blob: 9ed9c955add7b9c957f2f1be5628ca633bfa7a08 [file] [log] [blame]
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHE_H
#define _BCACHE_H
* Bcache mostly works with cache sets, cache devices, and backing devices.
* Support for multiple cache devices hasn't quite been finished off yet, but
* it's about 95% plumbed through. A cache set and its cache devices is sort of
* like a md raid array and its component devices. Most of the code doesn't care
* about individual cache devices, the main abstraction is the cache set.
* Multiple cache devices is intended to give us the ability to mirror dirty
* cached data and metadata, without mirroring clean cached data.
* Backing devices are different, in that they have a lifetime independent of a
* cache set. When you register a newly formatted backing device it'll come up
* in passthrough mode, and then you can attach and detach a backing device from
* a cache set at runtime - while it's mounted and in use. Detaching implicitly
* invalidates any cached data for that backing device.
* A cache set can have multiple (many) backing devices attached to it.
* There's also flash only volumes - this is the reason for the distinction
* between struct cached_dev and struct bcache_device. A flash only volume
* works much like a bcache device that has a backing device, except the
* "cached" data is always dirty. The end result is that we get thin
* provisioning with very little additional code.
* Flash only volumes work but they're not production ready because the moving
* garbage collector needs more work. More on that later.
* Bcache is primarily designed for caching, which means that in normal
* operation all of our available space will be allocated. Thus, we need an
* efficient way of deleting things from the cache so we can write new things to
* it.
* To do this, we first divide the cache device up into buckets. A bucket is the
* unit of allocation; they're typically around 1 mb - anywhere from 128k to 2M+
* works efficiently.
* Each bucket has a 16 bit priority, and an 8 bit generation associated with
* it. The gens and priorities for all the buckets are stored contiguously and
* packed on disk (in a linked list of buckets - aside from the superblock, all
* of bcache's metadata is stored in buckets).
* The priority is used to implement an LRU. We reset a bucket's priority when
* we allocate it or on cache it, and every so often we decrement the priority
* of each bucket. It could be used to implement something more sophisticated,
* if anyone ever gets around to it.
* The generation is used for invalidating buckets. Each pointer also has an 8
* bit generation embedded in it; for a pointer to be considered valid, its gen
* must match the gen of the bucket it points into. Thus, to reuse a bucket all
* we have to do is increment its gen (and write its new gen to disk; we batch
* this up).
* Bcache is entirely COW - we never write twice to a bucket, even buckets that
* contain metadata (including btree nodes).
* Bcache is in large part design around the btree.
* At a high level, the btree is just an index of key -> ptr tuples.
* Keys represent extents, and thus have a size field. Keys also have a variable
* number of pointers attached to them (potentially zero, which is handy for
* invalidating the cache).
* The key itself is an inode:offset pair. The inode number corresponds to a
* backing device or a flash only volume. The offset is the ending offset of the
* extent within the inode - not the starting offset; this makes lookups
* slightly more convenient.
* Pointers contain the cache device id, the offset on that device, and an 8 bit
* generation number. More on the gen later.
* Index lookups are not fully abstracted - cache lookups in particular are
* still somewhat mixed in with the btree code, but things are headed in that
* direction.
* Updates are fairly well abstracted, though. There are two different ways of
* updating the btree; insert and replace.
* BTREE_INSERT will just take a list of keys and insert them into the btree -
* overwriting (possibly only partially) any extents they overlap with. This is
* used to update the index after a write.
* BTREE_REPLACE is really cmpxchg(); it inserts a key into the btree iff it is
* overwriting a key that matches another given key. This is used for inserting
* data into the cache after a cache miss, and for background writeback, and for
* the moving garbage collector.
* There is no "delete" operation; deleting things from the index is
* accomplished by either by invalidating pointers (by incrementing a bucket's
* gen) or by inserting a key with 0 pointers - which will overwrite anything
* previously present at that location in the index.
* This means that there are always stale/invalid keys in the btree. They're
* filtered out by the code that iterates through a btree node, and removed when
* a btree node is rewritten.
* Our unit of allocation is a bucket, and we we can't arbitrarily allocate and
* free smaller than a bucket - so, that's how big our btree nodes are.
* (If buckets are really big we'll only use part of the bucket for a btree node
* - no less than 1/4th - but a bucket still contains no more than a single
* btree node. I'd actually like to change this, but for now we rely on the
* bucket's gen for deleting btree nodes when we rewrite/split a node.)
* Anyways, btree nodes are big - big enough to be inefficient with a textbook
* btree implementation.
* The way this is solved is that btree nodes are internally log structured; we
* can append new keys to an existing btree node without rewriting it. This
* means each set of keys we write is sorted, but the node is not.
* We maintain this log structure in memory - keeping 1Mb of keys sorted would
* be expensive, and we have to distinguish between the keys we have written and
* the keys we haven't. So to do a lookup in a btree node, we have to search
* each sorted set. But we do merge written sets together lazily, so the cost of
* these extra searches is quite low (normally most of the keys in a btree node
* will be in one big set, and then there'll be one or two sets that are much
* smaller).
* This log structure makes bcache's btree more of a hybrid between a
* conventional btree and a compacting data structure, with some of the
* advantages of both.
* We can't just invalidate any bucket - it might contain dirty data or
* metadata. If it once contained dirty data, other writes might overwrite it
* later, leaving no valid pointers into that bucket in the index.
* Thus, the primary purpose of garbage collection is to find buckets to reuse.
* It also counts how much valid data it each bucket currently contains, so that
* allocation can reuse buckets sooner when they've been mostly overwritten.
* It also does some things that are really internal to the btree
* implementation. If a btree node contains pointers that are stale by more than
* some threshold, it rewrites the btree node to avoid the bucket's generation
* wrapping around. It also merges adjacent btree nodes if they're empty enough.
* Bcache's journal is not necessary for consistency; we always strictly
* order metadata writes so that the btree and everything else is consistent on
* disk in the event of an unclean shutdown, and in fact bcache had writeback
* caching (with recovery from unclean shutdown) before journalling was
* implemented.
* Rather, the journal is purely a performance optimization; we can't complete a
* write until we've updated the index on disk, otherwise the cache would be
* inconsistent in the event of an unclean shutdown. This means that without the
* journal, on random write workloads we constantly have to update all the leaf
* nodes in the btree, and those writes will be mostly empty (appending at most
* a few keys each) - highly inefficient in terms of amount of metadata writes,
* and it puts more strain on the various btree resorting/compacting code.
* The journal is just a log of keys we've inserted; on startup we just reinsert
* all the keys in the open journal entries. That means that when we're updating
* a node in the btree, we can wait until a 4k block of keys fills up before
* writing them out.
* For simplicity, we only journal updates to leaf nodes; updates to parent
* nodes are rare enough (since our leaf nodes are huge) that it wasn't worth
* the complexity to deal with journalling them (in particular, journal replay)
* - updates to non leaf nodes just happen synchronously (see btree_split()).
#define pr_fmt(fmt) "bcache: %s() " fmt, __func__
#include <linux/bio.h>
#include <linux/kobject.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/rbtree.h>
#include <linux/rwsem.h>
#include <linux/refcount.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <linux/kthread.h>
#include "bcache_ondisk.h"
#include "bset.h"
#include "util.h"
#include "closure.h"
struct bucket {
atomic_t pin;
uint16_t prio;
uint8_t gen;
uint8_t last_gc; /* Most out of date gen in the btree */
uint16_t gc_mark; /* Bitfield used by GC. See below for field */
* I'd use bitfields for these, but I don't trust the compiler not to screw me
* as multiple threads touch struct bucket without locking
BITMASK(GC_MARK, struct bucket, gc_mark, 0, 2);
#define GC_MARK_DIRTY 2
BITMASK(GC_SECTORS_USED, struct bucket, gc_mark, 2, GC_SECTORS_USED_SIZE);
BITMASK(GC_MOVE, struct bucket, gc_mark, 15, 1);
#include "journal.h"
#include "stats.h"
struct search;
struct btree;
struct keybuf;
struct keybuf_key {
struct rb_node node;
void *private;
struct keybuf {
struct bkey last_scanned;
spinlock_t lock;
* Beginning and end of range in rb tree - so that we can skip taking
* lock and checking the rb tree when we need to check for overlapping
* keys.
struct bkey start;
struct bkey end;
struct rb_root keys;
#define KEYBUF_NR 500
DECLARE_ARRAY_ALLOCATOR(struct keybuf_key, freelist, KEYBUF_NR);
struct bcache_device {
struct closure cl;
struct kobject kobj;
struct cache_set *c;
unsigned int id;
struct gendisk *disk;
unsigned long flags;
int nr_stripes;
unsigned int stripe_size;
atomic_t *stripe_sectors_dirty;
unsigned long *full_dirty_stripes;
struct bio_set bio_split;
unsigned int data_csum:1;
int (*cache_miss)(struct btree *b, struct search *s,
struct bio *bio, unsigned int sectors);
int (*ioctl)(struct bcache_device *d, fmode_t mode,
unsigned int cmd, unsigned long arg);
struct io {
/* Used to track sequential IO so it can be skipped */
struct hlist_node hash;
struct list_head lru;
unsigned long jiffies;
unsigned int sequential;
sector_t last;
enum stop_on_failure {
struct cached_dev {
struct list_head list;
struct bcache_device disk;
struct block_device *bdev;
struct cache_sb sb;
struct cache_sb_disk *sb_disk;
struct bio sb_bio;
struct bio_vec sb_bv[1];
struct closure sb_write;
struct semaphore sb_write_mutex;
/* Refcount on the cache set. Always nonzero when we're caching. */
refcount_t count;
struct work_struct detach;
* Device might not be running if it's dirty and the cache set hasn't
* showed up yet.
atomic_t running;
* Writes take a shared lock from start to finish; scanning for dirty
* data to refill the rb tree requires an exclusive lock.
struct rw_semaphore writeback_lock;
* Nonzero, and writeback has a refcount (d->count), iff there is dirty
* data in the cache. Protected by writeback_lock; must have an
* shared lock to set and exclusive lock to clear.
atomic_t has_dirty;
unsigned int cache_readahead_policy;
struct bch_ratelimit writeback_rate;
struct delayed_work writeback_rate_update;
/* Limit number of writeback bios in flight */
struct semaphore in_flight;
struct task_struct *writeback_thread;
struct workqueue_struct *writeback_write_wq;
struct keybuf writeback_keys;
struct task_struct *status_update_thread;
* Order the write-half of writeback operations strongly in dispatch
* order. (Maintain LBA order; don't allow reads completing out of
* order to re-order the writes...)
struct closure_waitlist writeback_ordering_wait;
atomic_t writeback_sequence_next;
/* For tracking sequential IO */
#define RECENT_IO_BITS 7
struct io io[RECENT_IO];
struct hlist_head io_hash[RECENT_IO + 1];
struct list_head io_lru;
spinlock_t io_lock;
struct cache_accounting accounting;
/* The rest of this all shows up in sysfs */
unsigned int sequential_cutoff;
unsigned int io_disable:1;
unsigned int verify:1;
unsigned int bypass_torture_test:1;
unsigned int partial_stripes_expensive:1;
unsigned int writeback_metadata:1;
unsigned int writeback_running:1;
unsigned int writeback_consider_fragment:1;
unsigned char writeback_percent;
unsigned int writeback_delay;
uint64_t writeback_rate_target;
int64_t writeback_rate_proportional;
int64_t writeback_rate_integral;
int64_t writeback_rate_integral_scaled;
int32_t writeback_rate_change;
unsigned int writeback_rate_update_seconds;
unsigned int writeback_rate_i_term_inverse;
unsigned int writeback_rate_p_term_inverse;
unsigned int writeback_rate_fp_term_low;
unsigned int writeback_rate_fp_term_mid;
unsigned int writeback_rate_fp_term_high;
unsigned int writeback_rate_minimum;
enum stop_on_failure stop_when_cache_set_failed;
atomic_t io_errors;
unsigned int error_limit;
unsigned int offline_seconds;
enum alloc_reserve {
struct cache {
struct cache_set *set;
struct cache_sb sb;
struct cache_sb_disk *sb_disk;
struct bio sb_bio;
struct bio_vec sb_bv[1];
struct kobject kobj;
struct block_device *bdev;
struct task_struct *alloc_thread;
struct closure prio;
struct prio_set *disk_buckets;
* When allocating new buckets, prio_write() gets first dibs - since we
* may not be allocate at all without writing priorities and gens.
* prio_last_buckets[] contains the last buckets we wrote priorities to
* (so gc can mark them as metadata), prio_buckets[] contains the
* buckets allocated for the next prio write.
uint64_t *prio_buckets;
uint64_t *prio_last_buckets;
* free: Buckets that are ready to be used
* free_inc: Incoming buckets - these are buckets that currently have
* cached data in them, and we can't reuse them until after we write
* their new gen to disk. After prio_write() finishes writing the new
* gens/prios, they'll be moved to the free list (and possibly discarded
* in the process)
DECLARE_FIFO(long, free_inc);
size_t fifo_last_bucket;
/* Allocation stuff: */
struct bucket *buckets;
DECLARE_HEAP(struct bucket *, heap);
* If nonzero, we know we aren't going to find any buckets to invalidate
* until a gc finishes - otherwise we could pointlessly burn a ton of
* cpu
unsigned int invalidate_needs_gc;
bool discard; /* Get rid of? */
struct journal_device journal;
/* The rest of this all shows up in sysfs */
#define IO_ERROR_SHIFT 20
atomic_t io_errors;
atomic_t io_count;
atomic_long_t meta_sectors_written;
atomic_long_t btree_sectors_written;
atomic_long_t sectors_written;
struct gc_stat {
size_t nodes;
size_t nodes_pre;
size_t key_bytes;
size_t nkeys;
uint64_t data; /* sectors */
unsigned int in_use; /* percent */
* Flag bits, for how the cache set is shutting down, and what phase it's at:
* CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching
* all the backing devices first (their cached data gets invalidated, and they
* won't automatically reattach).
* CACHE_SET_STOPPING always gets set first when we're closing down a cache set;
* we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e.
* flushing dirty data).
* CACHE_SET_RUNNING means all cache devices have been registered and journal
* replay is complete.
* CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all
* external and internal I/O should be denied when this flag is set.
struct cache_set {
struct closure cl;
struct list_head list;
struct kobject kobj;
struct kobject internal;
struct dentry *debug;
struct cache_accounting accounting;
unsigned long flags;
atomic_t idle_counter;
atomic_t at_max_writeback_rate;
struct cache *cache;
struct bcache_device **devices;
unsigned int devices_max_used;
atomic_t attached_dev_nr;
struct list_head cached_devs;
uint64_t cached_dev_sectors;
atomic_long_t flash_dev_dirty_sectors;
struct closure caching;
struct closure sb_write;
struct semaphore sb_write_mutex;
mempool_t search;
mempool_t bio_meta;
struct bio_set bio_split;
/* For the btree cache */
struct shrinker shrink;
/* For the btree cache and anything allocation related */
struct mutex bucket_lock;
/* log2(bucket_size), in sectors */
unsigned short bucket_bits;
/* log2(block_size), in sectors */
unsigned short block_bits;
* Default number of pages for a new btree node - may be less than a
* full bucket
unsigned int btree_pages;
* Lists of struct btrees; lru is the list for structs that have memory
* allocated for actual btree node, freed is for structs that do not.
* We never free a struct btree, except on shutdown - we just put it on
* the btree_cache_freed list and reuse it later. This simplifies the
* code, and it doesn't cost us much memory as the memory usage is
* dominated by buffers that hold the actual btree node data and those
* can be freed - and the number of struct btrees allocated is
* effectively bounded.
* btree_cache_freeable effectively is a small cache - we use it because
* high order page allocations can be rather expensive, and it's quite
* common to delete and allocate btree nodes in quick succession. It
* should never grow past ~2-3 nodes in practice.
struct list_head btree_cache;
struct list_head btree_cache_freeable;
struct list_head btree_cache_freed;
/* Number of elements in btree_cache + btree_cache_freeable lists */
unsigned int btree_cache_used;
* If we need to allocate memory for a new btree node and that
* allocation fails, we can cannibalize another node in the btree cache
* to satisfy the allocation - lock to guarantee only one thread does
* this at a time:
wait_queue_head_t btree_cache_wait;
struct task_struct *btree_cache_alloc_lock;
spinlock_t btree_cannibalize_lock;
* When we free a btree node, we increment the gen of the bucket the
* node is in - but we can't rewrite the prios and gens until we
* finished whatever it is we were doing, otherwise after a crash the
* btree node would be freed but for say a split, we might not have the
* pointers to the new nodes inserted into the btree yet.
* This is a refcount that blocks prio_write() until the new keys are
* written.
atomic_t prio_blocked;
wait_queue_head_t bucket_wait;
* For any bio we don't skip we subtract the number of sectors from
* rescale; when it hits 0 we rescale all the bucket priorities.
atomic_t rescale;
* used for GC, identify if any front side I/Os is inflight
atomic_t search_inflight;
* When we invalidate buckets, we use both the priority and the amount
* of good data to determine which buckets to reuse first - to weight
* those together consistently we keep track of the smallest nonzero
* priority of any bucket.
uint16_t min_prio;
* max(gen - last_gc) for all buckets. When it gets too big we have to
* gc to keep gens from wrapping around.
uint8_t need_gc;
struct gc_stat gc_stats;
size_t nbuckets;
size_t avail_nbuckets;
struct task_struct *gc_thread;
/* Where in the btree gc currently is */
struct bkey gc_done;
* For automatical garbage collection after writeback completed, this
* varialbe is used as bit fields,
* - 0000 0001b (BCH_ENABLE_AUTO_GC): enable gc after writeback
* - 0000 0010b (BCH_DO_AUTO_GC): do gc after writeback
* This is an optimization for following write request after writeback
* finished, but read hit rate dropped due to clean data on cache is
* discarded. Unless user explicitly sets it via sysfs, it won't be
* enabled.
#define BCH_DO_AUTO_GC 2
uint8_t gc_after_writeback;
* The allocation code needs gc_mark in struct bucket to be correct, but
* it's not while a gc is in progress. Protected by bucket_lock.
int gc_mark_valid;
/* Counts how many sectors bio_insert has added to the cache */
atomic_t sectors_to_gc;
wait_queue_head_t gc_wait;
struct keybuf moving_gc_keys;
/* Number of moving GC bios in flight */
struct semaphore moving_in_flight;
struct workqueue_struct *moving_gc_wq;
struct btree *root;
struct btree *verify_data;
struct bset *verify_ondisk;
struct mutex verify_lock;
uint8_t set_uuid[16];
unsigned int nr_uuids;
struct uuid_entry *uuids;
struct closure uuid_write;
struct semaphore uuid_write_mutex;
* A btree node on disk could have too many bsets for an iterator to fit
* on the stack - have to dynamically allocate them.
* bch_cache_set_alloc() will make sure the pool can allocate iterators
* equipped with enough room that can host
* (sb.bucket_size / sb.block_size)
* btree_iter_sets, which is more than static MAX_BSETS.
mempool_t fill_iter;
struct bset_sort_state sort;
/* List of buckets we're currently writing data to */
struct list_head data_buckets;
spinlock_t data_bucket_lock;
struct journal journal;
#define CONGESTED_MAX 1024
unsigned int congested_last_us;
atomic_t congested;
/* The rest of this all shows up in sysfs */
unsigned int congested_read_threshold_us;
unsigned int congested_write_threshold_us;
struct time_stats btree_gc_time;
struct time_stats btree_split_time;
struct time_stats btree_read_time;
atomic_long_t cache_read_races;
atomic_long_t writeback_keys_done;
atomic_long_t writeback_keys_failed;
atomic_long_t reclaim;
atomic_long_t reclaimed_journal_buckets;
atomic_long_t flush_write;
enum {
} on_error;
unsigned int error_limit;
unsigned int error_decay;
unsigned short journal_delay_ms;
bool expensive_debug_checks;
unsigned int verify:1;
unsigned int key_merging_disabled:1;
unsigned int gc_always_rewrite:1;
unsigned int shrinker_disabled:1;
unsigned int copy_gc_enabled:1;
unsigned int idle_max_writeback_rate_enabled:1;
struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS];
struct bbio {
unsigned int submit_time_us;
union {
struct bkey key;
uint64_t _pad[3];
* We only need pad = 3 here because we only ever carry around a
* single pointer - i.e. the pointer we're doing io to/from.
struct bio bio;
#define INITIAL_PRIO 32768U
#define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE)
#define btree_blocks(b) \
((unsigned int) (KEY_SIZE(&b->key) >> (b)->c->block_bits))
#define btree_default_blocks(c) \
((unsigned int) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits))
#define bucket_bytes(ca) ((ca)->sb.bucket_size << 9)
#define block_bytes(ca) ((ca)->sb.block_size << 9)
static inline unsigned int meta_bucket_pages(struct cache_sb *sb)
unsigned int n, max_pages;
max_pages = min_t(unsigned int,
__rounddown_pow_of_two(USHRT_MAX) / PAGE_SECTORS,
n = sb->bucket_size / PAGE_SECTORS;
if (n > max_pages)
n = max_pages;
return n;
static inline unsigned int meta_bucket_bytes(struct cache_sb *sb)
return meta_bucket_pages(sb) << PAGE_SHIFT;
#define prios_per_bucket(ca) \
((meta_bucket_bytes(&(ca)->sb) - sizeof(struct prio_set)) / \
sizeof(struct bucket_disk))
#define prio_buckets(ca) \
DIV_ROUND_UP((size_t) (ca)->sb.nbuckets, prios_per_bucket(ca))
static inline size_t sector_to_bucket(struct cache_set *c, sector_t s)
return s >> c->bucket_bits;
static inline sector_t bucket_to_sector(struct cache_set *c, size_t b)
return ((sector_t) b) << c->bucket_bits;
static inline sector_t bucket_remainder(struct cache_set *c, sector_t s)
return s & (c->cache->sb.bucket_size - 1);
static inline size_t PTR_BUCKET_NR(struct cache_set *c,
const struct bkey *k,
unsigned int ptr)
return sector_to_bucket(c, PTR_OFFSET(k, ptr));
static inline struct bucket *PTR_BUCKET(struct cache_set *c,
const struct bkey *k,
unsigned int ptr)
return c->cache->buckets + PTR_BUCKET_NR(c, k, ptr);
static inline uint8_t gen_after(uint8_t a, uint8_t b)
uint8_t r = a - b;
return r > 128U ? 0 : r;
static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k,
unsigned int i)
return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i));
static inline bool ptr_available(struct cache_set *c, const struct bkey *k,
unsigned int i)
return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && c->cache;
/* Btree key macros */
* This is used for various on disk data structures - cache_sb, prio_set, bset,
* jset: The checksum is _always_ the first 8 bytes of these structs
#define csum_set(i) \
bch_crc64(((void *) (i)) + sizeof(uint64_t), \
((void *) bset_bkey_last(i)) - \
(((void *) (i)) + sizeof(uint64_t)))
/* Error handling macros */
#define btree_bug(b, ...) \
do { \
if (bch_cache_set_error((b)->c, __VA_ARGS__)) \
dump_stack(); \
} while (0)
#define cache_bug(c, ...) \
do { \
if (bch_cache_set_error(c, __VA_ARGS__)) \
dump_stack(); \
} while (0)
#define btree_bug_on(cond, b, ...) \
do { \
if (cond) \
btree_bug(b, __VA_ARGS__); \
} while (0)
#define cache_bug_on(cond, c, ...) \
do { \
if (cond) \
cache_bug(c, __VA_ARGS__); \
} while (0)
#define cache_set_err_on(cond, c, ...) \
do { \
if (cond) \
bch_cache_set_error(c, __VA_ARGS__); \
} while (0)
/* Looping macros */
#define for_each_bucket(b, ca) \
for (b = (ca)->buckets + (ca)->sb.first_bucket; \
b < (ca)->buckets + (ca)->sb.nbuckets; b++)
static inline void cached_dev_put(struct cached_dev *dc)
if (refcount_dec_and_test(&dc->count))
static inline bool cached_dev_get(struct cached_dev *dc)
if (!refcount_inc_not_zero(&dc->count))
return false;
/* Paired with the mb in cached_dev_attach */
return true;
* bucket_gc_gen() returns the difference between the bucket's current gen and
* the oldest gen of any pointer into that bucket in the btree (last_gc).
static inline uint8_t bucket_gc_gen(struct bucket *b)
return b->gen - b->last_gc;
#define kobj_attribute_write(n, fn) \
static struct kobj_attribute ksysfs_##n = __ATTR(n, 0200, NULL, fn)
#define kobj_attribute_rw(n, show, store) \
static struct kobj_attribute ksysfs_##n = \
__ATTR(n, 0600, show, store)
static inline void wake_up_allocators(struct cache_set *c)
struct cache *ca = c->cache;
static inline void closure_bio_submit(struct cache_set *c,
struct bio *bio,
struct closure *cl)
if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) {
bio->bi_status = BLK_STS_IOERR;
* Prevent the kthread exits directly, and make sure when kthread_stop()
* is called to stop a kthread, it is still alive. If a kthread might be
* stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is
* necessary before the kthread returns.
static inline void wait_for_kthread_stop(void)
while (!kthread_should_stop()) {
/* Forward declarations */
void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio);
void bch_count_io_errors(struct cache *ca, blk_status_t error,
int is_read, const char *m);
void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
blk_status_t error, const char *m);
void bch_bbio_endio(struct cache_set *c, struct bio *bio,
blk_status_t error, const char *m);
void bch_bbio_free(struct bio *bio, struct cache_set *c);
struct bio *bch_bbio_alloc(struct cache_set *c);
void __bch_submit_bbio(struct bio *bio, struct cache_set *c);
void bch_submit_bbio(struct bio *bio, struct cache_set *c,
struct bkey *k, unsigned int ptr);
uint8_t bch_inc_gen(struct cache *ca, struct bucket *b);
void bch_rescale_priorities(struct cache_set *c, int sectors);
bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b);
void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b);
void __bch_bucket_free(struct cache *ca, struct bucket *b);
void bch_bucket_free(struct cache_set *c, struct bkey *k);
long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait);
int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
struct bkey *k, bool wait);
int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
struct bkey *k, bool wait);
bool bch_alloc_sectors(struct cache_set *c, struct bkey *k,
unsigned int sectors, unsigned int write_point,
unsigned int write_prio, bool wait);
bool bch_cached_dev_error(struct cached_dev *dc);
__printf(2, 3)
bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...);
int bch_prio_write(struct cache *ca, bool wait);
void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent);
extern struct workqueue_struct *bcache_wq;
extern struct workqueue_struct *bch_journal_wq;
extern struct workqueue_struct *bch_flush_wq;
extern struct mutex bch_register_lock;
extern struct list_head bch_cache_sets;
extern struct kobj_type bch_cached_dev_ktype;
extern struct kobj_type bch_flash_dev_ktype;
extern struct kobj_type bch_cache_set_ktype;
extern struct kobj_type bch_cache_set_internal_ktype;
extern struct kobj_type bch_cache_ktype;
void bch_cached_dev_release(struct kobject *kobj);
void bch_flash_dev_release(struct kobject *kobj);
void bch_cache_set_release(struct kobject *kobj);
void bch_cache_release(struct kobject *kobj);
int bch_uuid_write(struct cache_set *c);
void bcache_write_super(struct cache_set *c);
int bch_flash_dev_create(struct cache_set *c, uint64_t size);
int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,
uint8_t *set_uuid);
void bch_cached_dev_detach(struct cached_dev *dc);
int bch_cached_dev_run(struct cached_dev *dc);
void bcache_device_stop(struct bcache_device *d);
void bch_cache_set_unregister(struct cache_set *c);
void bch_cache_set_stop(struct cache_set *c);
struct cache_set *bch_cache_set_alloc(struct cache_sb *sb);
void bch_btree_cache_free(struct cache_set *c);
int bch_btree_cache_alloc(struct cache_set *c);
void bch_moving_init_cache_set(struct cache_set *c);
int bch_open_buckets_alloc(struct cache_set *c);
void bch_open_buckets_free(struct cache_set *c);
int bch_cache_allocator_start(struct cache *ca);
void bch_debug_exit(void);
void bch_debug_init(void);
void bch_request_exit(void);
int bch_request_init(void);
void bch_btree_exit(void);
int bch_btree_init(void);
#endif /* _BCACHE_H */