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c6b4fcba JT |
1 | /* |
2 | * Copyright (C) 2012 Red Hat. All rights reserved. | |
3 | * | |
4 | * This file is released under the GPL. | |
5 | */ | |
6 | ||
7 | #include "dm.h" | |
8 | #include "dm-bio-prison.h" | |
9 | #include "dm-cache-metadata.h" | |
10 | ||
11 | #include <linux/dm-io.h> | |
12 | #include <linux/dm-kcopyd.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/mempool.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/vmalloc.h> | |
18 | ||
19 | #define DM_MSG_PREFIX "cache" | |
20 | ||
21 | DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle, | |
22 | "A percentage of time allocated for copying to and/or from cache"); | |
23 | ||
24 | /*----------------------------------------------------------------*/ | |
25 | ||
26 | /* | |
27 | * Glossary: | |
28 | * | |
29 | * oblock: index of an origin block | |
30 | * cblock: index of a cache block | |
31 | * promotion: movement of a block from origin to cache | |
32 | * demotion: movement of a block from cache to origin | |
33 | * migration: movement of a block between the origin and cache device, | |
34 | * either direction | |
35 | */ | |
36 | ||
37 | /*----------------------------------------------------------------*/ | |
38 | ||
39 | static size_t bitset_size_in_bytes(unsigned nr_entries) | |
40 | { | |
41 | return sizeof(unsigned long) * dm_div_up(nr_entries, BITS_PER_LONG); | |
42 | } | |
43 | ||
44 | static unsigned long *alloc_bitset(unsigned nr_entries) | |
45 | { | |
46 | size_t s = bitset_size_in_bytes(nr_entries); | |
47 | return vzalloc(s); | |
48 | } | |
49 | ||
50 | static void clear_bitset(void *bitset, unsigned nr_entries) | |
51 | { | |
52 | size_t s = bitset_size_in_bytes(nr_entries); | |
53 | memset(bitset, 0, s); | |
54 | } | |
55 | ||
56 | static void free_bitset(unsigned long *bits) | |
57 | { | |
58 | vfree(bits); | |
59 | } | |
60 | ||
61 | /*----------------------------------------------------------------*/ | |
62 | ||
63 | #define PRISON_CELLS 1024 | |
64 | #define MIGRATION_POOL_SIZE 128 | |
65 | #define COMMIT_PERIOD HZ | |
66 | #define MIGRATION_COUNT_WINDOW 10 | |
67 | ||
68 | /* | |
69 | * The block size of the device holding cache data must be >= 32KB | |
70 | */ | |
71 | #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT) | |
72 | ||
73 | /* | |
74 | * FIXME: the cache is read/write for the time being. | |
75 | */ | |
76 | enum cache_mode { | |
77 | CM_WRITE, /* metadata may be changed */ | |
78 | CM_READ_ONLY, /* metadata may not be changed */ | |
79 | }; | |
80 | ||
81 | struct cache_features { | |
82 | enum cache_mode mode; | |
83 | bool write_through:1; | |
84 | }; | |
85 | ||
86 | struct cache_stats { | |
87 | atomic_t read_hit; | |
88 | atomic_t read_miss; | |
89 | atomic_t write_hit; | |
90 | atomic_t write_miss; | |
91 | atomic_t demotion; | |
92 | atomic_t promotion; | |
93 | atomic_t copies_avoided; | |
94 | atomic_t cache_cell_clash; | |
95 | atomic_t commit_count; | |
96 | atomic_t discard_count; | |
97 | }; | |
98 | ||
99 | struct cache { | |
100 | struct dm_target *ti; | |
101 | struct dm_target_callbacks callbacks; | |
102 | ||
103 | /* | |
104 | * Metadata is written to this device. | |
105 | */ | |
106 | struct dm_dev *metadata_dev; | |
107 | ||
108 | /* | |
109 | * The slower of the two data devices. Typically a spindle. | |
110 | */ | |
111 | struct dm_dev *origin_dev; | |
112 | ||
113 | /* | |
114 | * The faster of the two data devices. Typically an SSD. | |
115 | */ | |
116 | struct dm_dev *cache_dev; | |
117 | ||
118 | /* | |
119 | * Cache features such as write-through. | |
120 | */ | |
121 | struct cache_features features; | |
122 | ||
123 | /* | |
124 | * Size of the origin device in _complete_ blocks and native sectors. | |
125 | */ | |
126 | dm_oblock_t origin_blocks; | |
127 | sector_t origin_sectors; | |
128 | ||
129 | /* | |
130 | * Size of the cache device in blocks. | |
131 | */ | |
132 | dm_cblock_t cache_size; | |
133 | ||
134 | /* | |
135 | * Fields for converting from sectors to blocks. | |
136 | */ | |
137 | uint32_t sectors_per_block; | |
138 | int sectors_per_block_shift; | |
139 | ||
140 | struct dm_cache_metadata *cmd; | |
141 | ||
142 | spinlock_t lock; | |
143 | struct bio_list deferred_bios; | |
144 | struct bio_list deferred_flush_bios; | |
145 | struct list_head quiesced_migrations; | |
146 | struct list_head completed_migrations; | |
147 | struct list_head need_commit_migrations; | |
148 | sector_t migration_threshold; | |
149 | atomic_t nr_migrations; | |
150 | wait_queue_head_t migration_wait; | |
151 | ||
152 | /* | |
153 | * cache_size entries, dirty if set | |
154 | */ | |
155 | dm_cblock_t nr_dirty; | |
156 | unsigned long *dirty_bitset; | |
157 | ||
158 | /* | |
159 | * origin_blocks entries, discarded if set. | |
160 | */ | |
161 | sector_t discard_block_size; /* a power of 2 times sectors per block */ | |
162 | dm_dblock_t discard_nr_blocks; | |
163 | unsigned long *discard_bitset; | |
164 | ||
165 | struct dm_kcopyd_client *copier; | |
166 | struct workqueue_struct *wq; | |
167 | struct work_struct worker; | |
168 | ||
169 | struct delayed_work waker; | |
170 | unsigned long last_commit_jiffies; | |
171 | ||
172 | struct dm_bio_prison *prison; | |
173 | struct dm_deferred_set *all_io_ds; | |
174 | ||
175 | mempool_t *migration_pool; | |
176 | struct dm_cache_migration *next_migration; | |
177 | ||
178 | struct dm_cache_policy *policy; | |
179 | unsigned policy_nr_args; | |
180 | ||
181 | bool need_tick_bio:1; | |
182 | bool sized:1; | |
183 | bool quiescing:1; | |
184 | bool commit_requested:1; | |
185 | bool loaded_mappings:1; | |
186 | bool loaded_discards:1; | |
187 | ||
188 | struct cache_stats stats; | |
189 | ||
190 | /* | |
191 | * Rather than reconstructing the table line for the status we just | |
192 | * save it and regurgitate. | |
193 | */ | |
194 | unsigned nr_ctr_args; | |
195 | const char **ctr_args; | |
196 | }; | |
197 | ||
198 | struct per_bio_data { | |
199 | bool tick:1; | |
200 | unsigned req_nr:2; | |
201 | struct dm_deferred_entry *all_io_entry; | |
202 | }; | |
203 | ||
204 | struct dm_cache_migration { | |
205 | struct list_head list; | |
206 | struct cache *cache; | |
207 | ||
208 | unsigned long start_jiffies; | |
209 | dm_oblock_t old_oblock; | |
210 | dm_oblock_t new_oblock; | |
211 | dm_cblock_t cblock; | |
212 | ||
213 | bool err:1; | |
214 | bool writeback:1; | |
215 | bool demote:1; | |
216 | bool promote:1; | |
217 | ||
218 | struct dm_bio_prison_cell *old_ocell; | |
219 | struct dm_bio_prison_cell *new_ocell; | |
220 | }; | |
221 | ||
222 | /* | |
223 | * Processing a bio in the worker thread may require these memory | |
224 | * allocations. We prealloc to avoid deadlocks (the same worker thread | |
225 | * frees them back to the mempool). | |
226 | */ | |
227 | struct prealloc { | |
228 | struct dm_cache_migration *mg; | |
229 | struct dm_bio_prison_cell *cell1; | |
230 | struct dm_bio_prison_cell *cell2; | |
231 | }; | |
232 | ||
233 | static void wake_worker(struct cache *cache) | |
234 | { | |
235 | queue_work(cache->wq, &cache->worker); | |
236 | } | |
237 | ||
238 | /*----------------------------------------------------------------*/ | |
239 | ||
240 | static struct dm_bio_prison_cell *alloc_prison_cell(struct cache *cache) | |
241 | { | |
242 | /* FIXME: change to use a local slab. */ | |
243 | return dm_bio_prison_alloc_cell(cache->prison, GFP_NOWAIT); | |
244 | } | |
245 | ||
246 | static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell *cell) | |
247 | { | |
248 | dm_bio_prison_free_cell(cache->prison, cell); | |
249 | } | |
250 | ||
251 | static int prealloc_data_structs(struct cache *cache, struct prealloc *p) | |
252 | { | |
253 | if (!p->mg) { | |
254 | p->mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT); | |
255 | if (!p->mg) | |
256 | return -ENOMEM; | |
257 | } | |
258 | ||
259 | if (!p->cell1) { | |
260 | p->cell1 = alloc_prison_cell(cache); | |
261 | if (!p->cell1) | |
262 | return -ENOMEM; | |
263 | } | |
264 | ||
265 | if (!p->cell2) { | |
266 | p->cell2 = alloc_prison_cell(cache); | |
267 | if (!p->cell2) | |
268 | return -ENOMEM; | |
269 | } | |
270 | ||
271 | return 0; | |
272 | } | |
273 | ||
274 | static void prealloc_free_structs(struct cache *cache, struct prealloc *p) | |
275 | { | |
276 | if (p->cell2) | |
277 | free_prison_cell(cache, p->cell2); | |
278 | ||
279 | if (p->cell1) | |
280 | free_prison_cell(cache, p->cell1); | |
281 | ||
282 | if (p->mg) | |
283 | mempool_free(p->mg, cache->migration_pool); | |
284 | } | |
285 | ||
286 | static struct dm_cache_migration *prealloc_get_migration(struct prealloc *p) | |
287 | { | |
288 | struct dm_cache_migration *mg = p->mg; | |
289 | ||
290 | BUG_ON(!mg); | |
291 | p->mg = NULL; | |
292 | ||
293 | return mg; | |
294 | } | |
295 | ||
296 | /* | |
297 | * You must have a cell within the prealloc struct to return. If not this | |
298 | * function will BUG() rather than returning NULL. | |
299 | */ | |
300 | static struct dm_bio_prison_cell *prealloc_get_cell(struct prealloc *p) | |
301 | { | |
302 | struct dm_bio_prison_cell *r = NULL; | |
303 | ||
304 | if (p->cell1) { | |
305 | r = p->cell1; | |
306 | p->cell1 = NULL; | |
307 | ||
308 | } else if (p->cell2) { | |
309 | r = p->cell2; | |
310 | p->cell2 = NULL; | |
311 | } else | |
312 | BUG(); | |
313 | ||
314 | return r; | |
315 | } | |
316 | ||
317 | /* | |
318 | * You can't have more than two cells in a prealloc struct. BUG() will be | |
319 | * called if you try and overfill. | |
320 | */ | |
321 | static void prealloc_put_cell(struct prealloc *p, struct dm_bio_prison_cell *cell) | |
322 | { | |
323 | if (!p->cell2) | |
324 | p->cell2 = cell; | |
325 | ||
326 | else if (!p->cell1) | |
327 | p->cell1 = cell; | |
328 | ||
329 | else | |
330 | BUG(); | |
331 | } | |
332 | ||
333 | /*----------------------------------------------------------------*/ | |
334 | ||
335 | static void build_key(dm_oblock_t oblock, struct dm_cell_key *key) | |
336 | { | |
337 | key->virtual = 0; | |
338 | key->dev = 0; | |
339 | key->block = from_oblock(oblock); | |
340 | } | |
341 | ||
342 | /* | |
343 | * The caller hands in a preallocated cell, and a free function for it. | |
344 | * The cell will be freed if there's an error, or if it wasn't used because | |
345 | * a cell with that key already exists. | |
346 | */ | |
347 | typedef void (*cell_free_fn)(void *context, struct dm_bio_prison_cell *cell); | |
348 | ||
349 | static int bio_detain(struct cache *cache, dm_oblock_t oblock, | |
350 | struct bio *bio, struct dm_bio_prison_cell *cell_prealloc, | |
351 | cell_free_fn free_fn, void *free_context, | |
352 | struct dm_bio_prison_cell **cell_result) | |
353 | { | |
354 | int r; | |
355 | struct dm_cell_key key; | |
356 | ||
357 | build_key(oblock, &key); | |
358 | r = dm_bio_detain(cache->prison, &key, bio, cell_prealloc, cell_result); | |
359 | if (r) | |
360 | free_fn(free_context, cell_prealloc); | |
361 | ||
362 | return r; | |
363 | } | |
364 | ||
365 | static int get_cell(struct cache *cache, | |
366 | dm_oblock_t oblock, | |
367 | struct prealloc *structs, | |
368 | struct dm_bio_prison_cell **cell_result) | |
369 | { | |
370 | int r; | |
371 | struct dm_cell_key key; | |
372 | struct dm_bio_prison_cell *cell_prealloc; | |
373 | ||
374 | cell_prealloc = prealloc_get_cell(structs); | |
375 | ||
376 | build_key(oblock, &key); | |
377 | r = dm_get_cell(cache->prison, &key, cell_prealloc, cell_result); | |
378 | if (r) | |
379 | prealloc_put_cell(structs, cell_prealloc); | |
380 | ||
381 | return r; | |
382 | } | |
383 | ||
384 | /*----------------------------------------------------------------*/ | |
385 | ||
386 | static bool is_dirty(struct cache *cache, dm_cblock_t b) | |
387 | { | |
388 | return test_bit(from_cblock(b), cache->dirty_bitset); | |
389 | } | |
390 | ||
391 | static void set_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock) | |
392 | { | |
393 | if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) { | |
394 | cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) + 1); | |
395 | policy_set_dirty(cache->policy, oblock); | |
396 | } | |
397 | } | |
398 | ||
399 | static void clear_dirty(struct cache *cache, dm_oblock_t oblock, dm_cblock_t cblock) | |
400 | { | |
401 | if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) { | |
402 | policy_clear_dirty(cache->policy, oblock); | |
403 | cache->nr_dirty = to_cblock(from_cblock(cache->nr_dirty) - 1); | |
404 | if (!from_cblock(cache->nr_dirty)) | |
405 | dm_table_event(cache->ti->table); | |
406 | } | |
407 | } | |
408 | ||
409 | /*----------------------------------------------------------------*/ | |
410 | static bool block_size_is_power_of_two(struct cache *cache) | |
411 | { | |
412 | return cache->sectors_per_block_shift >= 0; | |
413 | } | |
414 | ||
415 | static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock) | |
416 | { | |
417 | sector_t discard_blocks = cache->discard_block_size; | |
418 | dm_block_t b = from_oblock(oblock); | |
419 | ||
420 | if (!block_size_is_power_of_two(cache)) | |
421 | (void) sector_div(discard_blocks, cache->sectors_per_block); | |
422 | else | |
423 | discard_blocks >>= cache->sectors_per_block_shift; | |
424 | ||
425 | (void) sector_div(b, discard_blocks); | |
426 | ||
427 | return to_dblock(b); | |
428 | } | |
429 | ||
430 | static void set_discard(struct cache *cache, dm_dblock_t b) | |
431 | { | |
432 | unsigned long flags; | |
433 | ||
434 | atomic_inc(&cache->stats.discard_count); | |
435 | ||
436 | spin_lock_irqsave(&cache->lock, flags); | |
437 | set_bit(from_dblock(b), cache->discard_bitset); | |
438 | spin_unlock_irqrestore(&cache->lock, flags); | |
439 | } | |
440 | ||
441 | static void clear_discard(struct cache *cache, dm_dblock_t b) | |
442 | { | |
443 | unsigned long flags; | |
444 | ||
445 | spin_lock_irqsave(&cache->lock, flags); | |
446 | clear_bit(from_dblock(b), cache->discard_bitset); | |
447 | spin_unlock_irqrestore(&cache->lock, flags); | |
448 | } | |
449 | ||
450 | static bool is_discarded(struct cache *cache, dm_dblock_t b) | |
451 | { | |
452 | int r; | |
453 | unsigned long flags; | |
454 | ||
455 | spin_lock_irqsave(&cache->lock, flags); | |
456 | r = test_bit(from_dblock(b), cache->discard_bitset); | |
457 | spin_unlock_irqrestore(&cache->lock, flags); | |
458 | ||
459 | return r; | |
460 | } | |
461 | ||
462 | static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b) | |
463 | { | |
464 | int r; | |
465 | unsigned long flags; | |
466 | ||
467 | spin_lock_irqsave(&cache->lock, flags); | |
468 | r = test_bit(from_dblock(oblock_to_dblock(cache, b)), | |
469 | cache->discard_bitset); | |
470 | spin_unlock_irqrestore(&cache->lock, flags); | |
471 | ||
472 | return r; | |
473 | } | |
474 | ||
475 | /*----------------------------------------------------------------*/ | |
476 | ||
477 | static void load_stats(struct cache *cache) | |
478 | { | |
479 | struct dm_cache_statistics stats; | |
480 | ||
481 | dm_cache_metadata_get_stats(cache->cmd, &stats); | |
482 | atomic_set(&cache->stats.read_hit, stats.read_hits); | |
483 | atomic_set(&cache->stats.read_miss, stats.read_misses); | |
484 | atomic_set(&cache->stats.write_hit, stats.write_hits); | |
485 | atomic_set(&cache->stats.write_miss, stats.write_misses); | |
486 | } | |
487 | ||
488 | static void save_stats(struct cache *cache) | |
489 | { | |
490 | struct dm_cache_statistics stats; | |
491 | ||
492 | stats.read_hits = atomic_read(&cache->stats.read_hit); | |
493 | stats.read_misses = atomic_read(&cache->stats.read_miss); | |
494 | stats.write_hits = atomic_read(&cache->stats.write_hit); | |
495 | stats.write_misses = atomic_read(&cache->stats.write_miss); | |
496 | ||
497 | dm_cache_metadata_set_stats(cache->cmd, &stats); | |
498 | } | |
499 | ||
500 | /*---------------------------------------------------------------- | |
501 | * Per bio data | |
502 | *--------------------------------------------------------------*/ | |
503 | static struct per_bio_data *get_per_bio_data(struct bio *bio) | |
504 | { | |
505 | struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); | |
506 | BUG_ON(!pb); | |
507 | return pb; | |
508 | } | |
509 | ||
510 | static struct per_bio_data *init_per_bio_data(struct bio *bio) | |
511 | { | |
512 | struct per_bio_data *pb = get_per_bio_data(bio); | |
513 | ||
514 | pb->tick = false; | |
515 | pb->req_nr = dm_bio_get_target_bio_nr(bio); | |
516 | pb->all_io_entry = NULL; | |
517 | ||
518 | return pb; | |
519 | } | |
520 | ||
521 | /*---------------------------------------------------------------- | |
522 | * Remapping | |
523 | *--------------------------------------------------------------*/ | |
524 | static void remap_to_origin(struct cache *cache, struct bio *bio) | |
525 | { | |
526 | bio->bi_bdev = cache->origin_dev->bdev; | |
527 | } | |
528 | ||
529 | static void remap_to_cache(struct cache *cache, struct bio *bio, | |
530 | dm_cblock_t cblock) | |
531 | { | |
532 | sector_t bi_sector = bio->bi_sector; | |
533 | ||
534 | bio->bi_bdev = cache->cache_dev->bdev; | |
535 | if (!block_size_is_power_of_two(cache)) | |
536 | bio->bi_sector = (from_cblock(cblock) * cache->sectors_per_block) + | |
537 | sector_div(bi_sector, cache->sectors_per_block); | |
538 | else | |
539 | bio->bi_sector = (from_cblock(cblock) << cache->sectors_per_block_shift) | | |
540 | (bi_sector & (cache->sectors_per_block - 1)); | |
541 | } | |
542 | ||
543 | static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio) | |
544 | { | |
545 | unsigned long flags; | |
546 | struct per_bio_data *pb = get_per_bio_data(bio); | |
547 | ||
548 | spin_lock_irqsave(&cache->lock, flags); | |
549 | if (cache->need_tick_bio && | |
550 | !(bio->bi_rw & (REQ_FUA | REQ_FLUSH | REQ_DISCARD))) { | |
551 | pb->tick = true; | |
552 | cache->need_tick_bio = false; | |
553 | } | |
554 | spin_unlock_irqrestore(&cache->lock, flags); | |
555 | } | |
556 | ||
557 | static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio, | |
558 | dm_oblock_t oblock) | |
559 | { | |
560 | check_if_tick_bio_needed(cache, bio); | |
561 | remap_to_origin(cache, bio); | |
562 | if (bio_data_dir(bio) == WRITE) | |
563 | clear_discard(cache, oblock_to_dblock(cache, oblock)); | |
564 | } | |
565 | ||
566 | static void remap_to_cache_dirty(struct cache *cache, struct bio *bio, | |
567 | dm_oblock_t oblock, dm_cblock_t cblock) | |
568 | { | |
569 | remap_to_cache(cache, bio, cblock); | |
570 | if (bio_data_dir(bio) == WRITE) { | |
571 | set_dirty(cache, oblock, cblock); | |
572 | clear_discard(cache, oblock_to_dblock(cache, oblock)); | |
573 | } | |
574 | } | |
575 | ||
576 | static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio) | |
577 | { | |
578 | sector_t block_nr = bio->bi_sector; | |
579 | ||
580 | if (!block_size_is_power_of_two(cache)) | |
581 | (void) sector_div(block_nr, cache->sectors_per_block); | |
582 | else | |
583 | block_nr >>= cache->sectors_per_block_shift; | |
584 | ||
585 | return to_oblock(block_nr); | |
586 | } | |
587 | ||
588 | static int bio_triggers_commit(struct cache *cache, struct bio *bio) | |
589 | { | |
590 | return bio->bi_rw & (REQ_FLUSH | REQ_FUA); | |
591 | } | |
592 | ||
593 | static void issue(struct cache *cache, struct bio *bio) | |
594 | { | |
595 | unsigned long flags; | |
596 | ||
597 | if (!bio_triggers_commit(cache, bio)) { | |
598 | generic_make_request(bio); | |
599 | return; | |
600 | } | |
601 | ||
602 | /* | |
603 | * Batch together any bios that trigger commits and then issue a | |
604 | * single commit for them in do_worker(). | |
605 | */ | |
606 | spin_lock_irqsave(&cache->lock, flags); | |
607 | cache->commit_requested = true; | |
608 | bio_list_add(&cache->deferred_flush_bios, bio); | |
609 | spin_unlock_irqrestore(&cache->lock, flags); | |
610 | } | |
611 | ||
612 | /*---------------------------------------------------------------- | |
613 | * Migration processing | |
614 | * | |
615 | * Migration covers moving data from the origin device to the cache, or | |
616 | * vice versa. | |
617 | *--------------------------------------------------------------*/ | |
618 | static void free_migration(struct dm_cache_migration *mg) | |
619 | { | |
620 | mempool_free(mg, mg->cache->migration_pool); | |
621 | } | |
622 | ||
623 | static void inc_nr_migrations(struct cache *cache) | |
624 | { | |
625 | atomic_inc(&cache->nr_migrations); | |
626 | } | |
627 | ||
628 | static void dec_nr_migrations(struct cache *cache) | |
629 | { | |
630 | atomic_dec(&cache->nr_migrations); | |
631 | ||
632 | /* | |
633 | * Wake the worker in case we're suspending the target. | |
634 | */ | |
635 | wake_up(&cache->migration_wait); | |
636 | } | |
637 | ||
638 | static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell, | |
639 | bool holder) | |
640 | { | |
641 | (holder ? dm_cell_release : dm_cell_release_no_holder) | |
642 | (cache->prison, cell, &cache->deferred_bios); | |
643 | free_prison_cell(cache, cell); | |
644 | } | |
645 | ||
646 | static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell, | |
647 | bool holder) | |
648 | { | |
649 | unsigned long flags; | |
650 | ||
651 | spin_lock_irqsave(&cache->lock, flags); | |
652 | __cell_defer(cache, cell, holder); | |
653 | spin_unlock_irqrestore(&cache->lock, flags); | |
654 | ||
655 | wake_worker(cache); | |
656 | } | |
657 | ||
658 | static void cleanup_migration(struct dm_cache_migration *mg) | |
659 | { | |
660 | dec_nr_migrations(mg->cache); | |
661 | free_migration(mg); | |
662 | } | |
663 | ||
664 | static void migration_failure(struct dm_cache_migration *mg) | |
665 | { | |
666 | struct cache *cache = mg->cache; | |
667 | ||
668 | if (mg->writeback) { | |
669 | DMWARN_LIMIT("writeback failed; couldn't copy block"); | |
670 | set_dirty(cache, mg->old_oblock, mg->cblock); | |
671 | cell_defer(cache, mg->old_ocell, false); | |
672 | ||
673 | } else if (mg->demote) { | |
674 | DMWARN_LIMIT("demotion failed; couldn't copy block"); | |
675 | policy_force_mapping(cache->policy, mg->new_oblock, mg->old_oblock); | |
676 | ||
677 | cell_defer(cache, mg->old_ocell, mg->promote ? 0 : 1); | |
678 | if (mg->promote) | |
679 | cell_defer(cache, mg->new_ocell, 1); | |
680 | } else { | |
681 | DMWARN_LIMIT("promotion failed; couldn't copy block"); | |
682 | policy_remove_mapping(cache->policy, mg->new_oblock); | |
683 | cell_defer(cache, mg->new_ocell, 1); | |
684 | } | |
685 | ||
686 | cleanup_migration(mg); | |
687 | } | |
688 | ||
689 | static void migration_success_pre_commit(struct dm_cache_migration *mg) | |
690 | { | |
691 | unsigned long flags; | |
692 | struct cache *cache = mg->cache; | |
693 | ||
694 | if (mg->writeback) { | |
695 | cell_defer(cache, mg->old_ocell, false); | |
696 | clear_dirty(cache, mg->old_oblock, mg->cblock); | |
697 | cleanup_migration(mg); | |
698 | return; | |
699 | ||
700 | } else if (mg->demote) { | |
701 | if (dm_cache_remove_mapping(cache->cmd, mg->cblock)) { | |
702 | DMWARN_LIMIT("demotion failed; couldn't update on disk metadata"); | |
703 | policy_force_mapping(cache->policy, mg->new_oblock, | |
704 | mg->old_oblock); | |
705 | if (mg->promote) | |
706 | cell_defer(cache, mg->new_ocell, true); | |
707 | cleanup_migration(mg); | |
708 | return; | |
709 | } | |
710 | } else { | |
711 | if (dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock)) { | |
712 | DMWARN_LIMIT("promotion failed; couldn't update on disk metadata"); | |
713 | policy_remove_mapping(cache->policy, mg->new_oblock); | |
714 | cleanup_migration(mg); | |
715 | return; | |
716 | } | |
717 | } | |
718 | ||
719 | spin_lock_irqsave(&cache->lock, flags); | |
720 | list_add_tail(&mg->list, &cache->need_commit_migrations); | |
721 | cache->commit_requested = true; | |
722 | spin_unlock_irqrestore(&cache->lock, flags); | |
723 | } | |
724 | ||
725 | static void migration_success_post_commit(struct dm_cache_migration *mg) | |
726 | { | |
727 | unsigned long flags; | |
728 | struct cache *cache = mg->cache; | |
729 | ||
730 | if (mg->writeback) { | |
731 | DMWARN("writeback unexpectedly triggered commit"); | |
732 | return; | |
733 | ||
734 | } else if (mg->demote) { | |
735 | cell_defer(cache, mg->old_ocell, mg->promote ? 0 : 1); | |
736 | ||
737 | if (mg->promote) { | |
738 | mg->demote = false; | |
739 | ||
740 | spin_lock_irqsave(&cache->lock, flags); | |
741 | list_add_tail(&mg->list, &cache->quiesced_migrations); | |
742 | spin_unlock_irqrestore(&cache->lock, flags); | |
743 | ||
744 | } else | |
745 | cleanup_migration(mg); | |
746 | ||
747 | } else { | |
748 | cell_defer(cache, mg->new_ocell, true); | |
749 | clear_dirty(cache, mg->new_oblock, mg->cblock); | |
750 | cleanup_migration(mg); | |
751 | } | |
752 | } | |
753 | ||
754 | static void copy_complete(int read_err, unsigned long write_err, void *context) | |
755 | { | |
756 | unsigned long flags; | |
757 | struct dm_cache_migration *mg = (struct dm_cache_migration *) context; | |
758 | struct cache *cache = mg->cache; | |
759 | ||
760 | if (read_err || write_err) | |
761 | mg->err = true; | |
762 | ||
763 | spin_lock_irqsave(&cache->lock, flags); | |
764 | list_add_tail(&mg->list, &cache->completed_migrations); | |
765 | spin_unlock_irqrestore(&cache->lock, flags); | |
766 | ||
767 | wake_worker(cache); | |
768 | } | |
769 | ||
770 | static void issue_copy_real(struct dm_cache_migration *mg) | |
771 | { | |
772 | int r; | |
773 | struct dm_io_region o_region, c_region; | |
774 | struct cache *cache = mg->cache; | |
775 | ||
776 | o_region.bdev = cache->origin_dev->bdev; | |
777 | o_region.count = cache->sectors_per_block; | |
778 | ||
779 | c_region.bdev = cache->cache_dev->bdev; | |
780 | c_region.sector = from_cblock(mg->cblock) * cache->sectors_per_block; | |
781 | c_region.count = cache->sectors_per_block; | |
782 | ||
783 | if (mg->writeback || mg->demote) { | |
784 | /* demote */ | |
785 | o_region.sector = from_oblock(mg->old_oblock) * cache->sectors_per_block; | |
786 | r = dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, mg); | |
787 | } else { | |
788 | /* promote */ | |
789 | o_region.sector = from_oblock(mg->new_oblock) * cache->sectors_per_block; | |
790 | r = dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, mg); | |
791 | } | |
792 | ||
793 | if (r < 0) | |
794 | migration_failure(mg); | |
795 | } | |
796 | ||
797 | static void avoid_copy(struct dm_cache_migration *mg) | |
798 | { | |
799 | atomic_inc(&mg->cache->stats.copies_avoided); | |
800 | migration_success_pre_commit(mg); | |
801 | } | |
802 | ||
803 | static void issue_copy(struct dm_cache_migration *mg) | |
804 | { | |
805 | bool avoid; | |
806 | struct cache *cache = mg->cache; | |
807 | ||
808 | if (mg->writeback || mg->demote) | |
809 | avoid = !is_dirty(cache, mg->cblock) || | |
810 | is_discarded_oblock(cache, mg->old_oblock); | |
811 | else | |
812 | avoid = is_discarded_oblock(cache, mg->new_oblock); | |
813 | ||
814 | avoid ? avoid_copy(mg) : issue_copy_real(mg); | |
815 | } | |
816 | ||
817 | static void complete_migration(struct dm_cache_migration *mg) | |
818 | { | |
819 | if (mg->err) | |
820 | migration_failure(mg); | |
821 | else | |
822 | migration_success_pre_commit(mg); | |
823 | } | |
824 | ||
825 | static void process_migrations(struct cache *cache, struct list_head *head, | |
826 | void (*fn)(struct dm_cache_migration *)) | |
827 | { | |
828 | unsigned long flags; | |
829 | struct list_head list; | |
830 | struct dm_cache_migration *mg, *tmp; | |
831 | ||
832 | INIT_LIST_HEAD(&list); | |
833 | spin_lock_irqsave(&cache->lock, flags); | |
834 | list_splice_init(head, &list); | |
835 | spin_unlock_irqrestore(&cache->lock, flags); | |
836 | ||
837 | list_for_each_entry_safe(mg, tmp, &list, list) | |
838 | fn(mg); | |
839 | } | |
840 | ||
841 | static void __queue_quiesced_migration(struct dm_cache_migration *mg) | |
842 | { | |
843 | list_add_tail(&mg->list, &mg->cache->quiesced_migrations); | |
844 | } | |
845 | ||
846 | static void queue_quiesced_migration(struct dm_cache_migration *mg) | |
847 | { | |
848 | unsigned long flags; | |
849 | struct cache *cache = mg->cache; | |
850 | ||
851 | spin_lock_irqsave(&cache->lock, flags); | |
852 | __queue_quiesced_migration(mg); | |
853 | spin_unlock_irqrestore(&cache->lock, flags); | |
854 | ||
855 | wake_worker(cache); | |
856 | } | |
857 | ||
858 | static void queue_quiesced_migrations(struct cache *cache, struct list_head *work) | |
859 | { | |
860 | unsigned long flags; | |
861 | struct dm_cache_migration *mg, *tmp; | |
862 | ||
863 | spin_lock_irqsave(&cache->lock, flags); | |
864 | list_for_each_entry_safe(mg, tmp, work, list) | |
865 | __queue_quiesced_migration(mg); | |
866 | spin_unlock_irqrestore(&cache->lock, flags); | |
867 | ||
868 | wake_worker(cache); | |
869 | } | |
870 | ||
871 | static void check_for_quiesced_migrations(struct cache *cache, | |
872 | struct per_bio_data *pb) | |
873 | { | |
874 | struct list_head work; | |
875 | ||
876 | if (!pb->all_io_entry) | |
877 | return; | |
878 | ||
879 | INIT_LIST_HEAD(&work); | |
880 | if (pb->all_io_entry) | |
881 | dm_deferred_entry_dec(pb->all_io_entry, &work); | |
882 | ||
883 | if (!list_empty(&work)) | |
884 | queue_quiesced_migrations(cache, &work); | |
885 | } | |
886 | ||
887 | static void quiesce_migration(struct dm_cache_migration *mg) | |
888 | { | |
889 | if (!dm_deferred_set_add_work(mg->cache->all_io_ds, &mg->list)) | |
890 | queue_quiesced_migration(mg); | |
891 | } | |
892 | ||
893 | static void promote(struct cache *cache, struct prealloc *structs, | |
894 | dm_oblock_t oblock, dm_cblock_t cblock, | |
895 | struct dm_bio_prison_cell *cell) | |
896 | { | |
897 | struct dm_cache_migration *mg = prealloc_get_migration(structs); | |
898 | ||
899 | mg->err = false; | |
900 | mg->writeback = false; | |
901 | mg->demote = false; | |
902 | mg->promote = true; | |
903 | mg->cache = cache; | |
904 | mg->new_oblock = oblock; | |
905 | mg->cblock = cblock; | |
906 | mg->old_ocell = NULL; | |
907 | mg->new_ocell = cell; | |
908 | mg->start_jiffies = jiffies; | |
909 | ||
910 | inc_nr_migrations(cache); | |
911 | quiesce_migration(mg); | |
912 | } | |
913 | ||
914 | static void writeback(struct cache *cache, struct prealloc *structs, | |
915 | dm_oblock_t oblock, dm_cblock_t cblock, | |
916 | struct dm_bio_prison_cell *cell) | |
917 | { | |
918 | struct dm_cache_migration *mg = prealloc_get_migration(structs); | |
919 | ||
920 | mg->err = false; | |
921 | mg->writeback = true; | |
922 | mg->demote = false; | |
923 | mg->promote = false; | |
924 | mg->cache = cache; | |
925 | mg->old_oblock = oblock; | |
926 | mg->cblock = cblock; | |
927 | mg->old_ocell = cell; | |
928 | mg->new_ocell = NULL; | |
929 | mg->start_jiffies = jiffies; | |
930 | ||
931 | inc_nr_migrations(cache); | |
932 | quiesce_migration(mg); | |
933 | } | |
934 | ||
935 | static void demote_then_promote(struct cache *cache, struct prealloc *structs, | |
936 | dm_oblock_t old_oblock, dm_oblock_t new_oblock, | |
937 | dm_cblock_t cblock, | |
938 | struct dm_bio_prison_cell *old_ocell, | |
939 | struct dm_bio_prison_cell *new_ocell) | |
940 | { | |
941 | struct dm_cache_migration *mg = prealloc_get_migration(structs); | |
942 | ||
943 | mg->err = false; | |
944 | mg->writeback = false; | |
945 | mg->demote = true; | |
946 | mg->promote = true; | |
947 | mg->cache = cache; | |
948 | mg->old_oblock = old_oblock; | |
949 | mg->new_oblock = new_oblock; | |
950 | mg->cblock = cblock; | |
951 | mg->old_ocell = old_ocell; | |
952 | mg->new_ocell = new_ocell; | |
953 | mg->start_jiffies = jiffies; | |
954 | ||
955 | inc_nr_migrations(cache); | |
956 | quiesce_migration(mg); | |
957 | } | |
958 | ||
959 | /*---------------------------------------------------------------- | |
960 | * bio processing | |
961 | *--------------------------------------------------------------*/ | |
962 | static void defer_bio(struct cache *cache, struct bio *bio) | |
963 | { | |
964 | unsigned long flags; | |
965 | ||
966 | spin_lock_irqsave(&cache->lock, flags); | |
967 | bio_list_add(&cache->deferred_bios, bio); | |
968 | spin_unlock_irqrestore(&cache->lock, flags); | |
969 | ||
970 | wake_worker(cache); | |
971 | } | |
972 | ||
973 | static void process_flush_bio(struct cache *cache, struct bio *bio) | |
974 | { | |
975 | struct per_bio_data *pb = get_per_bio_data(bio); | |
976 | ||
977 | BUG_ON(bio->bi_size); | |
978 | if (!pb->req_nr) | |
979 | remap_to_origin(cache, bio); | |
980 | else | |
981 | remap_to_cache(cache, bio, 0); | |
982 | ||
983 | issue(cache, bio); | |
984 | } | |
985 | ||
986 | /* | |
987 | * People generally discard large parts of a device, eg, the whole device | |
988 | * when formatting. Splitting these large discards up into cache block | |
989 | * sized ios and then quiescing (always neccessary for discard) takes too | |
990 | * long. | |
991 | * | |
992 | * We keep it simple, and allow any size of discard to come in, and just | |
993 | * mark off blocks on the discard bitset. No passdown occurs! | |
994 | * | |
995 | * To implement passdown we need to change the bio_prison such that a cell | |
996 | * can have a key that spans many blocks. | |
997 | */ | |
998 | static void process_discard_bio(struct cache *cache, struct bio *bio) | |
999 | { | |
1000 | dm_block_t start_block = dm_sector_div_up(bio->bi_sector, | |
1001 | cache->discard_block_size); | |
1002 | dm_block_t end_block = bio->bi_sector + bio_sectors(bio); | |
1003 | dm_block_t b; | |
1004 | ||
1005 | (void) sector_div(end_block, cache->discard_block_size); | |
1006 | ||
1007 | for (b = start_block; b < end_block; b++) | |
1008 | set_discard(cache, to_dblock(b)); | |
1009 | ||
1010 | bio_endio(bio, 0); | |
1011 | } | |
1012 | ||
1013 | static bool spare_migration_bandwidth(struct cache *cache) | |
1014 | { | |
1015 | sector_t current_volume = (atomic_read(&cache->nr_migrations) + 1) * | |
1016 | cache->sectors_per_block; | |
1017 | return current_volume < cache->migration_threshold; | |
1018 | } | |
1019 | ||
1020 | static bool is_writethrough_io(struct cache *cache, struct bio *bio, | |
1021 | dm_cblock_t cblock) | |
1022 | { | |
1023 | return bio_data_dir(bio) == WRITE && | |
1024 | cache->features.write_through && !is_dirty(cache, cblock); | |
1025 | } | |
1026 | ||
1027 | static void inc_hit_counter(struct cache *cache, struct bio *bio) | |
1028 | { | |
1029 | atomic_inc(bio_data_dir(bio) == READ ? | |
1030 | &cache->stats.read_hit : &cache->stats.write_hit); | |
1031 | } | |
1032 | ||
1033 | static void inc_miss_counter(struct cache *cache, struct bio *bio) | |
1034 | { | |
1035 | atomic_inc(bio_data_dir(bio) == READ ? | |
1036 | &cache->stats.read_miss : &cache->stats.write_miss); | |
1037 | } | |
1038 | ||
1039 | static void process_bio(struct cache *cache, struct prealloc *structs, | |
1040 | struct bio *bio) | |
1041 | { | |
1042 | int r; | |
1043 | bool release_cell = true; | |
1044 | dm_oblock_t block = get_bio_block(cache, bio); | |
1045 | struct dm_bio_prison_cell *cell_prealloc, *old_ocell, *new_ocell; | |
1046 | struct policy_result lookup_result; | |
1047 | struct per_bio_data *pb = get_per_bio_data(bio); | |
1048 | bool discarded_block = is_discarded_oblock(cache, block); | |
1049 | bool can_migrate = discarded_block || spare_migration_bandwidth(cache); | |
1050 | ||
1051 | /* | |
1052 | * Check to see if that block is currently migrating. | |
1053 | */ | |
1054 | cell_prealloc = prealloc_get_cell(structs); | |
1055 | r = bio_detain(cache, block, bio, cell_prealloc, | |
1056 | (cell_free_fn) prealloc_put_cell, | |
1057 | structs, &new_ocell); | |
1058 | if (r > 0) | |
1059 | return; | |
1060 | ||
1061 | r = policy_map(cache->policy, block, true, can_migrate, discarded_block, | |
1062 | bio, &lookup_result); | |
1063 | ||
1064 | if (r == -EWOULDBLOCK) | |
1065 | /* migration has been denied */ | |
1066 | lookup_result.op = POLICY_MISS; | |
1067 | ||
1068 | switch (lookup_result.op) { | |
1069 | case POLICY_HIT: | |
1070 | inc_hit_counter(cache, bio); | |
1071 | pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); | |
1072 | ||
1073 | if (is_writethrough_io(cache, bio, lookup_result.cblock)) { | |
1074 | /* | |
1075 | * No need to mark anything dirty in write through mode. | |
1076 | */ | |
1077 | pb->req_nr == 0 ? | |
1078 | remap_to_cache(cache, bio, lookup_result.cblock) : | |
1079 | remap_to_origin_clear_discard(cache, bio, block); | |
1080 | } else | |
1081 | remap_to_cache_dirty(cache, bio, block, lookup_result.cblock); | |
1082 | ||
1083 | issue(cache, bio); | |
1084 | break; | |
1085 | ||
1086 | case POLICY_MISS: | |
1087 | inc_miss_counter(cache, bio); | |
1088 | pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); | |
1089 | ||
1090 | if (pb->req_nr != 0) { | |
1091 | /* | |
1092 | * This is a duplicate writethrough io that is no | |
1093 | * longer needed because the block has been demoted. | |
1094 | */ | |
1095 | bio_endio(bio, 0); | |
1096 | } else { | |
1097 | remap_to_origin_clear_discard(cache, bio, block); | |
1098 | issue(cache, bio); | |
1099 | } | |
1100 | break; | |
1101 | ||
1102 | case POLICY_NEW: | |
1103 | atomic_inc(&cache->stats.promotion); | |
1104 | promote(cache, structs, block, lookup_result.cblock, new_ocell); | |
1105 | release_cell = false; | |
1106 | break; | |
1107 | ||
1108 | case POLICY_REPLACE: | |
1109 | cell_prealloc = prealloc_get_cell(structs); | |
1110 | r = bio_detain(cache, lookup_result.old_oblock, bio, cell_prealloc, | |
1111 | (cell_free_fn) prealloc_put_cell, | |
1112 | structs, &old_ocell); | |
1113 | if (r > 0) { | |
1114 | /* | |
1115 | * We have to be careful to avoid lock inversion of | |
1116 | * the cells. So we back off, and wait for the | |
1117 | * old_ocell to become free. | |
1118 | */ | |
1119 | policy_force_mapping(cache->policy, block, | |
1120 | lookup_result.old_oblock); | |
1121 | atomic_inc(&cache->stats.cache_cell_clash); | |
1122 | break; | |
1123 | } | |
1124 | atomic_inc(&cache->stats.demotion); | |
1125 | atomic_inc(&cache->stats.promotion); | |
1126 | ||
1127 | demote_then_promote(cache, structs, lookup_result.old_oblock, | |
1128 | block, lookup_result.cblock, | |
1129 | old_ocell, new_ocell); | |
1130 | release_cell = false; | |
1131 | break; | |
1132 | ||
1133 | default: | |
1134 | DMERR_LIMIT("%s: erroring bio, unknown policy op: %u", __func__, | |
1135 | (unsigned) lookup_result.op); | |
1136 | bio_io_error(bio); | |
1137 | } | |
1138 | ||
1139 | if (release_cell) | |
1140 | cell_defer(cache, new_ocell, false); | |
1141 | } | |
1142 | ||
1143 | static int need_commit_due_to_time(struct cache *cache) | |
1144 | { | |
1145 | return jiffies < cache->last_commit_jiffies || | |
1146 | jiffies > cache->last_commit_jiffies + COMMIT_PERIOD; | |
1147 | } | |
1148 | ||
1149 | static int commit_if_needed(struct cache *cache) | |
1150 | { | |
1151 | if (dm_cache_changed_this_transaction(cache->cmd) && | |
1152 | (cache->commit_requested || need_commit_due_to_time(cache))) { | |
1153 | atomic_inc(&cache->stats.commit_count); | |
1154 | cache->last_commit_jiffies = jiffies; | |
1155 | cache->commit_requested = false; | |
1156 | return dm_cache_commit(cache->cmd, false); | |
1157 | } | |
1158 | ||
1159 | return 0; | |
1160 | } | |
1161 | ||
1162 | static void process_deferred_bios(struct cache *cache) | |
1163 | { | |
1164 | unsigned long flags; | |
1165 | struct bio_list bios; | |
1166 | struct bio *bio; | |
1167 | struct prealloc structs; | |
1168 | ||
1169 | memset(&structs, 0, sizeof(structs)); | |
1170 | bio_list_init(&bios); | |
1171 | ||
1172 | spin_lock_irqsave(&cache->lock, flags); | |
1173 | bio_list_merge(&bios, &cache->deferred_bios); | |
1174 | bio_list_init(&cache->deferred_bios); | |
1175 | spin_unlock_irqrestore(&cache->lock, flags); | |
1176 | ||
1177 | while (!bio_list_empty(&bios)) { | |
1178 | /* | |
1179 | * If we've got no free migration structs, and processing | |
1180 | * this bio might require one, we pause until there are some | |
1181 | * prepared mappings to process. | |
1182 | */ | |
1183 | if (prealloc_data_structs(cache, &structs)) { | |
1184 | spin_lock_irqsave(&cache->lock, flags); | |
1185 | bio_list_merge(&cache->deferred_bios, &bios); | |
1186 | spin_unlock_irqrestore(&cache->lock, flags); | |
1187 | break; | |
1188 | } | |
1189 | ||
1190 | bio = bio_list_pop(&bios); | |
1191 | ||
1192 | if (bio->bi_rw & REQ_FLUSH) | |
1193 | process_flush_bio(cache, bio); | |
1194 | else if (bio->bi_rw & REQ_DISCARD) | |
1195 | process_discard_bio(cache, bio); | |
1196 | else | |
1197 | process_bio(cache, &structs, bio); | |
1198 | } | |
1199 | ||
1200 | prealloc_free_structs(cache, &structs); | |
1201 | } | |
1202 | ||
1203 | static void process_deferred_flush_bios(struct cache *cache, bool submit_bios) | |
1204 | { | |
1205 | unsigned long flags; | |
1206 | struct bio_list bios; | |
1207 | struct bio *bio; | |
1208 | ||
1209 | bio_list_init(&bios); | |
1210 | ||
1211 | spin_lock_irqsave(&cache->lock, flags); | |
1212 | bio_list_merge(&bios, &cache->deferred_flush_bios); | |
1213 | bio_list_init(&cache->deferred_flush_bios); | |
1214 | spin_unlock_irqrestore(&cache->lock, flags); | |
1215 | ||
1216 | while ((bio = bio_list_pop(&bios))) | |
1217 | submit_bios ? generic_make_request(bio) : bio_io_error(bio); | |
1218 | } | |
1219 | ||
1220 | static void writeback_some_dirty_blocks(struct cache *cache) | |
1221 | { | |
1222 | int r = 0; | |
1223 | dm_oblock_t oblock; | |
1224 | dm_cblock_t cblock; | |
1225 | struct prealloc structs; | |
1226 | struct dm_bio_prison_cell *old_ocell; | |
1227 | ||
1228 | memset(&structs, 0, sizeof(structs)); | |
1229 | ||
1230 | while (spare_migration_bandwidth(cache)) { | |
1231 | if (prealloc_data_structs(cache, &structs)) | |
1232 | break; | |
1233 | ||
1234 | r = policy_writeback_work(cache->policy, &oblock, &cblock); | |
1235 | if (r) | |
1236 | break; | |
1237 | ||
1238 | r = get_cell(cache, oblock, &structs, &old_ocell); | |
1239 | if (r) { | |
1240 | policy_set_dirty(cache->policy, oblock); | |
1241 | break; | |
1242 | } | |
1243 | ||
1244 | writeback(cache, &structs, oblock, cblock, old_ocell); | |
1245 | } | |
1246 | ||
1247 | prealloc_free_structs(cache, &structs); | |
1248 | } | |
1249 | ||
1250 | /*---------------------------------------------------------------- | |
1251 | * Main worker loop | |
1252 | *--------------------------------------------------------------*/ | |
1253 | static void start_quiescing(struct cache *cache) | |
1254 | { | |
1255 | unsigned long flags; | |
1256 | ||
1257 | spin_lock_irqsave(&cache->lock, flags); | |
1258 | cache->quiescing = 1; | |
1259 | spin_unlock_irqrestore(&cache->lock, flags); | |
1260 | } | |
1261 | ||
1262 | static void stop_quiescing(struct cache *cache) | |
1263 | { | |
1264 | unsigned long flags; | |
1265 | ||
1266 | spin_lock_irqsave(&cache->lock, flags); | |
1267 | cache->quiescing = 0; | |
1268 | spin_unlock_irqrestore(&cache->lock, flags); | |
1269 | } | |
1270 | ||
1271 | static bool is_quiescing(struct cache *cache) | |
1272 | { | |
1273 | int r; | |
1274 | unsigned long flags; | |
1275 | ||
1276 | spin_lock_irqsave(&cache->lock, flags); | |
1277 | r = cache->quiescing; | |
1278 | spin_unlock_irqrestore(&cache->lock, flags); | |
1279 | ||
1280 | return r; | |
1281 | } | |
1282 | ||
1283 | static void wait_for_migrations(struct cache *cache) | |
1284 | { | |
1285 | wait_event(cache->migration_wait, !atomic_read(&cache->nr_migrations)); | |
1286 | } | |
1287 | ||
1288 | static void stop_worker(struct cache *cache) | |
1289 | { | |
1290 | cancel_delayed_work(&cache->waker); | |
1291 | flush_workqueue(cache->wq); | |
1292 | } | |
1293 | ||
1294 | static void requeue_deferred_io(struct cache *cache) | |
1295 | { | |
1296 | struct bio *bio; | |
1297 | struct bio_list bios; | |
1298 | ||
1299 | bio_list_init(&bios); | |
1300 | bio_list_merge(&bios, &cache->deferred_bios); | |
1301 | bio_list_init(&cache->deferred_bios); | |
1302 | ||
1303 | while ((bio = bio_list_pop(&bios))) | |
1304 | bio_endio(bio, DM_ENDIO_REQUEUE); | |
1305 | } | |
1306 | ||
1307 | static int more_work(struct cache *cache) | |
1308 | { | |
1309 | if (is_quiescing(cache)) | |
1310 | return !list_empty(&cache->quiesced_migrations) || | |
1311 | !list_empty(&cache->completed_migrations) || | |
1312 | !list_empty(&cache->need_commit_migrations); | |
1313 | else | |
1314 | return !bio_list_empty(&cache->deferred_bios) || | |
1315 | !bio_list_empty(&cache->deferred_flush_bios) || | |
1316 | !list_empty(&cache->quiesced_migrations) || | |
1317 | !list_empty(&cache->completed_migrations) || | |
1318 | !list_empty(&cache->need_commit_migrations); | |
1319 | } | |
1320 | ||
1321 | static void do_worker(struct work_struct *ws) | |
1322 | { | |
1323 | struct cache *cache = container_of(ws, struct cache, worker); | |
1324 | ||
1325 | do { | |
1326 | if (!is_quiescing(cache)) | |
1327 | process_deferred_bios(cache); | |
1328 | ||
1329 | process_migrations(cache, &cache->quiesced_migrations, issue_copy); | |
1330 | process_migrations(cache, &cache->completed_migrations, complete_migration); | |
1331 | ||
1332 | writeback_some_dirty_blocks(cache); | |
1333 | ||
1334 | if (commit_if_needed(cache)) { | |
1335 | process_deferred_flush_bios(cache, false); | |
1336 | ||
1337 | /* | |
1338 | * FIXME: rollback metadata or just go into a | |
1339 | * failure mode and error everything | |
1340 | */ | |
1341 | } else { | |
1342 | process_deferred_flush_bios(cache, true); | |
1343 | process_migrations(cache, &cache->need_commit_migrations, | |
1344 | migration_success_post_commit); | |
1345 | } | |
1346 | } while (more_work(cache)); | |
1347 | } | |
1348 | ||
1349 | /* | |
1350 | * We want to commit periodically so that not too much | |
1351 | * unwritten metadata builds up. | |
1352 | */ | |
1353 | static void do_waker(struct work_struct *ws) | |
1354 | { | |
1355 | struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker); | |
1356 | wake_worker(cache); | |
1357 | queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD); | |
1358 | } | |
1359 | ||
1360 | /*----------------------------------------------------------------*/ | |
1361 | ||
1362 | static int is_congested(struct dm_dev *dev, int bdi_bits) | |
1363 | { | |
1364 | struct request_queue *q = bdev_get_queue(dev->bdev); | |
1365 | return bdi_congested(&q->backing_dev_info, bdi_bits); | |
1366 | } | |
1367 | ||
1368 | static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits) | |
1369 | { | |
1370 | struct cache *cache = container_of(cb, struct cache, callbacks); | |
1371 | ||
1372 | return is_congested(cache->origin_dev, bdi_bits) || | |
1373 | is_congested(cache->cache_dev, bdi_bits); | |
1374 | } | |
1375 | ||
1376 | /*---------------------------------------------------------------- | |
1377 | * Target methods | |
1378 | *--------------------------------------------------------------*/ | |
1379 | ||
1380 | /* | |
1381 | * This function gets called on the error paths of the constructor, so we | |
1382 | * have to cope with a partially initialised struct. | |
1383 | */ | |
1384 | static void destroy(struct cache *cache) | |
1385 | { | |
1386 | unsigned i; | |
1387 | ||
1388 | if (cache->next_migration) | |
1389 | mempool_free(cache->next_migration, cache->migration_pool); | |
1390 | ||
1391 | if (cache->migration_pool) | |
1392 | mempool_destroy(cache->migration_pool); | |
1393 | ||
1394 | if (cache->all_io_ds) | |
1395 | dm_deferred_set_destroy(cache->all_io_ds); | |
1396 | ||
1397 | if (cache->prison) | |
1398 | dm_bio_prison_destroy(cache->prison); | |
1399 | ||
1400 | if (cache->wq) | |
1401 | destroy_workqueue(cache->wq); | |
1402 | ||
1403 | if (cache->dirty_bitset) | |
1404 | free_bitset(cache->dirty_bitset); | |
1405 | ||
1406 | if (cache->discard_bitset) | |
1407 | free_bitset(cache->discard_bitset); | |
1408 | ||
1409 | if (cache->copier) | |
1410 | dm_kcopyd_client_destroy(cache->copier); | |
1411 | ||
1412 | if (cache->cmd) | |
1413 | dm_cache_metadata_close(cache->cmd); | |
1414 | ||
1415 | if (cache->metadata_dev) | |
1416 | dm_put_device(cache->ti, cache->metadata_dev); | |
1417 | ||
1418 | if (cache->origin_dev) | |
1419 | dm_put_device(cache->ti, cache->origin_dev); | |
1420 | ||
1421 | if (cache->cache_dev) | |
1422 | dm_put_device(cache->ti, cache->cache_dev); | |
1423 | ||
1424 | if (cache->policy) | |
1425 | dm_cache_policy_destroy(cache->policy); | |
1426 | ||
1427 | for (i = 0; i < cache->nr_ctr_args ; i++) | |
1428 | kfree(cache->ctr_args[i]); | |
1429 | kfree(cache->ctr_args); | |
1430 | ||
1431 | kfree(cache); | |
1432 | } | |
1433 | ||
1434 | static void cache_dtr(struct dm_target *ti) | |
1435 | { | |
1436 | struct cache *cache = ti->private; | |
1437 | ||
1438 | destroy(cache); | |
1439 | } | |
1440 | ||
1441 | static sector_t get_dev_size(struct dm_dev *dev) | |
1442 | { | |
1443 | return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT; | |
1444 | } | |
1445 | ||
1446 | /*----------------------------------------------------------------*/ | |
1447 | ||
1448 | /* | |
1449 | * Construct a cache device mapping. | |
1450 | * | |
1451 | * cache <metadata dev> <cache dev> <origin dev> <block size> | |
1452 | * <#feature args> [<feature arg>]* | |
1453 | * <policy> <#policy args> [<policy arg>]* | |
1454 | * | |
1455 | * metadata dev : fast device holding the persistent metadata | |
1456 | * cache dev : fast device holding cached data blocks | |
1457 | * origin dev : slow device holding original data blocks | |
1458 | * block size : cache unit size in sectors | |
1459 | * | |
1460 | * #feature args : number of feature arguments passed | |
1461 | * feature args : writethrough. (The default is writeback.) | |
1462 | * | |
1463 | * policy : the replacement policy to use | |
1464 | * #policy args : an even number of policy arguments corresponding | |
1465 | * to key/value pairs passed to the policy | |
1466 | * policy args : key/value pairs passed to the policy | |
1467 | * E.g. 'sequential_threshold 1024' | |
1468 | * See cache-policies.txt for details. | |
1469 | * | |
1470 | * Optional feature arguments are: | |
1471 | * writethrough : write through caching that prohibits cache block | |
1472 | * content from being different from origin block content. | |
1473 | * Without this argument, the default behaviour is to write | |
1474 | * back cache block contents later for performance reasons, | |
1475 | * so they may differ from the corresponding origin blocks. | |
1476 | */ | |
1477 | struct cache_args { | |
1478 | struct dm_target *ti; | |
1479 | ||
1480 | struct dm_dev *metadata_dev; | |
1481 | ||
1482 | struct dm_dev *cache_dev; | |
1483 | sector_t cache_sectors; | |
1484 | ||
1485 | struct dm_dev *origin_dev; | |
1486 | sector_t origin_sectors; | |
1487 | ||
1488 | uint32_t block_size; | |
1489 | ||
1490 | const char *policy_name; | |
1491 | int policy_argc; | |
1492 | const char **policy_argv; | |
1493 | ||
1494 | struct cache_features features; | |
1495 | }; | |
1496 | ||
1497 | static void destroy_cache_args(struct cache_args *ca) | |
1498 | { | |
1499 | if (ca->metadata_dev) | |
1500 | dm_put_device(ca->ti, ca->metadata_dev); | |
1501 | ||
1502 | if (ca->cache_dev) | |
1503 | dm_put_device(ca->ti, ca->cache_dev); | |
1504 | ||
1505 | if (ca->origin_dev) | |
1506 | dm_put_device(ca->ti, ca->origin_dev); | |
1507 | ||
1508 | kfree(ca); | |
1509 | } | |
1510 | ||
1511 | static bool at_least_one_arg(struct dm_arg_set *as, char **error) | |
1512 | { | |
1513 | if (!as->argc) { | |
1514 | *error = "Insufficient args"; | |
1515 | return false; | |
1516 | } | |
1517 | ||
1518 | return true; | |
1519 | } | |
1520 | ||
1521 | static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as, | |
1522 | char **error) | |
1523 | { | |
1524 | int r; | |
1525 | sector_t metadata_dev_size; | |
1526 | char b[BDEVNAME_SIZE]; | |
1527 | ||
1528 | if (!at_least_one_arg(as, error)) | |
1529 | return -EINVAL; | |
1530 | ||
1531 | r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE, | |
1532 | &ca->metadata_dev); | |
1533 | if (r) { | |
1534 | *error = "Error opening metadata device"; | |
1535 | return r; | |
1536 | } | |
1537 | ||
1538 | metadata_dev_size = get_dev_size(ca->metadata_dev); | |
1539 | if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING) | |
1540 | DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.", | |
1541 | bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS); | |
1542 | ||
1543 | return 0; | |
1544 | } | |
1545 | ||
1546 | static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as, | |
1547 | char **error) | |
1548 | { | |
1549 | int r; | |
1550 | ||
1551 | if (!at_least_one_arg(as, error)) | |
1552 | return -EINVAL; | |
1553 | ||
1554 | r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE, | |
1555 | &ca->cache_dev); | |
1556 | if (r) { | |
1557 | *error = "Error opening cache device"; | |
1558 | return r; | |
1559 | } | |
1560 | ca->cache_sectors = get_dev_size(ca->cache_dev); | |
1561 | ||
1562 | return 0; | |
1563 | } | |
1564 | ||
1565 | static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as, | |
1566 | char **error) | |
1567 | { | |
1568 | int r; | |
1569 | ||
1570 | if (!at_least_one_arg(as, error)) | |
1571 | return -EINVAL; | |
1572 | ||
1573 | r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE, | |
1574 | &ca->origin_dev); | |
1575 | if (r) { | |
1576 | *error = "Error opening origin device"; | |
1577 | return r; | |
1578 | } | |
1579 | ||
1580 | ca->origin_sectors = get_dev_size(ca->origin_dev); | |
1581 | if (ca->ti->len > ca->origin_sectors) { | |
1582 | *error = "Device size larger than cached device"; | |
1583 | return -EINVAL; | |
1584 | } | |
1585 | ||
1586 | return 0; | |
1587 | } | |
1588 | ||
1589 | static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as, | |
1590 | char **error) | |
1591 | { | |
1592 | unsigned long tmp; | |
1593 | ||
1594 | if (!at_least_one_arg(as, error)) | |
1595 | return -EINVAL; | |
1596 | ||
1597 | if (kstrtoul(dm_shift_arg(as), 10, &tmp) || !tmp || | |
1598 | tmp < DATA_DEV_BLOCK_SIZE_MIN_SECTORS || | |
1599 | tmp & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) { | |
1600 | *error = "Invalid data block size"; | |
1601 | return -EINVAL; | |
1602 | } | |
1603 | ||
1604 | if (tmp > ca->cache_sectors) { | |
1605 | *error = "Data block size is larger than the cache device"; | |
1606 | return -EINVAL; | |
1607 | } | |
1608 | ||
1609 | ca->block_size = tmp; | |
1610 | ||
1611 | return 0; | |
1612 | } | |
1613 | ||
1614 | static void init_features(struct cache_features *cf) | |
1615 | { | |
1616 | cf->mode = CM_WRITE; | |
1617 | cf->write_through = false; | |
1618 | } | |
1619 | ||
1620 | static int parse_features(struct cache_args *ca, struct dm_arg_set *as, | |
1621 | char **error) | |
1622 | { | |
1623 | static struct dm_arg _args[] = { | |
1624 | {0, 1, "Invalid number of cache feature arguments"}, | |
1625 | }; | |
1626 | ||
1627 | int r; | |
1628 | unsigned argc; | |
1629 | const char *arg; | |
1630 | struct cache_features *cf = &ca->features; | |
1631 | ||
1632 | init_features(cf); | |
1633 | ||
1634 | r = dm_read_arg_group(_args, as, &argc, error); | |
1635 | if (r) | |
1636 | return -EINVAL; | |
1637 | ||
1638 | while (argc--) { | |
1639 | arg = dm_shift_arg(as); | |
1640 | ||
1641 | if (!strcasecmp(arg, "writeback")) | |
1642 | cf->write_through = false; | |
1643 | ||
1644 | else if (!strcasecmp(arg, "writethrough")) | |
1645 | cf->write_through = true; | |
1646 | ||
1647 | else { | |
1648 | *error = "Unrecognised cache feature requested"; | |
1649 | return -EINVAL; | |
1650 | } | |
1651 | } | |
1652 | ||
1653 | return 0; | |
1654 | } | |
1655 | ||
1656 | static int parse_policy(struct cache_args *ca, struct dm_arg_set *as, | |
1657 | char **error) | |
1658 | { | |
1659 | static struct dm_arg _args[] = { | |
1660 | {0, 1024, "Invalid number of policy arguments"}, | |
1661 | }; | |
1662 | ||
1663 | int r; | |
1664 | ||
1665 | if (!at_least_one_arg(as, error)) | |
1666 | return -EINVAL; | |
1667 | ||
1668 | ca->policy_name = dm_shift_arg(as); | |
1669 | ||
1670 | r = dm_read_arg_group(_args, as, &ca->policy_argc, error); | |
1671 | if (r) | |
1672 | return -EINVAL; | |
1673 | ||
1674 | ca->policy_argv = (const char **)as->argv; | |
1675 | dm_consume_args(as, ca->policy_argc); | |
1676 | ||
1677 | return 0; | |
1678 | } | |
1679 | ||
1680 | static int parse_cache_args(struct cache_args *ca, int argc, char **argv, | |
1681 | char **error) | |
1682 | { | |
1683 | int r; | |
1684 | struct dm_arg_set as; | |
1685 | ||
1686 | as.argc = argc; | |
1687 | as.argv = argv; | |
1688 | ||
1689 | r = parse_metadata_dev(ca, &as, error); | |
1690 | if (r) | |
1691 | return r; | |
1692 | ||
1693 | r = parse_cache_dev(ca, &as, error); | |
1694 | if (r) | |
1695 | return r; | |
1696 | ||
1697 | r = parse_origin_dev(ca, &as, error); | |
1698 | if (r) | |
1699 | return r; | |
1700 | ||
1701 | r = parse_block_size(ca, &as, error); | |
1702 | if (r) | |
1703 | return r; | |
1704 | ||
1705 | r = parse_features(ca, &as, error); | |
1706 | if (r) | |
1707 | return r; | |
1708 | ||
1709 | r = parse_policy(ca, &as, error); | |
1710 | if (r) | |
1711 | return r; | |
1712 | ||
1713 | return 0; | |
1714 | } | |
1715 | ||
1716 | /*----------------------------------------------------------------*/ | |
1717 | ||
1718 | static struct kmem_cache *migration_cache; | |
1719 | ||
1720 | static int set_config_values(struct dm_cache_policy *p, int argc, const char **argv) | |
1721 | { | |
1722 | int r = 0; | |
1723 | ||
1724 | if (argc & 1) { | |
1725 | DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs."); | |
1726 | return -EINVAL; | |
1727 | } | |
1728 | ||
1729 | while (argc) { | |
1730 | r = policy_set_config_value(p, argv[0], argv[1]); | |
1731 | if (r) { | |
1732 | DMWARN("policy_set_config_value failed: key = '%s', value = '%s'", | |
1733 | argv[0], argv[1]); | |
1734 | return r; | |
1735 | } | |
1736 | ||
1737 | argc -= 2; | |
1738 | argv += 2; | |
1739 | } | |
1740 | ||
1741 | return r; | |
1742 | } | |
1743 | ||
1744 | static int create_cache_policy(struct cache *cache, struct cache_args *ca, | |
1745 | char **error) | |
1746 | { | |
1747 | int r; | |
1748 | ||
1749 | cache->policy = dm_cache_policy_create(ca->policy_name, | |
1750 | cache->cache_size, | |
1751 | cache->origin_sectors, | |
1752 | cache->sectors_per_block); | |
1753 | if (!cache->policy) { | |
1754 | *error = "Error creating cache's policy"; | |
1755 | return -ENOMEM; | |
1756 | } | |
1757 | ||
1758 | r = set_config_values(cache->policy, ca->policy_argc, ca->policy_argv); | |
1759 | if (r) | |
1760 | dm_cache_policy_destroy(cache->policy); | |
1761 | ||
1762 | return r; | |
1763 | } | |
1764 | ||
1765 | /* | |
1766 | * We want the discard block size to be a power of two, at least the size | |
1767 | * of the cache block size, and have no more than 2^14 discard blocks | |
1768 | * across the origin. | |
1769 | */ | |
1770 | #define MAX_DISCARD_BLOCKS (1 << 14) | |
1771 | ||
1772 | static bool too_many_discard_blocks(sector_t discard_block_size, | |
1773 | sector_t origin_size) | |
1774 | { | |
1775 | (void) sector_div(origin_size, discard_block_size); | |
1776 | ||
1777 | return origin_size > MAX_DISCARD_BLOCKS; | |
1778 | } | |
1779 | ||
1780 | static sector_t calculate_discard_block_size(sector_t cache_block_size, | |
1781 | sector_t origin_size) | |
1782 | { | |
1783 | sector_t discard_block_size; | |
1784 | ||
1785 | discard_block_size = roundup_pow_of_two(cache_block_size); | |
1786 | ||
1787 | if (origin_size) | |
1788 | while (too_many_discard_blocks(discard_block_size, origin_size)) | |
1789 | discard_block_size *= 2; | |
1790 | ||
1791 | return discard_block_size; | |
1792 | } | |
1793 | ||
1794 | #define DEFAULT_MIGRATION_THRESHOLD (2048 * 100) | |
1795 | ||
1796 | static unsigned cache_num_write_bios(struct dm_target *ti, struct bio *bio); | |
1797 | ||
1798 | static int cache_create(struct cache_args *ca, struct cache **result) | |
1799 | { | |
1800 | int r = 0; | |
1801 | char **error = &ca->ti->error; | |
1802 | struct cache *cache; | |
1803 | struct dm_target *ti = ca->ti; | |
1804 | dm_block_t origin_blocks; | |
1805 | struct dm_cache_metadata *cmd; | |
1806 | bool may_format = ca->features.mode == CM_WRITE; | |
1807 | ||
1808 | cache = kzalloc(sizeof(*cache), GFP_KERNEL); | |
1809 | if (!cache) | |
1810 | return -ENOMEM; | |
1811 | ||
1812 | cache->ti = ca->ti; | |
1813 | ti->private = cache; | |
1814 | ti->per_bio_data_size = sizeof(struct per_bio_data); | |
1815 | ti->num_flush_bios = 2; | |
1816 | ti->flush_supported = true; | |
1817 | ||
1818 | ti->num_discard_bios = 1; | |
1819 | ti->discards_supported = true; | |
1820 | ti->discard_zeroes_data_unsupported = true; | |
1821 | ||
1822 | memcpy(&cache->features, &ca->features, sizeof(cache->features)); | |
1823 | ||
1824 | if (cache->features.write_through) | |
1825 | ti->num_write_bios = cache_num_write_bios; | |
1826 | ||
1827 | cache->callbacks.congested_fn = cache_is_congested; | |
1828 | dm_table_add_target_callbacks(ti->table, &cache->callbacks); | |
1829 | ||
1830 | cache->metadata_dev = ca->metadata_dev; | |
1831 | cache->origin_dev = ca->origin_dev; | |
1832 | cache->cache_dev = ca->cache_dev; | |
1833 | ||
1834 | ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL; | |
1835 | ||
1836 | /* FIXME: factor out this whole section */ | |
1837 | origin_blocks = cache->origin_sectors = ca->origin_sectors; | |
1838 | (void) sector_div(origin_blocks, ca->block_size); | |
1839 | cache->origin_blocks = to_oblock(origin_blocks); | |
1840 | ||
1841 | cache->sectors_per_block = ca->block_size; | |
1842 | if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) { | |
1843 | r = -EINVAL; | |
1844 | goto bad; | |
1845 | } | |
1846 | ||
1847 | if (ca->block_size & (ca->block_size - 1)) { | |
1848 | dm_block_t cache_size = ca->cache_sectors; | |
1849 | ||
1850 | cache->sectors_per_block_shift = -1; | |
1851 | (void) sector_div(cache_size, ca->block_size); | |
1852 | cache->cache_size = to_cblock(cache_size); | |
1853 | } else { | |
1854 | cache->sectors_per_block_shift = __ffs(ca->block_size); | |
1855 | cache->cache_size = to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift); | |
1856 | } | |
1857 | ||
1858 | r = create_cache_policy(cache, ca, error); | |
1859 | if (r) | |
1860 | goto bad; | |
1861 | cache->policy_nr_args = ca->policy_argc; | |
1862 | ||
1863 | cmd = dm_cache_metadata_open(cache->metadata_dev->bdev, | |
1864 | ca->block_size, may_format, | |
1865 | dm_cache_policy_get_hint_size(cache->policy)); | |
1866 | if (IS_ERR(cmd)) { | |
1867 | *error = "Error creating metadata object"; | |
1868 | r = PTR_ERR(cmd); | |
1869 | goto bad; | |
1870 | } | |
1871 | cache->cmd = cmd; | |
1872 | ||
1873 | spin_lock_init(&cache->lock); | |
1874 | bio_list_init(&cache->deferred_bios); | |
1875 | bio_list_init(&cache->deferred_flush_bios); | |
1876 | INIT_LIST_HEAD(&cache->quiesced_migrations); | |
1877 | INIT_LIST_HEAD(&cache->completed_migrations); | |
1878 | INIT_LIST_HEAD(&cache->need_commit_migrations); | |
1879 | cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD; | |
1880 | atomic_set(&cache->nr_migrations, 0); | |
1881 | init_waitqueue_head(&cache->migration_wait); | |
1882 | ||
1883 | cache->nr_dirty = 0; | |
1884 | cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size)); | |
1885 | if (!cache->dirty_bitset) { | |
1886 | *error = "could not allocate dirty bitset"; | |
1887 | goto bad; | |
1888 | } | |
1889 | clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size)); | |
1890 | ||
1891 | cache->discard_block_size = | |
1892 | calculate_discard_block_size(cache->sectors_per_block, | |
1893 | cache->origin_sectors); | |
1894 | cache->discard_nr_blocks = oblock_to_dblock(cache, cache->origin_blocks); | |
1895 | cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks)); | |
1896 | if (!cache->discard_bitset) { | |
1897 | *error = "could not allocate discard bitset"; | |
1898 | goto bad; | |
1899 | } | |
1900 | clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks)); | |
1901 | ||
1902 | cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle); | |
1903 | if (IS_ERR(cache->copier)) { | |
1904 | *error = "could not create kcopyd client"; | |
1905 | r = PTR_ERR(cache->copier); | |
1906 | goto bad; | |
1907 | } | |
1908 | ||
1909 | cache->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM); | |
1910 | if (!cache->wq) { | |
1911 | *error = "could not create workqueue for metadata object"; | |
1912 | goto bad; | |
1913 | } | |
1914 | INIT_WORK(&cache->worker, do_worker); | |
1915 | INIT_DELAYED_WORK(&cache->waker, do_waker); | |
1916 | cache->last_commit_jiffies = jiffies; | |
1917 | ||
1918 | cache->prison = dm_bio_prison_create(PRISON_CELLS); | |
1919 | if (!cache->prison) { | |
1920 | *error = "could not create bio prison"; | |
1921 | goto bad; | |
1922 | } | |
1923 | ||
1924 | cache->all_io_ds = dm_deferred_set_create(); | |
1925 | if (!cache->all_io_ds) { | |
1926 | *error = "could not create all_io deferred set"; | |
1927 | goto bad; | |
1928 | } | |
1929 | ||
1930 | cache->migration_pool = mempool_create_slab_pool(MIGRATION_POOL_SIZE, | |
1931 | migration_cache); | |
1932 | if (!cache->migration_pool) { | |
1933 | *error = "Error creating cache's migration mempool"; | |
1934 | goto bad; | |
1935 | } | |
1936 | ||
1937 | cache->next_migration = NULL; | |
1938 | ||
1939 | cache->need_tick_bio = true; | |
1940 | cache->sized = false; | |
1941 | cache->quiescing = false; | |
1942 | cache->commit_requested = false; | |
1943 | cache->loaded_mappings = false; | |
1944 | cache->loaded_discards = false; | |
1945 | ||
1946 | load_stats(cache); | |
1947 | ||
1948 | atomic_set(&cache->stats.demotion, 0); | |
1949 | atomic_set(&cache->stats.promotion, 0); | |
1950 | atomic_set(&cache->stats.copies_avoided, 0); | |
1951 | atomic_set(&cache->stats.cache_cell_clash, 0); | |
1952 | atomic_set(&cache->stats.commit_count, 0); | |
1953 | atomic_set(&cache->stats.discard_count, 0); | |
1954 | ||
1955 | *result = cache; | |
1956 | return 0; | |
1957 | ||
1958 | bad: | |
1959 | destroy(cache); | |
1960 | return r; | |
1961 | } | |
1962 | ||
1963 | static int copy_ctr_args(struct cache *cache, int argc, const char **argv) | |
1964 | { | |
1965 | unsigned i; | |
1966 | const char **copy; | |
1967 | ||
1968 | copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL); | |
1969 | if (!copy) | |
1970 | return -ENOMEM; | |
1971 | for (i = 0; i < argc; i++) { | |
1972 | copy[i] = kstrdup(argv[i], GFP_KERNEL); | |
1973 | if (!copy[i]) { | |
1974 | while (i--) | |
1975 | kfree(copy[i]); | |
1976 | kfree(copy); | |
1977 | return -ENOMEM; | |
1978 | } | |
1979 | } | |
1980 | ||
1981 | cache->nr_ctr_args = argc; | |
1982 | cache->ctr_args = copy; | |
1983 | ||
1984 | return 0; | |
1985 | } | |
1986 | ||
1987 | static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv) | |
1988 | { | |
1989 | int r = -EINVAL; | |
1990 | struct cache_args *ca; | |
1991 | struct cache *cache = NULL; | |
1992 | ||
1993 | ca = kzalloc(sizeof(*ca), GFP_KERNEL); | |
1994 | if (!ca) { | |
1995 | ti->error = "Error allocating memory for cache"; | |
1996 | return -ENOMEM; | |
1997 | } | |
1998 | ca->ti = ti; | |
1999 | ||
2000 | r = parse_cache_args(ca, argc, argv, &ti->error); | |
2001 | if (r) | |
2002 | goto out; | |
2003 | ||
2004 | r = cache_create(ca, &cache); | |
2005 | ||
2006 | r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3); | |
2007 | if (r) { | |
2008 | destroy(cache); | |
2009 | goto out; | |
2010 | } | |
2011 | ||
2012 | ti->private = cache; | |
2013 | ||
2014 | out: | |
2015 | destroy_cache_args(ca); | |
2016 | return r; | |
2017 | } | |
2018 | ||
2019 | static unsigned cache_num_write_bios(struct dm_target *ti, struct bio *bio) | |
2020 | { | |
2021 | int r; | |
2022 | struct cache *cache = ti->private; | |
2023 | dm_oblock_t block = get_bio_block(cache, bio); | |
2024 | dm_cblock_t cblock; | |
2025 | ||
2026 | r = policy_lookup(cache->policy, block, &cblock); | |
2027 | if (r < 0) | |
2028 | return 2; /* assume the worst */ | |
2029 | ||
2030 | return (!r && !is_dirty(cache, cblock)) ? 2 : 1; | |
2031 | } | |
2032 | ||
2033 | static int cache_map(struct dm_target *ti, struct bio *bio) | |
2034 | { | |
2035 | struct cache *cache = ti->private; | |
2036 | ||
2037 | int r; | |
2038 | dm_oblock_t block = get_bio_block(cache, bio); | |
2039 | bool can_migrate = false; | |
2040 | bool discarded_block; | |
2041 | struct dm_bio_prison_cell *cell; | |
2042 | struct policy_result lookup_result; | |
2043 | struct per_bio_data *pb; | |
2044 | ||
2045 | if (from_oblock(block) > from_oblock(cache->origin_blocks)) { | |
2046 | /* | |
2047 | * This can only occur if the io goes to a partial block at | |
2048 | * the end of the origin device. We don't cache these. | |
2049 | * Just remap to the origin and carry on. | |
2050 | */ | |
2051 | remap_to_origin_clear_discard(cache, bio, block); | |
2052 | return DM_MAPIO_REMAPPED; | |
2053 | } | |
2054 | ||
2055 | pb = init_per_bio_data(bio); | |
2056 | ||
2057 | if (bio->bi_rw & (REQ_FLUSH | REQ_FUA | REQ_DISCARD)) { | |
2058 | defer_bio(cache, bio); | |
2059 | return DM_MAPIO_SUBMITTED; | |
2060 | } | |
2061 | ||
2062 | /* | |
2063 | * Check to see if that block is currently migrating. | |
2064 | */ | |
2065 | cell = alloc_prison_cell(cache); | |
2066 | if (!cell) { | |
2067 | defer_bio(cache, bio); | |
2068 | return DM_MAPIO_SUBMITTED; | |
2069 | } | |
2070 | ||
2071 | r = bio_detain(cache, block, bio, cell, | |
2072 | (cell_free_fn) free_prison_cell, | |
2073 | cache, &cell); | |
2074 | if (r) { | |
2075 | if (r < 0) | |
2076 | defer_bio(cache, bio); | |
2077 | ||
2078 | return DM_MAPIO_SUBMITTED; | |
2079 | } | |
2080 | ||
2081 | discarded_block = is_discarded_oblock(cache, block); | |
2082 | ||
2083 | r = policy_map(cache->policy, block, false, can_migrate, discarded_block, | |
2084 | bio, &lookup_result); | |
2085 | if (r == -EWOULDBLOCK) { | |
2086 | cell_defer(cache, cell, true); | |
2087 | return DM_MAPIO_SUBMITTED; | |
2088 | ||
2089 | } else if (r) { | |
2090 | DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r); | |
2091 | bio_io_error(bio); | |
2092 | return DM_MAPIO_SUBMITTED; | |
2093 | } | |
2094 | ||
2095 | switch (lookup_result.op) { | |
2096 | case POLICY_HIT: | |
2097 | inc_hit_counter(cache, bio); | |
2098 | pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); | |
2099 | ||
2100 | if (is_writethrough_io(cache, bio, lookup_result.cblock)) { | |
2101 | /* | |
2102 | * No need to mark anything dirty in write through mode. | |
2103 | */ | |
2104 | pb->req_nr == 0 ? | |
2105 | remap_to_cache(cache, bio, lookup_result.cblock) : | |
2106 | remap_to_origin_clear_discard(cache, bio, block); | |
2107 | cell_defer(cache, cell, false); | |
2108 | } else { | |
2109 | remap_to_cache_dirty(cache, bio, block, lookup_result.cblock); | |
2110 | cell_defer(cache, cell, false); | |
2111 | } | |
2112 | break; | |
2113 | ||
2114 | case POLICY_MISS: | |
2115 | inc_miss_counter(cache, bio); | |
2116 | pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds); | |
2117 | ||
2118 | if (pb->req_nr != 0) { | |
2119 | /* | |
2120 | * This is a duplicate writethrough io that is no | |
2121 | * longer needed because the block has been demoted. | |
2122 | */ | |
2123 | bio_endio(bio, 0); | |
2124 | cell_defer(cache, cell, false); | |
2125 | return DM_MAPIO_SUBMITTED; | |
2126 | } else { | |
2127 | remap_to_origin_clear_discard(cache, bio, block); | |
2128 | cell_defer(cache, cell, false); | |
2129 | } | |
2130 | break; | |
2131 | ||
2132 | default: | |
2133 | DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__, | |
2134 | (unsigned) lookup_result.op); | |
2135 | bio_io_error(bio); | |
2136 | return DM_MAPIO_SUBMITTED; | |
2137 | } | |
2138 | ||
2139 | return DM_MAPIO_REMAPPED; | |
2140 | } | |
2141 | ||
2142 | static int cache_end_io(struct dm_target *ti, struct bio *bio, int error) | |
2143 | { | |
2144 | struct cache *cache = ti->private; | |
2145 | unsigned long flags; | |
2146 | struct per_bio_data *pb = get_per_bio_data(bio); | |
2147 | ||
2148 | if (pb->tick) { | |
2149 | policy_tick(cache->policy); | |
2150 | ||
2151 | spin_lock_irqsave(&cache->lock, flags); | |
2152 | cache->need_tick_bio = true; | |
2153 | spin_unlock_irqrestore(&cache->lock, flags); | |
2154 | } | |
2155 | ||
2156 | check_for_quiesced_migrations(cache, pb); | |
2157 | ||
2158 | return 0; | |
2159 | } | |
2160 | ||
2161 | static int write_dirty_bitset(struct cache *cache) | |
2162 | { | |
2163 | unsigned i, r; | |
2164 | ||
2165 | for (i = 0; i < from_cblock(cache->cache_size); i++) { | |
2166 | r = dm_cache_set_dirty(cache->cmd, to_cblock(i), | |
2167 | is_dirty(cache, to_cblock(i))); | |
2168 | if (r) | |
2169 | return r; | |
2170 | } | |
2171 | ||
2172 | return 0; | |
2173 | } | |
2174 | ||
2175 | static int write_discard_bitset(struct cache *cache) | |
2176 | { | |
2177 | unsigned i, r; | |
2178 | ||
2179 | r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size, | |
2180 | cache->discard_nr_blocks); | |
2181 | if (r) { | |
2182 | DMERR("could not resize on-disk discard bitset"); | |
2183 | return r; | |
2184 | } | |
2185 | ||
2186 | for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) { | |
2187 | r = dm_cache_set_discard(cache->cmd, to_dblock(i), | |
2188 | is_discarded(cache, to_dblock(i))); | |
2189 | if (r) | |
2190 | return r; | |
2191 | } | |
2192 | ||
2193 | return 0; | |
2194 | } | |
2195 | ||
2196 | static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock, | |
2197 | uint32_t hint) | |
2198 | { | |
2199 | struct cache *cache = context; | |
2200 | return dm_cache_save_hint(cache->cmd, cblock, hint); | |
2201 | } | |
2202 | ||
2203 | static int write_hints(struct cache *cache) | |
2204 | { | |
2205 | int r; | |
2206 | ||
2207 | r = dm_cache_begin_hints(cache->cmd, cache->policy); | |
2208 | if (r) { | |
2209 | DMERR("dm_cache_begin_hints failed"); | |
2210 | return r; | |
2211 | } | |
2212 | ||
2213 | r = policy_walk_mappings(cache->policy, save_hint, cache); | |
2214 | if (r) | |
2215 | DMERR("policy_walk_mappings failed"); | |
2216 | ||
2217 | return r; | |
2218 | } | |
2219 | ||
2220 | /* | |
2221 | * returns true on success | |
2222 | */ | |
2223 | static bool sync_metadata(struct cache *cache) | |
2224 | { | |
2225 | int r1, r2, r3, r4; | |
2226 | ||
2227 | r1 = write_dirty_bitset(cache); | |
2228 | if (r1) | |
2229 | DMERR("could not write dirty bitset"); | |
2230 | ||
2231 | r2 = write_discard_bitset(cache); | |
2232 | if (r2) | |
2233 | DMERR("could not write discard bitset"); | |
2234 | ||
2235 | save_stats(cache); | |
2236 | ||
2237 | r3 = write_hints(cache); | |
2238 | if (r3) | |
2239 | DMERR("could not write hints"); | |
2240 | ||
2241 | /* | |
2242 | * If writing the above metadata failed, we still commit, but don't | |
2243 | * set the clean shutdown flag. This will effectively force every | |
2244 | * dirty bit to be set on reload. | |
2245 | */ | |
2246 | r4 = dm_cache_commit(cache->cmd, !r1 && !r2 && !r3); | |
2247 | if (r4) | |
2248 | DMERR("could not write cache metadata. Data loss may occur."); | |
2249 | ||
2250 | return !r1 && !r2 && !r3 && !r4; | |
2251 | } | |
2252 | ||
2253 | static void cache_postsuspend(struct dm_target *ti) | |
2254 | { | |
2255 | struct cache *cache = ti->private; | |
2256 | ||
2257 | start_quiescing(cache); | |
2258 | wait_for_migrations(cache); | |
2259 | stop_worker(cache); | |
2260 | requeue_deferred_io(cache); | |
2261 | stop_quiescing(cache); | |
2262 | ||
2263 | (void) sync_metadata(cache); | |
2264 | } | |
2265 | ||
2266 | static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock, | |
2267 | bool dirty, uint32_t hint, bool hint_valid) | |
2268 | { | |
2269 | int r; | |
2270 | struct cache *cache = context; | |
2271 | ||
2272 | r = policy_load_mapping(cache->policy, oblock, cblock, hint, hint_valid); | |
2273 | if (r) | |
2274 | return r; | |
2275 | ||
2276 | if (dirty) | |
2277 | set_dirty(cache, oblock, cblock); | |
2278 | else | |
2279 | clear_dirty(cache, oblock, cblock); | |
2280 | ||
2281 | return 0; | |
2282 | } | |
2283 | ||
2284 | static int load_discard(void *context, sector_t discard_block_size, | |
2285 | dm_dblock_t dblock, bool discard) | |
2286 | { | |
2287 | struct cache *cache = context; | |
2288 | ||
2289 | /* FIXME: handle mis-matched block size */ | |
2290 | ||
2291 | if (discard) | |
2292 | set_discard(cache, dblock); | |
2293 | else | |
2294 | clear_discard(cache, dblock); | |
2295 | ||
2296 | return 0; | |
2297 | } | |
2298 | ||
2299 | static int cache_preresume(struct dm_target *ti) | |
2300 | { | |
2301 | int r = 0; | |
2302 | struct cache *cache = ti->private; | |
2303 | sector_t actual_cache_size = get_dev_size(cache->cache_dev); | |
2304 | (void) sector_div(actual_cache_size, cache->sectors_per_block); | |
2305 | ||
2306 | /* | |
2307 | * Check to see if the cache has resized. | |
2308 | */ | |
2309 | if (from_cblock(cache->cache_size) != actual_cache_size || !cache->sized) { | |
2310 | cache->cache_size = to_cblock(actual_cache_size); | |
2311 | ||
2312 | r = dm_cache_resize(cache->cmd, cache->cache_size); | |
2313 | if (r) { | |
2314 | DMERR("could not resize cache metadata"); | |
2315 | return r; | |
2316 | } | |
2317 | ||
2318 | cache->sized = true; | |
2319 | } | |
2320 | ||
2321 | if (!cache->loaded_mappings) { | |
2322 | r = dm_cache_load_mappings(cache->cmd, | |
2323 | dm_cache_policy_get_name(cache->policy), | |
2324 | load_mapping, cache); | |
2325 | if (r) { | |
2326 | DMERR("could not load cache mappings"); | |
2327 | return r; | |
2328 | } | |
2329 | ||
2330 | cache->loaded_mappings = true; | |
2331 | } | |
2332 | ||
2333 | if (!cache->loaded_discards) { | |
2334 | r = dm_cache_load_discards(cache->cmd, load_discard, cache); | |
2335 | if (r) { | |
2336 | DMERR("could not load origin discards"); | |
2337 | return r; | |
2338 | } | |
2339 | ||
2340 | cache->loaded_discards = true; | |
2341 | } | |
2342 | ||
2343 | return r; | |
2344 | } | |
2345 | ||
2346 | static void cache_resume(struct dm_target *ti) | |
2347 | { | |
2348 | struct cache *cache = ti->private; | |
2349 | ||
2350 | cache->need_tick_bio = true; | |
2351 | do_waker(&cache->waker.work); | |
2352 | } | |
2353 | ||
2354 | /* | |
2355 | * Status format: | |
2356 | * | |
2357 | * <#used metadata blocks>/<#total metadata blocks> | |
2358 | * <#read hits> <#read misses> <#write hits> <#write misses> | |
2359 | * <#demotions> <#promotions> <#blocks in cache> <#dirty> | |
2360 | * <#features> <features>* | |
2361 | * <#core args> <core args> | |
2362 | * <#policy args> <policy args>* | |
2363 | */ | |
2364 | static void cache_status(struct dm_target *ti, status_type_t type, | |
2365 | unsigned status_flags, char *result, unsigned maxlen) | |
2366 | { | |
2367 | int r = 0; | |
2368 | unsigned i; | |
2369 | ssize_t sz = 0; | |
2370 | dm_block_t nr_free_blocks_metadata = 0; | |
2371 | dm_block_t nr_blocks_metadata = 0; | |
2372 | char buf[BDEVNAME_SIZE]; | |
2373 | struct cache *cache = ti->private; | |
2374 | dm_cblock_t residency; | |
2375 | ||
2376 | switch (type) { | |
2377 | case STATUSTYPE_INFO: | |
2378 | /* Commit to ensure statistics aren't out-of-date */ | |
2379 | if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti)) { | |
2380 | r = dm_cache_commit(cache->cmd, false); | |
2381 | if (r) | |
2382 | DMERR("could not commit metadata for accurate status"); | |
2383 | } | |
2384 | ||
2385 | r = dm_cache_get_free_metadata_block_count(cache->cmd, | |
2386 | &nr_free_blocks_metadata); | |
2387 | if (r) { | |
2388 | DMERR("could not get metadata free block count"); | |
2389 | goto err; | |
2390 | } | |
2391 | ||
2392 | r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata); | |
2393 | if (r) { | |
2394 | DMERR("could not get metadata device size"); | |
2395 | goto err; | |
2396 | } | |
2397 | ||
2398 | residency = policy_residency(cache->policy); | |
2399 | ||
2400 | DMEMIT("%llu/%llu %u %u %u %u %u %u %llu %u ", | |
2401 | (unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata), | |
2402 | (unsigned long long)nr_blocks_metadata, | |
2403 | (unsigned) atomic_read(&cache->stats.read_hit), | |
2404 | (unsigned) atomic_read(&cache->stats.read_miss), | |
2405 | (unsigned) atomic_read(&cache->stats.write_hit), | |
2406 | (unsigned) atomic_read(&cache->stats.write_miss), | |
2407 | (unsigned) atomic_read(&cache->stats.demotion), | |
2408 | (unsigned) atomic_read(&cache->stats.promotion), | |
2409 | (unsigned long long) from_cblock(residency), | |
2410 | cache->nr_dirty); | |
2411 | ||
2412 | if (cache->features.write_through) | |
2413 | DMEMIT("1 writethrough "); | |
2414 | else | |
2415 | DMEMIT("0 "); | |
2416 | ||
2417 | DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold); | |
2418 | if (sz < maxlen) { | |
2419 | r = policy_emit_config_values(cache->policy, result + sz, maxlen - sz); | |
2420 | if (r) | |
2421 | DMERR("policy_emit_config_values returned %d", r); | |
2422 | } | |
2423 | ||
2424 | break; | |
2425 | ||
2426 | case STATUSTYPE_TABLE: | |
2427 | format_dev_t(buf, cache->metadata_dev->bdev->bd_dev); | |
2428 | DMEMIT("%s ", buf); | |
2429 | format_dev_t(buf, cache->cache_dev->bdev->bd_dev); | |
2430 | DMEMIT("%s ", buf); | |
2431 | format_dev_t(buf, cache->origin_dev->bdev->bd_dev); | |
2432 | DMEMIT("%s", buf); | |
2433 | ||
2434 | for (i = 0; i < cache->nr_ctr_args - 1; i++) | |
2435 | DMEMIT(" %s", cache->ctr_args[i]); | |
2436 | if (cache->nr_ctr_args) | |
2437 | DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]); | |
2438 | } | |
2439 | ||
2440 | return; | |
2441 | ||
2442 | err: | |
2443 | DMEMIT("Error"); | |
2444 | } | |
2445 | ||
2446 | #define NOT_CORE_OPTION 1 | |
2447 | ||
2448 | static int process_config_option(struct cache *cache, char **argv) | |
2449 | { | |
2450 | unsigned long tmp; | |
2451 | ||
2452 | if (!strcasecmp(argv[0], "migration_threshold")) { | |
2453 | if (kstrtoul(argv[1], 10, &tmp)) | |
2454 | return -EINVAL; | |
2455 | ||
2456 | cache->migration_threshold = tmp; | |
2457 | return 0; | |
2458 | } | |
2459 | ||
2460 | return NOT_CORE_OPTION; | |
2461 | } | |
2462 | ||
2463 | /* | |
2464 | * Supports <key> <value>. | |
2465 | * | |
2466 | * The key migration_threshold is supported by the cache target core. | |
2467 | */ | |
2468 | static int cache_message(struct dm_target *ti, unsigned argc, char **argv) | |
2469 | { | |
2470 | int r; | |
2471 | struct cache *cache = ti->private; | |
2472 | ||
2473 | if (argc != 2) | |
2474 | return -EINVAL; | |
2475 | ||
2476 | r = process_config_option(cache, argv); | |
2477 | if (r == NOT_CORE_OPTION) | |
2478 | return policy_set_config_value(cache->policy, argv[0], argv[1]); | |
2479 | ||
2480 | return r; | |
2481 | } | |
2482 | ||
2483 | static int cache_iterate_devices(struct dm_target *ti, | |
2484 | iterate_devices_callout_fn fn, void *data) | |
2485 | { | |
2486 | int r = 0; | |
2487 | struct cache *cache = ti->private; | |
2488 | ||
2489 | r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data); | |
2490 | if (!r) | |
2491 | r = fn(ti, cache->origin_dev, 0, ti->len, data); | |
2492 | ||
2493 | return r; | |
2494 | } | |
2495 | ||
2496 | /* | |
2497 | * We assume I/O is going to the origin (which is the volume | |
2498 | * more likely to have restrictions e.g. by being striped). | |
2499 | * (Looking up the exact location of the data would be expensive | |
2500 | * and could always be out of date by the time the bio is submitted.) | |
2501 | */ | |
2502 | static int cache_bvec_merge(struct dm_target *ti, | |
2503 | struct bvec_merge_data *bvm, | |
2504 | struct bio_vec *biovec, int max_size) | |
2505 | { | |
2506 | struct cache *cache = ti->private; | |
2507 | struct request_queue *q = bdev_get_queue(cache->origin_dev->bdev); | |
2508 | ||
2509 | if (!q->merge_bvec_fn) | |
2510 | return max_size; | |
2511 | ||
2512 | bvm->bi_bdev = cache->origin_dev->bdev; | |
2513 | return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); | |
2514 | } | |
2515 | ||
2516 | static void set_discard_limits(struct cache *cache, struct queue_limits *limits) | |
2517 | { | |
2518 | /* | |
2519 | * FIXME: these limits may be incompatible with the cache device | |
2520 | */ | |
2521 | limits->max_discard_sectors = cache->discard_block_size * 1024; | |
2522 | limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT; | |
2523 | } | |
2524 | ||
2525 | static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits) | |
2526 | { | |
2527 | struct cache *cache = ti->private; | |
2528 | ||
2529 | blk_limits_io_min(limits, 0); | |
2530 | blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT); | |
2531 | set_discard_limits(cache, limits); | |
2532 | } | |
2533 | ||
2534 | /*----------------------------------------------------------------*/ | |
2535 | ||
2536 | static struct target_type cache_target = { | |
2537 | .name = "cache", | |
2538 | .version = {1, 0, 0}, | |
2539 | .module = THIS_MODULE, | |
2540 | .ctr = cache_ctr, | |
2541 | .dtr = cache_dtr, | |
2542 | .map = cache_map, | |
2543 | .end_io = cache_end_io, | |
2544 | .postsuspend = cache_postsuspend, | |
2545 | .preresume = cache_preresume, | |
2546 | .resume = cache_resume, | |
2547 | .status = cache_status, | |
2548 | .message = cache_message, | |
2549 | .iterate_devices = cache_iterate_devices, | |
2550 | .merge = cache_bvec_merge, | |
2551 | .io_hints = cache_io_hints, | |
2552 | }; | |
2553 | ||
2554 | static int __init dm_cache_init(void) | |
2555 | { | |
2556 | int r; | |
2557 | ||
2558 | r = dm_register_target(&cache_target); | |
2559 | if (r) { | |
2560 | DMERR("cache target registration failed: %d", r); | |
2561 | return r; | |
2562 | } | |
2563 | ||
2564 | migration_cache = KMEM_CACHE(dm_cache_migration, 0); | |
2565 | if (!migration_cache) { | |
2566 | dm_unregister_target(&cache_target); | |
2567 | return -ENOMEM; | |
2568 | } | |
2569 | ||
2570 | return 0; | |
2571 | } | |
2572 | ||
2573 | static void __exit dm_cache_exit(void) | |
2574 | { | |
2575 | dm_unregister_target(&cache_target); | |
2576 | kmem_cache_destroy(migration_cache); | |
2577 | } | |
2578 | ||
2579 | module_init(dm_cache_init); | |
2580 | module_exit(dm_cache_exit); | |
2581 | ||
2582 | MODULE_DESCRIPTION(DM_NAME " cache target"); | |
2583 | MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>"); | |
2584 | MODULE_LICENSE("GPL"); |