1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _BCACHE_H
3 #define _BCACHE_H
4
5 /*
6 * SOME HIGH LEVEL CODE DOCUMENTATION:
7 *
8 * Bcache mostly works with cache sets, cache devices, and backing devices.
9 *
10 * Support for multiple cache devices hasn't quite been finished off yet, but
11 * it's about 95% plumbed through. A cache set and its cache devices is sort of
12 * like a md raid array and its component devices. Most of the code doesn't care
13 * about individual cache devices, the main abstraction is the cache set.
14 *
15 * Multiple cache devices is intended to give us the ability to mirror dirty
16 * cached data and metadata, without mirroring clean cached data.
17 *
18 * Backing devices are different, in that they have a lifetime independent of a
19 * cache set. When you register a newly formatted backing device it'll come up
20 * in passthrough mode, and then you can attach and detach a backing device from
21 * a cache set at runtime - while it's mounted and in use. Detaching implicitly
22 * invalidates any cached data for that backing device.
23 *
24 * A cache set can have multiple (many) backing devices attached to it.
25 *
26 * There's also flash only volumes - this is the reason for the distinction
27 * between struct cached_dev and struct bcache_device. A flash only volume
28 * works much like a bcache device that has a backing device, except the
29 * "cached" data is always dirty. The end result is that we get thin
30 * provisioning with very little additional code.
31 *
32 * Flash only volumes work but they're not production ready because the moving
33 * garbage collector needs more work. More on that later.
34 *
35 * BUCKETS/ALLOCATION:
36 *
37 * Bcache is primarily designed for caching, which means that in normal
38 * operation all of our available space will be allocated. Thus, we need an
39 * efficient way of deleting things from the cache so we can write new things to
40 * it.
41 *
42 * To do this, we first divide the cache device up into buckets. A bucket is the
43 * unit of allocation; they're typically around 1 mb - anywhere from 128k to 2M+
44 * works efficiently.
45 *
46 * Each bucket has a 16 bit priority, and an 8 bit generation associated with
47 * it. The gens and priorities for all the buckets are stored contiguously and
48 * packed on disk (in a linked list of buckets - aside from the superblock, all
49 * of bcache's metadata is stored in buckets).
50 *
51 * The priority is used to implement an LRU. We reset a bucket's priority when
52 * we allocate it or on cache it, and every so often we decrement the priority
53 * of each bucket. It could be used to implement something more sophisticated,
54 * if anyone ever gets around to it.
55 *
56 * The generation is used for invalidating buckets. Each pointer also has an 8
57 * bit generation embedded in it; for a pointer to be considered valid, its gen
58 * must match the gen of the bucket it points into. Thus, to reuse a bucket all
59 * we have to do is increment its gen (and write its new gen to disk; we batch
60 * this up).
61 *
62 * Bcache is entirely COW - we never write twice to a bucket, even buckets that
63 * contain metadata (including btree nodes).
64 *
65 * THE BTREE:
66 *
67 * Bcache is in large part design around the btree.
68 *
69 * At a high level, the btree is just an index of key -> ptr tuples.
70 *
71 * Keys represent extents, and thus have a size field. Keys also have a variable
72 * number of pointers attached to them (potentially zero, which is handy for
73 * invalidating the cache).
74 *
75 * The key itself is an inode:offset pair. The inode number corresponds to a
76 * backing device or a flash only volume. The offset is the ending offset of the
77 * extent within the inode - not the starting offset; this makes lookups
78 * slightly more convenient.
79 *
80 * Pointers contain the cache device id, the offset on that device, and an 8 bit
81 * generation number. More on the gen later.
82 *
83 * Index lookups are not fully abstracted - cache lookups in particular are
84 * still somewhat mixed in with the btree code, but things are headed in that
85 * direction.
86 *
87 * Updates are fairly well abstracted, though. There are two different ways of
88 * updating the btree; insert and replace.
89 *
90 * BTREE_INSERT will just take a list of keys and insert them into the btree -
91 * overwriting (possibly only partially) any extents they overlap with. This is
92 * used to update the index after a write.
93 *
94 * BTREE_REPLACE is really cmpxchg(); it inserts a key into the btree iff it is
95 * overwriting a key that matches another given key. This is used for inserting
96 * data into the cache after a cache miss, and for background writeback, and for
97 * the moving garbage collector.
98 *
99 * There is no "delete" operation; deleting things from the index is
100 * accomplished by either by invalidating pointers (by incrementing a bucket's
101 * gen) or by inserting a key with 0 pointers - which will overwrite anything
102 * previously present at that location in the index.
103 *
104 * This means that there are always stale/invalid keys in the btree. They're
105 * filtered out by the code that iterates through a btree node, and removed when
106 * a btree node is rewritten.
107 *
108 * BTREE NODES:
109 *
110 * Our unit of allocation is a bucket, and we we can't arbitrarily allocate and
111 * free smaller than a bucket - so, that's how big our btree nodes are.
112 *
113 * (If buckets are really big we'll only use part of the bucket for a btree node
114 * - no less than 1/4th - but a bucket still contains no more than a single
115 * btree node. I'd actually like to change this, but for now we rely on the
116 * bucket's gen for deleting btree nodes when we rewrite/split a node.)
117 *
118 * Anyways, btree nodes are big - big enough to be inefficient with a textbook
119 * btree implementation.
120 *
121 * The way this is solved is that btree nodes are internally log structured; we
122 * can append new keys to an existing btree node without rewriting it. This
123 * means each set of keys we write is sorted, but the node is not.
124 *
125 * We maintain this log structure in memory - keeping 1Mb of keys sorted would
126 * be expensive, and we have to distinguish between the keys we have written and
127 * the keys we haven't. So to do a lookup in a btree node, we have to search
128 * each sorted set. But we do merge written sets together lazily, so the cost of
129 * these extra searches is quite low (normally most of the keys in a btree node
130 * will be in one big set, and then there'll be one or two sets that are much
131 * smaller).
132 *
133 * This log structure makes bcache's btree more of a hybrid between a
134 * conventional btree and a compacting data structure, with some of the
135 * advantages of both.
136 *
137 * GARBAGE COLLECTION:
138 *
139 * We can't just invalidate any bucket - it might contain dirty data or
140 * metadata. If it once contained dirty data, other writes might overwrite it
141 * later, leaving no valid pointers into that bucket in the index.
142 *
143 * Thus, the primary purpose of garbage collection is to find buckets to reuse.
144 * It also counts how much valid data it each bucket currently contains, so that
145 * allocation can reuse buckets sooner when they've been mostly overwritten.
146 *
147 * It also does some things that are really internal to the btree
148 * implementation. If a btree node contains pointers that are stale by more than
149 * some threshold, it rewrites the btree node to avoid the bucket's generation
150 * wrapping around. It also merges adjacent btree nodes if they're empty enough.
151 *
152 * THE JOURNAL:
153 *
154 * Bcache's journal is not necessary for consistency; we always strictly
155 * order metadata writes so that the btree and everything else is consistent on
156 * disk in the event of an unclean shutdown, and in fact bcache had writeback
157 * caching (with recovery from unclean shutdown) before journalling was
158 * implemented.
159 *
160 * Rather, the journal is purely a performance optimization; we can't complete a
161 * write until we've updated the index on disk, otherwise the cache would be
162 * inconsistent in the event of an unclean shutdown. This means that without the
163 * journal, on random write workloads we constantly have to update all the leaf
164 * nodes in the btree, and those writes will be mostly empty (appending at most
165 * a few keys each) - highly inefficient in terms of amount of metadata writes,
166 * and it puts more strain on the various btree resorting/compacting code.
167 *
168 * The journal is just a log of keys we've inserted; on startup we just reinsert
169 * all the keys in the open journal entries. That means that when we're updating
170 * a node in the btree, we can wait until a 4k block of keys fills up before
171 * writing them out.
172 *
173 * For simplicity, we only journal updates to leaf nodes; updates to parent
174 * nodes are rare enough (since our leaf nodes are huge) that it wasn't worth
175 * the complexity to deal with journalling them (in particular, journal replay)
176 * - updates to non leaf nodes just happen synchronously (see btree_split()).
177 */
178
179 #define pr_fmt(fmt) "bcache: %s() " fmt "\n", __func__
180
181 #include <linux/bcache.h>
182 #include <linux/bio.h>
183 #include <linux/kobject.h>
184 #include <linux/list.h>
185 #include <linux/mutex.h>
186 #include <linux/rbtree.h>
187 #include <linux/rwsem.h>
188 #include <linux/refcount.h>
189 #include <linux/types.h>
190 #include <linux/workqueue.h>
191 #include <linux/kthread.h>
192
193 #include "bset.h"
194 #include "util.h"
195 #include "closure.h"
196
197 struct bucket {
198 atomic_t pin;
199 uint16_t prio;
200 uint8_t gen;
201 uint8_t last_gc; /* Most out of date gen in the btree */
202 uint16_t gc_mark; /* Bitfield used by GC. See below for field */
203 };
204
205 /*
206 * I'd use bitfields for these, but I don't trust the compiler not to screw me
207 * as multiple threads touch struct bucket without locking
208 */
209
210 BITMASK(GC_MARK, struct bucket, gc_mark, 0, 2);
211 #define GC_MARK_RECLAIMABLE 1
212 #define GC_MARK_DIRTY 2
213 #define GC_MARK_METADATA 3
214 #define GC_SECTORS_USED_SIZE 13
215 #define MAX_GC_SECTORS_USED (~(~0ULL << GC_SECTORS_USED_SIZE))
216 BITMASK(GC_SECTORS_USED, struct bucket, gc_mark, 2, GC_SECTORS_USED_SIZE);
217 BITMASK(GC_MOVE, struct bucket, gc_mark, 15, 1);
218
219 #include "journal.h"
220 #include "stats.h"
221 struct search;
222 struct btree;
223 struct keybuf;
224
225 struct keybuf_key {
226 struct rb_node node;
227 BKEY_PADDED(key);
228 void *private;
229 };
230
231 struct keybuf {
232 struct bkey last_scanned;
233 spinlock_t lock;
234
235 /*
236 * Beginning and end of range in rb tree - so that we can skip taking
237 * lock and checking the rb tree when we need to check for overlapping
238 * keys.
239 */
240 struct bkey start;
241 struct bkey end;
242
243 struct rb_root keys;
244
245 #define KEYBUF_NR 500
246 DECLARE_ARRAY_ALLOCATOR(struct keybuf_key, freelist, KEYBUF_NR);
247 };
248
249 struct bcache_device {
250 struct closure cl;
251
252 struct kobject kobj;
253
254 struct cache_set *c;
255 unsigned int id;
256 #define BCACHEDEVNAME_SIZE 12
257 char name[BCACHEDEVNAME_SIZE];
258
259 struct gendisk *disk;
260
261 unsigned long flags;
262 #define BCACHE_DEV_CLOSING 0
263 #define BCACHE_DEV_DETACHING 1
264 #define BCACHE_DEV_UNLINK_DONE 2
265 #define BCACHE_DEV_WB_RUNNING 3
266 #define BCACHE_DEV_RATE_DW_RUNNING 4
267 unsigned int nr_stripes;
268 unsigned int stripe_size;
269 atomic_t *stripe_sectors_dirty;
270 unsigned long *full_dirty_stripes;
271
272 struct bio_set bio_split;
273
274 unsigned int data_csum:1;
275
276 int (*cache_miss)(struct btree *b, struct search *s,
277 struct bio *bio, unsigned int sectors);
278 int (*ioctl)(struct bcache_device *d, fmode_t mode,
279 unsigned int cmd, unsigned long arg);
280 };
281
282 struct io {
283 /* Used to track sequential IO so it can be skipped */
284 struct hlist_node hash;
285 struct list_head lru;
286
287 unsigned long jiffies;
288 unsigned int sequential;
289 sector_t last;
290 };
291
292 enum stop_on_failure {
293 BCH_CACHED_DEV_STOP_AUTO = 0,
294 BCH_CACHED_DEV_STOP_ALWAYS,
295 BCH_CACHED_DEV_STOP_MODE_MAX,
296 };
297
298 struct cached_dev {
299 struct list_head list;
300 struct bcache_device disk;
301 struct block_device *bdev;
302
303 struct cache_sb sb;
304 struct bio sb_bio;
305 struct bio_vec sb_bv[1];
306 struct closure sb_write;
307 struct semaphore sb_write_mutex;
308
309 /* Refcount on the cache set. Always nonzero when we're caching. */
310 refcount_t count;
311 struct work_struct detach;
312
313 /*
314 * Device might not be running if it's dirty and the cache set hasn't
315 * showed up yet.
316 */
317 atomic_t running;
318
319 /*
320 * Writes take a shared lock from start to finish; scanning for dirty
321 * data to refill the rb tree requires an exclusive lock.
322 */
323 struct rw_semaphore writeback_lock;
324
325 /*
326 * Nonzero, and writeback has a refcount (d->count), iff there is dirty
327 * data in the cache. Protected by writeback_lock; must have an
328 * shared lock to set and exclusive lock to clear.
329 */
330 atomic_t has_dirty;
331
332 struct bch_ratelimit writeback_rate;
333 struct delayed_work writeback_rate_update;
334
335 /* Limit number of writeback bios in flight */
336 struct semaphore in_flight;
337 struct task_struct *writeback_thread;
338 struct workqueue_struct *writeback_write_wq;
339
340 struct keybuf writeback_keys;
341
342 struct task_struct *status_update_thread;
343 /*
344 * Order the write-half of writeback operations strongly in dispatch
345 * order. (Maintain LBA order; don't allow reads completing out of
346 * order to re-order the writes...)
347 */
348 struct closure_waitlist writeback_ordering_wait;
349 atomic_t writeback_sequence_next;
350
351 /* For tracking sequential IO */
352 #define RECENT_IO_BITS 7
353 #define RECENT_IO (1 << RECENT_IO_BITS)
354 struct io io[RECENT_IO];
355 struct hlist_head io_hash[RECENT_IO + 1];
356 struct list_head io_lru;
357 spinlock_t io_lock;
358
359 struct cache_accounting accounting;
360
361 /* The rest of this all shows up in sysfs */
362 unsigned int sequential_cutoff;
363 unsigned int readahead;
364
365 unsigned int io_disable:1;
366 unsigned int verify:1;
367 unsigned int bypass_torture_test:1;
368
369 unsigned int partial_stripes_expensive:1;
370 unsigned int writeback_metadata:1;
371 unsigned int writeback_running:1;
372 unsigned char writeback_percent;
373 unsigned int writeback_delay;
374
375 uint64_t writeback_rate_target;
376 int64_t writeback_rate_proportional;
377 int64_t writeback_rate_integral;
378 int64_t writeback_rate_integral_scaled;
379 int32_t writeback_rate_change;
380
381 unsigned int writeback_rate_update_seconds;
382 unsigned int writeback_rate_i_term_inverse;
383 unsigned int writeback_rate_p_term_inverse;
384 unsigned int writeback_rate_minimum;
385
386 enum stop_on_failure stop_when_cache_set_failed;
387 #define DEFAULT_CACHED_DEV_ERROR_LIMIT 64
388 atomic_t io_errors;
389 unsigned int error_limit;
390 unsigned int offline_seconds;
391
392 char backing_dev_name[BDEVNAME_SIZE];
393 };
394
395 enum alloc_reserve {
396 RESERVE_BTREE,
397 RESERVE_PRIO,
398 RESERVE_MOVINGGC,
399 RESERVE_NONE,
400 RESERVE_NR,
401 };
402
403 struct cache {
404 struct cache_set *set;
405 struct cache_sb sb;
406 struct bio sb_bio;
407 struct bio_vec sb_bv[1];
408
409 struct kobject kobj;
410 struct block_device *bdev;
411
412 struct task_struct *alloc_thread;
413
414 struct closure prio;
415 struct prio_set *disk_buckets;
416
417 /*
418 * When allocating new buckets, prio_write() gets first dibs - since we
419 * may not be allocate at all without writing priorities and gens.
420 * prio_last_buckets[] contains the last buckets we wrote priorities to
421 * (so gc can mark them as metadata), prio_buckets[] contains the
422 * buckets allocated for the next prio write.
423 */
424 uint64_t *prio_buckets;
425 uint64_t *prio_last_buckets;
426
427 /*
428 * free: Buckets that are ready to be used
429 *
430 * free_inc: Incoming buckets - these are buckets that currently have
431 * cached data in them, and we can't reuse them until after we write
432 * their new gen to disk. After prio_write() finishes writing the new
433 * gens/prios, they'll be moved to the free list (and possibly discarded
434 * in the process)
435 */
436 DECLARE_FIFO(long, free)[RESERVE_NR];
437 DECLARE_FIFO(long, free_inc);
438
439 size_t fifo_last_bucket;
440
441 /* Allocation stuff: */
442 struct bucket *buckets;
443
444 DECLARE_HEAP(struct bucket *, heap);
445
446 /*
447 * If nonzero, we know we aren't going to find any buckets to invalidate
448 * until a gc finishes - otherwise we could pointlessly burn a ton of
449 * cpu
450 */
451 unsigned int invalidate_needs_gc;
452
453 bool discard; /* Get rid of? */
454
455 struct journal_device journal;
456
457 /* The rest of this all shows up in sysfs */
458 #define IO_ERROR_SHIFT 20
459 atomic_t io_errors;
460 atomic_t io_count;
461
462 atomic_long_t meta_sectors_written;
463 atomic_long_t btree_sectors_written;
464 atomic_long_t sectors_written;
465
466 char cache_dev_name[BDEVNAME_SIZE];
467 };
468
469 struct gc_stat {
470 size_t nodes;
471 size_t nodes_pre;
472 size_t key_bytes;
473
474 size_t nkeys;
475 uint64_t data; /* sectors */
476 unsigned int in_use; /* percent */
477 };
478
479 /*
480 * Flag bits, for how the cache set is shutting down, and what phase it's at:
481 *
482 * CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching
483 * all the backing devices first (their cached data gets invalidated, and they
484 * won't automatically reattach).
485 *
486 * CACHE_SET_STOPPING always gets set first when we're closing down a cache set;
487 * we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e.
488 * flushing dirty data).
489 *
490 * CACHE_SET_RUNNING means all cache devices have been registered and journal
491 * replay is complete.
492 *
493 * CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all
494 * external and internal I/O should be denied when this flag is set.
495 *
496 */
497 #define CACHE_SET_UNREGISTERING 0
498 #define CACHE_SET_STOPPING 1
499 #define CACHE_SET_RUNNING 2
500 #define CACHE_SET_IO_DISABLE 3
501
502 struct cache_set {
503 struct closure cl;
504
505 struct list_head list;
506 struct kobject kobj;
507 struct kobject internal;
508 struct dentry *debug;
509 struct cache_accounting accounting;
510
511 unsigned long flags;
512 atomic_t idle_counter;
513 atomic_t at_max_writeback_rate;
514
515 struct cache_sb sb;
516
517 struct cache *cache[MAX_CACHES_PER_SET];
518 struct cache *cache_by_alloc[MAX_CACHES_PER_SET];
519 int caches_loaded;
520
521 struct bcache_device **devices;
522 unsigned int devices_max_used;
523 atomic_t attached_dev_nr;
524 struct list_head cached_devs;
525 uint64_t cached_dev_sectors;
526 atomic_long_t flash_dev_dirty_sectors;
527 struct closure caching;
528
529 struct closure sb_write;
530 struct semaphore sb_write_mutex;
531
532 mempool_t search;
533 mempool_t bio_meta;
534 struct bio_set bio_split;
535
536 /* For the btree cache */
537 struct shrinker shrink;
538
539 /* For the btree cache and anything allocation related */
540 struct mutex bucket_lock;
541
542 /* log2(bucket_size), in sectors */
543 unsigned short bucket_bits;
544
545 /* log2(block_size), in sectors */
546 unsigned short block_bits;
547
548 /*
549 * Default number of pages for a new btree node - may be less than a
550 * full bucket
551 */
552 unsigned int btree_pages;
553
554 /*
555 * Lists of struct btrees; lru is the list for structs that have memory
556 * allocated for actual btree node, freed is for structs that do not.
557 *
558 * We never free a struct btree, except on shutdown - we just put it on
559 * the btree_cache_freed list and reuse it later. This simplifies the
560 * code, and it doesn't cost us much memory as the memory usage is
561 * dominated by buffers that hold the actual btree node data and those
562 * can be freed - and the number of struct btrees allocated is
563 * effectively bounded.
564 *
565 * btree_cache_freeable effectively is a small cache - we use it because
566 * high order page allocations can be rather expensive, and it's quite
567 * common to delete and allocate btree nodes in quick succession. It
568 * should never grow past ~2-3 nodes in practice.
569 */
570 struct list_head btree_cache;
571 struct list_head btree_cache_freeable;
572 struct list_head btree_cache_freed;
573
574 /* Number of elements in btree_cache + btree_cache_freeable lists */
575 unsigned int btree_cache_used;
576
577 /*
578 * If we need to allocate memory for a new btree node and that
579 * allocation fails, we can cannibalize another node in the btree cache
580 * to satisfy the allocation - lock to guarantee only one thread does
581 * this at a time:
582 */
583 wait_queue_head_t btree_cache_wait;
584 struct task_struct *btree_cache_alloc_lock;
585
586 /*
587 * When we free a btree node, we increment the gen of the bucket the
588 * node is in - but we can't rewrite the prios and gens until we
589 * finished whatever it is we were doing, otherwise after a crash the
590 * btree node would be freed but for say a split, we might not have the
591 * pointers to the new nodes inserted into the btree yet.
592 *
593 * This is a refcount that blocks prio_write() until the new keys are
594 * written.
595 */
596 atomic_t prio_blocked;
597 wait_queue_head_t bucket_wait;
598
599 /*
600 * For any bio we don't skip we subtract the number of sectors from
601 * rescale; when it hits 0 we rescale all the bucket priorities.
602 */
603 atomic_t rescale;
604 /*
605 * used for GC, identify if any front side I/Os is inflight
606 */
607 atomic_t search_inflight;
608 /*
609 * When we invalidate buckets, we use both the priority and the amount
610 * of good data to determine which buckets to reuse first - to weight
611 * those together consistently we keep track of the smallest nonzero
612 * priority of any bucket.
613 */
614 uint16_t min_prio;
615
616 /*
617 * max(gen - last_gc) for all buckets. When it gets too big we have to
618 * gc to keep gens from wrapping around.
619 */
620 uint8_t need_gc;
621 struct gc_stat gc_stats;
622 size_t nbuckets;
623 size_t avail_nbuckets;
624
625 struct task_struct *gc_thread;
626 /* Where in the btree gc currently is */
627 struct bkey gc_done;
628
629 /*
630 * The allocation code needs gc_mark in struct bucket to be correct, but
631 * it's not while a gc is in progress. Protected by bucket_lock.
632 */
633 int gc_mark_valid;
634
635 /* Counts how many sectors bio_insert has added to the cache */
636 atomic_t sectors_to_gc;
637 wait_queue_head_t gc_wait;
638
639 struct keybuf moving_gc_keys;
640 /* Number of moving GC bios in flight */
641 struct semaphore moving_in_flight;
642
643 struct workqueue_struct *moving_gc_wq;
644
645 struct btree *root;
646
647 #ifdef CONFIG_BCACHE_DEBUG
648 struct btree *verify_data;
649 struct bset *verify_ondisk;
650 struct mutex verify_lock;
651 #endif
652
653 unsigned int nr_uuids;
654 struct uuid_entry *uuids;
655 BKEY_PADDED(uuid_bucket);
656 struct closure uuid_write;
657 struct semaphore uuid_write_mutex;
658
659 /*
660 * A btree node on disk could have too many bsets for an iterator to fit
661 * on the stack - have to dynamically allocate them
662 */
663 mempool_t fill_iter;
664
665 struct bset_sort_state sort;
666
667 /* List of buckets we're currently writing data to */
668 struct list_head data_buckets;
669 spinlock_t data_bucket_lock;
670
671 struct journal journal;
672
673 #define CONGESTED_MAX 1024
674 unsigned int congested_last_us;
675 atomic_t congested;
676
677 /* The rest of this all shows up in sysfs */
678 unsigned int congested_read_threshold_us;
679 unsigned int congested_write_threshold_us;
680
681 struct time_stats btree_gc_time;
682 struct time_stats btree_split_time;
683 struct time_stats btree_read_time;
684
685 atomic_long_t cache_read_races;
686 atomic_long_t writeback_keys_done;
687 atomic_long_t writeback_keys_failed;
688
689 atomic_long_t reclaim;
690 atomic_long_t flush_write;
691 atomic_long_t retry_flush_write;
692
693 enum {
694 ON_ERROR_UNREGISTER,
695 ON_ERROR_PANIC,
696 } on_error;
697 #define DEFAULT_IO_ERROR_LIMIT 8
698 unsigned int error_limit;
699 unsigned int error_decay;
700
701 unsigned short journal_delay_ms;
702 bool expensive_debug_checks;
703 unsigned int verify:1;
704 unsigned int key_merging_disabled:1;
705 unsigned int gc_always_rewrite:1;
706 unsigned int shrinker_disabled:1;
707 unsigned int copy_gc_enabled:1;
708
709 #define BUCKET_HASH_BITS 12
710 struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS];
711
712 DECLARE_HEAP(struct btree *, flush_btree);
713 };
714
715 struct bbio {
716 unsigned int submit_time_us;
717 union {
718 struct bkey key;
719 uint64_t _pad[3];
720 /*
721 * We only need pad = 3 here because we only ever carry around a
722 * single pointer - i.e. the pointer we're doing io to/from.
723 */
724 };
725 struct bio bio;
726 };
727
728 #define BTREE_PRIO USHRT_MAX
729 #define INITIAL_PRIO 32768U
730
731 #define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE)
732 #define btree_blocks(b) \
733 ((unsigned int) (KEY_SIZE(&b->key) >> (b)->c->block_bits))
734
735 #define btree_default_blocks(c) \
736 ((unsigned int) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits))
737
738 #define bucket_pages(c) ((c)->sb.bucket_size / PAGE_SECTORS)
739 #define bucket_bytes(c) ((c)->sb.bucket_size << 9)
740 #define block_bytes(c) ((c)->sb.block_size << 9)
741
742 #define prios_per_bucket(c) \
743 ((bucket_bytes(c) - sizeof(struct prio_set)) / \
744 sizeof(struct bucket_disk))
745 #define prio_buckets(c) \
746 DIV_ROUND_UP((size_t) (c)->sb.nbuckets, prios_per_bucket(c))
747
sector_to_bucket(struct cache_set * c,sector_t s)748 static inline size_t sector_to_bucket(struct cache_set *c, sector_t s)
749 {
750 return s >> c->bucket_bits;
751 }
752
bucket_to_sector(struct cache_set * c,size_t b)753 static inline sector_t bucket_to_sector(struct cache_set *c, size_t b)
754 {
755 return ((sector_t) b) << c->bucket_bits;
756 }
757
bucket_remainder(struct cache_set * c,sector_t s)758 static inline sector_t bucket_remainder(struct cache_set *c, sector_t s)
759 {
760 return s & (c->sb.bucket_size - 1);
761 }
762
PTR_CACHE(struct cache_set * c,const struct bkey * k,unsigned int ptr)763 static inline struct cache *PTR_CACHE(struct cache_set *c,
764 const struct bkey *k,
765 unsigned int ptr)
766 {
767 return c->cache[PTR_DEV(k, ptr)];
768 }
769
PTR_BUCKET_NR(struct cache_set * c,const struct bkey * k,unsigned int ptr)770 static inline size_t PTR_BUCKET_NR(struct cache_set *c,
771 const struct bkey *k,
772 unsigned int ptr)
773 {
774 return sector_to_bucket(c, PTR_OFFSET(k, ptr));
775 }
776
PTR_BUCKET(struct cache_set * c,const struct bkey * k,unsigned int ptr)777 static inline struct bucket *PTR_BUCKET(struct cache_set *c,
778 const struct bkey *k,
779 unsigned int ptr)
780 {
781 return PTR_CACHE(c, k, ptr)->buckets + PTR_BUCKET_NR(c, k, ptr);
782 }
783
gen_after(uint8_t a,uint8_t b)784 static inline uint8_t gen_after(uint8_t a, uint8_t b)
785 {
786 uint8_t r = a - b;
787
788 return r > 128U ? 0 : r;
789 }
790
ptr_stale(struct cache_set * c,const struct bkey * k,unsigned int i)791 static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k,
792 unsigned int i)
793 {
794 return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i));
795 }
796
ptr_available(struct cache_set * c,const struct bkey * k,unsigned int i)797 static inline bool ptr_available(struct cache_set *c, const struct bkey *k,
798 unsigned int i)
799 {
800 return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && PTR_CACHE(c, k, i);
801 }
802
803 /* Btree key macros */
804
805 /*
806 * This is used for various on disk data structures - cache_sb, prio_set, bset,
807 * jset: The checksum is _always_ the first 8 bytes of these structs
808 */
809 #define csum_set(i) \
810 bch_crc64(((void *) (i)) + sizeof(uint64_t), \
811 ((void *) bset_bkey_last(i)) - \
812 (((void *) (i)) + sizeof(uint64_t)))
813
814 /* Error handling macros */
815
816 #define btree_bug(b, ...) \
817 do { \
818 if (bch_cache_set_error((b)->c, __VA_ARGS__)) \
819 dump_stack(); \
820 } while (0)
821
822 #define cache_bug(c, ...) \
823 do { \
824 if (bch_cache_set_error(c, __VA_ARGS__)) \
825 dump_stack(); \
826 } while (0)
827
828 #define btree_bug_on(cond, b, ...) \
829 do { \
830 if (cond) \
831 btree_bug(b, __VA_ARGS__); \
832 } while (0)
833
834 #define cache_bug_on(cond, c, ...) \
835 do { \
836 if (cond) \
837 cache_bug(c, __VA_ARGS__); \
838 } while (0)
839
840 #define cache_set_err_on(cond, c, ...) \
841 do { \
842 if (cond) \
843 bch_cache_set_error(c, __VA_ARGS__); \
844 } while (0)
845
846 /* Looping macros */
847
848 #define for_each_cache(ca, cs, iter) \
849 for (iter = 0; ca = cs->cache[iter], iter < (cs)->sb.nr_in_set; iter++)
850
851 #define for_each_bucket(b, ca) \
852 for (b = (ca)->buckets + (ca)->sb.first_bucket; \
853 b < (ca)->buckets + (ca)->sb.nbuckets; b++)
854
cached_dev_put(struct cached_dev * dc)855 static inline void cached_dev_put(struct cached_dev *dc)
856 {
857 if (refcount_dec_and_test(&dc->count))
858 schedule_work(&dc->detach);
859 }
860
cached_dev_get(struct cached_dev * dc)861 static inline bool cached_dev_get(struct cached_dev *dc)
862 {
863 if (!refcount_inc_not_zero(&dc->count))
864 return false;
865
866 /* Paired with the mb in cached_dev_attach */
867 smp_mb__after_atomic();
868 return true;
869 }
870
871 /*
872 * bucket_gc_gen() returns the difference between the bucket's current gen and
873 * the oldest gen of any pointer into that bucket in the btree (last_gc).
874 */
875
bucket_gc_gen(struct bucket * b)876 static inline uint8_t bucket_gc_gen(struct bucket *b)
877 {
878 return b->gen - b->last_gc;
879 }
880
881 #define BUCKET_GC_GEN_MAX 96U
882
883 #define kobj_attribute_write(n, fn) \
884 static struct kobj_attribute ksysfs_##n = __ATTR(n, 0200, NULL, fn)
885
886 #define kobj_attribute_rw(n, show, store) \
887 static struct kobj_attribute ksysfs_##n = \
888 __ATTR(n, 0600, show, store)
889
wake_up_allocators(struct cache_set * c)890 static inline void wake_up_allocators(struct cache_set *c)
891 {
892 struct cache *ca;
893 unsigned int i;
894
895 for_each_cache(ca, c, i)
896 wake_up_process(ca->alloc_thread);
897 }
898
closure_bio_submit(struct cache_set * c,struct bio * bio,struct closure * cl)899 static inline void closure_bio_submit(struct cache_set *c,
900 struct bio *bio,
901 struct closure *cl)
902 {
903 closure_get(cl);
904 if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) {
905 bio->bi_status = BLK_STS_IOERR;
906 bio_endio(bio);
907 return;
908 }
909 generic_make_request(bio);
910 }
911
912 /*
913 * Prevent the kthread exits directly, and make sure when kthread_stop()
914 * is called to stop a kthread, it is still alive. If a kthread might be
915 * stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is
916 * necessary before the kthread returns.
917 */
wait_for_kthread_stop(void)918 static inline void wait_for_kthread_stop(void)
919 {
920 while (!kthread_should_stop()) {
921 set_current_state(TASK_INTERRUPTIBLE);
922 schedule();
923 }
924 }
925
926 /* Forward declarations */
927
928 void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio);
929 void bch_count_io_errors(struct cache *ca, blk_status_t error,
930 int is_read, const char *m);
931 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
932 blk_status_t error, const char *m);
933 void bch_bbio_endio(struct cache_set *c, struct bio *bio,
934 blk_status_t error, const char *m);
935 void bch_bbio_free(struct bio *bio, struct cache_set *c);
936 struct bio *bch_bbio_alloc(struct cache_set *c);
937
938 void __bch_submit_bbio(struct bio *bio, struct cache_set *c);
939 void bch_submit_bbio(struct bio *bio, struct cache_set *c,
940 struct bkey *k, unsigned int ptr);
941
942 uint8_t bch_inc_gen(struct cache *ca, struct bucket *b);
943 void bch_rescale_priorities(struct cache_set *c, int sectors);
944
945 bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b);
946 void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b);
947
948 void __bch_bucket_free(struct cache *ca, struct bucket *b);
949 void bch_bucket_free(struct cache_set *c, struct bkey *k);
950
951 long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait);
952 int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
953 struct bkey *k, int n, bool wait);
954 int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
955 struct bkey *k, int n, bool wait);
956 bool bch_alloc_sectors(struct cache_set *c, struct bkey *k,
957 unsigned int sectors, unsigned int write_point,
958 unsigned int write_prio, bool wait);
959 bool bch_cached_dev_error(struct cached_dev *dc);
960
961 __printf(2, 3)
962 bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...);
963
964 void bch_prio_write(struct cache *ca);
965 void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent);
966
967 extern struct workqueue_struct *bcache_wq;
968 extern struct workqueue_struct *bch_journal_wq;
969 extern struct mutex bch_register_lock;
970 extern struct list_head bch_cache_sets;
971
972 extern struct kobj_type bch_cached_dev_ktype;
973 extern struct kobj_type bch_flash_dev_ktype;
974 extern struct kobj_type bch_cache_set_ktype;
975 extern struct kobj_type bch_cache_set_internal_ktype;
976 extern struct kobj_type bch_cache_ktype;
977
978 void bch_cached_dev_release(struct kobject *kobj);
979 void bch_flash_dev_release(struct kobject *kobj);
980 void bch_cache_set_release(struct kobject *kobj);
981 void bch_cache_release(struct kobject *kobj);
982
983 int bch_uuid_write(struct cache_set *c);
984 void bcache_write_super(struct cache_set *c);
985
986 int bch_flash_dev_create(struct cache_set *c, uint64_t size);
987
988 int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,
989 uint8_t *set_uuid);
990 void bch_cached_dev_detach(struct cached_dev *dc);
991 void bch_cached_dev_run(struct cached_dev *dc);
992 void bcache_device_stop(struct bcache_device *d);
993
994 void bch_cache_set_unregister(struct cache_set *c);
995 void bch_cache_set_stop(struct cache_set *c);
996
997 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb);
998 void bch_btree_cache_free(struct cache_set *c);
999 int bch_btree_cache_alloc(struct cache_set *c);
1000 void bch_moving_init_cache_set(struct cache_set *c);
1001 int bch_open_buckets_alloc(struct cache_set *c);
1002 void bch_open_buckets_free(struct cache_set *c);
1003
1004 int bch_cache_allocator_start(struct cache *ca);
1005
1006 void bch_debug_exit(void);
1007 void bch_debug_init(struct kobject *kobj);
1008 void bch_request_exit(void);
1009 int bch_request_init(void);
1010
1011 #endif /* _BCACHE_H */
1012
