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| -rw-r--r-- | drivers/md/bcache/bcache.h | 1050 |
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diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h new file mode 100644 index 000000000..5804a8e6e --- /dev/null +++ b/drivers/md/bcache/bcache.h @@ -0,0 +1,1050 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _BCACHE_H +#define _BCACHE_H + +/* + * SOME HIGH LEVEL CODE DOCUMENTATION: + * + * 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. + * + * BUCKETS/ALLOCATION: + * + * 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). + * + * THE BTREE: + * + * 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. + * + * BTREE NODES: + * + * 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. + * + * GARBAGE COLLECTION: + * + * 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. + * + * THE JOURNAL: + * + * 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/bcache.h> +#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 "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_RECLAIMABLE 1 +#define GC_MARK_DIRTY 2 +#define GC_MARK_METADATA 3 +#define GC_SECTORS_USED_SIZE 13 +#define MAX_GC_SECTORS_USED (~(~0ULL << GC_SECTORS_USED_SIZE)) +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; + BKEY_PADDED(key); + 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; +#define BCACHEDEVNAME_SIZE 12 + char name[BCACHEDEVNAME_SIZE]; + + struct gendisk *disk; + + unsigned long flags; +#define BCACHE_DEV_CLOSING 0 +#define BCACHE_DEV_DETACHING 1 +#define BCACHE_DEV_UNLINK_DONE 2 +#define BCACHE_DEV_WB_RUNNING 3 +#define BCACHE_DEV_RATE_DW_RUNNING 4 + int nr_stripes; +#define BCH_MIN_STRIPE_SZ ((4 << 20) >> SECTOR_SHIFT) + 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 { + BCH_CACHED_DEV_STOP_AUTO = 0, + BCH_CACHED_DEV_STOP_ALWAYS, + BCH_CACHED_DEV_STOP_MODE_MAX, +}; + +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; + +#define BCH_CACHE_READA_ALL 0 +#define BCH_CACHE_READA_META_ONLY 1 + 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 +#define RECENT_IO (1 << RECENT_IO_BITS) + 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 readahead; + + 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 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_minimum; + + enum stop_on_failure stop_when_cache_set_failed; +#define DEFAULT_CACHED_DEV_ERROR_LIMIT 64 + atomic_t io_errors; + unsigned int error_limit; + unsigned int offline_seconds; + + char backing_dev_name[BDEVNAME_SIZE]; +}; + +enum alloc_reserve { + RESERVE_BTREE, + RESERVE_PRIO, + RESERVE_MOVINGGC, + RESERVE_NONE, + RESERVE_NR, +}; + +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)[RESERVE_NR]; + 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; + + char cache_dev_name[BDEVNAME_SIZE]; +}; + +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. + * + */ +#define CACHE_SET_UNREGISTERING 0 +#define CACHE_SET_STOPPING 1 +#define CACHE_SET_RUNNING 2 +#define CACHE_SET_IO_DISABLE 3 + +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_ENABLE_AUTO_GC 1 +#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; + +#ifdef CONFIG_BCACHE_DEBUG + struct btree *verify_data; + struct bset *verify_ondisk; + struct mutex verify_lock; +#endif + + uint8_t set_uuid[16]; + unsigned int nr_uuids; + struct uuid_entry *uuids; + BKEY_PADDED(uuid_bucket); + 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_UNREGISTER, + ON_ERROR_PANIC, + } on_error; +#define DEFAULT_IO_ERROR_LIMIT 8 + 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; + +#define BUCKET_HASH_BITS 12 + 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 BTREE_PRIO USHRT_MAX +#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, + MAX_ORDER_NR_PAGES); + + 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 struct cache *PTR_CACHE(struct cache_set *c, + const struct bkey *k, + unsigned int ptr) +{ + return c->cache; +} + +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 PTR_CACHE(c, k, ptr)->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) && PTR_CACHE(c, k, i); +} + +/* 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)) + schedule_work(&dc->detach); +} + +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 */ + smp_mb__after_atomic(); + 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 BUCKET_GC_GEN_MAX 96U + +#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; + + wake_up_process(ca->alloc_thread); +} + +static inline void closure_bio_submit(struct cache_set *c, + struct bio *bio, + struct closure *cl) +{ + closure_get(cl); + if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) { + bio->bi_status = BLK_STS_IOERR; + bio_endio(bio); + return; + } + submit_bio_noacct(bio); +} + +/* + * 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()) { + set_current_state(TASK_INTERRUPTIBLE); + schedule(); + } +} + +/* 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 */ |