- 根目录:
- drivers
- md
- bcache
- btree.c
/*
* Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
*
* Uses a block device as cache for other block devices; optimized for SSDs.
* All allocation is done in buckets, which should match the erase block size
* of the device.
*
* Buckets containing cached data are kept on a heap sorted by priority;
* bucket priority is increased on cache hit, and periodically all the buckets
* on the heap have their priority scaled down. This currently is just used as
* an LRU but in the future should allow for more intelligent heuristics.
*
* Buckets have an 8 bit counter; freeing is accomplished by incrementing the
* counter. Garbage collection is used to remove stale pointers.
*
* Indexing is done via a btree; nodes are not necessarily fully sorted, rather
* as keys are inserted we only sort the pages that have not yet been written.
* When garbage collection is run, we resort the entire node.
*
* All configuration is done via sysfs; see Documentation/bcache.txt.
*/
#include "bcache.h"
#include "btree.h"
#include "debug.h"
#include "extents.h"
#include <linux/slab.h>
#include <linux/bitops.h>
#include <linux/freezer.h>
#include <linux/hash.h>
#include <linux/kthread.h>
#include <linux/prefetch.h>
#include <linux/random.h>
#include <linux/rcupdate.h>
#include <trace/events/bcache.h>
/*
* Todo:
* register_bcache: Return errors out to userspace correctly
*
* Writeback: don't undirty key until after a cache flush
*
* Create an iterator for key pointers
*
* On btree write error, mark bucket such that it won't be freed from the cache
*
* Journalling:
* Check for bad keys in replay
* Propagate barriers
* Refcount journal entries in journal_replay
*
* Garbage collection:
* Finish incremental gc
* Gc should free old UUIDs, data for invalid UUIDs
*
* Provide a way to list backing device UUIDs we have data cached for, and
* probably how long it's been since we've seen them, and a way to invalidate
* dirty data for devices that will never be attached again
*
* Keep 1 min/5 min/15 min statistics of how busy a block device has been, so
* that based on that and how much dirty data we have we can keep writeback
* from being starved
*
* Add a tracepoint or somesuch to watch for writeback starvation
*
* When btree depth > 1 and splitting an interior node, we have to make sure
* alloc_bucket() cannot fail. This should be true but is not completely
* obvious.
*
* Plugging?
*
* If data write is less than hard sector size of ssd, round up offset in open
* bucket to the next whole sector
*
* Superblock needs to be fleshed out for multiple cache devices
*
* Add a sysfs tunable for the number of writeback IOs in flight
*
* Add a sysfs tunable for the number of open data buckets
*
* IO tracking: Can we track when one process is doing io on behalf of another?
* IO tracking: Don't use just an average, weigh more recent stuff higher
*
* Test module load/unload
*/
#define MAX_NEED_GC 64
#define MAX_SAVE_PRIO 72
#define PTR_DIRTY_BIT (((uint64_t) 1 << 36))
#define PTR_HASH(c, k) \
(((k)->ptr[0] >> c->bucket_bits) | PTR_GEN(k, 0))
#define insert_lock(s, b) ((b)->level <= (s)->lock)
/*
* These macros are for recursing down the btree - they handle the details of
* locking and looking up nodes in the cache for you. They're best treated as
* mere syntax when reading code that uses them.
*
* op->lock determines whether we take a read or a write lock at a given depth.
* If you've got a read lock and find that you need a write lock (i.e. you're
* going to have to split), set op->lock and return -EINTR; btree_root() will
* call you again and you'll have the correct lock.
*/
/**
* btree - recurse down the btree on a specified key
* @fn: function to call, which will be passed the child node
* @key: key to recurse on
* @b: parent btree node
* @op: pointer to struct btree_op
*/
#define btree(fn, key, b, op, ...) \
({ \
int _r, l = (b)->level - 1; \
bool _w = l <= (op)->lock; \
struct btree *_child = bch_btree_node_get((b)->c, op, key, l, \
_w, b); \
if (!IS_ERR(_child)) { \
_r = bch_btree_ ## fn(_child, op, ##__VA_ARGS__); \
rw_unlock(_w, _child); \
} else \
_r = PTR_ERR(_child); \
_r; \
})
/**
* btree_root - call a function on the root of the btree
* @fn: function to call, which will be passed the child node
* @c: cache set
* @op: pointer to struct btree_op
*/
#define btree_root(fn, c, op, ...) \
({ \
int _r = -EINTR; \
do { \
struct btree *_b = (c)->root; \
bool _w = insert_lock(op, _b); \
rw_lock(_w, _b, _b->level); \
if (_b == (c)->root && \
_w == insert_lock(op, _b)) { \
_r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__); \
} \
rw_unlock(_w, _b); \
bch_cannibalize_unlock(c); \
if (_r == -EINTR) \
schedule(); \
} while (_r == -EINTR); \
\
finish_wait(&(c)->btree_cache_wait, &(op)->wait); \
_r; \
})
static inline struct bset *write_block(struct btree *b)
{
return ((void *) btree_bset_first(b)) + b->written * block_bytes(b->c);
}
static void bch_btree_init_next(struct btree *b)
{
/* If not a leaf node, always sort */
if (b->level && b->keys.nsets)
bch_btree_sort(&b->keys, &b->c->sort);
else
bch_btree_sort_lazy(&b->keys, &b->c->sort);
if (b->written < btree_blocks(b))
bch_bset_init_next(&b->keys, write_block(b),
bset_magic(&b->c->sb));
}
/* Btree key manipulation */
void bkey_put(struct cache_set *c, struct bkey *k)
{
unsigned i;
for (i = 0; i < KEY_PTRS(k); i++)
if (ptr_available(c, k, i))
atomic_dec_bug(&PTR_BUCKET(c, k, i)->pin);
}
/* Btree IO */
static uint64_t btree_csum_set(struct btree *b, struct bset *i)
{
uint64_t crc = b->key.ptr[0];
void *data = (void *) i + 8, *end = bset_bkey_last(i);
crc = bch_crc64_update(crc, data, end - data);
return crc ^ 0xffffffffffffffffULL;
}
void bch_btree_node_read_done(struct btree *b)
{
const char *err = "bad btree header";
struct bset *i = btree_bset_first(b);
struct btree_iter *iter;
iter = mempool_alloc(b->c->fill_iter, GFP_NOIO);
iter->size = b->c->sb.bucket_size / b->c->sb.block_size;
iter->used = 0;
#ifdef CONFIG_BCACHE_DEBUG
iter->b = &b->keys;
#endif
if (!i->seq)
goto err;
for (;
b->written < btree_blocks(b) && i->seq == b->keys.set[0].data->seq;
i = write_block(b)) {
err = "unsupported bset version";
if (i->version > BCACHE_BSET_VERSION)
goto err;
err = "bad btree header";
if (b->written + set_blocks(i, block_bytes(b->c)) >
btree_blocks(b))
goto err;
err = "bad magic";
if (i->magic != bset_magic(&b->c->sb))
goto err;
err = "bad checksum";
switch (i->version) {
case 0:
if (i->csum != csum_set(i))
goto err;
break;
case BCACHE_BSET_VERSION:
if (i->csum != btree_csum_set(b, i))
goto err;
break;
}
err = "empty set";
if (i != b->keys.set[0].data && !i->keys)
goto err;
bch_btree_iter_push(iter, i->start, bset_bkey_last(i));
b->written += set_blocks(i, block_bytes(b->c));
}
err = "corrupted btree";
for (i = write_block(b);
bset_sector_offset(&b->keys, i) < KEY_SIZE(&b->key);
i = ((void *) i) + block_bytes(b->c))
if (i->seq == b->keys.set[0].data->seq)
goto err;
bch_btree_sort_and_fix_extents(&b->keys, iter, &b->c->sort);
i = b->keys.set[0].data;
err = "short btree key";
if (b->keys.set[0].size &&
bkey_cmp(&b->key, &b->keys.set[0].end) < 0)
goto err;
if (b->written < btree_blocks(b))
bch_bset_init_next(&b->keys, write_block(b),
bset_magic(&b->c->sb));
out:
mempool_free(iter, b->c->fill_iter);
return;
err:
set_btree_node_io_error(b);
bch_cache_set_error(b->c, "%s at bucket %zu, block %u, %u keys",
err, PTR_BUCKET_NR(b->c, &b->key, 0),
bset_block_offset(b, i), i->keys);
goto out;
}
static void btree_node_read_endio(struct bio *bio)
{
struct closure *cl = bio->bi_private;
closure_put(cl);
}
static void bch_btree_node_read(struct btree *b)
{
uint64_t start_time = local_clock();
struct closure cl;
struct bio *bio;
trace_bcache_btree_read(b);
closure_init_stack(&cl);
bio = bch_bbio_alloc(b->c);
bio->bi_rw = REQ_META|READ_SYNC;
bio->bi_iter.bi_size = KEY_SIZE(&b->key) << 9;
bio->bi_end_io = btree_node_read_endio;
bio->bi_private = &cl;
bch_bio_map(bio, b->keys.set[0].data);
bch_submit_bbio(bio, b->c, &b->key, 0);
closure_sync(&cl);
if (bio->bi_error)
set_btree_node_io_error(b);
bch_bbio_free(bio, b->c);
if (btree_node_io_error(b))
goto err;
bch_btree_node_read_done(b);
bch_time_stats_update(&b->c->btree_read_time, start_time);
return;
err:
bch_cache_set_error(b->c, "io error reading bucket %zu",
PTR_BUCKET_NR(b->c, &b->key, 0));
}
static void btree_complete_write(struct btree *b, struct btree_write *w)
{
if (w->prio_blocked &&
!atomic_sub_return(w->prio_blocked, &b->c->prio_blocked))
wake_up_allocators(b->c);
if (w->journal) {
atomic_dec_bug(w->journal);
__closure_wake_up(&b->c->journal.wait);
}
w->prio_blocked = 0;
w->journal = NULL;
}
static void btree_node_write_unlock(struct closure *cl)
{
struct btree *b = container_of(cl, struct btree, io);
up(&b->io_mutex);
}
static void __btree_node_write_done(struct closure *cl)
{
struct btree *b = container_of(cl, struct btree, io);
struct btree_write *w = btree_prev_write(b);
bch_bbio_free(b->bio, b->c);
b->bio = NULL;
btree_complete_write(b, w);
if (btree_node_dirty(b))
schedule_delayed_work(&b->work, 30 * HZ);
closure_return_with_destructor(cl, btree_node_write_unlock);
}
static void btree_node_write_done(struct closure *cl)
{
struct btree *b = container_of(cl, struct btree, io);
struct bio_vec *bv;
int n;
bio_for_each_segment_all(bv, b->bio, n)
__free_page(bv->bv_page);
__btree_node_write_done(cl);
}
static void btree_node_write_endio(struct bio *bio)
{
struct closure *cl = bio->bi_private;
struct btree *b = container_of(cl, struct btree, io);
if (bio->bi_error)
set_btree_node_io_error(b);
bch_bbio_count_io_errors(b->c, bio, bio->bi_error, "writing btree");
closure_put(cl);
}
static void do_btree_node_write(struct btree *b)
{
struct closure *cl = &b->io;
struct bset *i = btree_bset_last(b);
BKEY_PADDED(key) k;
i->version = BCACHE_BSET_VERSION;
i->csum = btree_csum_set(b, i);
BUG_ON(b->bio);
b->bio = bch_bbio_alloc(b->c);
b->bio->bi_end_io = btree_node_write_endio;
b->bio->bi_private = cl;
b->bio->bi_rw = REQ_META|WRITE_SYNC|REQ_FUA;
b->bio->bi_iter.bi_size = roundup(set_bytes(i), block_bytes(b->c));
bch_bio_map(b->bio, i);
/*
* If we're appending to a leaf node, we don't technically need FUA -
* this write just needs to be persisted before the next journal write,
* which will be marked FLUSH|FUA.
*
* Similarly if we're writing a new btree root - the pointer is going to
* be in the next journal entry.
*
* But if we're writing a new btree node (that isn't a root) or
* appending to a non leaf btree node, we need either FUA or a flush
* when we write the parent with the new pointer. FUA is cheaper than a
* flush, and writes appending to leaf nodes aren't blocking anything so
* just make all btree node writes FUA to keep things sane.
*/
bkey_copy(&k.key, &b->key);
SET_PTR_OFFSET(&k.key, 0, PTR_OFFSET(&k.key, 0) +
bset_sector_offset(&b->keys, i));
if (!bio_alloc_pages(b->bio, __GFP_NOWARN|GFP_NOWAIT)) {
int j;
struct bio_vec *bv;
void *base = (void *) ((unsigned long) i & ~(PAGE_SIZE - 1));
bio_for_each_segment_all(bv, b->bio, j)
memcpy(page_address(bv->bv_page),
base + j * PAGE_SIZE, PAGE_SIZE);
bch_submit_bbio(b->bio, b->c, &k.key, 0);
continue_at(cl, btree_node_write_done, NULL);
} else {
b->bio->bi_vcnt = 0;
bch_bio_map(b->bio, i);
bch_submit_bbio(b->bio, b->c, &k.key, 0);
closure_sync(cl);
continue_at_nobarrier(cl, __btree_node_write_done, NULL);
}
}
void __bch_btree_node_write(struct btree *b, struct closure *parent)
{
struct bset *i = btree_bset_last(b);
lockdep_assert_held(&b->write_lock);
trace_bcache_btree_write(b);
BUG_ON(current->bio_list);
BUG_ON(b->written >= btree_blocks(b));
BUG_ON(b->written && !i->keys);
BUG_ON(btree_bset_first(b)->seq != i->seq);
bch_check_keys(&b->keys, "writing");
cancel_delayed_work(&b->work);
/* If caller isn't waiting for write, parent refcount is cache set */
down(&b->io_mutex);
closure_init(&b->io, parent ?: &b->c->cl);
clear_bit(BTREE_NODE_dirty, &b->flags);
change_bit(BTREE_NODE_write_idx, &b->flags);
do_btree_node_write(b);
atomic_long_add(set_blocks(i, block_bytes(b->c)) * b->c->sb.block_size,
&PTR_CACHE(b->c, &b->key, 0)->btree_sectors_written);
b->written += set_blocks(i, block_bytes(b->c));
}
void bch_btree_node_write(struct btree *b, struct closure *parent)
{
unsigned nsets = b->keys.nsets;
lockdep_assert_held(&b->lock);
__bch_btree_node_write(b, parent);
/*
* do verify if there was more than one set initially (i.e. we did a
* sort) and we sorted down to a single set:
*/
if (nsets && !b->keys.nsets)
bch_btree_verify(b);
bch_btree_init_next(b);
}
static void bch_btree_node_write_sync(struct btree *b)
{
struct closure cl;
closure_init_stack(&cl);
mutex_lock(&b->write_lock);
bch_btree_node_write(b, &cl);
mutex_unlock(&b->write_lock);
closure_sync(&cl);
}
static void btree_node_write_work(struct work_struct *w)
{
struct btree *b = container_of(to_delayed_work(w), struct btree, work);
mutex_lock(&b->write_lock);
if (btree_node_dirty(b))
__bch_btree_node_write(b, NULL);
mutex_unlock(&b->write_lock);
}
static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref)
{
struct bset *i = btree_bset_last(b);
struct btree_write *w = btree_current_write(b);
lockdep_assert_held(&b->write_lock);
BUG_ON(!b->written);
BUG_ON(!i->keys);
if (!btree_node_dirty(b))
schedule_delayed_work(&b->work, 30 * HZ);
set_btree_node_dirty(b);
if (journal_ref) {
if (w->journal &&
journal_pin_cmp(b->c, w->journal, journal_ref)) {
atomic_dec_bug(w->journal);
w->journal = NULL;
}
if (!w->journal) {
w->journal = journal_ref;
atomic_inc(w->journal);
}
}
/* Force write if set is too big */
if (set_bytes(i) > PAGE_SIZE - 48 &&
!current->bio_list)
bch_btree_node_write(b, NULL);
}
/*
* Btree in memory cache - allocation/freeing
* mca -> memory cache
*/
#define mca_reserve(c) (((c->root && c->root->level) \
? c->root->level : 1) * 8 + 16)
#define mca_can_free(c) \
max_t(int, 0, c->btree_cache_used - mca_reserve(c))
static void mca_data_free(struct btree *b)
{
BUG_ON(b->io_mutex.count != 1);
bch_btree_keys_free(&b->keys);
b->c->btree_cache_used--;
list_move(&b->list, &b->c->btree_cache_freed);
}
static void mca_bucket_free(struct btree *b)
{
BUG_ON(btree_node_dirty(b));
b->key.ptr[0] = 0;
hlist_del_init_rcu(&b->hash);
list_move(&b->list, &b->c->btree_cache_freeable);
}
static unsigned btree_order(struct bkey *k)
{
return ilog2(KEY_SIZE(k) / PAGE_SECTORS ?: 1);
}
static void mca_data_alloc(struct btree *b, struct bkey *k, gfp_t gfp)
{
if (!bch_btree_keys_alloc(&b->keys,
max_t(unsigned,
ilog2(b->c->btree_pages),
btree_order(k)),
gfp)) {
b->c->btree_cache_used++;
list_move(&b->list, &b->c->btree_cache);
} else {
list_move(&b->list, &b->c->btree_cache_freed);
}
}
static struct btree *mca_bucket_alloc(struct cache_set *c,
struct bkey *k, gfp_t gfp)
{
struct btree *b = kzalloc(sizeof(struct btree), gfp);
if (!b)
return NULL;
init_rwsem(&b->lock);
lockdep_set_novalidate_class(&b->lock);
mutex_init(&b->write_lock);
lockdep_set_novalidate_class(&b->write_lock);
INIT_LIST_HEAD(&b->list);
INIT_DELAYED_WORK(&b->work, btree_node_write_work);
b->c = c;
sema_init(&b->io_mutex, 1);
mca_data_alloc(b, k, gfp);
return b;
}
static int mca_reap(struct btree *b, unsigned min_order, bool flush)
{
struct closure cl;
closure_init_stack(&cl);
lockdep_assert_held(&b->c->bucket_lock);
if (!down_write_trylock(&b->lock))
return -ENOMEM;
BUG_ON(btree_node_dirty(b) && !b->keys.set[0].data);
if (b->keys.page_order < min_order)
goto out_unlock;
if (!flush) {
if (btree_node_dirty(b))
goto out_unlock;
if (down_trylock(&b->io_mutex))
goto out_unlock;
up(&b->io_mutex);
}
mutex_lock(&b->write_lock);
if (btree_node_dirty(b))
__bch_btree_node_write(b, &cl);
mutex_unlock(&b->write_lock);
closure_sync(&cl);
/* wait for any in flight btree write */
down(&b->io_mutex);
up(&b->io_mutex);
return 0;
out_unlock:
rw_unlock(true, b);
return -ENOMEM;
}
static unsigned long bch_mca_scan(struct shrinker *shrink,
struct shrink_control *sc)
{
struct cache_set *c = container_of(shrink, struct cache_set, shrink);
struct btree *b, *t;
unsigned long i, nr = sc->nr_to_scan;
unsigned long freed = 0;
if (c->shrinker_disabled)
return SHRINK_STOP;
if (c->btree_cache_alloc_lock)
return SHRINK_STOP;
/* Return -1 if we can't do anything right now */
if (sc->gfp_mask & __GFP_IO)
mutex_lock(&c->bucket_lock);
else if (!mutex_trylock(&c->bucket_lock))
return -1;
/*
* It's _really_ critical that we don't free too many btree nodes - we
* have to always leave ourselves a reserve. The reserve is how we
* guarantee that allocating memory for a new btree node can always
* succeed, so that inserting keys into the btree can always succeed and
* IO can always make forward progress:
*/
nr /= c->btree_pages;
nr = min_t(unsigned long, nr, mca_can_free(c));
i = 0;
list_for_each_entry_safe(b, t, &c->btree_cache_freeable, list) {
if (freed >= nr)
break;
if (++i > 3 &&
!mca_reap(b, 0, false)) {
mca_data_free(b);
rw_unlock(true, b);
freed++;
}
}
for (i = 0; (nr--) && i < c->btree_cache_used; i++) {
if (list_empty(&c->btree_cache))
goto out;
b = list_first_entry(&c->btree_cache, struct btree, list);
list_rotate_left(&c->btree_cache);
if (!b->accessed &&
!mca_reap(b, 0, false)) {
mca_bucket_free(b);
mca_data_free(b);
rw_unlock(true, b);
freed++;
} else
b->accessed = 0;
}
out:
mutex_unlock(&c->bucket_lock);
return freed;
}
static unsigned long bch_mca_count(struct shrinker *shrink,
struct shrink_control *sc)
{
struct cache_set *c = container_of(shrink, struct cache_set, shrink);
if (c->shrinker_disabled)
return 0;
if (c->btree_cache_alloc_lock)
return 0;
return mca_can_free(c) * c->btree_pages;
}
void bch_btree_cache_free(struct cache_set *c)
{
struct btree *b;
struct closure cl;
closure_init_stack(&cl);
if (c->shrink.list.next)
unregister_shrinker(&c->shrink);
mutex_lock(&c->bucket_lock);
#ifdef CONFIG_BCACHE_DEBUG
if (c->verify_data)
list_move(&c->verify_data->list, &c->btree_cache);
free_pages((unsigned long) c->verify_ondisk, ilog2(bucket_pages(c)));
#endif
list_splice(&c->btree_cache_freeable,
&c->btree_cache);
while (!list_empty(&c->btree_cache)) {
b = list_first_entry(&c->btree_cache, struct btree, list);
if (btree_node_dirty(b))
btree_complete_write(b, btree_current_write(b));
clear_bit(BTREE_NODE_dirty, &b->flags);
mca_data_free(b);
}
while (!list_empty(&c->btree_cache_freed)) {
b = list_first_entry(&c->btree_cache_freed,
struct btree, list);
list_del(&b->list);
cancel_delayed_work_sync(&b->work);
kfree(b);
}
mutex_unlock(&c->bucket_lock);
}
int bch_btree_cache_alloc(struct cache_set *c)
{
unsigned i;
for (i = 0; i < mca_reserve(c); i++)
if (!mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL))
return -ENOMEM;
list_splice_init(&c->btree_cache,
&c->btree_cache_freeable);
#ifdef CONFIG_BCACHE_DEBUG
mutex_init(&c->verify_lock);
c->verify_ondisk = (void *)
__get_free_pages(GFP_KERNEL, ilog2(bucket_pages(c)));
c->verify_data = mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
if (c->verify_data &&
c->verify_data->keys.set->data)
list_del_init(&c->verify_data->list);
else
c->verify_data = NULL;
#endif
c->shrink.count_objects = bch_mca_count;
c->shrink.scan_objects = bch_mca_scan;
c->shrink.seeks = 4;
c->shrink.batch = c->btree_pages * 2;
register_shrinker(&c->shrink);
return 0;
}
/* Btree in memory cache - hash table */
static struct hlist_head *mca_hash(struct cache_set *c, struct bkey *k)
{
return &c->bucket_hash[hash_32(PTR_HASH(c, k), BUCKET_HASH_BITS)];
}
static struct btree *mca_find(struct cache_set *c, struct bkey *k)
{
struct btree *b;
rcu_read_lock();
hlist_for_each_entry_rcu(b, mca_hash(c, k), hash)
if (PTR_HASH(c, &b->key) == PTR_HASH(c, k))
goto out;
b = NULL;
out:
rcu_read_unlock();
return b;
}
static int mca_cannibalize_lock(struct cache_set *c, struct btree_op *op)
{
struct task_struct *old;
old = cmpxchg(&c->btree_cache_alloc_lock, NULL, current);
if (old && old != current) {
if (op)
prepare_to_wait(&c->btree_cache_wait, &op->wait,
TASK_UNINTERRUPTIBLE);
return -EINTR;
}
return 0;
}
static struct btree *mca_cannibalize(struct cache_set *c, struct btree_op *op,
struct bkey *k)
{
struct btree *b;
trace_bcache_btree_cache_cannibalize(c);
if (mca_cannibalize_lock(c, op))
return ERR_PTR(-EINTR);
list_for_each_entry_reverse(b, &c->btree_cache, list)
if (!mca_reap(b, btree_order(k), false))
return b;
list_for_each_entry_reverse(b, &c->btree_cache, list)
if (!mca_reap(b, btree_order(k), true))
return b;
WARN(1, "btree cache cannibalize failed\n");
return ERR_PTR(-ENOMEM);
}
/*
* We can only have one thread cannibalizing other cached btree nodes at a time,
* or we'll deadlock. We use an open coded mutex to ensure that, which a
* cannibalize_bucket() will take. This means every time we unlock the root of
* the btree, we need to release this lock if we have it held.
*/
static void bch_cannibalize_unlock(struct cache_set *c)
{
if (c->btree_cache_alloc_lock == current) {
c->btree_cache_alloc_lock = NULL;
wake_up(&c->btree_cache_wait);
}
}
static struct btree *mca_alloc(struct cache_set *c, struct btree_op *op,
struct bkey *k, int level)
{
struct btree *b;
BUG_ON(current->bio_list);
lockdep_assert_held(&c->bucket_lock);
if (mca_find(c, k))
return NULL;
/* btree_free() doesn't free memory; it sticks the node on the end of
* the list. Check if there's any freed nodes there:
*/
list_for_each_entry(b, &c->btree_cache_freeable, list)
if (!mca_reap(b, btree_order(k), false))
goto out;
/* We never free struct btree itself, just the memory that holds the on
* disk node. Check the freed list before allocating a new one:
*/
list_for_each_entry(b, &c->btree_cache_freed, list)
if (!mca_reap(b, 0, false)) {
mca_data_alloc(b, k, __GFP_NOWARN|GFP_NOIO);
if (!b->keys.set[0].data)
goto err;
else
goto out;
}
b = mca_bucket_alloc(c, k, __GFP_NOWARN|GFP_NOIO);
if (!b)
goto err;
BUG_ON(!down_write_trylock(&b->lock));
if (!b->keys.set->data)
goto err;
out:
BUG_ON(b->io_mutex.count != 1);
bkey_copy(&b->key, k);
list_move(&b->list, &c->btree_cache);
hlist_del_init_rcu(&b->hash);
hlist_add_head_rcu(&b->hash, mca_hash(c, k));
lock_set_subclass(&b->lock.dep_map, level + 1, _THIS_IP_);
b->parent = (void *) ~0UL;
b->flags = 0;
b->written = 0;
b->level = level;
if (!b->level)
bch_btree_keys_init(&b->keys, &bch_extent_keys_ops,
&b->c->expensive_debug_checks);
else
bch_btree_keys_init(&b->keys, &bch_btree_keys_ops,
&b->c->expensive_debug_checks);
return b;
err:
if (b)
rw_unlock(true, b);
b = mca_cannibalize(c, op, k);
if (!IS_ERR(b))
goto out;
return b;
}
/**
* bch_btree_node_get - find a btree node in the cache and lock it, reading it
* in from disk if necessary.
*
* If IO is necessary and running under generic_make_request, returns -EAGAIN.
*
* The btree node will have either a read or a write lock held, depending on
* level and op->lock.
*/
struct btree *bch_btree_node_get(struct cache_set *c, struct btree_op *op,
struct bkey *k, int level, bool write,
struct btree *parent)
{
int i = 0;
struct btree *b;
BUG_ON(level < 0);
retry:
b = mca_find(c, k);
if (!b) {
if (current->bio_list)
return ERR_PTR(-EAGAIN);
mutex_lock(&c->bucket_lock);
b = mca_alloc(c, op, k, level);
mutex_unlock(&c->bucket_lock);
if (!b)
goto retry;
if (IS_ERR(b))
return b;
bch_btree_node_read(b);
if (!write)
downgrade_write(&b->lock);
} else {
rw_lock(write, b, level);
if (PTR_HASH(c, &b->key) != PTR_HASH(c, k)) {
rw_unlock(write, b);
goto retry;
}
BUG_ON(b->level != level);
}
b->parent = parent;
b->accessed = 1;
for (; i <= b->keys.nsets && b->keys.set[i].size; i++) {
prefetch(b->keys.set[i].tree);
prefetch(b->keys.set[i].data);
}
for (; i <= b->keys.nsets; i++)
prefetch(b->keys.set[i].data);
if (btree_node_io_error(b)) {
rw_unlock(write, b);
return ERR_PTR(-EIO);
}
BUG_ON(!b->written);
return b;
}
static void btree_node_prefetch(struct btree *parent, struct bkey *k)
{
struct btree *b;
mutex_lock(&parent->c->bucket_lock);
b = mca_alloc(parent->c, NULL, k, parent->level - 1);
mutex_unlock(&parent->c->bucket_lock);
if (!IS_ERR_OR_NULL(b)) {
b->parent = parent;
bch_btree_node_read(b);
rw_unlock(true, b);
}
}
/* Btree alloc */
static void btree_node_free(struct btree *b)
{
trace_bcache_btree_node_free(b);
BUG_ON(b == b->c->root);
mutex_lock(&b->write_lock);
if (btree_node_dirty(b))
btree_complete_write(b, btree_current_write(b));
clear_bit(BTREE_NODE_dirty, &b->flags);
mutex_unlock(&b->write_lock);
cancel_delayed_work(&b->work);
mutex_lock(&b->c->bucket_lock);
bch_bucket_free(b->c, &b->key);
mca_bucket_free(b);
mutex_unlock(&b->c->bucket_lock);
}
struct btree *__bch_btree_node_alloc(struct cache_set *c, struct btree_op *op,
int level, bool wait,
struct btree *parent)
{
BKEY_PADDED(key) k;
struct btree *b = ERR_PTR(-EAGAIN);
mutex_lock(&c->bucket_lock);
retry:
if (__bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, 1, wait))
goto err;
bkey_put(c, &k.key);
SET_KEY_SIZE(&k.key, c->btree_pages * PAGE_SECTORS);
b = mca_alloc(c, op, &k.key, level);
if (IS_ERR(b))
goto err_free;
if (!b) {
cache_bug(c,
"Tried to allocate bucket that was in btree cache");
goto retry;
}
b->accessed = 1;
b->parent = parent;
bch_bset_init_next(&b->keys, b->keys.set->data, bset_magic(&b->c->sb));
mutex_unlock(&c->bucket_lock);
trace_bcache_btree_node_alloc(b);
return b;
err_free:
bch_bucket_free(c, &k.key);
err:
mutex_unlock(&c->bucket_lock);
trace_bcache_btree_node_alloc_fail(c);
return b;
}
static struct btree *bch_btree_node_alloc(struct cache_set *c,
struct btree_op *op, int level,
struct btree *parent)
{
return __bch_btree_node_alloc(c, op, level, op != NULL, parent);
}
static struct btree *btree_node_alloc_replacement(struct btree *b,
struct btree_op *op)
{
struct btree *n = bch_btree_node_alloc(b->c, op, b->level, b->parent);
if (!IS_ERR_OR_NULL(n)) {
mutex_lock(&n->write_lock);
bch_btree_sort_into(&b->keys, &n->keys, &b->c->sort);
bkey_copy_key(&n->key, &b->key);
mutex_unlock(&n->write_lock);
}
return n;
}
static void make_btree_freeing_key(struct btree *b, struct bkey *k)
{
unsigned i;
mutex_lock(&b->c->bucket_lock);
atomic_inc(&b->c->prio_blocked);
bkey_copy(k, &b->key);
bkey_copy_key(k, &ZERO_KEY);
for (i = 0; i < KEY_PTRS(k); i++)
SET_PTR_GEN(k, i,
bch_inc_gen(PTR_CACHE(b->c, &b->key, i),
PTR_BUCKET(b->c, &b->key, i)));
mutex_unlock(&b->c->bucket_lock);
}
static int btree_check_reserve(struct btree *b, struct btree_op *op)
{
struct cache_set *c = b->c;
struct cache *ca;
unsigned i, reserve = (c->root->level - b->level) * 2 + 1;
mutex_lock(&c->bucket_lock);
for_each_cache(ca, c, i)
if (fifo_used(&ca->free[RESERVE_BTREE]) < reserve) {
if (op)
prepare_to_wait(&c->btree_cache_wait, &op->wait,
TASK_UNINTERRUPTIBLE);
mutex_unlock(&c->bucket_lock);
return -EINTR;
}
mutex_unlock(&c->bucket_lock);
return mca_cannibalize_lock(b->c, op);
}
/* Garbage collection */
static uint8_t __bch_btree_mark_key(struct cache_set *c, int level,
struct bkey *k)
{
uint8_t stale = 0;
unsigned i;
struct bucket *g;
/*
* ptr_invalid() can't return true for the keys that mark btree nodes as
* freed, but since ptr_bad() returns true we'll never actually use them
* for anything and thus we don't want mark their pointers here
*/
if (!bkey_cmp(k, &ZERO_KEY))
return stale;
for (i = 0; i < KEY_PTRS(k); i++) {
if (!ptr_available(c, k, i))
continue;
g = PTR_BUCKET(c, k, i);
if (gen_after(g->last_gc, PTR_GEN(k, i)))
g->last_gc = PTR_GEN(k, i);
if (ptr_stale(c, k, i)) {
stale = max(stale, ptr_stale(c, k, i));
continue;
}
cache_bug_on(GC_MARK(g) &&
(GC_MARK(g) == GC_MARK_METADATA) != (level != 0),
c, "inconsistent ptrs: mark = %llu, level = %i",
GC_MARK(g), level);
if (level)
SET_GC_MARK(g, GC_MARK_METADATA);
else if (KEY_DIRTY(k))
SET_GC_MARK(g, GC_MARK_DIRTY);
else if (!GC_MARK(g))
SET_GC_MARK(g, GC_MARK_RECLAIMABLE);
/* guard against overflow */
SET_GC_SECTORS_USED(g, min_t(unsigned,
GC_SECTORS_USED(g) + KEY_SIZE(k),
MAX_GC_SECTORS_USED));
BUG_ON(!GC_SECTORS_USED(g));
}
return stale;
}
#define btree_mark_key(b, k) __bch_btree_mark_key(b->c, b->level, k)
void bch_initial_mark_key(struct cache_set *c, int level, struct bkey *k)
{
unsigned i;
for (i = 0; i < KEY_PTRS(k); i++)
if (ptr_available(c, k, i) &&
!ptr_stale(c, k, i)) {
struct bucket *b = PTR_BUCKET(c, k, i);
b->gen = PTR_GEN(k, i);
if (level && bkey_cmp(k, &ZERO_KEY))
b->prio = BTREE_PRIO;
else if (!level && b->prio == BTREE_PRIO)
b->prio = INITIAL_PRIO;
}
__bch_btree_mark_key(c, level, k);
}
static bool btree_gc_mark_node(struct btree *b, struct gc_stat *gc)
{
uint8_t stale = 0;
unsigned keys = 0, good_keys = 0;
struct bkey *k;
struct btree_iter iter;
struct bset_tree *t;
gc->nodes++;
for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid) {
stale = max(stale, btree_mark_key(b, k));
keys++;
if (bch_ptr_bad(&b->keys, k))
continue;
gc->key_bytes += bkey_u64s(k);
gc->nkeys++;
good_keys++;
gc->data += KEY_SIZE(k);
}
for (t = b->keys.set; t <= &b->keys.set[b->keys.nsets]; t++)
btree_bug_on(t->size &&
bset_written(&b->keys, t) &&
bkey_cmp(&b->key, &t->end) < 0,
b, "found short btree key in gc");
if (b->c->gc_always_rewrite)
return true;
if (stale > 10)
return true;
if ((keys - good_keys) * 2 > keys)
return true;
return false;
}
#define GC_MERGE_NODES 4U
struct gc_merge_info {
struct btree *b;
unsigned keys;
};
static int bch_btree_insert_node(struct btree *, struct btree_op *,
struct keylist *, atomic_t *, struct bkey *);
static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
struct gc_stat *gc, struct gc_merge_info *r)
{
unsigned i, nodes = 0, keys = 0, blocks;
struct btree *new_nodes[GC_MERGE_NODES];
struct keylist keylist;
struct closure cl;
struct bkey *k;
bch_keylist_init(&keylist);
if (btree_check_reserve(b, NULL))
return 0;
memset(new_nodes, 0, sizeof(new_nodes));
closure_init_stack(&cl);
while (nodes < GC_MERGE_NODES && !IS_ERR_OR_NULL(r[nodes].b))
keys += r[nodes++].keys;
blocks = btree_default_blocks(b->c) * 2 / 3;
if (nodes < 2 ||
__set_blocks(b->keys.set[0].data, keys,
block_bytes(b->c)) > blocks * (nodes - 1))
return 0;
for (i = 0; i < nodes; i++) {
new_nodes[i] = btree_node_alloc_replacement(r[i].b, NULL);
if (IS_ERR_OR_NULL(new_nodes[i]))
goto out_nocoalesce;
}
/*
* We have to check the reserve here, after we've allocated our new
* nodes, to make sure the insert below will succeed - we also check
* before as an optimization to potentially avoid a bunch of expensive
* allocs/sorts
*/
if (btree_check_reserve(b, NULL))
goto out_nocoalesce;
for (i = 0; i < nodes; i++)
mutex_lock(&new_nodes[i]->write_lock);
for (i = nodes - 1; i > 0; --i) {
struct bset *n1 = btree_bset_first(new_nodes[i]);
struct bset *n2 = btree_bset_first(new_nodes[i - 1]);
struct bkey *k, *last = NULL;
keys = 0;
if (i > 1) {
for (k = n2->start;
k < bset_bkey_last(n2);
k = bkey_next(k)) {
if (__set_blocks(n1, n1->keys + keys +
bkey_u64s(k),
block_bytes(b->c)) > blocks)
break;
last = k;
keys += bkey_u64s(k);
}
} else {
/*
* Last node we're not getting rid of - we're getting
* rid of the node at r[0]. Have to try and fit all of
* the remaining keys into this node; we can't ensure
* they will always fit due to rounding and variable
* length keys (shouldn't be possible in practice,
* though)
*/
if (__set_blocks(n1, n1->keys + n2->keys,
block_bytes(b->c)) >
btree_blocks(new_nodes[i]))
goto out_nocoalesce;
keys = n2->keys;
/* Take the key of the node we're getting rid of */
last = &r->b->key;
}
BUG_ON(__set_blocks(n1, n1->keys + keys, block_bytes(b->c)) >
btree_blocks(new_nodes[i]));
if (last)
bkey_copy_key(&new_nodes[i]->key, last);
memcpy(bset_bkey_last(n1),
n2->start,
(void *) bset_bkey_idx(n2, keys) - (void *) n2->start);
n1->keys += keys;
r[i].keys = n1->keys;
memmove(n2->start,
bset_bkey_idx(n2, keys),
(void *) bset_bkey_last(n2) -
(void *) bset_bkey_idx(n2, keys));
n2->keys -= keys;
if (__bch_keylist_realloc(&keylist,
bkey_u64s(&new_nodes[i]->key)))
goto out_nocoalesce;
bch_btree_node_write(new_nodes[i], &cl);
bch_keylist_add(&keylist, &new_nodes[i]->key);
}
for (i = 0; i < nodes; i++)
mutex_unlock(&new_nodes[i]->write_lock);
closure_sync(&cl);
/* We emptied out this node */
BUG_ON(btree_bset_first(new_nodes[0])->keys);
btree_node_free(new_nodes[0]);
rw_unlock(true, new_nodes[0]);
new_nodes[0] = NULL;
for (i = 0; i < nodes; i++) {
if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b->key)))
goto out_nocoalesce;
make_btree_freeing_key(r[i].b, keylist.top);
bch_keylist_push(&keylist);
}
bch_btree_insert_node(b, op, &keylist, NULL, NULL);
BUG_ON(!bch_keylist_empty(&keylist));
for (i = 0; i < nodes; i++) {
btree_node_free(r[i].b);
rw_unlock(true, r[i].b);
r[i].b = new_nodes[i];
}
memmove(r, r + 1, sizeof(r[0]) * (nodes - 1));
r[nodes - 1].b = ERR_PTR(-EINTR);
trace_bcache_btree_gc_coalesce(nodes);
gc->nodes--;
bch_keylist_free(&keylist);
/* Invalidated our iterator */
return -EINTR;
out_nocoalesce:
closure_sync(&cl);
bch_keylist_free(&keylist);
while ((k = bch_keylist_pop(&keylist)))
if (!bkey_cmp(k, &ZERO_KEY))
atomic_dec(&b->c->prio_blocked);
for (i = 0; i < nodes; i++)
if (!IS_ERR_OR_NULL(new_nodes[i])) {
btree_node_free(new_nodes[i]);
rw_unlock(true, new_nodes[i]);
}
return 0;
}
static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op,
struct btree *replace)
{
struct keylist keys;
struct btree *n;
if (btree_check_reserve(b, NULL))
return 0;
n = btree_node_alloc_replacement(replace, NULL);
/* recheck reserve after allocating replacement node */
if (btree_check_reserve(b, NULL)) {
btree_node_free(n);
rw_unlock(true, n);
return 0;
}
bch_btree_node_write_sync(n);
bch_keylist_init(&keys);
bch_keylist_add(&keys, &n->key);
make_btree_freeing_key(replace, keys.top);
bch_keylist_push(&keys);
bch_btree_insert_node(b, op, &keys, NULL, NULL);
BUG_ON(!bch_keylist_empty(&keys));
btree_node_free(replace);
rw_unlock(true, n);
/* Invalidated our iterator */
return -EINTR;
}
static unsigned btree_gc_count_keys(struct btree *b)
{
struct bkey *k;
struct btree_iter iter;
unsigned ret = 0;
for_each_key_filter(&b->keys, k, &iter, bch_ptr_bad)
ret += bkey_u64s(k);
return ret;
}
static int btree_gc_recurse(struct btree *b, struct btree_op *op,
struct closure *writes, struct gc_stat *gc)
{
int ret = 0;
bool should_rewrite;
struct bkey *k;
struct btree_iter iter;
struct gc_merge_info r[GC_MERGE_NODES];
struct gc_merge_info *i, *last = r + ARRAY_SIZE(r) - 1;
bch_btree_iter_init(&b->keys, &iter, &b->c->gc_done);
for (i = r; i < r + ARRAY_SIZE(r); i++)
i->b = ERR_PTR(-EINTR);
while (1) {
k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad);
if (k) {
r->b = bch_btree_node_get(b->c, op, k, b->level - 1,
true, b);
if (IS_ERR(r->b)) {
ret = PTR_ERR(r->b);
break;
}
r->keys = btree_gc_count_keys(r->b);
ret = btree_gc_coalesce(b, op, gc, r);
if (ret)
break;
}
if (!last->b)
break;
if (!IS_ERR(last->b)) {
should_rewrite = btree_gc_mark_node(last->b, gc);
if (should_rewrite) {
ret = btree_gc_rewrite_node(b, op, last->b);
if (ret)
break;
}
if (last->b->level) {
ret = btree_gc_recurse(last->b, op, writes, gc);
if (ret)
break;
}
bkey_copy_key(&b->c->gc_done, &last->b->key);
/*
* Must flush leaf nodes before gc ends, since replace
* operations aren't journalled
*/
mutex_lock(&last->b->write_lock);
if (btree_node_dirty(last->b))
bch_btree_node_write(last->b, writes);
mutex_unlock(&last->b->write_lock);
rw_unlock(true, last->b);
}
memmove(r + 1, r, sizeof(r[0]) * (GC_MERGE_NODES - 1));
r->b = NULL;
if (need_resched()) {
ret = -EAGAIN;
break;
}
}
for (i = r; i < r + ARRAY_SIZE(r); i++)
if (!IS_ERR_OR_NULL(i->b)) {
mutex_lock(&i->b->write_lock);
if (btree_node_dirty(i->b))
bch_btree_node_write(i->b, writes);
mutex_unlock(&i->b->write_lock);
rw_unlock(true, i->b);
}
return ret;
}
static int bch_btree_gc_root(struct btree *b, struct btree_op *op,
struct closure *writes, struct gc_stat *gc)
{
struct btree *n = NULL;
int ret = 0;
bool should_rewrite;
should_rewrite = btree_gc_mark_node(b, gc);
if (should_rewrite) {
n = btree_node_alloc_replacement(b, NULL);
if (!IS_ERR_OR_NULL(n)) {
bch_btree_node_write_sync(n);
bch_btree_set_root(n);
btree_node_free(b);
rw_unlock(true, n);
return -EINTR;
}
}
__bch_btree_mark_key(b->c, b->level + 1, &b->key);
if (b->level) {
ret = btree_gc_recurse(b, op, writes, gc);
if (ret)
return ret;
}
bkey_copy_key(&b->c->gc_done, &b->key);
return ret;
}
static void btree_gc_start(struct cache_set *c)
{
struct cache *ca;
struct bucket *b;
unsigned i;
if (!c->gc_mark_valid)
return;
mutex_lock(&c->bucket_lock);
c->gc_mark_valid = 0;
c->gc_done = ZERO_KEY;
for_each_cache(ca, c, i)
for_each_bucket(b, ca) {
b->last_gc = b->gen;
if (!atomic_read(&b->pin)) {
SET_GC_MARK(b, 0);
SET_GC_SECTORS_USED(b, 0);
}
}
mutex_unlock(&c->bucket_lock);
}
static size_t bch_btree_gc_finish(struct cache_set *c)
{
size_t available = 0;
struct bucket *b;
struct cache *ca;
unsigned i;
mutex_lock(&c->bucket_lock);
set_gc_sectors(c);
c->gc_mark_valid = 1;
c->need_gc = 0;
for (i = 0; i < KEY_PTRS(&c->uuid_bucket); i++)
SET_GC_MARK(PTR_BUCKET(c, &c->uuid_bucket, i),
GC_MARK_METADATA);
/* don't reclaim buckets to which writeback keys point */
rcu_read_lock();
for (i = 0; i < c->nr_uuids; i++) {
struct bcache_device *d = c->devices[i];
struct cached_dev *dc;
struct keybuf_key *w, *n;
unsigned j;
if (!d || UUID_FLASH_ONLY(&c->uuids[i]))
continue;
dc = container_of(d, struct cached_dev, disk);
spin_lock(&dc->writeback_keys.lock);
rbtree_postorder_for_each_entry_safe(w, n,
&dc->writeback_keys.keys, node)
for (j = 0; j < KEY_PTRS(&w->key); j++)
SET_GC_MARK(PTR_BUCKET(c, &w->key, j),
GC_MARK_DIRTY);
spin_unlock(&dc->writeback_keys.lock);
}
rcu_read_unlock();
for_each_cache(ca, c, i) {
uint64_t *i;
ca->invalidate_needs_gc = 0;
for (i = ca->sb.d; i < ca->sb.d + ca->sb.keys; i++)
SET_GC_MARK(ca->buckets + *i, GC_MARK_METADATA);
for (i = ca->prio_buckets;
i < ca->prio_buckets + prio_buckets(ca) * 2; i++)
SET_GC_MARK(ca->buckets + *i, GC_MARK_METADATA);
for_each_bucket(b, ca) {
c->need_gc = max(c->need_gc, bucket_gc_gen(b));
if (atomic_read(&b->pin))
continue;
BUG_ON(!GC_MARK(b) && GC_SECTORS_USED(b));
if (!GC_MARK(b) || GC_MARK(b) == GC_MARK_RECLAIMABLE)
available++;
}
}
mutex_unlock(&c->bucket_lock);
return available;
}
static void bch_btree_gc(struct cache_set *c)
{
int ret;
unsigned long available;
struct gc_stat stats;
struct closure writes;
struct btree_op op;
uint64_t start_time = local_clock();
trace_bcache_gc_start(c);
memset(&stats, 0, sizeof(struct gc_stat));
closure_init_stack(&writes);
bch_btree_op_init(&op, SHRT_MAX);
btree_gc_start(c);
do {
ret = btree_root(gc_root, c, &op, &writes, &stats);
closure_sync(&writes);
if (ret && ret != -EAGAIN)
pr_warn("gc failed!");
} while (ret);
available = bch_btree_gc_finish(c);
wake_up_allocators(c);
bch_time_stats_update(&c->btree_gc_time, start_time);
stats.key_bytes *= sizeof(uint64_t);
stats.data <<= 9;
stats.in_use = (c->nbuckets - available) * 100 / c->nbuckets;
memcpy(&c->gc_stats, &stats, sizeof(struct gc_stat));
trace_bcache_gc_end(c);
bch_moving_gc(c);
}
static int bch_gc_thread(void *arg)
{
struct cache_set *c = arg;
struct cache *ca;
unsigned i;
while (1) {
again:
bch_btree_gc(c);
set_current_state(TASK_INTERRUPTIBLE);
if (kthread_should_stop())
break;
mutex_lock(&c->bucket_lock);
for_each_cache(ca, c, i)
if (ca->invalidate_needs_gc) {
mutex_unlock(&c->bucket_lock);
set_current_state(TASK_RUNNING);
goto again;
}
mutex_unlock(&c->bucket_lock);
try_to_freeze();
schedule();
}
return 0;
}
int bch_gc_thread_start(struct cache_set *c)
{
c->gc_thread = kthread_create(bch_gc_thread, c, "bcache_gc");
if (IS_ERR(c->gc_thread))
return PTR_ERR(c->gc_thread);
set_task_state(c->gc_thread, TASK_INTERRUPTIBLE);
return 0;
}
/* Initial partial gc */
static int bch_btree_check_recurse(struct btree *b, struct btree_op *op)
{
int ret = 0;
struct bkey *k, *p = NULL;
struct btree_iter iter;
for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid)
bch_initial_mark_key(b->c, b->level, k);
bch_initial_mark_key(b->c, b->level + 1, &b->key);
if (b->level) {
bch_btree_iter_init(&b->keys, &iter, NULL);
do {
k = bch_btree_iter_next_filter(&iter, &b->keys,
bch_ptr_bad);
if (k)
btree_node_prefetch(b, k);
if (p)
ret = btree(check_recurse, p, b, op);
p = k;
} while (p && !ret);
}
return ret;
}
int bch_btree_check(struct cache_set *c)
{
struct btree_op op;
bch_btree_op_init(&op, SHRT_MAX);
return btree_root(check_recurse, c, &op);
}
void bch_initial_gc_finish(struct cache_set *c)
{
struct cache *ca;
struct bucket *b;
unsigned i;
bch_btree_gc_finish(c);
mutex_lock(&c->bucket_lock);
/*
* We need to put some unused buckets directly on the prio freelist in
* order to get the allocator thread started - it needs freed buckets in
* order to rewrite the prios and gens, and it needs to rewrite prios
* and gens in order to free buckets.
*
* This is only safe for buckets that have no live data in them, which
* there should always be some of.
*/
for_each_cache(ca, c, i) {
for_each_bucket(b, ca) {
if (fifo_full(&ca->free[RESERVE_PRIO]))
break;
if (bch_can_invalidate_bucket(ca, b) &&
!GC_MARK(b)) {
__bch_invalidate_one_bucket(ca, b);
fifo_push(&ca->free[RESERVE_PRIO],
b - ca->buckets);
}
}
}
mutex_unlock(&c->bucket_lock);
}
/* Btree insertion */
static bool btree_insert_key(struct btree *b, struct bkey *k,
struct bkey *replace_key)
{
unsigned status;
BUG_ON(bkey_cmp(k, &b->key) > 0);
status = bch_btree_insert_key(&b->keys, k, replace_key);
if (status != BTREE_INSERT_STATUS_NO_INSERT) {
bch_check_keys(&b->keys, "%u for %s", status,
replace_key ? "replace" : "insert");
trace_bcache_btree_insert_key(b, k, replace_key != NULL,
status);
return true;
} else
return false;
}
static size_t insert_u64s_remaining(struct btree *b)
{
long ret = bch_btree_keys_u64s_remaining(&b->keys);
/*
* Might land in the middle of an existing extent and have to split it
*/
if (b->keys.ops->is_extents)
ret -= KEY_MAX_U64S;
return max(ret, 0L);
}
static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op,
struct keylist *insert_keys,
struct bkey *replace_key)
{
bool ret = false;
int oldsize = bch_count_data(&b->keys);
while (!bch_keylist_empty(insert_keys)) {
struct bkey *k = insert_keys->keys;
if (bkey_u64s(k) > insert_u64s_remaining(b))
break;
if (bkey_cmp(k, &b->key) <= 0) {
if (!b->level)
bkey_put(b->c, k);
ret |= btree_insert_key(b, k, replace_key);
bch_keylist_pop_front(insert_keys);
} else if (bkey_cmp(&START_KEY(k), &b->key) < 0) {
BKEY_PADDED(key) temp;
bkey_copy(&temp.key, insert_keys->keys);
bch_cut_back(&b->key, &temp.key);
bch_cut_front(&b->key, insert_keys->keys);
ret |= btree_insert_key(b, &temp.key, replace_key);
break;
} else {
break;
}
}
if (!ret)
op->insert_collision = true;
BUG_ON(!bch_keylist_empty(insert_keys) && b->level);
BUG_ON(bch_count_data(&b->keys) < oldsize);
return ret;
}
static int btree_split(struct btree *b, struct btree_op *op,
struct keylist *insert_keys,
struct bkey *replace_key)
{
bool split;
struct btree *n1, *n2 = NULL, *n3 = NULL;
uint64_t start_time = local_clock();
struct closure cl;
struct keylist parent_keys;
closure_init_stack(&cl);
bch_keylist_init(&parent_keys);
if (btree_check_reserve(b, op)) {
if (!b->level)
return -EINTR;
else
WARN(1, "insufficient reserve for split\n");
}
n1 = btree_node_alloc_replacement(b, op);
if (IS_ERR(n1))
goto err;
split = set_blocks(btree_bset_first(n1),
block_bytes(n1->c)) > (btree_blocks(b) * 4) / 5;
if (split) {
unsigned keys = 0;
trace_bcache_btree_node_split(b, btree_bset_first(n1)->keys);
n2 = bch_btree_node_alloc(b->c, op, b->level, b->parent);
if (IS_ERR(n2))
goto err_free1;
if (!b->parent) {
n3 = bch_btree_node_alloc(b->c, op, b->level + 1, NULL);
if (IS_ERR(n3))
goto err_free2;
}
mutex_lock(&n1->write_lock);
mutex_lock(&n2->write_lock);
bch_btree_insert_keys(n1, op, insert_keys, replace_key);
/*
* Has to be a linear search because we don't have an auxiliary
* search tree yet
*/
while (keys < (btree_bset_first(n1)->keys * 3) / 5)
keys += bkey_u64s(bset_bkey_idx(btree_bset_first(n1),
keys));
bkey_copy_key(&n1->key,
bset_bkey_idx(btree_bset_first(n1), keys));
keys += bkey_u64s(bset_bkey_idx(btree_bset_first(n1), keys));
btree_bset_first(n2)->keys = btree_bset_first(n1)->keys - keys;
btree_bset_first(n1)->keys = keys;
memcpy(btree_bset_first(n2)->start,
bset_bkey_last(btree_bset_first(n1)),
btree_bset_first(n2)->keys * sizeof(uint64_t));
bkey_copy_key(&n2->key, &b->key);
bch_keylist_add(&parent_keys, &n2->key);
bch_btree_node_write(n2, &cl);
mutex_unlock(&n2->write_lock);
rw_unlock(true, n2);
} else {
trace_bcache_btree_node_compact(b, btree_bset_first(n1)->keys);
mutex_lock(&n1->write_lock);
bch_btree_insert_keys(n1, op, insert_keys, replace_key);
}
bch_keylist_add(&parent_keys, &n1->key);
bch_btree_node_write(n1, &cl);
mutex_unlock(&n1->write_lock);
if (n3) {
/* Depth increases, make a new root */
mutex_lock(&n3->write_lock);
bkey_copy_key(&n3->key, &MAX_KEY);
bch_btree_insert_keys(n3, op, &parent_keys, NULL);
bch_btree_node_write(n3, &cl);
mutex_unlock(&n3->write_lock);
closure_sync(&cl);
bch_btree_set_root(n3);
rw_unlock(true, n3);
} else if (!b->parent) {
/* Root filled up but didn't need to be split */
closure_sync(&cl);
bch_btree_set_root(n1);
} else {
/* Split a non root node */
closure_sync(&cl);
make_btree_freeing_key(b, parent_keys.top);
bch_keylist_push(&parent_keys);
bch_btree_insert_node(b->parent, op, &parent_keys, NULL, NULL);
BUG_ON(!bch_keylist_empty(&parent_keys));
}
btree_node_free(b);
rw_unlock(true, n1);
bch_time_stats_update(&b->c->btree_split_time, start_time);
return 0;
err_free2:
bkey_put(b->c, &n2->key);
btree_node_free(n2);
rw_unlock(true, n2);
err_free1:
bkey_put(b->c, &n1->key);
btree_node_free(n1);
rw_unlock(true, n1);
err:
WARN(1, "bcache: btree split failed (level %u)", b->level);
if (n3 == ERR_PTR(-EAGAIN) ||
n2 == ERR_PTR(-EAGAIN) ||
n1 == ERR_PTR(-EAGAIN))
return -EAGAIN;
return -ENOMEM;
}
static int bch_btree_insert_node(struct btree *b, struct btree_op *op,
struct keylist *insert_keys,
atomic_t *journal_ref,
struct bkey *replace_key)
{
struct closure cl;
BUG_ON(b->level && replace_key);
closure_init_stack(&cl);
mutex_lock(&b->write_lock);
if (write_block(b) != btree_bset_last(b) &&
b->keys.last_set_unwritten)
bch_btree_init_next(b); /* just wrote a set */
if (bch_keylist_nkeys(insert_keys) > insert_u64s_remaining(b)) {
mutex_unlock(&b->write_lock);
goto split;
}
BUG_ON(write_block(b) != btree_bset_last(b));
if (bch_btree_insert_keys(b, op, insert_keys, replace_key)) {
if (!b->level)
bch_btree_leaf_dirty(b, journal_ref);
else
bch_btree_node_write(b, &cl);
}
mutex_unlock(&b->write_lock);
/* wait for btree node write if necessary, after unlock */
closure_sync(&cl);
return 0;
split:
if (current->bio_list) {
op->lock = b->c->root->level + 1;
return -EAGAIN;
} else if (op->lock <= b->c->root->level) {
op->lock = b->c->root->level + 1;
return -EINTR;
} else {
/* Invalidated all iterators */
int ret = btree_split(b, op, insert_keys, replace_key);
if (bch_keylist_empty(insert_keys))
return 0;
else if (!ret)
return -EINTR;
return ret;
}
}
int bch_btree_insert_check_key(struct btree *b, struct btree_op *op,
struct bkey *check_key)
{
int ret = -EINTR;
uint64_t btree_ptr = b->key.ptr[0];
unsigned long seq = b->seq;
struct keylist insert;
bool upgrade = op->lock == -1;
bch_keylist_init(&insert);
if (upgrade) {
rw_unlock(false, b);
rw_lock(true, b, b->level);
if (b->key.ptr[0] != btree_ptr ||
b->seq != seq + 1)
goto out;
}
SET_KEY_PTRS(check_key, 1);
get_random_bytes(&check_key->ptr[0], sizeof(uint64_t));
SET_PTR_DEV(check_key, 0, PTR_CHECK_DEV);
bch_keylist_add(&insert, check_key);
ret = bch_btree_insert_node(b, op, &insert, NULL, NULL);
BUG_ON(!ret && !bch_keylist_empty(&insert));
out:
if (upgrade)
downgrade_write(&b->lock);
return ret;
}
struct btree_insert_op {
struct btree_op op;
struct keylist *keys;
atomic_t *journal_ref;
struct bkey *replace_key;
};
static int btree_insert_fn(struct btree_op *b_op, struct btree *b)
{
struct btree_insert_op *op = container_of(b_op,
struct btree_insert_op, op);
int ret = bch_btree_insert_node(b, &op->op, op->keys,
op->journal_ref, op->replace_key);
if (ret && !bch_keylist_empty(op->keys))
return ret;
else
return MAP_DONE;
}
int bch_btree_insert(struct cache_set *c, struct keylist *keys,
atomic_t *journal_ref, struct bkey *replace_key)
{
struct btree_insert_op op;
int ret = 0;
BUG_ON(current->bio_list);
BUG_ON(bch_keylist_empty(keys));
bch_btree_op_init(&op.op, 0);
op.keys = keys;
op.journal_ref = journal_ref;
op.replace_key = replace_key;
while (!ret && !bch_keylist_empty(keys)) {
op.op.lock = 0;
ret = bch_btree_map_leaf_nodes(&op.op, c,
&START_KEY(keys->keys),
btree_insert_fn);
}
if (ret) {
struct bkey *k;
pr_err("error %i", ret);
while ((k = bch_keylist_pop(keys)))
bkey_put(c, k);
} else if (op.op.insert_collision)
ret = -ESRCH;
return ret;
}
void bch_btree_set_root(struct btree *b)
{
unsigned i;
struct closure cl;
closure_init_stack(&cl);
trace_bcache_btree_set_root(b);
BUG_ON(!b->written);
for (i = 0; i < KEY_PTRS(&b->key); i++)
BUG_ON(PTR_BUCKET(b->c, &b->key, i)->prio != BTREE_PRIO);
mutex_lock(&b->c->bucket_lock);
list_del_init(&b->list);
mutex_unlock(&b->c->bucket_lock);
b->c->root = b;
bch_journal_meta(b->c, &cl);
closure_sync(&cl);
}
/* Map across nodes or keys */
static int bch_btree_map_nodes_recurse(struct btree *b, struct btree_op *op,
struct bkey *from,
btree_map_nodes_fn *fn, int flags)
{
int ret = MAP_CONTINUE;
if (b->level) {
struct bkey *k;
struct btree_iter iter;
bch_btree_iter_init(&b->keys, &iter, from);
while ((k = bch_btree_iter_next_filter(&iter, &b->keys,
bch_ptr_bad))) {
ret = btree(map_nodes_recurse, k, b,
op, from, fn, flags);
from = NULL;
if (ret != MAP_CONTINUE)
return ret;
}
}
if (!b->level || flags == MAP_ALL_NODES)
ret = fn(op, b);
return ret;
}
int __bch_btree_map_nodes(struct btree_op *op, struct cache_set *c,
struct bkey *from, btree_map_nodes_fn *fn, int flags)
{
return btree_root(map_nodes_recurse, c, op, from, fn, flags);
}
static int bch_btree_map_keys_recurse(struct btree *b, struct btree_op *op,
struct bkey *from, btree_map_keys_fn *fn,
int flags)
{
int ret = MAP_CONTINUE;
struct bkey *k;
struct btree_iter iter;
bch_btree_iter_init(&b->keys, &iter, from);
while ((k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad))) {
ret = !b->level
? fn(op, b, k)
: btree(map_keys_recurse, k, b, op, from, fn, flags);
from = NULL;
if (ret != MAP_CONTINUE)
return ret;
}
if (!b->level && (flags & MAP_END_KEY))
ret = fn(op, b, &KEY(KEY_INODE(&b->key),
KEY_OFFSET(&b->key), 0));
return ret;
}
int bch_btree_map_keys(struct btree_op *op, struct cache_set *c,
struct bkey *from, btree_map_keys_fn *fn, int flags)
{
return btree_root(map_keys_recurse, c, op, from, fn, flags);
}
/* Keybuf code */
static inline int keybuf_cmp(struct keybuf_key *l, struct keybuf_key *r)
{
/* Overlapping keys compare equal */
if (bkey_cmp(&l->key, &START_KEY(&r->key)) <= 0)
return -1;
if (bkey_cmp(&START_KEY(&l->key), &r->key) >= 0)
return 1;
return 0;
}
static inline int keybuf_nonoverlapping_cmp(struct keybuf_key *l,
struct keybuf_key *r)
{
return clamp_t(int64_t, bkey_cmp(&l->key, &r->key), -1, 1);
}
struct refill {
struct btree_op op;
unsigned nr_found;
struct keybuf *buf;
struct bkey *end;
keybuf_pred_fn *pred;
};
static int refill_keybuf_fn(struct btree_op *op, struct btree *b,
struct bkey *k)
{
struct refill *refill = container_of(op, struct refill, op);
struct keybuf *buf = refill->buf;
int ret = MAP_CONTINUE;
if (bkey_cmp(k, refill->end) >= 0) {
ret = MAP_DONE;
goto out;
}
if (!KEY_SIZE(k)) /* end key */
goto out;
if (refill->pred(buf, k)) {
struct keybuf_key *w;
spin_lock(&buf->lock);
w = array_alloc(&buf->freelist);
if (!w) {
spin_unlock(&buf->lock);
return MAP_DONE;
}
w->private = NULL;
bkey_copy(&w->key, k);
if (RB_INSERT(&buf->keys, w, node, keybuf_cmp))
array_free(&buf->freelist, w);
else
refill->nr_found++;
if (array_freelist_empty(&buf->freelist))
ret = MAP_DONE;
spin_unlock(&buf->lock);
}
out:
buf->last_scanned = *k;
return ret;
}
void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf,
struct bkey *end, keybuf_pred_fn *pred)
{
struct bkey start = buf->last_scanned;
struct refill refill;
cond_resched();
bch_btree_op_init(&refill.op, -1);
refill.nr_found = 0;
refill.buf = buf;
refill.end = end;
refill.pred = pred;
bch_btree_map_keys(&refill.op, c, &buf->last_scanned,
refill_keybuf_fn, MAP_END_KEY);
trace_bcache_keyscan(refill.nr_found,
KEY_INODE(&start), KEY_OFFSET(&start),
KEY_INODE(&buf->last_scanned),
KEY_OFFSET(&buf->last_scanned));
spin_lock(&buf->lock);
if (!RB_EMPTY_ROOT(&buf->keys)) {
struct keybuf_key *w;
w = RB_FIRST(&buf->keys, struct keybuf_key, node);
buf->start = START_KEY(&w->key);
w = RB_LAST(&buf->keys, struct keybuf_key, node);
buf->end = w->key;
} else {
buf->start = MAX_KEY;
buf->end = MAX_KEY;
}
spin_unlock(&buf->lock);
}
static void __bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
{
rb_erase(&w->node, &buf->keys);
array_free(&buf->freelist, w);
}
void bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
{
spin_lock(&buf->lock);
__bch_keybuf_del(buf, w);
spin_unlock(&buf->lock);
}
bool bch_keybuf_check_overlapping(struct keybuf *buf, struct bkey *start,
struct bkey *end)
{
bool ret = false;
struct keybuf_key *p, *w, s;
s.key = *start;
if (bkey_cmp(end, &buf->start) <= 0 ||
bkey_cmp(start, &buf->end) >= 0)
return false;
spin_lock(&buf->lock);
w = RB_GREATER(&buf->keys, s, node, keybuf_nonoverlapping_cmp);
while (w && bkey_cmp(&START_KEY(&w->key), end) < 0) {
p = w;
w = RB_NEXT(w, node);
if (p->private)
ret = true;
else
__bch_keybuf_del(buf, p);
}
spin_unlock(&buf->lock);
return ret;
}
struct keybuf_key *bch_keybuf_next(struct keybuf *buf)
{
struct keybuf_key *w;
spin_lock(&buf->lock);
w = RB_FIRST(&buf->keys, struct keybuf_key, node);
while (w && w->private)
w = RB_NEXT(w, node);
if (w)
w->private = ERR_PTR(-EINTR);
spin_unlock(&buf->lock);
return w;
}
struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
struct keybuf *buf,
struct bkey *end,
keybuf_pred_fn *pred)
{
struct keybuf_key *ret;
while (1) {
ret = bch_keybuf_next(buf);
if (ret)
break;
if (bkey_cmp(&buf->last_scanned, end) >= 0) {
pr_debug("scan finished");
break;
}
bch_refill_keybuf(c, buf, end, pred);
}
return ret;
}
void bch_keybuf_init(struct keybuf *buf)
{
buf->last_scanned = MAX_KEY;
buf->keys = RB_ROOT;
spin_lock_init(&buf->lock);
array_allocator_init(&buf->freelist);
}