be628be095
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
929 lines
28 KiB
C
929 lines
28 KiB
C
#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/types.h>
|
|
#include <linux/workqueue.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 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
|
|
|
|
unsigned nr_stripes;
|
|
unsigned stripe_size;
|
|
atomic_t *stripe_sectors_dirty;
|
|
unsigned long *full_dirty_stripes;
|
|
|
|
unsigned long sectors_dirty_last;
|
|
long sectors_dirty_derivative;
|
|
|
|
struct bio_set *bio_split;
|
|
|
|
unsigned data_csum:1;
|
|
|
|
int (*cache_miss)(struct btree *, struct search *,
|
|
struct bio *, unsigned);
|
|
int (*ioctl) (struct bcache_device *, fmode_t, unsigned, unsigned long);
|
|
};
|
|
|
|
struct io {
|
|
/* Used to track sequential IO so it can be skipped */
|
|
struct hlist_node hash;
|
|
struct list_head lru;
|
|
|
|
unsigned long jiffies;
|
|
unsigned sequential;
|
|
sector_t last;
|
|
};
|
|
|
|
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. */
|
|
atomic_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;
|
|
|
|
/*
|
|
* Internal to the writeback code, so read_dirty() can keep track of
|
|
* where it's at.
|
|
*/
|
|
sector_t last_read;
|
|
|
|
/* Limit number of writeback bios in flight */
|
|
struct semaphore in_flight;
|
|
struct task_struct *writeback_thread;
|
|
|
|
struct keybuf writeback_keys;
|
|
|
|
/* 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 sequential_cutoff;
|
|
unsigned readahead;
|
|
|
|
unsigned verify:1;
|
|
unsigned bypass_torture_test:1;
|
|
|
|
unsigned partial_stripes_expensive:1;
|
|
unsigned writeback_metadata:1;
|
|
unsigned writeback_running:1;
|
|
unsigned char writeback_percent;
|
|
unsigned writeback_delay;
|
|
|
|
uint64_t writeback_rate_target;
|
|
int64_t writeback_rate_proportional;
|
|
int64_t writeback_rate_derivative;
|
|
int64_t writeback_rate_change;
|
|
|
|
unsigned writeback_rate_update_seconds;
|
|
unsigned writeback_rate_d_term;
|
|
unsigned writeback_rate_p_term_inverse;
|
|
};
|
|
|
|
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_buckets[] contains the last buckets we wrote priorities to (so
|
|
* gc can mark them as metadata), prio_next[] 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 invalidate_needs_gc;
|
|
|
|
bool discard; /* Get rid of? */
|
|
|
|
struct journal_device journal;
|
|
|
|
/* The rest of this all shows up in sysfs */
|
|
#define IO_ERROR_SHIFT 20
|
|
atomic_t io_errors;
|
|
atomic_t io_count;
|
|
|
|
atomic_long_t meta_sectors_written;
|
|
atomic_long_t btree_sectors_written;
|
|
atomic_long_t sectors_written;
|
|
};
|
|
|
|
struct gc_stat {
|
|
size_t nodes;
|
|
size_t key_bytes;
|
|
|
|
size_t nkeys;
|
|
uint64_t data; /* sectors */
|
|
unsigned 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.
|
|
*/
|
|
#define CACHE_SET_UNREGISTERING 0
|
|
#define CACHE_SET_STOPPING 1
|
|
#define CACHE_SET_RUNNING 2
|
|
|
|
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;
|
|
|
|
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;
|
|
struct list_head cached_devs;
|
|
uint64_t cached_dev_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 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 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;
|
|
/*
|
|
* 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;
|
|
|
|
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 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 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 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;
|
|
|
|
enum {
|
|
ON_ERROR_UNREGISTER,
|
|
ON_ERROR_PANIC,
|
|
} on_error;
|
|
unsigned error_limit;
|
|
unsigned error_decay;
|
|
|
|
unsigned short journal_delay_ms;
|
|
bool expensive_debug_checks;
|
|
unsigned verify:1;
|
|
unsigned key_merging_disabled:1;
|
|
unsigned gc_always_rewrite:1;
|
|
unsigned shrinker_disabled:1;
|
|
unsigned copy_gc_enabled:1;
|
|
|
|
#define BUCKET_HASH_BITS 12
|
|
struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS];
|
|
};
|
|
|
|
struct bbio {
|
|
unsigned 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) (KEY_SIZE(&b->key) >> (b)->c->block_bits))
|
|
|
|
#define btree_default_blocks(c) \
|
|
((unsigned) ((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 ptr)
|
|
{
|
|
return c->cache[PTR_DEV(k, ptr)];
|
|
}
|
|
|
|
static inline size_t PTR_BUCKET_NR(struct cache_set *c,
|
|
const struct bkey *k,
|
|
unsigned 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 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 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 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 (atomic_dec_and_test(&dc->count))
|
|
schedule_work(&dc->detach);
|
|
}
|
|
|
|
static inline bool cached_dev_get(struct cached_dev *dc)
|
|
{
|
|
if (!atomic_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, S_IWUSR, NULL, fn)
|
|
|
|
#define kobj_attribute_rw(n, show, store) \
|
|
static struct kobj_attribute ksysfs_##n = \
|
|
__ATTR(n, S_IWUSR|S_IRUSR, show, store)
|
|
|
|
static inline void wake_up_allocators(struct cache_set *c)
|
|
{
|
|
struct cache *ca;
|
|
unsigned i;
|
|
|
|
for_each_cache(ca, c, i)
|
|
wake_up_process(ca->alloc_thread);
|
|
}
|
|
|
|
/* Forward declarations */
|
|
|
|
void bch_count_io_errors(struct cache *, int, const char *);
|
|
void bch_bbio_count_io_errors(struct cache_set *, struct bio *,
|
|
int, const char *);
|
|
void bch_bbio_endio(struct cache_set *, struct bio *, int, const char *);
|
|
void bch_bbio_free(struct bio *, struct cache_set *);
|
|
struct bio *bch_bbio_alloc(struct cache_set *);
|
|
|
|
void __bch_submit_bbio(struct bio *, struct cache_set *);
|
|
void bch_submit_bbio(struct bio *, struct cache_set *, struct bkey *, unsigned);
|
|
|
|
uint8_t bch_inc_gen(struct cache *, struct bucket *);
|
|
void bch_rescale_priorities(struct cache_set *, int);
|
|
|
|
bool bch_can_invalidate_bucket(struct cache *, struct bucket *);
|
|
void __bch_invalidate_one_bucket(struct cache *, struct bucket *);
|
|
|
|
void __bch_bucket_free(struct cache *, struct bucket *);
|
|
void bch_bucket_free(struct cache_set *, struct bkey *);
|
|
|
|
long bch_bucket_alloc(struct cache *, unsigned, bool);
|
|
int __bch_bucket_alloc_set(struct cache_set *, unsigned,
|
|
struct bkey *, int, bool);
|
|
int bch_bucket_alloc_set(struct cache_set *, unsigned,
|
|
struct bkey *, int, bool);
|
|
bool bch_alloc_sectors(struct cache_set *, struct bkey *, unsigned,
|
|
unsigned, unsigned, bool);
|
|
|
|
__printf(2, 3)
|
|
bool bch_cache_set_error(struct cache_set *, const char *, ...);
|
|
|
|
void bch_prio_write(struct cache *);
|
|
void bch_write_bdev_super(struct cached_dev *, struct closure *);
|
|
|
|
extern struct workqueue_struct *bcache_wq;
|
|
extern const char * const bch_cache_modes[];
|
|
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 *);
|
|
void bch_flash_dev_release(struct kobject *);
|
|
void bch_cache_set_release(struct kobject *);
|
|
void bch_cache_release(struct kobject *);
|
|
|
|
int bch_uuid_write(struct cache_set *);
|
|
void bcache_write_super(struct cache_set *);
|
|
|
|
int bch_flash_dev_create(struct cache_set *c, uint64_t size);
|
|
|
|
int bch_cached_dev_attach(struct cached_dev *, struct cache_set *);
|
|
void bch_cached_dev_detach(struct cached_dev *);
|
|
void bch_cached_dev_run(struct cached_dev *);
|
|
void bcache_device_stop(struct bcache_device *);
|
|
|
|
void bch_cache_set_unregister(struct cache_set *);
|
|
void bch_cache_set_stop(struct cache_set *);
|
|
|
|
struct cache_set *bch_cache_set_alloc(struct cache_sb *);
|
|
void bch_btree_cache_free(struct cache_set *);
|
|
int bch_btree_cache_alloc(struct cache_set *);
|
|
void bch_moving_init_cache_set(struct cache_set *);
|
|
int bch_open_buckets_alloc(struct cache_set *);
|
|
void bch_open_buckets_free(struct cache_set *);
|
|
|
|
int bch_cache_allocator_start(struct cache *ca);
|
|
|
|
void bch_debug_exit(void);
|
|
int bch_debug_init(struct kobject *);
|
|
void bch_request_exit(void);
|
|
int bch_request_init(void);
|
|
|
|
#endif /* _BCACHE_H */
|