v4.19.13 snapshot.
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
new file mode 100644
index 0000000..954dad2
--- /dev/null
+++ b/drivers/md/bcache/bcache.h
@@ -0,0 +1,1011 @@
+/* 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 "\n", __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
+ unsigned 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 {
+ 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 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;
+
+ 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 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_sb sb;
+
+ struct cache *cache[MAX_CACHES_PER_SET];
+ struct cache *cache_by_alloc[MAX_CACHES_PER_SET];
+ int caches_loaded;
+
+ 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;
+
+ /*
+ * 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;
+
+ /*
+ * 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
+
+ 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
+ */
+ 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 flush_write;
+ atomic_long_t retry_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;
+
+#define BUCKET_HASH_BITS 12
+ struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS];
+
+ DECLARE_HEAP(struct btree *, flush_btree);
+};
+
+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_pages(c) ((c)->sb.bucket_size / PAGE_SECTORS)
+#define bucket_bytes(c) ((c)->sb.bucket_size << 9)
+#define block_bytes(c) ((c)->sb.block_size << 9)
+
+#define prios_per_bucket(c) \
+ ((bucket_bytes(c) - sizeof(struct prio_set)) / \
+ sizeof(struct bucket_disk))
+#define prio_buckets(c) \
+ DIV_ROUND_UP((size_t) (c)->sb.nbuckets, prios_per_bucket(c))
+
+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->sb.bucket_size - 1);
+}
+
+static inline struct cache *PTR_CACHE(struct cache_set *c,
+ const struct bkey *k,
+ unsigned int ptr)
+{
+ return c->cache[PTR_DEV(k, ptr)];
+}
+
+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_cache(ca, cs, iter) \
+ for (iter = 0; ca = cs->cache[iter], iter < (cs)->sb.nr_in_set; iter++)
+
+#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;
+ unsigned int i;
+
+ for_each_cache(ca, c, i)
+ 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;
+ }
+ generic_make_request(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, int n, bool wait);
+int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
+ struct bkey *k, int n, 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, ...);
+
+void bch_prio_write(struct cache *ca);
+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 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);
+void 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(struct kobject *kobj);
+void bch_request_exit(void);
+int bch_request_init(void);
+
+#endif /* _BCACHE_H */