1 /* SPDX-License-Identifier: GPL-2.0 */
6 * SOME HIGH LEVEL CODE DOCUMENTATION:
8 * Bcache mostly works with cache sets, cache devices, and backing devices.
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.
15 * Multiple cache devices is intended to give us the ability to mirror dirty
16 * cached data and metadata, without mirroring clean cached data.
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.
24 * A cache set can have multiple (many) backing devices attached to it.
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.
32 * Flash only volumes work but they're not production ready because the moving
33 * garbage collector needs more work. More on that later.
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
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+
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).
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.
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
62 * Bcache is entirely COW - we never write twice to a bucket, even buckets that
63 * contain metadata (including btree nodes).
67 * Bcache is in large part design around the btree.
69 * At a high level, the btree is just an index of key -> ptr tuples.
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).
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.
80 * Pointers contain the cache device id, the offset on that device, and an 8 bit
81 * generation number. More on the gen later.
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
87 * Updates are fairly well abstracted, though. There are two different ways of
88 * updating the btree; insert and replace.
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.
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.
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.
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.
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.
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.)
118 * Anyways, btree nodes are big - big enough to be inefficient with a textbook
119 * btree implementation.
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.
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
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.
137 * GARBAGE COLLECTION:
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.
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.
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.
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
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.
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
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()).
179 #define pr_fmt(fmt) "bcache: %s() " fmt, __func__
181 #include <linux/bio.h>
182 #include <linux/kobject.h>
183 #include <linux/list.h>
184 #include <linux/mutex.h>
185 #include <linux/rbtree.h>
186 #include <linux/rwsem.h>
187 #include <linux/refcount.h>
188 #include <linux/types.h>
189 #include <linux/workqueue.h>
190 #include <linux/kthread.h>
192 #include "bcache_ondisk.h"
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 */
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
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);
232 struct bkey last_scanned;
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
245 #define KEYBUF_NR 500
246 DECLARE_ARRAY_ALLOCATOR(struct keybuf_key, freelist, KEYBUF_NR);
249 struct bcache_device {
256 #define BCACHEDEVNAME_SIZE 12
257 char name[BCACHEDEVNAME_SIZE];
259 struct gendisk *disk;
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
268 unsigned int stripe_size;
269 atomic_t *stripe_sectors_dirty;
270 unsigned long *full_dirty_stripes;
272 struct bio_set bio_split;
274 unsigned int data_csum:1;
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);
283 /* Used to track sequential IO so it can be skipped */
284 struct hlist_node hash;
285 struct list_head lru;
287 unsigned long jiffies;
288 unsigned int sequential;
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,
299 struct list_head list;
300 struct bcache_device disk;
301 struct block_device *bdev;
304 struct cache_sb_disk *sb_disk;
306 struct bio_vec sb_bv[1];
307 struct closure sb_write;
308 struct semaphore sb_write_mutex;
310 /* Refcount on the cache set. Always nonzero when we're caching. */
312 struct work_struct detach;
315 * Device might not be running if it's dirty and the cache set hasn't
321 * Writes take a shared lock from start to finish; scanning for dirty
322 * data to refill the rb tree requires an exclusive lock.
324 struct rw_semaphore writeback_lock;
327 * Nonzero, and writeback has a refcount (d->count), iff there is dirty
328 * data in the cache. Protected by writeback_lock; must have an
329 * shared lock to set and exclusive lock to clear.
333 #define BCH_CACHE_READA_ALL 0
334 #define BCH_CACHE_READA_META_ONLY 1
335 unsigned int cache_readahead_policy;
336 struct bch_ratelimit writeback_rate;
337 struct delayed_work writeback_rate_update;
339 /* Limit number of writeback bios in flight */
340 struct semaphore in_flight;
341 struct task_struct *writeback_thread;
342 struct workqueue_struct *writeback_write_wq;
344 struct keybuf writeback_keys;
346 struct task_struct *status_update_thread;
348 * Order the write-half of writeback operations strongly in dispatch
349 * order. (Maintain LBA order; don't allow reads completing out of
350 * order to re-order the writes...)
352 struct closure_waitlist writeback_ordering_wait;
353 atomic_t writeback_sequence_next;
355 /* For tracking sequential IO */
356 #define RECENT_IO_BITS 7
357 #define RECENT_IO (1 << RECENT_IO_BITS)
358 struct io io[RECENT_IO];
359 struct hlist_head io_hash[RECENT_IO + 1];
360 struct list_head io_lru;
363 struct cache_accounting accounting;
365 /* The rest of this all shows up in sysfs */
366 unsigned int sequential_cutoff;
368 unsigned int io_disable:1;
369 unsigned int verify:1;
370 unsigned int bypass_torture_test:1;
372 unsigned int partial_stripes_expensive:1;
373 unsigned int writeback_metadata:1;
374 unsigned int writeback_running:1;
375 unsigned int writeback_consider_fragment:1;
376 unsigned char writeback_percent;
377 unsigned int writeback_delay;
379 uint64_t writeback_rate_target;
380 int64_t writeback_rate_proportional;
381 int64_t writeback_rate_integral;
382 int64_t writeback_rate_integral_scaled;
383 int32_t writeback_rate_change;
385 unsigned int writeback_rate_update_seconds;
386 unsigned int writeback_rate_i_term_inverse;
387 unsigned int writeback_rate_p_term_inverse;
388 unsigned int writeback_rate_fp_term_low;
389 unsigned int writeback_rate_fp_term_mid;
390 unsigned int writeback_rate_fp_term_high;
391 unsigned int writeback_rate_minimum;
393 enum stop_on_failure stop_when_cache_set_failed;
394 #define DEFAULT_CACHED_DEV_ERROR_LIMIT 64
396 unsigned int error_limit;
397 unsigned int offline_seconds;
400 * Retry to update writeback_rate if contention happens for
401 * down_read(dc->writeback_lock) in update_writeback_rate()
403 #define BCH_WBRATE_UPDATE_MAX_SKIPS 15
404 unsigned int rate_update_retry;
416 struct cache_set *set;
418 struct cache_sb_disk *sb_disk;
420 struct bio_vec sb_bv[1];
423 struct block_device *bdev;
425 struct task_struct *alloc_thread;
428 struct prio_set *disk_buckets;
431 * When allocating new buckets, prio_write() gets first dibs - since we
432 * may not be allocate at all without writing priorities and gens.
433 * prio_last_buckets[] contains the last buckets we wrote priorities to
434 * (so gc can mark them as metadata), prio_buckets[] contains the
435 * buckets allocated for the next prio write.
437 uint64_t *prio_buckets;
438 uint64_t *prio_last_buckets;
441 * free: Buckets that are ready to be used
443 * free_inc: Incoming buckets - these are buckets that currently have
444 * cached data in them, and we can't reuse them until after we write
445 * their new gen to disk. After prio_write() finishes writing the new
446 * gens/prios, they'll be moved to the free list (and possibly discarded
449 DECLARE_FIFO(long, free)[RESERVE_NR];
450 DECLARE_FIFO(long, free_inc);
452 size_t fifo_last_bucket;
454 /* Allocation stuff: */
455 struct bucket *buckets;
457 DECLARE_HEAP(struct bucket *, heap);
460 * If nonzero, we know we aren't going to find any buckets to invalidate
461 * until a gc finishes - otherwise we could pointlessly burn a ton of
464 unsigned int invalidate_needs_gc;
466 bool discard; /* Get rid of? */
468 struct journal_device journal;
470 /* The rest of this all shows up in sysfs */
471 #define IO_ERROR_SHIFT 20
475 atomic_long_t meta_sectors_written;
476 atomic_long_t btree_sectors_written;
477 atomic_long_t sectors_written;
486 uint64_t data; /* sectors */
487 unsigned int in_use; /* percent */
491 * Flag bits, for how the cache set is shutting down, and what phase it's at:
493 * CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching
494 * all the backing devices first (their cached data gets invalidated, and they
495 * won't automatically reattach).
497 * CACHE_SET_STOPPING always gets set first when we're closing down a cache set;
498 * we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e.
499 * flushing dirty data).
501 * CACHE_SET_RUNNING means all cache devices have been registered and journal
502 * replay is complete.
504 * CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all
505 * external and internal I/O should be denied when this flag is set.
508 #define CACHE_SET_UNREGISTERING 0
509 #define CACHE_SET_STOPPING 1
510 #define CACHE_SET_RUNNING 2
511 #define CACHE_SET_IO_DISABLE 3
516 struct list_head list;
518 struct kobject internal;
519 struct dentry *debug;
520 struct cache_accounting accounting;
523 atomic_t idle_counter;
524 atomic_t at_max_writeback_rate;
528 struct bcache_device **devices;
529 unsigned int devices_max_used;
530 atomic_t attached_dev_nr;
531 struct list_head cached_devs;
532 uint64_t cached_dev_sectors;
533 atomic_long_t flash_dev_dirty_sectors;
534 struct closure caching;
536 struct closure sb_write;
537 struct semaphore sb_write_mutex;
541 struct bio_set bio_split;
543 /* For the btree cache */
544 struct shrinker shrink;
546 /* For the btree cache and anything allocation related */
547 struct mutex bucket_lock;
549 /* log2(bucket_size), in sectors */
550 unsigned short bucket_bits;
552 /* log2(block_size), in sectors */
553 unsigned short block_bits;
556 * Default number of pages for a new btree node - may be less than a
559 unsigned int btree_pages;
562 * Lists of struct btrees; lru is the list for structs that have memory
563 * allocated for actual btree node, freed is for structs that do not.
565 * We never free a struct btree, except on shutdown - we just put it on
566 * the btree_cache_freed list and reuse it later. This simplifies the
567 * code, and it doesn't cost us much memory as the memory usage is
568 * dominated by buffers that hold the actual btree node data and those
569 * can be freed - and the number of struct btrees allocated is
570 * effectively bounded.
572 * btree_cache_freeable effectively is a small cache - we use it because
573 * high order page allocations can be rather expensive, and it's quite
574 * common to delete and allocate btree nodes in quick succession. It
575 * should never grow past ~2-3 nodes in practice.
577 struct list_head btree_cache;
578 struct list_head btree_cache_freeable;
579 struct list_head btree_cache_freed;
581 /* Number of elements in btree_cache + btree_cache_freeable lists */
582 unsigned int btree_cache_used;
585 * If we need to allocate memory for a new btree node and that
586 * allocation fails, we can cannibalize another node in the btree cache
587 * to satisfy the allocation - lock to guarantee only one thread does
590 wait_queue_head_t btree_cache_wait;
591 struct task_struct *btree_cache_alloc_lock;
592 spinlock_t btree_cannibalize_lock;
595 * When we free a btree node, we increment the gen of the bucket the
596 * node is in - but we can't rewrite the prios and gens until we
597 * finished whatever it is we were doing, otherwise after a crash the
598 * btree node would be freed but for say a split, we might not have the
599 * pointers to the new nodes inserted into the btree yet.
601 * This is a refcount that blocks prio_write() until the new keys are
604 atomic_t prio_blocked;
605 wait_queue_head_t bucket_wait;
608 * For any bio we don't skip we subtract the number of sectors from
609 * rescale; when it hits 0 we rescale all the bucket priorities.
613 * used for GC, identify if any front side I/Os is inflight
615 atomic_t search_inflight;
617 * When we invalidate buckets, we use both the priority and the amount
618 * of good data to determine which buckets to reuse first - to weight
619 * those together consistently we keep track of the smallest nonzero
620 * priority of any bucket.
625 * max(gen - last_gc) for all buckets. When it gets too big we have to
626 * gc to keep gens from wrapping around.
629 struct gc_stat gc_stats;
631 size_t avail_nbuckets;
633 struct task_struct *gc_thread;
634 /* Where in the btree gc currently is */
638 * For automatical garbage collection after writeback completed, this
639 * varialbe is used as bit fields,
640 * - 0000 0001b (BCH_ENABLE_AUTO_GC): enable gc after writeback
641 * - 0000 0010b (BCH_DO_AUTO_GC): do gc after writeback
642 * This is an optimization for following write request after writeback
643 * finished, but read hit rate dropped due to clean data on cache is
644 * discarded. Unless user explicitly sets it via sysfs, it won't be
647 #define BCH_ENABLE_AUTO_GC 1
648 #define BCH_DO_AUTO_GC 2
649 uint8_t gc_after_writeback;
652 * The allocation code needs gc_mark in struct bucket to be correct, but
653 * it's not while a gc is in progress. Protected by bucket_lock.
657 /* Counts how many sectors bio_insert has added to the cache */
658 atomic_t sectors_to_gc;
659 wait_queue_head_t gc_wait;
661 struct keybuf moving_gc_keys;
662 /* Number of moving GC bios in flight */
663 struct semaphore moving_in_flight;
665 struct workqueue_struct *moving_gc_wq;
669 #ifdef CONFIG_BCACHE_DEBUG
670 struct btree *verify_data;
671 struct bset *verify_ondisk;
672 struct mutex verify_lock;
675 uint8_t set_uuid[16];
676 unsigned int nr_uuids;
677 struct uuid_entry *uuids;
678 BKEY_PADDED(uuid_bucket);
679 struct closure uuid_write;
680 struct semaphore uuid_write_mutex;
683 * A btree node on disk could have too many bsets for an iterator to fit
684 * on the stack - have to dynamically allocate them.
685 * bch_cache_set_alloc() will make sure the pool can allocate iterators
686 * equipped with enough room that can host
687 * (sb.bucket_size / sb.block_size)
688 * btree_iter_sets, which is more than static MAX_BSETS.
692 struct bset_sort_state sort;
694 /* List of buckets we're currently writing data to */
695 struct list_head data_buckets;
696 spinlock_t data_bucket_lock;
698 struct journal journal;
700 #define CONGESTED_MAX 1024
701 unsigned int congested_last_us;
704 /* The rest of this all shows up in sysfs */
705 unsigned int congested_read_threshold_us;
706 unsigned int congested_write_threshold_us;
708 struct time_stats btree_gc_time;
709 struct time_stats btree_split_time;
710 struct time_stats btree_read_time;
712 atomic_long_t cache_read_races;
713 atomic_long_t writeback_keys_done;
714 atomic_long_t writeback_keys_failed;
716 atomic_long_t reclaim;
717 atomic_long_t reclaimed_journal_buckets;
718 atomic_long_t flush_write;
724 #define DEFAULT_IO_ERROR_LIMIT 8
725 unsigned int error_limit;
726 unsigned int error_decay;
728 unsigned short journal_delay_ms;
729 bool expensive_debug_checks;
730 unsigned int verify:1;
731 unsigned int key_merging_disabled:1;
732 unsigned int gc_always_rewrite:1;
733 unsigned int shrinker_disabled:1;
734 unsigned int copy_gc_enabled:1;
735 unsigned int idle_max_writeback_rate_enabled:1;
737 #define BUCKET_HASH_BITS 12
738 struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS];
742 unsigned int submit_time_us;
747 * We only need pad = 3 here because we only ever carry around a
748 * single pointer - i.e. the pointer we're doing io to/from.
754 #define BTREE_PRIO USHRT_MAX
755 #define INITIAL_PRIO 32768U
757 #define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE)
758 #define btree_blocks(b) \
759 ((unsigned int) (KEY_SIZE(&b->key) >> (b)->c->block_bits))
761 #define btree_default_blocks(c) \
762 ((unsigned int) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits))
764 #define bucket_bytes(ca) ((ca)->sb.bucket_size << 9)
765 #define block_bytes(ca) ((ca)->sb.block_size << 9)
767 static inline unsigned int meta_bucket_pages(struct cache_sb *sb)
769 unsigned int n, max_pages;
771 max_pages = min_t(unsigned int,
772 __rounddown_pow_of_two(USHRT_MAX) / PAGE_SECTORS,
775 n = sb->bucket_size / PAGE_SECTORS;
782 static inline unsigned int meta_bucket_bytes(struct cache_sb *sb)
784 return meta_bucket_pages(sb) << PAGE_SHIFT;
787 #define prios_per_bucket(ca) \
788 ((meta_bucket_bytes(&(ca)->sb) - sizeof(struct prio_set)) / \
789 sizeof(struct bucket_disk))
791 #define prio_buckets(ca) \
792 DIV_ROUND_UP((size_t) (ca)->sb.nbuckets, prios_per_bucket(ca))
794 static inline size_t sector_to_bucket(struct cache_set *c, sector_t s)
796 return s >> c->bucket_bits;
799 static inline sector_t bucket_to_sector(struct cache_set *c, size_t b)
801 return ((sector_t) b) << c->bucket_bits;
804 static inline sector_t bucket_remainder(struct cache_set *c, sector_t s)
806 return s & (c->cache->sb.bucket_size - 1);
809 static inline size_t PTR_BUCKET_NR(struct cache_set *c,
810 const struct bkey *k,
813 return sector_to_bucket(c, PTR_OFFSET(k, ptr));
816 static inline struct bucket *PTR_BUCKET(struct cache_set *c,
817 const struct bkey *k,
820 return c->cache->buckets + PTR_BUCKET_NR(c, k, ptr);
823 static inline uint8_t gen_after(uint8_t a, uint8_t b)
827 return r > 128U ? 0 : r;
830 static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k,
833 return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i));
836 static inline bool ptr_available(struct cache_set *c, const struct bkey *k,
839 return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && c->cache;
842 /* Btree key macros */
845 * This is used for various on disk data structures - cache_sb, prio_set, bset,
846 * jset: The checksum is _always_ the first 8 bytes of these structs
848 #define csum_set(i) \
849 bch_crc64(((void *) (i)) + sizeof(uint64_t), \
850 ((void *) bset_bkey_last(i)) - \
851 (((void *) (i)) + sizeof(uint64_t)))
853 /* Error handling macros */
855 #define btree_bug(b, ...) \
857 if (bch_cache_set_error((b)->c, __VA_ARGS__)) \
861 #define cache_bug(c, ...) \
863 if (bch_cache_set_error(c, __VA_ARGS__)) \
867 #define btree_bug_on(cond, b, ...) \
870 btree_bug(b, __VA_ARGS__); \
873 #define cache_bug_on(cond, c, ...) \
876 cache_bug(c, __VA_ARGS__); \
879 #define cache_set_err_on(cond, c, ...) \
882 bch_cache_set_error(c, __VA_ARGS__); \
887 #define for_each_bucket(b, ca) \
888 for (b = (ca)->buckets + (ca)->sb.first_bucket; \
889 b < (ca)->buckets + (ca)->sb.nbuckets; b++)
891 static inline void cached_dev_put(struct cached_dev *dc)
893 if (refcount_dec_and_test(&dc->count))
894 schedule_work(&dc->detach);
897 static inline bool cached_dev_get(struct cached_dev *dc)
899 if (!refcount_inc_not_zero(&dc->count))
902 /* Paired with the mb in cached_dev_attach */
903 smp_mb__after_atomic();
908 * bucket_gc_gen() returns the difference between the bucket's current gen and
909 * the oldest gen of any pointer into that bucket in the btree (last_gc).
912 static inline uint8_t bucket_gc_gen(struct bucket *b)
914 return b->gen - b->last_gc;
917 #define BUCKET_GC_GEN_MAX 96U
919 #define kobj_attribute_write(n, fn) \
920 static struct kobj_attribute ksysfs_##n = __ATTR(n, 0200, NULL, fn)
922 #define kobj_attribute_rw(n, show, store) \
923 static struct kobj_attribute ksysfs_##n = \
924 __ATTR(n, 0600, show, store)
926 static inline void wake_up_allocators(struct cache_set *c)
928 struct cache *ca = c->cache;
930 wake_up_process(ca->alloc_thread);
933 static inline void closure_bio_submit(struct cache_set *c,
938 if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) {
939 bio->bi_status = BLK_STS_IOERR;
943 submit_bio_noacct(bio);
947 * Prevent the kthread exits directly, and make sure when kthread_stop()
948 * is called to stop a kthread, it is still alive. If a kthread might be
949 * stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is
950 * necessary before the kthread returns.
952 static inline void wait_for_kthread_stop(void)
954 while (!kthread_should_stop()) {
955 set_current_state(TASK_INTERRUPTIBLE);
960 /* Forward declarations */
962 void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio);
963 void bch_count_io_errors(struct cache *ca, blk_status_t error,
964 int is_read, const char *m);
965 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
966 blk_status_t error, const char *m);
967 void bch_bbio_endio(struct cache_set *c, struct bio *bio,
968 blk_status_t error, const char *m);
969 void bch_bbio_free(struct bio *bio, struct cache_set *c);
970 struct bio *bch_bbio_alloc(struct cache_set *c);
972 void __bch_submit_bbio(struct bio *bio, struct cache_set *c);
973 void bch_submit_bbio(struct bio *bio, struct cache_set *c,
974 struct bkey *k, unsigned int ptr);
976 uint8_t bch_inc_gen(struct cache *ca, struct bucket *b);
977 void bch_rescale_priorities(struct cache_set *c, int sectors);
979 bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b);
980 void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b);
982 void __bch_bucket_free(struct cache *ca, struct bucket *b);
983 void bch_bucket_free(struct cache_set *c, struct bkey *k);
985 long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait);
986 int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
987 struct bkey *k, bool wait);
988 int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
989 struct bkey *k, bool wait);
990 bool bch_alloc_sectors(struct cache_set *c, struct bkey *k,
991 unsigned int sectors, unsigned int write_point,
992 unsigned int write_prio, bool wait);
993 bool bch_cached_dev_error(struct cached_dev *dc);
996 bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...);
998 int bch_prio_write(struct cache *ca, bool wait);
999 void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent);
1001 extern struct workqueue_struct *bcache_wq;
1002 extern struct workqueue_struct *bch_journal_wq;
1003 extern struct workqueue_struct *bch_flush_wq;
1004 extern struct mutex bch_register_lock;
1005 extern struct list_head bch_cache_sets;
1007 extern struct kobj_type bch_cached_dev_ktype;
1008 extern struct kobj_type bch_flash_dev_ktype;
1009 extern struct kobj_type bch_cache_set_ktype;
1010 extern struct kobj_type bch_cache_set_internal_ktype;
1011 extern struct kobj_type bch_cache_ktype;
1013 void bch_cached_dev_release(struct kobject *kobj);
1014 void bch_flash_dev_release(struct kobject *kobj);
1015 void bch_cache_set_release(struct kobject *kobj);
1016 void bch_cache_release(struct kobject *kobj);
1018 int bch_uuid_write(struct cache_set *c);
1019 void bcache_write_super(struct cache_set *c);
1021 int bch_flash_dev_create(struct cache_set *c, uint64_t size);
1023 int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,
1025 void bch_cached_dev_detach(struct cached_dev *dc);
1026 int bch_cached_dev_run(struct cached_dev *dc);
1027 void bcache_device_stop(struct bcache_device *d);
1029 void bch_cache_set_unregister(struct cache_set *c);
1030 void bch_cache_set_stop(struct cache_set *c);
1032 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb);
1033 void bch_btree_cache_free(struct cache_set *c);
1034 int bch_btree_cache_alloc(struct cache_set *c);
1035 void bch_moving_init_cache_set(struct cache_set *c);
1036 int bch_open_buckets_alloc(struct cache_set *c);
1037 void bch_open_buckets_free(struct cache_set *c);
1039 int bch_cache_allocator_start(struct cache *ca);
1041 void bch_debug_exit(void);
1042 void bch_debug_init(void);
1043 void bch_request_exit(void);
1044 int bch_request_init(void);
1045 void bch_btree_exit(void);
1046 int bch_btree_init(void);
1048 #endif /* _BCACHE_H */