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Diffstat (limited to 'libbcache/bcache.h')
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diff --git a/libbcache/bcache.h b/libbcache/bcache.h new file mode 100644 index 0000000..9a43a69 --- /dev/null +++ b/libbcache/bcache.h @@ -0,0 +1,831 @@ +#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()). + */ + +#undef pr_fmt +#define pr_fmt(fmt) "bcache: %s() " fmt "\n", __func__ + +#include <linux/bug.h> +#include <linux/bcache.h> +#include <linux/bio.h> +#include <linux/kobject.h> +#include <linux/lglock.h> +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/percpu-refcount.h> +#include <linux/radix-tree.h> +#include <linux/rbtree.h> +#include <linux/rhashtable.h> +#include <linux/rwsem.h> +#include <linux/seqlock.h> +#include <linux/shrinker.h> +#include <linux/types.h> +#include <linux/workqueue.h> + +#include "bset.h" +#include "fifo.h" +#include "util.h" +#include "closure.h" +#include "opts.h" + +#include <linux/dynamic_fault.h> + +#define cache_set_init_fault(name) \ + dynamic_fault("bcache:cache_set_init:" name) +#define bch_meta_read_fault(name) \ + dynamic_fault("bcache:meta:read:" name) +#define bch_meta_write_fault(name) \ + dynamic_fault("bcache:meta:write:" name) + +#define bch_fmt(_c, fmt) \ + "bcache (%s): " fmt "\n", ((_c)->name) + +#define bch_info(c, fmt, ...) \ + printk(KERN_INFO bch_fmt(c, fmt), ##__VA_ARGS__) +#define bch_notice(c, fmt, ...) \ + printk(KERN_NOTICE bch_fmt(c, fmt), ##__VA_ARGS__) +#define bch_warn(c, fmt, ...) \ + printk(KERN_WARNING bch_fmt(c, fmt), ##__VA_ARGS__) +#define bch_err(c, fmt, ...) \ + printk(KERN_ERR bch_fmt(c, fmt), ##__VA_ARGS__) + +#define bch_verbose(c, fmt, ...) \ +do { \ + if ((c)->opts.verbose_recovery) \ + bch_info(c, fmt, ##__VA_ARGS__); \ +} while (0) + +/* Parameters that are useful for debugging, but should always be compiled in: */ +#define BCH_DEBUG_PARAMS_ALWAYS() \ + BCH_DEBUG_PARAM(key_merging_disabled, \ + "Disables merging of extents") \ + BCH_DEBUG_PARAM(btree_gc_always_rewrite, \ + "Causes mark and sweep to compact and rewrite every " \ + "btree node it traverses") \ + BCH_DEBUG_PARAM(btree_gc_rewrite_disabled, \ + "Disables rewriting of btree nodes during mark and sweep")\ + BCH_DEBUG_PARAM(btree_gc_coalesce_disabled, \ + "Disables coalescing of btree nodes") \ + BCH_DEBUG_PARAM(btree_shrinker_disabled, \ + "Disables the shrinker callback for the btree node cache") + +/* Parameters that should only be compiled in in debug mode: */ +#define BCH_DEBUG_PARAMS_DEBUG() \ + BCH_DEBUG_PARAM(expensive_debug_checks, \ + "Enables various runtime debugging checks that " \ + "significantly affect performance") \ + BCH_DEBUG_PARAM(debug_check_bkeys, \ + "Run bkey_debugcheck (primarily checking GC/allocation "\ + "information) when iterating over keys") \ + BCH_DEBUG_PARAM(version_stress_test, \ + "Assigns random version numbers to newly written " \ + "extents, to test overlapping extent cases") \ + BCH_DEBUG_PARAM(verify_btree_ondisk, \ + "Reread btree nodes at various points to verify the " \ + "mergesort in the read path against modifications " \ + "done in memory") \ + +#define BCH_DEBUG_PARAMS_ALL() BCH_DEBUG_PARAMS_ALWAYS() BCH_DEBUG_PARAMS_DEBUG() + +#ifdef CONFIG_BCACHE_DEBUG +#define BCH_DEBUG_PARAMS() BCH_DEBUG_PARAMS_ALL() +#else +#define BCH_DEBUG_PARAMS() BCH_DEBUG_PARAMS_ALWAYS() +#endif + +/* name, frequency_units, duration_units */ +#define BCH_TIME_STATS() \ + BCH_TIME_STAT(mca_alloc, sec, us) \ + BCH_TIME_STAT(mca_scan, sec, ms) \ + BCH_TIME_STAT(btree_gc, sec, ms) \ + BCH_TIME_STAT(btree_coalesce, sec, ms) \ + BCH_TIME_STAT(btree_split, sec, us) \ + BCH_TIME_STAT(btree_sort, ms, us) \ + BCH_TIME_STAT(btree_read, ms, us) \ + BCH_TIME_STAT(journal_write, us, us) \ + BCH_TIME_STAT(journal_delay, ms, us) \ + BCH_TIME_STAT(journal_blocked, sec, ms) \ + BCH_TIME_STAT(journal_flush_seq, us, us) + +#include "alloc_types.h" +#include "blockdev_types.h" +#include "buckets_types.h" +#include "clock_types.h" +#include "io_types.h" +#include "journal_types.h" +#include "keylist_types.h" +#include "keybuf_types.h" +#include "move_types.h" +#include "stats_types.h" +#include "super_types.h" + +/* 256k, in sectors */ +#define BTREE_NODE_SIZE_MAX 512 + +/* + * Number of nodes we might have to allocate in a worst case btree split + * operation - we split all the way up to the root, then allocate a new root. + */ +#define btree_reserve_required_nodes(depth) (((depth) + 1) * 2 + 1) + +/* Number of nodes btree coalesce will try to coalesce at once */ +#define GC_MERGE_NODES 4U + +/* Maximum number of nodes we might need to allocate atomically: */ +#define BTREE_RESERVE_MAX \ + (btree_reserve_required_nodes(BTREE_MAX_DEPTH) + GC_MERGE_NODES) + +/* Size of the freelist we allocate btree nodes from: */ +#define BTREE_NODE_RESERVE (BTREE_RESERVE_MAX * 2) + +struct btree; +struct cache; + +enum gc_phase { + GC_PHASE_PENDING_DELETE = BTREE_ID_NR + 1, + GC_PHASE_DONE +}; + +struct gc_pos { + enum gc_phase phase; + struct bpos pos; + unsigned level; +}; + +struct cache_member_cpu { + u64 nbuckets; /* device size */ + u16 first_bucket; /* index of first bucket used */ + u16 bucket_size; /* sectors */ + u8 state; + u8 tier; + u8 replication_set; + u8 has_metadata; + u8 has_data; + u8 replacement; + u8 discard; + u8 valid; +}; + +struct cache_member_rcu { + struct rcu_head rcu; + unsigned nr_in_set; + struct cache_member_cpu m[]; +}; + +/* cache->flags: */ +enum { + CACHE_DEV_REMOVING, + CACHE_DEV_FORCE_REMOVE, +}; + +struct cache { + struct percpu_ref ref; + struct rcu_head free_rcu; + struct work_struct free_work; + struct work_struct remove_work; + unsigned long flags; + + struct cache_set *set; + + struct cache_group self; + + /* + * Cached version of this device's member info from superblock + * Committed by write_super() + */ + struct { + u8 nr_this_dev; + } sb; + struct cache_member_cpu mi; + + struct bcache_superblock disk_sb; + + struct kobject kobj; + + /* biosets used in cloned bios for replicas and moving_gc */ + struct bio_set replica_set; + + struct task_struct *alloc_thread; + + 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). + */ + u64 *prio_buckets; + u64 *prio_last_buckets; + spinlock_t prio_buckets_lock; + struct bio *bio_prio; + + /* + * 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); + spinlock_t freelist_lock; + + size_t fifo_last_bucket; + + /* Allocation stuff: */ + + /* most out of date gen in the btree */ + u8 *oldest_gens; + struct bucket *buckets; + unsigned short bucket_bits; /* ilog2(bucket_size) */ + + /* last calculated minimum prio */ + u16 min_prio[2]; + + /* + * Bucket book keeping. The first element is updated by GC, the + * second contains a saved copy of the stats from the beginning + * of GC. + */ + struct bucket_stats_cache __percpu *bucket_stats_percpu; + struct bucket_stats_cache bucket_stats_cached; + + atomic_long_t saturated_count; + size_t inc_gen_needs_gc; + + struct mutex heap_lock; + DECLARE_HEAP(struct bucket_heap_entry, heap); + + /* Moving GC: */ + struct task_struct *moving_gc_read; + + struct bch_pd_controller moving_gc_pd; + + /* Tiering: */ + struct write_point tiering_write_point; + + struct write_point copygc_write_point; + + struct journal_device journal; + + struct work_struct io_error_work; + + /* The rest of this all shows up in sysfs */ +#define IO_ERROR_SHIFT 20 + atomic_t io_errors; + atomic_t io_count; + + atomic64_t meta_sectors_written; + atomic64_t btree_sectors_written; + u64 __percpu *sectors_written; +}; + +/* + * Flag bits for what phase of startup/shutdown the cache set is at, how we're + * shutting down, etc.: + * + * 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. + */ +enum { + /* Startup: */ + CACHE_SET_INITIAL_GC_DONE, + CACHE_SET_RUNNING, + + /* Shutdown: */ + CACHE_SET_UNREGISTERING, + CACHE_SET_STOPPING, + CACHE_SET_RO, + CACHE_SET_RO_COMPLETE, + CACHE_SET_EMERGENCY_RO, + CACHE_SET_WRITE_DISABLE_COMPLETE, + CACHE_SET_GC_STOPPING, + CACHE_SET_GC_FAILURE, + CACHE_SET_BDEV_MOUNTED, + CACHE_SET_ERROR, + CACHE_SET_FSCK_FIXED_ERRORS, +}; + +struct btree_debug { + unsigned id; + struct dentry *btree; + struct dentry *btree_format; + struct dentry *failed; +}; + +struct cache_set { + struct closure cl; + + struct list_head list; + struct kobject kobj; + struct kobject internal; + struct kobject opts_dir; + struct kobject time_stats; + struct completion *stop_completion; + unsigned long flags; + + int minor; + struct device *chardev; + struct super_block *vfs_sb; + char name[40]; + + /* Counts outstanding writes, for clean transition to read-only */ + struct percpu_ref writes; + struct work_struct read_only_work; + + struct cache __rcu *cache[MAX_CACHES_PER_SET]; + + struct mutex mi_lock; + struct cache_member_rcu __rcu *members; + struct cache_member *disk_mi; /* protected by register_lock */ + + struct cache_set_opts opts; + + /* + * Cached copy in native endianness: + * Set by cache_sb_to_cache_set: + */ + struct { + u16 block_size; + u16 btree_node_size; + + u8 nr_in_set; + u8 clean; + + u8 meta_replicas_have; + u8 data_replicas_have; + + u8 str_hash_type; + } sb; + + struct cache_sb disk_sb; + unsigned short block_bits; /* ilog2(block_size) */ + + struct closure sb_write; + struct semaphore sb_write_mutex; + + struct backing_dev_info bdi; + + /* BTREE CACHE */ + struct bio_set btree_read_bio; + + struct btree_root btree_roots[BTREE_ID_NR]; + struct mutex btree_root_lock; + + bool btree_cache_table_init_done; + struct rhashtable btree_cache_table; + + /* + * 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 mutex btree_cache_lock; + 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 btree_cache_used; + unsigned btree_cache_reserve; + struct shrinker btree_cache_shrink; + + /* + * 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: + */ + struct closure_waitlist mca_wait; + struct task_struct *btree_cache_alloc_lock; + + mempool_t btree_reserve_pool; + + /* + * Cache of allocated btree nodes - if we allocate a btree node and + * don't use it, if we free it that space can't be reused until going + * _all_ the way through the allocator (which exposes us to a livelock + * when allocating btree reserves fail halfway through) - instead, we + * can stick them here: + */ + struct btree_alloc { + struct open_bucket *ob; + BKEY_PADDED(k); + } btree_reserve_cache[BTREE_NODE_RESERVE * 2]; + unsigned btree_reserve_cache_nr; + struct mutex btree_reserve_cache_lock; + + mempool_t btree_interior_update_pool; + struct list_head btree_interior_update_list; + struct mutex btree_interior_update_lock; + + struct workqueue_struct *wq; + /* copygc needs its own workqueue for index updates.. */ + struct workqueue_struct *copygc_wq; + + /* ALLOCATION */ + struct bch_pd_controller foreground_write_pd; + struct delayed_work pd_controllers_update; + unsigned pd_controllers_update_seconds; + spinlock_t foreground_write_pd_lock; + struct bch_write_op *write_wait_head; + struct bch_write_op *write_wait_tail; + + struct timer_list foreground_write_wakeup; + + /* + * These contain all r/w devices - i.e. devices we can currently + * allocate from: + */ + struct cache_group cache_all; + struct cache_group cache_tiers[CACHE_TIERS]; + + u64 capacity; /* sectors */ + + /* + * When capacity _decreases_ (due to a disk being removed), we + * increment capacity_gen - this invalidates outstanding reservations + * and forces them to be revalidated + */ + u32 capacity_gen; + + atomic64_t sectors_available; + + struct bucket_stats_cache_set __percpu *bucket_stats_percpu; + struct bucket_stats_cache_set bucket_stats_cached; + struct lglock bucket_stats_lock; + + struct mutex bucket_lock; + + struct closure_waitlist freelist_wait; + + + /* + * 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. + */ + struct prio_clock prio_clock[2]; + + struct io_clock io_clock[2]; + + /* SECTOR ALLOCATOR */ + struct list_head open_buckets_open; + struct list_head open_buckets_free; + unsigned open_buckets_nr_free; + struct closure_waitlist open_buckets_wait; + spinlock_t open_buckets_lock; + struct open_bucket open_buckets[OPEN_BUCKETS_COUNT]; + + struct write_point btree_write_point; + + struct write_point write_points[WRITE_POINT_COUNT]; + struct write_point promote_write_point; + + /* + * This write point is used for migrating data off a device + * and can point to any other device. + * We can't use the normal write points because those will + * gang up n replicas, and for migration we want only one new + * replica. + */ + struct write_point migration_write_point; + + /* GARBAGE COLLECTION */ + struct task_struct *gc_thread; + atomic_t kick_gc; + + /* + * Tracks GC's progress - everything in the range [ZERO_KEY..gc_cur_pos] + * has been marked by GC. + * + * gc_cur_phase is a superset of btree_ids (BTREE_ID_EXTENTS etc.) + * + * gc_cur_phase == GC_PHASE_DONE indicates that gc is finished/not + * currently running, and gc marks are currently valid + * + * Protected by gc_pos_lock. Only written to by GC thread, so GC thread + * can read without a lock. + */ + seqcount_t gc_pos_lock; + struct gc_pos gc_pos; + + /* + * The allocation code needs gc_mark in struct bucket to be correct, but + * it's not while a gc is in progress. + */ + struct rw_semaphore gc_lock; + + /* IO PATH */ + struct bio_set bio_read; + struct bio_set bio_read_split; + struct bio_set bio_write; + struct mutex bio_bounce_pages_lock; + mempool_t bio_bounce_pages; + + mempool_t lz4_workspace_pool; + void *zlib_workspace; + struct mutex zlib_workspace_lock; + mempool_t compression_bounce[2]; + struct bio_decompress_worker __percpu + *bio_decompress_worker; + + /* For punting bio submissions to workqueue, io.c */ + struct bio_list bio_submit_list; + struct work_struct bio_submit_work; + spinlock_t bio_submit_lock; + + struct bio_list read_retry_list; + struct work_struct read_retry_work; + spinlock_t read_retry_lock; + + /* FILESYSTEM */ + wait_queue_head_t writeback_wait; + atomic_t writeback_pages; + unsigned writeback_pages_max; + atomic_long_t nr_inodes; + + /* TIERING */ + struct task_struct *tiering_read; + struct bch_pd_controller tiering_pd; + + /* NOTIFICATIONS */ + struct mutex uevent_lock; + struct kobj_uevent_env uevent_env; + + /* DEBUG JUNK */ + struct dentry *debug; + struct btree_debug btree_debug[BTREE_ID_NR]; +#ifdef CONFIG_BCACHE_DEBUG + struct btree *verify_data; + struct btree_node *verify_ondisk; + struct mutex verify_lock; +#endif + + u64 unused_inode_hint; + + /* + * A btree node on disk could have too many bsets for an iterator to fit + * on the stack - have to dynamically allocate them + */ + mempool_t fill_iter; + + mempool_t btree_bounce_pool; + + struct journal journal; + + unsigned bucket_journal_seq; + + /* CACHING OTHER BLOCK DEVICES */ + mempool_t search; + struct radix_tree_root devices; + struct list_head cached_devs; + u64 cached_dev_sectors; + struct closure caching; + +#define CONGESTED_MAX 1024 + unsigned congested_last_us; + atomic_t congested; + + /* The rest of this all shows up in sysfs */ + unsigned congested_read_threshold_us; + unsigned congested_write_threshold_us; + + struct cache_accounting accounting; + atomic_long_t cache_read_races; + atomic_long_t writeback_keys_done; + atomic_long_t writeback_keys_failed; + + unsigned error_limit; + unsigned error_decay; + + unsigned foreground_write_ratelimit_enabled:1; + unsigned copy_gc_enabled:1; + unsigned tiering_enabled:1; + unsigned tiering_percent; + + /* + * foreground writes will be throttled when the number of free + * buckets is below this percentage + */ + unsigned foreground_target_percent; + +#define BCH_DEBUG_PARAM(name, description) bool name; + BCH_DEBUG_PARAMS_ALL() +#undef BCH_DEBUG_PARAM + +#define BCH_TIME_STAT(name, frequency_units, duration_units) \ + struct time_stats name##_time; + BCH_TIME_STATS() +#undef BCH_TIME_STAT +}; + +static inline unsigned bucket_pages(const struct cache *ca) +{ + return ca->mi.bucket_size / PAGE_SECTORS; +} + +static inline unsigned bucket_bytes(const struct cache *ca) +{ + return ca->mi.bucket_size << 9; +} + +static inline unsigned block_bytes(const struct cache_set *c) +{ + return c->sb.block_size << 9; +} + +#endif /* _BCACHE_H */ |