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bcache: Prune struct btree_op
[deliverable/linux.git] / drivers / md / bcache / writeback.c
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"
12 #include "writeback.h"
13
14 #include <linux/delay.h>
15 #include <linux/freezer.h>
16 #include <linux/kthread.h>
17 #include <trace/events/bcache.h>
18
19 /* Rate limiting */
20
21 static void __update_writeback_rate(struct cached_dev *dc)
22 {
23 struct cache_set *c = dc->disk.c;
24 uint64_t cache_sectors = c->nbuckets * c->sb.bucket_size;
25 uint64_t cache_dirty_target =
26 div_u64(cache_sectors * dc->writeback_percent, 100);
27
28 int64_t target = div64_u64(cache_dirty_target * bdev_sectors(dc->bdev),
29 c->cached_dev_sectors);
30
31 /* PD controller */
32
33 int change = 0;
34 int64_t error;
35 int64_t dirty = bcache_dev_sectors_dirty(&dc->disk);
36 int64_t derivative = dirty - dc->disk.sectors_dirty_last;
37
38 dc->disk.sectors_dirty_last = dirty;
39
40 derivative *= dc->writeback_rate_d_term;
41 derivative = clamp(derivative, -dirty, dirty);
42
43 derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative,
44 dc->writeback_rate_d_smooth, 0);
45
46 /* Avoid divide by zero */
47 if (!target)
48 goto out;
49
50 error = div64_s64((dirty + derivative - target) << 8, target);
51
52 change = div_s64((dc->writeback_rate.rate * error) >> 8,
53 dc->writeback_rate_p_term_inverse);
54
55 /* Don't increase writeback rate if the device isn't keeping up */
56 if (change > 0 &&
57 time_after64(local_clock(),
58 dc->writeback_rate.next + 10 * NSEC_PER_MSEC))
59 change = 0;
60
61 dc->writeback_rate.rate =
62 clamp_t(int64_t, dc->writeback_rate.rate + change,
63 1, NSEC_PER_MSEC);
64 out:
65 dc->writeback_rate_derivative = derivative;
66 dc->writeback_rate_change = change;
67 dc->writeback_rate_target = target;
68 }
69
70 static void update_writeback_rate(struct work_struct *work)
71 {
72 struct cached_dev *dc = container_of(to_delayed_work(work),
73 struct cached_dev,
74 writeback_rate_update);
75
76 down_read(&dc->writeback_lock);
77
78 if (atomic_read(&dc->has_dirty) &&
79 dc->writeback_percent)
80 __update_writeback_rate(dc);
81
82 up_read(&dc->writeback_lock);
83
84 schedule_delayed_work(&dc->writeback_rate_update,
85 dc->writeback_rate_update_seconds * HZ);
86 }
87
88 static unsigned writeback_delay(struct cached_dev *dc, unsigned sectors)
89 {
90 uint64_t ret;
91
92 if (atomic_read(&dc->disk.detaching) ||
93 !dc->writeback_percent)
94 return 0;
95
96 ret = bch_next_delay(&dc->writeback_rate, sectors * 10000000ULL);
97
98 return min_t(uint64_t, ret, HZ);
99 }
100
101 struct dirty_io {
102 struct closure cl;
103 struct cached_dev *dc;
104 struct bio bio;
105 };
106
107 static void dirty_init(struct keybuf_key *w)
108 {
109 struct dirty_io *io = w->private;
110 struct bio *bio = &io->bio;
111
112 bio_init(bio);
113 if (!io->dc->writeback_percent)
114 bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
115
116 bio->bi_size = KEY_SIZE(&w->key) << 9;
117 bio->bi_max_vecs = DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS);
118 bio->bi_private = w;
119 bio->bi_io_vec = bio->bi_inline_vecs;
120 bch_bio_map(bio, NULL);
121 }
122
123 static void dirty_io_destructor(struct closure *cl)
124 {
125 struct dirty_io *io = container_of(cl, struct dirty_io, cl);
126 kfree(io);
127 }
128
129 static void write_dirty_finish(struct closure *cl)
130 {
131 struct dirty_io *io = container_of(cl, struct dirty_io, cl);
132 struct keybuf_key *w = io->bio.bi_private;
133 struct cached_dev *dc = io->dc;
134 struct bio_vec *bv;
135 int i;
136
137 bio_for_each_segment_all(bv, &io->bio, i)
138 __free_page(bv->bv_page);
139
140 /* This is kind of a dumb way of signalling errors. */
141 if (KEY_DIRTY(&w->key)) {
142 unsigned i;
143 struct btree_op op;
144 struct keylist keys;
145
146 bch_btree_op_init_stack(&op);
147 bch_keylist_init(&keys);
148
149 op.type = BTREE_REPLACE;
150 bkey_copy(&op.replace, &w->key);
151
152 SET_KEY_DIRTY(&w->key, false);
153 bch_keylist_add(&keys, &w->key);
154
155 for (i = 0; i < KEY_PTRS(&w->key); i++)
156 atomic_inc(&PTR_BUCKET(dc->disk.c, &w->key, i)->pin);
157
158 bch_btree_insert(&op, dc->disk.c, &keys, NULL);
159 closure_sync(&op.cl);
160
161 if (op.insert_collision)
162 trace_bcache_writeback_collision(&w->key);
163
164 atomic_long_inc(op.insert_collision
165 ? &dc->disk.c->writeback_keys_failed
166 : &dc->disk.c->writeback_keys_done);
167 }
168
169 bch_keybuf_del(&dc->writeback_keys, w);
170 up(&dc->in_flight);
171
172 closure_return_with_destructor(cl, dirty_io_destructor);
173 }
174
175 static void dirty_endio(struct bio *bio, int error)
176 {
177 struct keybuf_key *w = bio->bi_private;
178 struct dirty_io *io = w->private;
179
180 if (error)
181 SET_KEY_DIRTY(&w->key, false);
182
183 closure_put(&io->cl);
184 }
185
186 static void write_dirty(struct closure *cl)
187 {
188 struct dirty_io *io = container_of(cl, struct dirty_io, cl);
189 struct keybuf_key *w = io->bio.bi_private;
190
191 dirty_init(w);
192 io->bio.bi_rw = WRITE;
193 io->bio.bi_sector = KEY_START(&w->key);
194 io->bio.bi_bdev = io->dc->bdev;
195 io->bio.bi_end_io = dirty_endio;
196
197 closure_bio_submit(&io->bio, cl, &io->dc->disk);
198
199 continue_at(cl, write_dirty_finish, system_wq);
200 }
201
202 static void read_dirty_endio(struct bio *bio, int error)
203 {
204 struct keybuf_key *w = bio->bi_private;
205 struct dirty_io *io = w->private;
206
207 bch_count_io_errors(PTR_CACHE(io->dc->disk.c, &w->key, 0),
208 error, "reading dirty data from cache");
209
210 dirty_endio(bio, error);
211 }
212
213 static void read_dirty_submit(struct closure *cl)
214 {
215 struct dirty_io *io = container_of(cl, struct dirty_io, cl);
216
217 closure_bio_submit(&io->bio, cl, &io->dc->disk);
218
219 continue_at(cl, write_dirty, system_wq);
220 }
221
222 static void read_dirty(struct cached_dev *dc)
223 {
224 unsigned delay = 0;
225 struct keybuf_key *w;
226 struct dirty_io *io;
227 struct closure cl;
228
229 closure_init_stack(&cl);
230
231 /*
232 * XXX: if we error, background writeback just spins. Should use some
233 * mempools.
234 */
235
236 while (!kthread_should_stop()) {
237 try_to_freeze();
238
239 w = bch_keybuf_next(&dc->writeback_keys);
240 if (!w)
241 break;
242
243 BUG_ON(ptr_stale(dc->disk.c, &w->key, 0));
244
245 if (KEY_START(&w->key) != dc->last_read ||
246 jiffies_to_msecs(delay) > 50)
247 while (!kthread_should_stop() && delay)
248 delay = schedule_timeout_interruptible(delay);
249
250 dc->last_read = KEY_OFFSET(&w->key);
251
252 io = kzalloc(sizeof(struct dirty_io) + sizeof(struct bio_vec)
253 * DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
254 GFP_KERNEL);
255 if (!io)
256 goto err;
257
258 w->private = io;
259 io->dc = dc;
260
261 dirty_init(w);
262 io->bio.bi_sector = PTR_OFFSET(&w->key, 0);
263 io->bio.bi_bdev = PTR_CACHE(dc->disk.c,
264 &w->key, 0)->bdev;
265 io->bio.bi_rw = READ;
266 io->bio.bi_end_io = read_dirty_endio;
267
268 if (bio_alloc_pages(&io->bio, GFP_KERNEL))
269 goto err_free;
270
271 trace_bcache_writeback(&w->key);
272
273 down(&dc->in_flight);
274 closure_call(&io->cl, read_dirty_submit, NULL, &cl);
275
276 delay = writeback_delay(dc, KEY_SIZE(&w->key));
277 }
278
279 if (0) {
280 err_free:
281 kfree(w->private);
282 err:
283 bch_keybuf_del(&dc->writeback_keys, w);
284 }
285
286 /*
287 * Wait for outstanding writeback IOs to finish (and keybuf slots to be
288 * freed) before refilling again
289 */
290 closure_sync(&cl);
291 }
292
293 /* Scan for dirty data */
294
295 void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned inode,
296 uint64_t offset, int nr_sectors)
297 {
298 struct bcache_device *d = c->devices[inode];
299 unsigned stripe_offset;
300 uint64_t stripe = offset;
301
302 if (!d)
303 return;
304
305 do_div(stripe, d->stripe_size);
306
307 stripe_offset = offset & (d->stripe_size - 1);
308
309 while (nr_sectors) {
310 int s = min_t(unsigned, abs(nr_sectors),
311 d->stripe_size - stripe_offset);
312
313 if (nr_sectors < 0)
314 s = -s;
315
316 atomic_add(s, d->stripe_sectors_dirty + stripe);
317 nr_sectors -= s;
318 stripe_offset = 0;
319 stripe++;
320 }
321 }
322
323 static bool dirty_pred(struct keybuf *buf, struct bkey *k)
324 {
325 return KEY_DIRTY(k);
326 }
327
328 static bool dirty_full_stripe_pred(struct keybuf *buf, struct bkey *k)
329 {
330 uint64_t stripe = KEY_START(k);
331 unsigned nr_sectors = KEY_SIZE(k);
332 struct cached_dev *dc = container_of(buf, struct cached_dev,
333 writeback_keys);
334
335 if (!KEY_DIRTY(k))
336 return false;
337
338 do_div(stripe, dc->disk.stripe_size);
339
340 while (1) {
341 if (atomic_read(dc->disk.stripe_sectors_dirty + stripe) ==
342 dc->disk.stripe_size)
343 return true;
344
345 if (nr_sectors <= dc->disk.stripe_size)
346 return false;
347
348 nr_sectors -= dc->disk.stripe_size;
349 stripe++;
350 }
351 }
352
353 static bool refill_dirty(struct cached_dev *dc)
354 {
355 struct keybuf *buf = &dc->writeback_keys;
356 bool searched_from_start = false;
357 struct bkey end = KEY(dc->disk.id, MAX_KEY_OFFSET, 0);
358
359 if (bkey_cmp(&buf->last_scanned, &end) >= 0) {
360 buf->last_scanned = KEY(dc->disk.id, 0, 0);
361 searched_from_start = true;
362 }
363
364 if (dc->partial_stripes_expensive) {
365 uint64_t i;
366
367 for (i = 0; i < dc->disk.nr_stripes; i++)
368 if (atomic_read(dc->disk.stripe_sectors_dirty + i) ==
369 dc->disk.stripe_size)
370 goto full_stripes;
371
372 goto normal_refill;
373 full_stripes:
374 searched_from_start = false; /* not searching entire btree */
375 bch_refill_keybuf(dc->disk.c, buf, &end,
376 dirty_full_stripe_pred);
377 } else {
378 normal_refill:
379 bch_refill_keybuf(dc->disk.c, buf, &end, dirty_pred);
380 }
381
382 return bkey_cmp(&buf->last_scanned, &end) >= 0 && searched_from_start;
383 }
384
385 static int bch_writeback_thread(void *arg)
386 {
387 struct cached_dev *dc = arg;
388 bool searched_full_index;
389
390 while (!kthread_should_stop()) {
391 down_write(&dc->writeback_lock);
392 if (!atomic_read(&dc->has_dirty) ||
393 (!atomic_read(&dc->disk.detaching) &&
394 !dc->writeback_running)) {
395 up_write(&dc->writeback_lock);
396 set_current_state(TASK_INTERRUPTIBLE);
397
398 if (kthread_should_stop())
399 return 0;
400
401 try_to_freeze();
402 schedule();
403 continue;
404 }
405
406 searched_full_index = refill_dirty(dc);
407
408 if (searched_full_index &&
409 RB_EMPTY_ROOT(&dc->writeback_keys.keys)) {
410 atomic_set(&dc->has_dirty, 0);
411 cached_dev_put(dc);
412 SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
413 bch_write_bdev_super(dc, NULL);
414 }
415
416 up_write(&dc->writeback_lock);
417
418 bch_ratelimit_reset(&dc->writeback_rate);
419 read_dirty(dc);
420
421 if (searched_full_index) {
422 unsigned delay = dc->writeback_delay * HZ;
423
424 while (delay &&
425 !kthread_should_stop() &&
426 !atomic_read(&dc->disk.detaching))
427 delay = schedule_timeout_interruptible(delay);
428 }
429 }
430
431 return 0;
432 }
433
434 /* Init */
435
436 struct sectors_dirty_init {
437 struct btree_op op;
438 unsigned inode;
439 };
440
441 static int sectors_dirty_init_fn(struct btree_op *_op, struct btree *b,
442 struct bkey *k)
443 {
444 struct sectors_dirty_init *op = container_of(_op,
445 struct sectors_dirty_init, op);
446 if (KEY_INODE(k) > op->inode)
447 return MAP_DONE;
448
449 if (KEY_DIRTY(k))
450 bcache_dev_sectors_dirty_add(b->c, KEY_INODE(k),
451 KEY_START(k), KEY_SIZE(k));
452
453 return MAP_CONTINUE;
454 }
455
456 void bch_sectors_dirty_init(struct cached_dev *dc)
457 {
458 struct sectors_dirty_init op;
459
460 bch_btree_op_init_stack(&op.op);
461 op.inode = dc->disk.id;
462
463 bch_btree_map_keys(&op.op, dc->disk.c, &KEY(op.inode, 0, 0),
464 sectors_dirty_init_fn, 0);
465 }
466
467 int bch_cached_dev_writeback_init(struct cached_dev *dc)
468 {
469 sema_init(&dc->in_flight, 64);
470 init_rwsem(&dc->writeback_lock);
471 bch_keybuf_init(&dc->writeback_keys);
472
473 dc->writeback_metadata = true;
474 dc->writeback_running = true;
475 dc->writeback_percent = 10;
476 dc->writeback_delay = 30;
477 dc->writeback_rate.rate = 1024;
478
479 dc->writeback_rate_update_seconds = 30;
480 dc->writeback_rate_d_term = 16;
481 dc->writeback_rate_p_term_inverse = 64;
482 dc->writeback_rate_d_smooth = 8;
483
484 dc->writeback_thread = kthread_create(bch_writeback_thread, dc,
485 "bcache_writeback");
486 if (IS_ERR(dc->writeback_thread))
487 return PTR_ERR(dc->writeback_thread);
488
489 set_task_state(dc->writeback_thread, TASK_INTERRUPTIBLE);
490
491 INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
492 schedule_delayed_work(&dc->writeback_rate_update,
493 dc->writeback_rate_update_seconds * HZ);
494
495 return 0;
496 }
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