3 | * device | |
4 | * | |
5 | * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com> | |
6 | * Copyright 2012 Google, Inc. | |
7 | */ | |
8 | ||
9 | #include "bcache.h" | |
10 | #include "btree.h" | |
11 | #include "debug.h" | |
279afbad | 12 | #include "writeback.h" |
cafe5635 | 13 | |
5e6926da | 14 | #include <linux/delay.h> |
5e6926da | 15 | #include <linux/kthread.h> |
c37511b8 KO |
16 | #include <trace/events/bcache.h> |
17 | ||
cafe5635 KO |
18 | /* Rate limiting */ |
19 | ||
20 | static void __update_writeback_rate(struct cached_dev *dc) | |
21 | { | |
22 | struct cache_set *c = dc->disk.c; | |
23 | uint64_t cache_sectors = c->nbuckets * c->sb.bucket_size; | |
24 | uint64_t cache_dirty_target = | |
25 | div_u64(cache_sectors * dc->writeback_percent, 100); | |
26 | ||
27 | int64_t target = div64_u64(cache_dirty_target * bdev_sectors(dc->bdev), | |
28 | c->cached_dev_sectors); | |
29 | ||
30 | /* PD controller */ | |
31 | ||
279afbad | 32 | int64_t dirty = bcache_dev_sectors_dirty(&dc->disk); |
cafe5635 | 33 | int64_t derivative = dirty - dc->disk.sectors_dirty_last; |
16749c23 KO |
34 | int64_t proportional = dirty - target; |
35 | int64_t change; | |
cafe5635 KO |
36 | |
37 | dc->disk.sectors_dirty_last = dirty; | |
38 | ||
16749c23 | 39 | /* Scale to sectors per second */ |
cafe5635 | 40 | |
16749c23 KO |
41 | proportional *= dc->writeback_rate_update_seconds; |
42 | proportional = div_s64(proportional, dc->writeback_rate_p_term_inverse); | |
cafe5635 | 43 | |
16749c23 | 44 | derivative = div_s64(derivative, dc->writeback_rate_update_seconds); |
cafe5635 | 45 | |
16749c23 KO |
46 | derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative, |
47 | (dc->writeback_rate_d_term / | |
48 | dc->writeback_rate_update_seconds) ?: 1, 0); | |
49 | ||
50 | derivative *= dc->writeback_rate_d_term; | |
51 | derivative = div_s64(derivative, dc->writeback_rate_p_term_inverse); | |
cafe5635 | 52 | |
16749c23 | 53 | change = proportional + derivative; |
cafe5635 KO |
54 | |
55 | /* Don't increase writeback rate if the device isn't keeping up */ | |
56 | if (change > 0 && | |
57 | time_after64(local_clock(), | |
16749c23 | 58 | dc->writeback_rate.next + NSEC_PER_MSEC)) |
cafe5635 KO |
59 | change = 0; |
60 | ||
61 | dc->writeback_rate.rate = | |
16749c23 | 62 | clamp_t(int64_t, (int64_t) dc->writeback_rate.rate + change, |
cafe5635 | 63 | 1, NSEC_PER_MSEC); |
16749c23 KO |
64 | |
65 | dc->writeback_rate_proportional = proportional; | |
cafe5635 KO |
66 | dc->writeback_rate_derivative = derivative; |
67 | dc->writeback_rate_change = change; | |
68 | dc->writeback_rate_target = target; | |
cafe5635 KO |
69 | } |
70 | ||
71 | static void update_writeback_rate(struct work_struct *work) | |
72 | { | |
73 | struct cached_dev *dc = container_of(to_delayed_work(work), | |
74 | struct cached_dev, | |
75 | writeback_rate_update); | |
76 | ||
77 | down_read(&dc->writeback_lock); | |
78 | ||
79 | if (atomic_read(&dc->has_dirty) && | |
80 | dc->writeback_percent) | |
81 | __update_writeback_rate(dc); | |
82 | ||
83 | up_read(&dc->writeback_lock); | |
5e6926da KO |
84 | |
85 | schedule_delayed_work(&dc->writeback_rate_update, | |
86 | dc->writeback_rate_update_seconds * HZ); | |
cafe5635 KO |
87 | } |
88 | ||
89 | static unsigned writeback_delay(struct cached_dev *dc, unsigned sectors) | |
90 | { | |
c4d951dd | 91 | if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) || |
cafe5635 KO |
92 | !dc->writeback_percent) |
93 | return 0; | |
94 | ||
16749c23 | 95 | return bch_next_delay(&dc->writeback_rate, sectors); |
cafe5635 KO |
96 | } |
97 | ||
5e6926da KO |
98 | struct dirty_io { |
99 | struct closure cl; | |
100 | struct cached_dev *dc; | |
101 | struct bio bio; | |
102 | }; | |
72c27061 | 103 | |
cafe5635 KO |
104 | static void dirty_init(struct keybuf_key *w) |
105 | { | |
106 | struct dirty_io *io = w->private; | |
107 | struct bio *bio = &io->bio; | |
108 | ||
109 | bio_init(bio); | |
110 | if (!io->dc->writeback_percent) | |
111 | bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0)); | |
112 | ||
4f024f37 | 113 | bio->bi_iter.bi_size = KEY_SIZE(&w->key) << 9; |
cafe5635 KO |
114 | bio->bi_max_vecs = DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS); |
115 | bio->bi_private = w; | |
116 | bio->bi_io_vec = bio->bi_inline_vecs; | |
169ef1cf | 117 | bch_bio_map(bio, NULL); |
cafe5635 KO |
118 | } |
119 | ||
cafe5635 KO |
120 | static void dirty_io_destructor(struct closure *cl) |
121 | { | |
122 | struct dirty_io *io = container_of(cl, struct dirty_io, cl); | |
123 | kfree(io); | |
124 | } | |
125 | ||
126 | static void write_dirty_finish(struct closure *cl) | |
127 | { | |
128 | struct dirty_io *io = container_of(cl, struct dirty_io, cl); | |
129 | struct keybuf_key *w = io->bio.bi_private; | |
130 | struct cached_dev *dc = io->dc; | |
cafe5635 | 131 | |
491221f8 | 132 | bio_free_pages(&io->bio); |
cafe5635 KO |
133 | |
134 | /* This is kind of a dumb way of signalling errors. */ | |
135 | if (KEY_DIRTY(&w->key)) { | |
cc7b8819 | 136 | int ret; |
cafe5635 | 137 | unsigned i; |
0b93207a KO |
138 | struct keylist keys; |
139 | ||
0b93207a | 140 | bch_keylist_init(&keys); |
cafe5635 | 141 | |
1b207d80 KO |
142 | bkey_copy(keys.top, &w->key); |
143 | SET_KEY_DIRTY(keys.top, false); | |
144 | bch_keylist_push(&keys); | |
cafe5635 KO |
145 | |
146 | for (i = 0; i < KEY_PTRS(&w->key); i++) | |
147 | atomic_inc(&PTR_BUCKET(dc->disk.c, &w->key, i)->pin); | |
148 | ||
cc7b8819 | 149 | ret = bch_btree_insert(dc->disk.c, &keys, NULL, &w->key); |
cafe5635 | 150 | |
6054c6d4 | 151 | if (ret) |
c37511b8 KO |
152 | trace_bcache_writeback_collision(&w->key); |
153 | ||
6054c6d4 | 154 | atomic_long_inc(ret |
cafe5635 KO |
155 | ? &dc->disk.c->writeback_keys_failed |
156 | : &dc->disk.c->writeback_keys_done); | |
157 | } | |
158 | ||
159 | bch_keybuf_del(&dc->writeback_keys, w); | |
c2a4f318 | 160 | up(&dc->in_flight); |
cafe5635 KO |
161 | |
162 | closure_return_with_destructor(cl, dirty_io_destructor); | |
163 | } | |
164 | ||
4246a0b6 | 165 | static void dirty_endio(struct bio *bio) |
cafe5635 KO |
166 | { |
167 | struct keybuf_key *w = bio->bi_private; | |
168 | struct dirty_io *io = w->private; | |
169 | ||
4246a0b6 | 170 | if (bio->bi_error) |
cafe5635 KO |
171 | SET_KEY_DIRTY(&w->key, false); |
172 | ||
173 | closure_put(&io->cl); | |
174 | } | |
175 | ||
176 | static void write_dirty(struct closure *cl) | |
177 | { | |
178 | struct dirty_io *io = container_of(cl, struct dirty_io, cl); | |
179 | struct keybuf_key *w = io->bio.bi_private; | |
180 | ||
181 | dirty_init(w); | |
ad0d9e76 | 182 | bio_set_op_attrs(&io->bio, REQ_OP_WRITE, 0); |
4f024f37 | 183 | io->bio.bi_iter.bi_sector = KEY_START(&w->key); |
cafe5635 KO |
184 | io->bio.bi_bdev = io->dc->bdev; |
185 | io->bio.bi_end_io = dirty_endio; | |
186 | ||
749b61da | 187 | closure_bio_submit(&io->bio, cl); |
cafe5635 | 188 | |
c2a4f318 | 189 | continue_at(cl, write_dirty_finish, system_wq); |
cafe5635 KO |
190 | } |
191 | ||
4246a0b6 | 192 | static void read_dirty_endio(struct bio *bio) |
cafe5635 KO |
193 | { |
194 | struct keybuf_key *w = bio->bi_private; | |
195 | struct dirty_io *io = w->private; | |
196 | ||
197 | bch_count_io_errors(PTR_CACHE(io->dc->disk.c, &w->key, 0), | |
4246a0b6 | 198 | bio->bi_error, "reading dirty data from cache"); |
cafe5635 | 199 | |
4246a0b6 | 200 | dirty_endio(bio); |
cafe5635 KO |
201 | } |
202 | ||
203 | static void read_dirty_submit(struct closure *cl) | |
204 | { | |
205 | struct dirty_io *io = container_of(cl, struct dirty_io, cl); | |
206 | ||
749b61da | 207 | closure_bio_submit(&io->bio, cl); |
cafe5635 | 208 | |
c2a4f318 | 209 | continue_at(cl, write_dirty, system_wq); |
cafe5635 KO |
210 | } |
211 | ||
5e6926da | 212 | static void read_dirty(struct cached_dev *dc) |
cafe5635 | 213 | { |
5e6926da | 214 | unsigned delay = 0; |
cafe5635 KO |
215 | struct keybuf_key *w; |
216 | struct dirty_io *io; | |
5e6926da KO |
217 | struct closure cl; |
218 | ||
219 | closure_init_stack(&cl); | |
cafe5635 KO |
220 | |
221 | /* | |
222 | * XXX: if we error, background writeback just spins. Should use some | |
223 | * mempools. | |
224 | */ | |
225 | ||
5e6926da | 226 | while (!kthread_should_stop()) { |
5e6926da | 227 | |
cafe5635 KO |
228 | w = bch_keybuf_next(&dc->writeback_keys); |
229 | if (!w) | |
230 | break; | |
231 | ||
232 | BUG_ON(ptr_stale(dc->disk.c, &w->key, 0)); | |
233 | ||
5e6926da KO |
234 | if (KEY_START(&w->key) != dc->last_read || |
235 | jiffies_to_msecs(delay) > 50) | |
236 | while (!kthread_should_stop() && delay) | |
9e5c3535 | 237 | delay = schedule_timeout_interruptible(delay); |
cafe5635 KO |
238 | |
239 | dc->last_read = KEY_OFFSET(&w->key); | |
240 | ||
241 | io = kzalloc(sizeof(struct dirty_io) + sizeof(struct bio_vec) | |
242 | * DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS), | |
243 | GFP_KERNEL); | |
244 | if (!io) | |
245 | goto err; | |
246 | ||
247 | w->private = io; | |
248 | io->dc = dc; | |
249 | ||
250 | dirty_init(w); | |
ad0d9e76 | 251 | bio_set_op_attrs(&io->bio, REQ_OP_READ, 0); |
4f024f37 | 252 | io->bio.bi_iter.bi_sector = PTR_OFFSET(&w->key, 0); |
cafe5635 KO |
253 | io->bio.bi_bdev = PTR_CACHE(dc->disk.c, |
254 | &w->key, 0)->bdev; | |
cafe5635 KO |
255 | io->bio.bi_end_io = read_dirty_endio; |
256 | ||
8e51e414 | 257 | if (bio_alloc_pages(&io->bio, GFP_KERNEL)) |
cafe5635 KO |
258 | goto err_free; |
259 | ||
c37511b8 | 260 | trace_bcache_writeback(&w->key); |
cafe5635 | 261 | |
c2a4f318 | 262 | down(&dc->in_flight); |
5e6926da | 263 | closure_call(&io->cl, read_dirty_submit, NULL, &cl); |
cafe5635 KO |
264 | |
265 | delay = writeback_delay(dc, KEY_SIZE(&w->key)); | |
cafe5635 KO |
266 | } |
267 | ||
268 | if (0) { | |
269 | err_free: | |
270 | kfree(w->private); | |
271 | err: | |
272 | bch_keybuf_del(&dc->writeback_keys, w); | |
273 | } | |
274 | ||
c2a4f318 KO |
275 | /* |
276 | * Wait for outstanding writeback IOs to finish (and keybuf slots to be | |
277 | * freed) before refilling again | |
278 | */ | |
5e6926da KO |
279 | closure_sync(&cl); |
280 | } | |
281 | ||
282 | /* Scan for dirty data */ | |
283 | ||
284 | void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned inode, | |
285 | uint64_t offset, int nr_sectors) | |
286 | { | |
287 | struct bcache_device *d = c->devices[inode]; | |
48a915a8 | 288 | unsigned stripe_offset, stripe, sectors_dirty; |
5e6926da KO |
289 | |
290 | if (!d) | |
291 | return; | |
292 | ||
48a915a8 | 293 | stripe = offset_to_stripe(d, offset); |
5e6926da KO |
294 | stripe_offset = offset & (d->stripe_size - 1); |
295 | ||
296 | while (nr_sectors) { | |
297 | int s = min_t(unsigned, abs(nr_sectors), | |
298 | d->stripe_size - stripe_offset); | |
299 | ||
300 | if (nr_sectors < 0) | |
301 | s = -s; | |
302 | ||
48a915a8 KO |
303 | if (stripe >= d->nr_stripes) |
304 | return; | |
305 | ||
306 | sectors_dirty = atomic_add_return(s, | |
307 | d->stripe_sectors_dirty + stripe); | |
308 | if (sectors_dirty == d->stripe_size) | |
309 | set_bit(stripe, d->full_dirty_stripes); | |
310 | else | |
311 | clear_bit(stripe, d->full_dirty_stripes); | |
312 | ||
5e6926da KO |
313 | nr_sectors -= s; |
314 | stripe_offset = 0; | |
315 | stripe++; | |
316 | } | |
317 | } | |
318 | ||
319 | static bool dirty_pred(struct keybuf *buf, struct bkey *k) | |
320 | { | |
627ccd20 KO |
321 | struct cached_dev *dc = container_of(buf, struct cached_dev, writeback_keys); |
322 | ||
323 | BUG_ON(KEY_INODE(k) != dc->disk.id); | |
324 | ||
5e6926da KO |
325 | return KEY_DIRTY(k); |
326 | } | |
327 | ||
48a915a8 | 328 | static void refill_full_stripes(struct cached_dev *dc) |
5e6926da | 329 | { |
48a915a8 KO |
330 | struct keybuf *buf = &dc->writeback_keys; |
331 | unsigned start_stripe, stripe, next_stripe; | |
332 | bool wrapped = false; | |
333 | ||
334 | stripe = offset_to_stripe(&dc->disk, KEY_OFFSET(&buf->last_scanned)); | |
5e6926da | 335 | |
48a915a8 KO |
336 | if (stripe >= dc->disk.nr_stripes) |
337 | stripe = 0; | |
5e6926da | 338 | |
48a915a8 | 339 | start_stripe = stripe; |
5e6926da KO |
340 | |
341 | while (1) { | |
48a915a8 KO |
342 | stripe = find_next_bit(dc->disk.full_dirty_stripes, |
343 | dc->disk.nr_stripes, stripe); | |
5e6926da | 344 | |
48a915a8 KO |
345 | if (stripe == dc->disk.nr_stripes) |
346 | goto next; | |
5e6926da | 347 | |
48a915a8 KO |
348 | next_stripe = find_next_zero_bit(dc->disk.full_dirty_stripes, |
349 | dc->disk.nr_stripes, stripe); | |
350 | ||
351 | buf->last_scanned = KEY(dc->disk.id, | |
352 | stripe * dc->disk.stripe_size, 0); | |
353 | ||
354 | bch_refill_keybuf(dc->disk.c, buf, | |
355 | &KEY(dc->disk.id, | |
356 | next_stripe * dc->disk.stripe_size, 0), | |
357 | dirty_pred); | |
358 | ||
359 | if (array_freelist_empty(&buf->freelist)) | |
360 | return; | |
361 | ||
362 | stripe = next_stripe; | |
363 | next: | |
364 | if (wrapped && stripe > start_stripe) | |
365 | return; | |
366 | ||
367 | if (stripe == dc->disk.nr_stripes) { | |
368 | stripe = 0; | |
369 | wrapped = true; | |
370 | } | |
5e6926da KO |
371 | } |
372 | } | |
373 | ||
627ccd20 KO |
374 | /* |
375 | * Returns true if we scanned the entire disk | |
376 | */ | |
5e6926da KO |
377 | static bool refill_dirty(struct cached_dev *dc) |
378 | { | |
379 | struct keybuf *buf = &dc->writeback_keys; | |
627ccd20 | 380 | struct bkey start = KEY(dc->disk.id, 0, 0); |
5e6926da | 381 | struct bkey end = KEY(dc->disk.id, MAX_KEY_OFFSET, 0); |
627ccd20 KO |
382 | struct bkey start_pos; |
383 | ||
384 | /* | |
385 | * make sure keybuf pos is inside the range for this disk - at bringup | |
386 | * we might not be attached yet so this disk's inode nr isn't | |
387 | * initialized then | |
388 | */ | |
389 | if (bkey_cmp(&buf->last_scanned, &start) < 0 || | |
390 | bkey_cmp(&buf->last_scanned, &end) > 0) | |
391 | buf->last_scanned = start; | |
48a915a8 KO |
392 | |
393 | if (dc->partial_stripes_expensive) { | |
394 | refill_full_stripes(dc); | |
395 | if (array_freelist_empty(&buf->freelist)) | |
396 | return false; | |
397 | } | |
5e6926da | 398 | |
627ccd20 | 399 | start_pos = buf->last_scanned; |
48a915a8 | 400 | bch_refill_keybuf(dc->disk.c, buf, &end, dirty_pred); |
5e6926da | 401 | |
627ccd20 KO |
402 | if (bkey_cmp(&buf->last_scanned, &end) < 0) |
403 | return false; | |
404 | ||
405 | /* | |
406 | * If we get to the end start scanning again from the beginning, and | |
407 | * only scan up to where we initially started scanning from: | |
408 | */ | |
409 | buf->last_scanned = start; | |
410 | bch_refill_keybuf(dc->disk.c, buf, &start_pos, dirty_pred); | |
411 | ||
412 | return bkey_cmp(&buf->last_scanned, &start_pos) >= 0; | |
5e6926da KO |
413 | } |
414 | ||
415 | static int bch_writeback_thread(void *arg) | |
416 | { | |
417 | struct cached_dev *dc = arg; | |
418 | bool searched_full_index; | |
419 | ||
420 | while (!kthread_should_stop()) { | |
421 | down_write(&dc->writeback_lock); | |
422 | if (!atomic_read(&dc->has_dirty) || | |
c4d951dd | 423 | (!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) && |
5e6926da KO |
424 | !dc->writeback_running)) { |
425 | up_write(&dc->writeback_lock); | |
426 | set_current_state(TASK_INTERRUPTIBLE); | |
427 | ||
428 | if (kthread_should_stop()) | |
429 | return 0; | |
430 | ||
5e6926da KO |
431 | schedule(); |
432 | continue; | |
433 | } | |
434 | ||
435 | searched_full_index = refill_dirty(dc); | |
436 | ||
437 | if (searched_full_index && | |
438 | RB_EMPTY_ROOT(&dc->writeback_keys.keys)) { | |
439 | atomic_set(&dc->has_dirty, 0); | |
440 | cached_dev_put(dc); | |
441 | SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN); | |
442 | bch_write_bdev_super(dc, NULL); | |
443 | } | |
444 | ||
445 | up_write(&dc->writeback_lock); | |
446 | ||
447 | bch_ratelimit_reset(&dc->writeback_rate); | |
448 | read_dirty(dc); | |
449 | ||
450 | if (searched_full_index) { | |
451 | unsigned delay = dc->writeback_delay * HZ; | |
452 | ||
453 | while (delay && | |
454 | !kthread_should_stop() && | |
c4d951dd | 455 | !test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)) |
9e5c3535 | 456 | delay = schedule_timeout_interruptible(delay); |
5e6926da KO |
457 | } |
458 | } | |
459 | ||
460 | return 0; | |
cafe5635 KO |
461 | } |
462 | ||
444fc0b6 KO |
463 | /* Init */ |
464 | ||
c18536a7 KO |
465 | struct sectors_dirty_init { |
466 | struct btree_op op; | |
467 | unsigned inode; | |
468 | }; | |
469 | ||
470 | static int sectors_dirty_init_fn(struct btree_op *_op, struct btree *b, | |
48dad8ba | 471 | struct bkey *k) |
444fc0b6 | 472 | { |
c18536a7 KO |
473 | struct sectors_dirty_init *op = container_of(_op, |
474 | struct sectors_dirty_init, op); | |
48dad8ba KO |
475 | if (KEY_INODE(k) > op->inode) |
476 | return MAP_DONE; | |
444fc0b6 | 477 | |
48dad8ba KO |
478 | if (KEY_DIRTY(k)) |
479 | bcache_dev_sectors_dirty_add(b->c, KEY_INODE(k), | |
480 | KEY_START(k), KEY_SIZE(k)); | |
481 | ||
482 | return MAP_CONTINUE; | |
444fc0b6 KO |
483 | } |
484 | ||
485 | void bch_sectors_dirty_init(struct cached_dev *dc) | |
486 | { | |
c18536a7 | 487 | struct sectors_dirty_init op; |
444fc0b6 | 488 | |
b54d6934 | 489 | bch_btree_op_init(&op.op, -1); |
48dad8ba KO |
490 | op.inode = dc->disk.id; |
491 | ||
c18536a7 | 492 | bch_btree_map_keys(&op.op, dc->disk.c, &KEY(op.inode, 0, 0), |
48dad8ba | 493 | sectors_dirty_init_fn, 0); |
16749c23 KO |
494 | |
495 | dc->disk.sectors_dirty_last = bcache_dev_sectors_dirty(&dc->disk); | |
444fc0b6 KO |
496 | } |
497 | ||
9e5c3535 | 498 | void bch_cached_dev_writeback_init(struct cached_dev *dc) |
cafe5635 | 499 | { |
c2a4f318 | 500 | sema_init(&dc->in_flight, 64); |
cafe5635 | 501 | init_rwsem(&dc->writeback_lock); |
72c27061 | 502 | bch_keybuf_init(&dc->writeback_keys); |
cafe5635 KO |
503 | |
504 | dc->writeback_metadata = true; | |
505 | dc->writeback_running = true; | |
506 | dc->writeback_percent = 10; | |
507 | dc->writeback_delay = 30; | |
508 | dc->writeback_rate.rate = 1024; | |
509 | ||
16749c23 KO |
510 | dc->writeback_rate_update_seconds = 5; |
511 | dc->writeback_rate_d_term = 30; | |
512 | dc->writeback_rate_p_term_inverse = 6000; | |
cafe5635 | 513 | |
9e5c3535 SP |
514 | INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate); |
515 | } | |
516 | ||
517 | int bch_cached_dev_writeback_start(struct cached_dev *dc) | |
518 | { | |
5e6926da KO |
519 | dc->writeback_thread = kthread_create(bch_writeback_thread, dc, |
520 | "bcache_writeback"); | |
521 | if (IS_ERR(dc->writeback_thread)) | |
522 | return PTR_ERR(dc->writeback_thread); | |
523 | ||
cafe5635 KO |
524 | schedule_delayed_work(&dc->writeback_rate_update, |
525 | dc->writeback_rate_update_seconds * HZ); | |
cafe5635 | 526 | |
9e5c3535 SP |
527 | bch_writeback_queue(dc); |
528 | ||
cafe5635 KO |
529 | return 0; |
530 | } |