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|
/*
* 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 "request.h"
#include "writeback.h"
#include <linux/slab.h>
#include <linux/bitops.h>
#include <linux/hash.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.
*
* Make sure all allocations get charged to the root cgroup
*
* Plugging?
*
* If data write is less than hard sector size of ssd, round up offset in open
* bucket to the next whole sector
*
* Also lookup by cgroup in get_open_bucket()
*
* 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
*/
static const char * const op_types[] = {
"insert", "replace"
};
static const char *op_type(struct btree_op *op)
{
return op_types[op->type];
}
#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))
struct workqueue_struct *bch_gc_wq;
static struct workqueue_struct *btree_io_wq;
void bch_btree_op_init_stack(struct btree_op *op)
{
memset(op, 0, sizeof(struct btree_op));
closure_init_stack(&op->cl);
op->lock = -1;
bch_keylist_init(&op->keys);
}
/* Btree key manipulation */
static void bkey_put(struct cache_set *c, struct bkey *k, int level)
{
if ((level && KEY_OFFSET(k)) || !level)
__bkey_put(c, k);
}
/* 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 = end(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 = b->sets[0].data;
struct btree_iter *iter;
iter = mempool_alloc(b->c->fill_iter, GFP_NOWAIT);
iter->size = b->c->sb.bucket_size / b->c->sb.block_size;
iter->used = 0;
if (!i->seq)
goto err;
for (;
b->written < btree_blocks(b) && i->seq == b->sets[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, b->c) > btree_blocks(b))
goto err;
err = "bad magic";
if (i->magic != bset_magic(b->c))
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->sets[0].data && !i->keys)
goto err;
bch_btree_iter_push(iter, i->start, end(i));
b->written += set_blocks(i, b->c);
}
err = "corrupted btree";
for (i = write_block(b);
index(i, b) < btree_blocks(b);
i = ((void *) i) + block_bytes(b->c))
if (i->seq == b->sets[0].data->seq)
goto err;
bch_btree_sort_and_fix_extents(b, iter);
i = b->sets[0].data;
err = "short btree key";
if (b->sets[0].size &&
bkey_cmp(&b->key, &b->sets[0].end) < 0)
goto err;
if (b->written < btree_blocks(b))
bch_bset_init_next(b);
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 %zu, %u keys",
err, PTR_BUCKET_NR(b->c, &b->key, 0),
index(i, b), i->keys);
goto out;
}
static void btree_node_read_endio(struct bio *bio, int error)
{
struct closure *cl = bio->bi_private;
closure_put(cl);
}
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_size = KEY_SIZE(&b->key) << 9;
bio->bi_end_io = btree_node_read_endio;
bio->bi_private = &cl;
bch_bio_map(bio, b->sets[0].data);
bch_submit_bbio(bio, b->c, &b->key, 0);
closure_sync(&cl);
if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
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);
spin_lock(&b->c->btree_read_time_lock);
bch_time_stats_update(&b->c->btree_read_time, start_time);
spin_unlock(&b->c->btree_read_time_lock);
return;
err:
bch_cache_set_error(b->c, "io error reading bucket %lu",
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_done(struct closure *cl)
{
struct btree *b = container_of(cl, struct btree, io.cl);
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))
queue_delayed_work(btree_io_wq, &b->work,
msecs_to_jiffies(30000));
closure_return(cl);
}
static void btree_node_write_done(struct closure *cl)
{
struct btree *b = container_of(cl, struct btree, io.cl);
struct bio_vec *bv;
int n;
__bio_for_each_segment(bv, b->bio, n, 0)
__free_page(bv->bv_page);
__btree_node_write_done(cl);
}
static void btree_node_write_endio(struct bio *bio, int error)
{
struct closure *cl = bio->bi_private;
struct btree *b = container_of(cl, struct btree, io.cl);
if (error)
set_btree_node_io_error(b);
bch_bbio_count_io_errors(b->c, bio, error, "writing btree");
closure_put(cl);
}
static void do_btree_node_write(struct btree *b)
{
struct closure *cl = &b->io.cl;
struct bset *i = b->sets[b->nsets].data;
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 = &b->io.cl;
b->bio->bi_rw = REQ_META|WRITE_SYNC;
b->bio->bi_size = set_blocks(i, b->c) * block_bytes(b->c);
bch_bio_map(b->bio, i);
bkey_copy(&k.key, &b->key);
SET_PTR_OFFSET(&k.key, 0, PTR_OFFSET(&k.key, 0) + bset_offset(b, i));
if (!bch_bio_alloc_pages(b->bio, GFP_NOIO)) {
int j;
struct bio_vec *bv;
void *base = (void *) ((unsigned long) i & ~(PAGE_SIZE - 1));
bio_for_each_segment(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);
__btree_node_write_done(cl);
}
}
void bch_btree_node_write(struct btree *b, struct closure *parent)
{
struct bset *i = b->sets[b->nsets].data;
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(b->sets->data->seq != i->seq);
bch_check_key_order(b, i);
cancel_delayed_work(&b->work);
/* If caller isn't waiting for write, parent refcount is cache set */
closure_lock(&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);
b->written += set_blocks(i, b->c);
atomic_long_add(set_blocks(i, b->c) * b->c->sb.block_size,
&PTR_CACHE(b->c, &b->key, 0)->btree_sectors_written);
bch_btree_sort_lazy(b);
if (b->written < btree_blocks(b))
bch_bset_init_next(b);
}
static void btree_node_write_work(struct work_struct *w)
{
struct btree *b = container_of(to_delayed_work(w), struct btree, work);
rw_lock(true, b, b->level);
if (btree_node_dirty(b))
bch_btree_node_write(b, NULL);
rw_unlock(true, b);
}
static void bch_btree_leaf_dirty(struct btree *b, struct btree_op *op)
{
struct bset *i = b->sets[b->nsets].data;
struct btree_write *w = btree_current_write(b);
BUG_ON(!b->written);
BUG_ON(!i->keys);
if (!btree_node_dirty(b))
queue_delayed_work(btree_io_wq, &b->work, 30 * HZ);
set_btree_node_dirty(b);
if (op && op->journal) {
if (w->journal &&
journal_pin_cmp(b->c, w, op)) {
atomic_dec_bug(w->journal);
w->journal = NULL;
}
if (!w->journal) {
w->journal = op->journal;
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
*/
static void mca_reinit(struct btree *b)
{
unsigned i;
b->flags = 0;
b->written = 0;
b->nsets = 0;
for (i = 0; i < MAX_BSETS; i++)
b->sets[i].size = 0;
/*
* Second loop starts at 1 because b->sets[0]->data is the memory we
* allocated
*/
for (i = 1; i < MAX_BSETS; i++)
b->sets[i].data = NULL;
}
#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->bucket_cache_used - mca_reserve(c))
static void mca_data_free(struct btree *b)
{
struct bset_tree *t = b->sets;
BUG_ON(!closure_is_unlocked(&b->io.cl));
if (bset_prev_bytes(b) < PAGE_SIZE)
kfree(t->prev);
else
free_pages((unsigned long) t->prev,
get_order(bset_prev_bytes(b)));
if (bset_tree_bytes(b) < PAGE_SIZE)
kfree(t->tree);
else
free_pages((unsigned long) t->tree,
get_order(bset_tree_bytes(b)));
free_pages((unsigned long) t->data, b->page_order);
t->prev = NULL;
t->tree = NULL;
t->data = NULL;
list_move(&b->list, &b->c->btree_cache_freed);
b->c->bucket_cache_used--;
}
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)
{
struct bset_tree *t = b->sets;
BUG_ON(t->data);
b->page_order = max_t(unsigned,
ilog2(b->c->btree_pages),
btree_order(k));
t->data = (void *) __get_free_pages(gfp, b->page_order);
if (!t->data)
goto err;
t->tree = bset_tree_bytes(b) < PAGE_SIZE
? kmalloc(bset_tree_bytes(b), gfp)
: (void *) __get_free_pages(gfp, get_order(bset_tree_bytes(b)));
if (!t->tree)
goto err;
t->prev = bset_prev_bytes(b) < PAGE_SIZE
? kmalloc(bset_prev_bytes(b), gfp)
: (void *) __get_free_pages(gfp, get_order(bset_prev_bytes(b)));
if (!t->prev)
goto err;
list_move(&b->list, &b->c->btree_cache);
b->c->bucket_cache_used++;
return;
err:
mca_data_free(b);
}
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);
INIT_LIST_HEAD(&b->list);
INIT_DELAYED_WORK(&b->work, btree_node_write_work);
b->c = c;
closure_init_unlocked(&b->io);
mca_data_alloc(b, k, gfp);
return b;
}
static int mca_reap(struct btree *b, struct closure *cl, unsigned min_order)
{
lockdep_assert_held(&b->c->bucket_lock);
if (!down_write_trylock(&b->lock))
return -ENOMEM;
if (b->page_order < min_order) {
rw_unlock(true, b);
return -ENOMEM;
}
BUG_ON(btree_node_dirty(b) && !b->sets[0].data);
if (cl && btree_node_dirty(b))
bch_btree_node_write(b, NULL);
if (cl)
closure_wait_event_async(&b->io.wait, cl,
atomic_read(&b->io.cl.remaining) == -1);
if (btree_node_dirty(b) ||
!closure_is_unlocked(&b->io.cl) ||
work_pending(&b->work.work)) {
rw_unlock(true, b);
return -EAGAIN;
}
return 0;
}
static int bch_mca_shrink(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;
if (c->shrinker_disabled)
return 0;
if (c->try_harder)
return 0;
/*
* If nr == 0, we're supposed to return the number of items we have
* cached. Not allowed to return -1.
*/
if (!nr)
return mca_can_free(c) * c->btree_pages;
/* Return -1 if we can't do anything right now */
if (sc->gfp_mask & __GFP_WAIT)
mutex_lock(&c->bucket_lock);
else if (!mutex_trylock(&c->bucket_lock))
return -1;
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 (!nr)
break;
if (++i > 3 &&
!mca_reap(b, NULL, 0)) {
mca_data_free(b);
rw_unlock(true, b);
--nr;
}
}
/*
* Can happen right when we first start up, before we've read in any
* btree nodes
*/
if (list_empty(&c->btree_cache))
goto out;
for (i = 0; nr && i < c->bucket_cache_used; i++) {
b = list_first_entry(&c->btree_cache, struct btree, list);
list_rotate_left(&c->btree_cache);
if (!b->accessed &&
!mca_reap(b, NULL, 0)) {
mca_bucket_free(b);
mca_data_free(b);
rw_unlock(true, b);
--nr;
} else
b->accessed = 0;
}
out:
nr = mca_can_free(c) * c->btree_pages;
mutex_unlock(&c->bucket_lock);
return nr;
}
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);
#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;
/* XXX: doesn't check for errors */
closure_init_unlocked(&c->gc);
for (i = 0; i < mca_reserve(c); i++)
mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
list_splice_init(&c->btree_cache,
&c->btree_cache_freeable);
#ifdef CONFIG_BCACHE_DEBUG
mutex_init(&c->verify_lock);
c->verify_data = mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
if (c->verify_data &&
c->verify_data->sets[0].data)
list_del_init(&c->verify_data->list);
else
c->verify_data = NULL;
#endif
c->shrink.shrink = bch_mca_shrink;
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 struct btree *mca_cannibalize(struct cache_set *c, struct bkey *k,
int level, struct closure *cl)
{
int ret = -ENOMEM;
struct btree *i;
trace_bcache_btree_cache_cannibalize(c);
if (!cl)
return ERR_PTR(-ENOMEM);
/*
* Trying to free up some memory - i.e. reuse some btree nodes - may
* require initiating IO to flush the dirty part of the node. If we're
* running under generic_make_request(), that IO will never finish and
* we would deadlock. Returning -EAGAIN causes the cache lookup code to
* punt to workqueue and retry.
*/
if (current->bio_list)
return ERR_PTR(-EAGAIN);
if (c->try_harder && c->try_harder != cl) {
closure_wait_event_async(&c->try_wait, cl, !c->try_harder);
return ERR_PTR(-EAGAIN);
}
c->try_harder = cl;
c->try_harder_start = local_clock();
retry:
list_for_each_entry_reverse(i, &c->btree_cache, list) {
int r = mca_reap(i, cl, btree_order(k));
if (!r)
return i;
if (r != -ENOMEM)
ret = r;
}
if (ret == -EAGAIN &&
closure_blocking(cl)) {
mutex_unlock(&c->bucket_lock);
closure_sync(cl);
mutex_lock(&c->bucket_lock);
goto retry;
}
return ERR_PTR(ret);
}
/*
* 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.
*/
void bch_cannibalize_unlock(struct cache_set *c, struct closure *cl)
{
if (c->try_harder == cl) {
bch_time_stats_update(&c->try_harder_time, c->try_harder_start);
c->try_harder = NULL;
__closure_wake_up(&c->try_wait);
}
}
static struct btree *mca_alloc(struct cache_set *c, struct bkey *k,
int level, struct closure *cl)
{
struct btree *b;
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, NULL, btree_order(k)))
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, NULL, 0)) {
mca_data_alloc(b, k, __GFP_NOWARN|GFP_NOIO);
if (!b->sets[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->sets->data)
goto err;
out:
BUG_ON(!closure_is_unlocked(&b->io.cl));
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->level = level;
mca_reinit(b);
return b;
err:
if (b)
rw_unlock(true, b);
b = mca_cannibalize(c, k, level, cl);
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, it uses the closure embedded in struct btree_op to wait;
* if that closure is in non blocking mode, will return -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 bkey *k,
int level, struct btree_op *op)
{
int i = 0;
bool write = level <= op->lock;
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, k, level, &op->cl);
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->accessed = 1;
for (; i <= b->nsets && b->sets[i].size; i++) {
prefetch(b->sets[i].tree);
prefetch(b->sets[i].data);
}
for (; i <= b->nsets; i++)
prefetch(b->sets[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 cache_set *c, struct bkey *k, int level)
{
struct btree *b;
mutex_lock(&c->bucket_lock);
b = mca_alloc(c, k, level, NULL);
mutex_unlock(&c->bucket_lock);
if (!IS_ERR_OR_NULL(b)) {
bch_btree_node_read(b);
rw_unlock(true, b);
}
}
/* Btree alloc */
static void btree_node_free(struct btree *b, struct btree_op *op)
{
unsigned i;
trace_bcache_btree_node_free(b);
/*
* The BUG_ON() in btree_node_get() implies that we must have a write
* lock on parent to free or even invalidate a node
*/
BUG_ON(op->lock <= b->level);
BUG_ON(b == b->c->root);
if (btree_node_dirty(b))
btree_complete_write(b, btree_current_write(b));
clear_bit(BTREE_NODE_dirty, &b->flags);
cancel_delayed_work(&b->work);
mutex_lock(&b->c->bucket_lock);
for (i = 0; i < KEY_PTRS(&b->key); i++) {
BUG_ON(atomic_read(&PTR_BUCKET(b->c, &b->key, i)->pin));
bch_inc_gen(PTR_CACHE(b->c, &b->key, i),
PTR_BUCKET(b->c, &b->key, i));
}
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, int level,
struct closure *cl)
{
BKEY_PADDED(key) k;
struct btree *b = ERR_PTR(-EAGAIN);
mutex_lock(&c->bucket_lock);
retry:
if (__bch_bucket_alloc_set(c, WATERMARK_METADATA, &k.key, 1, cl))
goto err;
SET_KEY_SIZE(&k.key, c->btree_pages * PAGE_SECTORS);
b = mca_alloc(c, &k.key, level, cl);
if (IS_ERR(b))
goto err_free;
if (!b) {
cache_bug(c,
"Tried to allocate bucket that was in btree cache");
__bkey_put(c, &k.key);
goto retry;
}
b->accessed = 1;
bch_bset_init_next(b);
mutex_unlock(&c->bucket_lock);
trace_bcache_btree_node_alloc(b);
return b;
err_free:
bch_bucket_free(c, &k.key);
__bkey_put(c, &k.key);
err:
mutex_unlock(&c->bucket_lock);
trace_bcache_btree_node_alloc_fail(b);
return b;
}
static struct btree *btree_node_alloc_replacement(struct btree *b,
struct closure *cl)
{
struct btree *n = bch_btree_node_alloc(b->c, b->level, cl);
if (!IS_ERR_OR_NULL(n))
bch_btree_sort_into(b, n);
return n;
}
/* Garbage collection */
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->gc_gen, PTR_GEN(k, i)))
g->gc_gen = 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);
/* guard against overflow */
SET_GC_SECTORS_USED(g, min_t(unsigned,
GC_SECTORS_USED(g) + KEY_SIZE(k),
(1 << 14) - 1));
BUG_ON(!GC_SECTORS_USED(g));
}
return stale;
}
#define btree_mark_key(b, k) __bch_btree_mark_key(b->c, b->level, k)
static int btree_gc_mark_node(struct btree *b, unsigned *keys,
struct gc_stat *gc)
{
uint8_t stale = 0;
unsigned last_dev = -1;
struct bcache_device *d = NULL;
struct bkey *k;
struct btree_iter iter;
struct bset_tree *t;
gc->nodes++;
for_each_key_filter(b, k, &iter, bch_ptr_invalid) {
if (last_dev != KEY_INODE(k)) {
last_dev = KEY_INODE(k);
d = KEY_INODE(k) < b->c->nr_uuids
? b->c->devices[last_dev]
: NULL;
}
stale = max(stale, btree_mark_key(b, k));
if (bch_ptr_bad(b, k))
continue;
*keys += bkey_u64s(k);
gc->key_bytes += bkey_u64s(k);
gc->nkeys++;
gc->data += KEY_SIZE(k);
if (KEY_DIRTY(k))
gc->dirty += KEY_SIZE(k);
}
for (t = b->sets; t <= &b->sets[b->nsets]; t++)
btree_bug_on(t->size &&
bset_written(b, t) &&
bkey_cmp(&b->key, &t->end) < 0,
b, "found short btree key in gc");
return stale;
}
static struct btree *btree_gc_alloc(struct btree *b, struct bkey *k,
struct btree_op *op)
{
/*
* We block priorities from being written for the duration of garbage
* collection, so we can't sleep in btree_alloc() ->
* bch_bucket_alloc_set(), or we'd risk deadlock - so we don't pass it
* our closure.
*/
struct btree *n = btree_node_alloc_replacement(b, NULL);
if (!IS_ERR_OR_NULL(n)) {
swap(b, n);
__bkey_put(b->c, &b->key);
memcpy(k->ptr, b->key.ptr,
sizeof(uint64_t) * KEY_PTRS(&b->key));
btree_node_free(n, op);
up_write(&n->lock);
}
return b;
}
/*
* Leaving this at 2 until we've got incremental garbage collection done; it
* could be higher (and has been tested with 4) except that garbage collection
* could take much longer, adversely affecting latency.
*/
#define GC_MERGE_NODES 2U
struct gc_merge_info {
struct btree *b;
struct bkey *k;
unsigned keys;
};
static void btree_gc_coalesce(struct btree *b, struct btree_op *op,
struct gc_stat *gc, struct gc_merge_info *r)
{
unsigned nodes = 0, keys = 0, blocks;
int i;
while (nodes < GC_MERGE_NODES && r[nodes].b)
keys += r[nodes++].keys;
blocks = btree_default_blocks(b->c) * 2 / 3;
if (nodes < 2 ||
__set_blocks(b->sets[0].data, keys, b->c) > blocks * (nodes - 1))
return;
for (i = nodes - 1; i >= 0; --i) {
if (r[i].b->written)
r[i].b = btree_gc_alloc(r[i].b, r[i].k, op);
if (r[i].b->written)
return;
}
for (i = nodes - 1; i > 0; --i) {
struct bset *n1 = r[i].b->sets->data;
struct bset *n2 = r[i - 1].b->sets->data;
struct bkey *k, *last = NULL;
keys = 0;
if (i == 1) {
/*
* 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 + r->keys,
b->c) > btree_blocks(r[i].b))
return;
keys = n2->keys;
last = &r->b->key;
} else
for (k = n2->start;
k < end(n2);
k = bkey_next(k)) {
if (__set_blocks(n1, n1->keys + keys +
bkey_u64s(k), b->c) > blocks)
break;
last = k;
keys += bkey_u64s(k);
}
BUG_ON(__set_blocks(n1, n1->keys + keys,
b->c) > btree_blocks(r[i].b));
if (last) {
bkey_copy_key(&r[i].b->key, last);
bkey_copy_key(r[i].k, last);
}
memcpy(end(n1),
n2->start,
(void *) node(n2, keys) - (void *) n2->start);
n1->keys += keys;
memmove(n2->start,
node(n2, keys),
(void *) end(n2) - (void *) node(n2, keys));
n2->keys -= keys;
r[i].keys = n1->keys;
r[i - 1].keys = n2->keys;
}
btree_node_free(r->b, op);
up_write(&r->b->lock);
trace_bcache_btree_gc_coalesce(nodes);
gc->nodes--;
nodes--;
memmove(&r[0], &r[1], sizeof(struct gc_merge_info) * nodes);
memset(&r[nodes], 0, sizeof(struct gc_merge_info));
}
static int btree_gc_recurse(struct btree *b, struct btree_op *op,
struct closure *writes, struct gc_stat *gc)
{
void write(struct btree *r)
{
if (!r->written)
bch_btree_node_write(r, &op->cl);
else if (btree_node_dirty(r))
bch_btree_node_write(r, writes);
up_write(&r->lock);
}
int ret = 0, stale;
unsigned i;
struct gc_merge_info r[GC_MERGE_NODES];
memset(r, 0, sizeof(r));
while ((r->k = bch_next_recurse_key(b, &b->c->gc_done))) {
r->b = bch_btree_node_get(b->c, r->k, b->level - 1, op);
if (IS_ERR(r->b)) {
ret = PTR_ERR(r->b);
break;
}
r->keys = 0;
stale = btree_gc_mark_node(r->b, &r->keys, gc);
if (!b->written &&
(r->b->level || stale > 10 ||
b->c->gc_always_rewrite))
r->b = btree_gc_alloc(r->b, r->k, op);
if (r->b->level)
ret = btree_gc_recurse(r->b, op, writes, gc);
if (ret) {
write(r->b);
break;
}
bkey_copy_key(&b->c->gc_done, r->k);
if (!b->written)
btree_gc_coalesce(b, op, gc, r);
if (r[GC_MERGE_NODES - 1].b)
write(r[GC_MERGE_NODES - 1].b);
memmove(&r[1], &r[0],
sizeof(struct gc_merge_info) * (GC_MERGE_NODES - 1));
/* When we've got incremental GC working, we'll want to do
* if (should_resched())
* return -EAGAIN;
*/
cond_resched();
#if 0
if (need_resched()) {
ret = -EAGAIN;
break;
}
#endif
}
for (i = 1; i < GC_MERGE_NODES && r[i].b; i++)
write(r[i].b);
/* Might have freed some children, must remove their keys */
if (!b->written)
bch_btree_sort(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;
unsigned keys = 0;
int ret = 0, stale = btree_gc_mark_node(b, &keys, gc);
if (b->level || stale > 10)
n = btree_node_alloc_replacement(b, NULL);
if (!IS_ERR_OR_NULL(n))
swap(b, n);
if (b->level)
ret = btree_gc_recurse(b, op, writes, gc);
if (!b->written || btree_node_dirty(b)) {
bch_btree_node_write(b, n ? &op->cl : NULL);
}
if (!IS_ERR_OR_NULL(n)) {
closure_sync(&op->cl);
bch_btree_set_root(b);
btree_node_free(n, op);
rw_unlock(true, b);
}
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->gc_gen = b->gen;
if (!atomic_read(&b->pin))
SET_GC_MARK(b, GC_MARK_RECLAIMABLE);
}
mutex_unlock(&c->bucket_lock);
}
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;
if (c->root)
for (i = 0; i < KEY_PTRS(&c->root->key); i++)
SET_GC_MARK(PTR_BUCKET(c, &c->root->key, i),
GC_MARK_METADATA);
for (i = 0; i < KEY_PTRS(&c->uuid_bucket); i++)
SET_GC_MARK(PTR_BUCKET(c, &c->uuid_bucket, i),
GC_MARK_METADATA);
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) {
b->last_gc = b->gc_gen;
c->need_gc = max(c->need_gc, bucket_gc_gen(b));
if (!atomic_read(&b->pin) &&
GC_MARK(b) == GC_MARK_RECLAIMABLE) {
available++;
if (!GC_SECTORS_USED(b))
bch_bucket_add_unused(ca, b);
}
}
}
mutex_unlock(&c->bucket_lock);
return available;
}
static void bch_btree_gc(struct closure *cl)
{
struct cache_set *c = container_of(cl, struct cache_set, gc.cl);
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_stack(&op);
op.lock = SHRT_MAX;
btree_gc_start(c);
atomic_inc(&c->prio_blocked);
ret = btree_root(gc_root, c, &op, &writes, &stats);
closure_sync(&op.cl);
closure_sync(&writes);
if (ret) {
pr_warn("gc failed!");
continue_at(cl, bch_btree_gc, bch_gc_wq);
}
/* Possibly wait for new UUIDs or whatever to hit disk */
bch_journal_meta(c, &op.cl);
closure_sync(&op.cl);
available = bch_btree_gc_finish(c);
atomic_dec(&c->prio_blocked);
wake_up_allocators(c);
bch_time_stats_update(&c->btree_gc_time, start_time);
stats.key_bytes *= sizeof(uint64_t);
stats.dirty <<= 9;
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);
continue_at(cl, bch_moving_gc, bch_gc_wq);
}
void bch_queue_gc(struct cache_set *c)
{
closure_trylock_call(&c->gc.cl, bch_btree_gc, bch_gc_wq, &c->cl);
}
/* Initial partial gc */
static int bch_btree_check_recurse(struct btree *b, struct btree_op *op,
unsigned long **seen)
{
int ret;
unsigned i;
struct bkey *k;
struct bucket *g;
struct btree_iter iter;
for_each_key_filter(b, k, &iter, bch_ptr_invalid) {
for (i = 0; i < KEY_PTRS(k); i++) {
if (!ptr_available(b->c, k, i))
continue;
g = PTR_BUCKET(b->c, k, i);
if (!__test_and_set_bit(PTR_BUCKET_NR(b->c, k, i),
seen[PTR_DEV(k, i)]) ||
!ptr_stale(b->c, k, i)) {
g->gen = PTR_GEN(k, i);
if (b->level)
g->prio = BTREE_PRIO;
else if (g->prio == BTREE_PRIO)
g->prio = INITIAL_PRIO;
}
}
btree_mark_key(b, k);
}
if (b->level) {
k = bch_next_recurse_key(b, &ZERO_KEY);
while (k) {
struct bkey *p = bch_next_recurse_key(b, k);
if (p)
btree_node_prefetch(b->c, p, b->level - 1);
ret = btree(check_recurse, k, b, op, seen);
if (ret)
return ret;
k = p;
}
}
return 0;
}
int bch_btree_check(struct cache_set *c, struct btree_op *op)
{
int ret = -ENOMEM;
unsigned i;
unsigned long *seen[MAX_CACHES_PER_SET];
memset(seen, 0, sizeof(seen));
for (i = 0; c->cache[i]; i++) {
size_t n = DIV_ROUND_UP(c->cache[i]->sb.nbuckets, 8);
seen[i] = kmalloc(n, GFP_KERNEL);
if (!seen[i])
goto err;
/* Disables the seen array until prio_read() uses it too */
memset(seen[i], 0xFF, n);
}
ret = btree_root(check_recurse, c, op, seen);
err:
for (i = 0; i < MAX_CACHES_PER_SET; i++)
kfree(seen[i]);
return ret;
}
/* Btree insertion */
static void shift_keys(struct btree *b, struct bkey *where, struct bkey *insert)
{
struct bset *i = b->sets[b->nsets].data;
memmove((uint64_t *) where + bkey_u64s(insert),
where,
(void *) end(i) - (void *) where);
i->keys += bkey_u64s(insert);
bkey_copy(where, insert);
bch_bset_fix_lookup_table(b, where);
}
static bool fix_overlapping_extents(struct btree *b,
struct bkey *insert,
struct btree_iter *iter,
struct btree_op *op)
{
void subtract_dirty(struct bkey *k, uint64_t offset, int sectors)
{
if (KEY_DIRTY(k))
bcache_dev_sectors_dirty_add(b->c, KEY_INODE(k),
offset, -sectors);
}
uint64_t old_offset;
unsigned old_size, sectors_found = 0;
while (1) {
struct bkey *k = bch_btree_iter_next(iter);
if (!k ||
bkey_cmp(&START_KEY(k), insert) >= 0)
break;
if (bkey_cmp(k, &START_KEY(insert)) <= 0)
continue;
old_offset = KEY_START(k);
old_size = KEY_SIZE(k);
/*
* We might overlap with 0 size extents; we can't skip these
* because if they're in the set we're inserting to we have to
* adjust them so they don't overlap with the key we're
* inserting. But we don't want to check them for BTREE_REPLACE
* operations.
*/
if (op->type == BTREE_REPLACE &&
KEY_SIZE(k)) {
/*
* k might have been split since we inserted/found the
* key we're replacing
*/
unsigned i;
uint64_t offset = KEY_START(k) -
KEY_START(&op->replace);
/* But it must be a subset of the replace key */
if (KEY_START(k) < KEY_START(&op->replace) ||
KEY_OFFSET(k) > KEY_OFFSET(&op->replace))
goto check_failed;
/* We didn't find a key that we were supposed to */
if (KEY_START(k) > KEY_START(insert) + sectors_found)
goto check_failed;
if (KEY_PTRS(&op->replace) != KEY_PTRS(k))
goto check_failed;
/* skip past gen */
offset <<= 8;
BUG_ON(!KEY_PTRS(&op->replace));
for (i = 0; i < KEY_PTRS(&op->replace); i++)
if (k->ptr[i] != op->replace.ptr[i] + offset)
goto check_failed;
sectors_found = KEY_OFFSET(k) - KEY_START(insert);
}
if (bkey_cmp(insert, k) < 0 &&
bkey_cmp(&START_KEY(insert), &START_KEY(k)) > 0) {
/*
* We overlapped in the middle of an existing key: that
* means we have to split the old key. But we have to do
* slightly different things depending on whether the
* old key has been written out yet.
*/
struct bkey *top;
subtract_dirty(k, KEY_START(insert), KEY_SIZE(insert));
if (bkey_written(b, k)) {
/*
* We insert a new key to cover the top of the
* old key, and the old key is modified in place
* to represent the bottom split.
*
* It's completely arbitrary whether the new key
* is the top or the bottom, but it has to match
* up with what btree_sort_fixup() does - it
* doesn't check for this kind of overlap, it
* depends on us inserting a new key for the top
* here.
*/
top = bch_bset_search(b, &b->sets[b->nsets],
insert);
shift_keys(b, top, k);
} else {
BKEY_PADDED(key) temp;
bkey_copy(&temp.key, k);
shift_keys(b, k, &temp.key);
top = bkey_next(k);
}
bch_cut_front(insert, top);
bch_cut_back(&START_KEY(insert), k);
bch_bset_fix_invalidated_key(b, k);
return false;
}
if (bkey_cmp(insert, k) < 0) {
bch_cut_front(insert, k);
} else {
if (bkey_written(b, k) &&
bkey_cmp(&START_KEY(insert), &START_KEY(k)) <= 0) {
/*
* Completely overwrote, so we don't have to
* invalidate the binary search tree
*/
bch_cut_front(k, k);
} else {
__bch_cut_back(&START_KEY(insert), k);
bch_bset_fix_invalidated_key(b, k);
}
}
subtract_dirty(k, old_offset, old_size - KEY_SIZE(k));
}
check_failed:
if (op->type == BTREE_REPLACE) {
if (!sectors_found) {
op->insert_collision = true;
return true;
} else if (sectors_found < KEY_SIZE(insert)) {
SET_KEY_OFFSET(insert, KEY_OFFSET(insert) -
(KEY_SIZE(insert) - sectors_found));
SET_KEY_SIZE(insert, sectors_found);
}
}
return false;
}
static bool btree_insert_key(struct btree *b, struct btree_op *op,
struct bkey *k)
{
struct bset *i = b->sets[b->nsets].data;
struct bkey *m, *prev;
unsigned status = BTREE_INSERT_STATUS_INSERT;
BUG_ON(bkey_cmp(k, &b->key) > 0);
BUG_ON(b->level && !KEY_PTRS(k));
BUG_ON(!b->level && !KEY_OFFSET(k));
if (!b->level) {
struct btree_iter iter;
struct bkey search = KEY(KEY_INODE(k), KEY_START(k), 0);
/*
* bset_search() returns the first key that is strictly greater
* than the search key - but for back merging, we want to find
* the first key that is greater than or equal to KEY_START(k) -
* unless KEY_START(k) is 0.
*/
if (KEY_OFFSET(&search))
SET_KEY_OFFSET(&search, KEY_OFFSET(&search) - 1);
prev = NULL;
m = bch_btree_iter_init(b, &iter, &search);
if (fix_overlapping_extents(b, k, &iter, op))
return false;
while (m != end(i) &&
bkey_cmp(k, &START_KEY(m)) > 0)
prev = m, m = bkey_next(m);
if (key_merging_disabled(b->c))
goto insert;
/* prev is in the tree, if we merge we're done */
status = BTREE_INSERT_STATUS_BACK_MERGE;
if (prev &&
bch_bkey_try_merge(b, prev, k))
goto merged;
status = BTREE_INSERT_STATUS_OVERWROTE;
if (m != end(i) &&
KEY_PTRS(m) == KEY_PTRS(k) && !KEY_SIZE(m))
goto copy;
status = BTREE_INSERT_STATUS_FRONT_MERGE;
if (m != end(i) &&
bch_bkey_try_merge(b, k, m))
goto copy;
} else
m = bch_bset_search(b, &b->sets[b->nsets], k);
insert: shift_keys(b, m, k);
copy: bkey_copy(m, k);
merged:
if (KEY_DIRTY(k))
bcache_dev_sectors_dirty_add(b->c, KEY_INODE(k),
KEY_START(k), KEY_SIZE(k));
bch_check_keys(b, "%u for %s", status, op_type(op));
if (b->level && !KEY_OFFSET(k))
btree_current_write(b)->prio_blocked++;
trace_bcache_btree_insert_key(b, k, op->type, status);
return true;
}
bool bch_btree_insert_keys(struct btree *b, struct btree_op *op)
{
bool ret = false;
struct bkey *k;
unsigned oldsize = bch_count_data(b);
while ((k = bch_keylist_pop(&op->keys))) {
bkey_put(b->c, k, b->level);
ret |= btree_insert_key(b, op, k);
}
BUG_ON(bch_count_data(b) < oldsize);
return ret;
}
bool bch_btree_insert_check_key(struct btree *b, struct btree_op *op,
struct bio *bio)
{
bool ret = false;
uint64_t btree_ptr = b->key.ptr[0];
unsigned long seq = b->seq;
BKEY_PADDED(k) tmp;
rw_unlock(false, b);
rw_lock(true, b, b->level);
if (b->key.ptr[0] != btree_ptr ||
b->seq != seq + 1 ||
should_split(b))
goto out;
op->replace = KEY(op->inode, bio_end(bio), bio_sectors(bio));
SET_KEY_PTRS(&op->replace, 1);
get_random_bytes(&op->replace.ptr[0], sizeof(uint64_t));
SET_PTR_DEV(&op->replace, 0, PTR_CHECK_DEV);
bkey_copy(&tmp.k, &op->replace);
BUG_ON(op->type != BTREE_INSERT);
BUG_ON(!btree_insert_key(b, op, &tmp.k));
ret = true;
out:
downgrade_write(&b->lock);
return ret;
}
static int btree_split(struct btree *b, struct btree_op *op)
{
bool split, root = b == b->c->root;
struct btree *n1, *n2 = NULL, *n3 = NULL;
uint64_t start_time = local_clock();
if (b->level)
set_closure_blocking(&op->cl);
n1 = btree_node_alloc_replacement(b, &op->cl);
if (IS_ERR(n1))
goto err;
split = set_blocks(n1->sets[0].data, n1->c) > (btree_blocks(b) * 4) / 5;
if (split) {
unsigned keys = 0;
trace_bcache_btree_node_split(b, n1->sets[0].data->keys);
n2 = bch_btree_node_alloc(b->c, b->level, &op->cl);
if (IS_ERR(n2))
goto err_free1;
if (root) {
n3 = bch_btree_node_alloc(b->c, b->level + 1, &op->cl);
if (IS_ERR(n3))
goto err_free2;
}
bch_btree_insert_keys(n1, op);
/* Has to be a linear search because we don't have an auxiliary
* search tree yet
*/
while (keys < (n1->sets[0].data->keys * 3) / 5)
keys += bkey_u64s(node(n1->sets[0].data, keys));
bkey_copy_key(&n1->key, node(n1->sets[0].data, keys));
keys += bkey_u64s(node(n1->sets[0].data, keys));
n2->sets[0].data->keys = n1->sets[0].data->keys - keys;
n1->sets[0].data->keys = keys;
memcpy(n2->sets[0].data->start,
end(n1->sets[0].data),
n2->sets[0].data->keys * sizeof(uint64_t));
bkey_copy_key(&n2->key, &b->key);
bch_keylist_add(&op->keys, &n2->key);
bch_btree_node_write(n2, &op->cl);
rw_unlock(true, n2);
} else {
trace_bcache_btree_node_compact(b, n1->sets[0].data->keys);
bch_btree_insert_keys(n1, op);
}
bch_keylist_add(&op->keys, &n1->key);
bch_btree_node_write(n1, &op->cl);
if (n3) {
bkey_copy_key(&n3->key, &MAX_KEY);
bch_btree_insert_keys(n3, op);
bch_btree_node_write(n3, &op->cl);
closure_sync(&op->cl);
bch_btree_set_root(n3);
rw_unlock(true, n3);
} else if (root) {
op->keys.top = op->keys.bottom;
closure_sync(&op->cl);
bch_btree_set_root(n1);
} else {
unsigned i;
bkey_copy(op->keys.top, &b->key);
bkey_copy_key(op->keys.top, &ZERO_KEY);
for (i = 0; i < KEY_PTRS(&b->key); i++) {
uint8_t g = PTR_BUCKET(b->c, &b->key, i)->gen + 1;
SET_PTR_GEN(op->keys.top, i, g);
}
bch_keylist_push(&op->keys);
closure_sync(&op->cl);
atomic_inc(&b->c->prio_blocked);
}
rw_unlock(true, n1);
btree_node_free(b, op);
bch_time_stats_update(&b->c->btree_split_time, start_time);
return 0;
err_free2:
__bkey_put(n2->c, &n2->key);
btree_node_free(n2, op);
rw_unlock(true, n2);
err_free1:
__bkey_put(n1->c, &n1->key);
btree_node_free(n1, op);
rw_unlock(true, n1);
err:
if (n3 == ERR_PTR(-EAGAIN) ||
n2 == ERR_PTR(-EAGAIN) ||
n1 == ERR_PTR(-EAGAIN))
return -EAGAIN;
pr_warn("couldn't split");
return -ENOMEM;
}
static int bch_btree_insert_recurse(struct btree *b, struct btree_op *op,
struct keylist *stack_keys)
{
if (b->level) {
int ret;
struct bkey *insert = op->keys.bottom;
struct bkey *k = bch_next_recurse_key(b, &START_KEY(insert));
if (!k) {
btree_bug(b, "no key to recurse on at level %i/%i",
b->level, b->c->root->level);
op->keys.top = op->keys.bottom;
return -EIO;
}
if (bkey_cmp(insert, k) > 0) {
unsigned i;
if (op->type == BTREE_REPLACE) {
__bkey_put(b->c, insert);
op->keys.top = op->keys.bottom;
op->insert_collision = true;
return 0;
}
for (i = 0; i < KEY_PTRS(insert); i++)
atomic_inc(&PTR_BUCKET(b->c, insert, i)->pin);
bkey_copy(stack_keys->top, insert);
bch_cut_back(k, insert);
bch_cut_front(k, stack_keys->top);
bch_keylist_push(stack_keys);
}
ret = btree(insert_recurse, k, b, op, stack_keys);
if (ret)
return ret;
}
if (!bch_keylist_empty(&op->keys)) {
if (should_split(b)) {
if (op->lock <= b->c->root->level) {
BUG_ON(b->level);
op->lock = b->c->root->level + 1;
return -EINTR;
}
return btree_split(b, op);
}
BUG_ON(write_block(b) != b->sets[b->nsets].data);
if (bch_btree_insert_keys(b, op)) {
if (!b->level)
bch_btree_leaf_dirty(b, op);
else
bch_btree_node_write(b, &op->cl);
}
}
return 0;
}
int bch_btree_insert(struct btree_op *op, struct cache_set *c)
{
int ret = 0;
struct keylist stack_keys;
/*
* Don't want to block with the btree locked unless we have to,
* otherwise we get deadlocks with try_harder and between split/gc
*/
clear_closure_blocking(&op->cl);
BUG_ON(bch_keylist_empty(&op->keys));
bch_keylist_copy(&stack_keys, &op->keys);
bch_keylist_init(&op->keys);
while (!bch_keylist_empty(&stack_keys) ||
!bch_keylist_empty(&op->keys)) {
if (bch_keylist_empty(&op->keys)) {
bch_keylist_add(&op->keys,
bch_keylist_pop(&stack_keys));
op->lock = 0;
}
ret = btree_root(insert_recurse, c, op, &stack_keys);
if (ret == -EAGAIN) {
ret = 0;
closure_sync(&op->cl);
} else if (ret) {
struct bkey *k;
pr_err("error %i trying to insert key for %s",
ret, op_type(op));
while ((k = bch_keylist_pop(&stack_keys) ?:
bch_keylist_pop(&op->keys)))
bkey_put(c, k, 0);
}
}
bch_keylist_free(&stack_keys);
if (op->journal)
atomic_dec_bug(op->journal);
op->journal = NULL;
return ret;
}
void bch_btree_set_root(struct btree *b)
{
unsigned i;
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;
__bkey_put(b->c, &b->key);
bch_journal_meta(b->c, NULL);
}
/* Cache lookup */
static int submit_partial_cache_miss(struct btree *b, struct btree_op *op,
struct bkey *k)
{
struct search *s = container_of(op, struct search, op);
struct bio *bio = &s->bio.bio;
int ret = 0;
while (!ret &&
!op->lookup_done) {
unsigned sectors = INT_MAX;
if (KEY_INODE(k) == op->inode) {
if (KEY_START(k) <= bio->bi_sector)
break;
sectors = min_t(uint64_t, sectors,
KEY_START(k) - bio->bi_sector);
}
ret = s->d->cache_miss(b, s, bio, sectors);
}
return ret;
}
/*
* Read from a single key, handling the initial cache miss if the key starts in
* the middle of the bio
*/
static int submit_partial_cache_hit(struct btree *b, struct btree_op *op,
struct bkey *k)
{
struct search *s = container_of(op, struct search, op);
struct bio *bio = &s->bio.bio;
unsigned ptr;
struct bio *n;
int ret = submit_partial_cache_miss(b, op, k);
if (ret || op->lookup_done)
return ret;
/* XXX: figure out best pointer - for multiple cache devices */
ptr = 0;
PTR_BUCKET(b->c, k, ptr)->prio = INITIAL_PRIO;
while (!op->lookup_done &&
KEY_INODE(k) == op->inode &&
bio->bi_sector < KEY_OFFSET(k)) {
struct bkey *bio_key;
sector_t sector = PTR_OFFSET(k, ptr) +
(bio->bi_sector - KEY_START(k));
unsigned sectors = min_t(uint64_t, INT_MAX,
KEY_OFFSET(k) - bio->bi_sector);
n = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
if (!n)
return -EAGAIN;
if (n == bio)
op->lookup_done = true;
bio_key = &container_of(n, struct bbio, bio)->key;
/*
* The bucket we're reading from might be reused while our bio
* is in flight, and we could then end up reading the wrong
* data.
*
* We guard against this by checking (in cache_read_endio()) if
* the pointer is stale again; if so, we treat it as an error
* and reread from the backing device (but we don't pass that
* error up anywhere).
*/
bch_bkey_copy_single_ptr(bio_key, k, ptr);
SET_PTR_OFFSET(bio_key, 0, sector);
n->bi_end_io = bch_cache_read_endio;
n->bi_private = &s->cl;
__bch_submit_bbio(n, b->c);
}
return 0;
}
int bch_btree_search_recurse(struct btree *b, struct btree_op *op)
{
struct search *s = container_of(op, struct search, op);
struct bio *bio = &s->bio.bio;
int ret = 0;
struct bkey *k;
struct btree_iter iter;
bch_btree_iter_init(b, &iter, &KEY(op->inode, bio->bi_sector, 0));
do {
k = bch_btree_iter_next_filter(&iter, b, bch_ptr_bad);
if (!k) {
/*
* b->key would be exactly what we want, except that
* pointers to btree nodes have nonzero size - we
* wouldn't go far enough
*/
ret = submit_partial_cache_miss(b, op,
&KEY(KEY_INODE(&b->key),
KEY_OFFSET(&b->key), 0));
break;
}
ret = b->level
? btree(search_recurse, k, b, op)
: submit_partial_cache_hit(b, op, k);
} while (!ret &&
!op->lookup_done);
return ret;
}
/* 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);
}
static int bch_btree_refill_keybuf(struct btree *b, struct btree_op *op,
struct keybuf *buf, struct bkey *end)
{
struct btree_iter iter;
bch_btree_iter_init(b, &iter, &buf->last_scanned);
while (!array_freelist_empty(&buf->freelist)) {
struct bkey *k = bch_btree_iter_next_filter(&iter, b,
bch_ptr_bad);
if (!b->level) {
if (!k) {
buf->last_scanned = b->key;
break;
}
buf->last_scanned = *k;
if (bkey_cmp(&buf->last_scanned, end) >= 0)
break;
if (buf->key_predicate(buf, k)) {
struct keybuf_key *w;
spin_lock(&buf->lock);
w = array_alloc(&buf->freelist);
w->private = NULL;
bkey_copy(&w->key, k);
if (RB_INSERT(&buf->keys, w, node, keybuf_cmp))
array_free(&buf->freelist, w);
spin_unlock(&buf->lock);
}
} else {
if (!k)
break;
btree(refill_keybuf, k, b, op, buf, end);
/*
* Might get an error here, but can't really do anything
* and it'll get logged elsewhere. Just read what we
* can.
*/
if (bkey_cmp(&buf->last_scanned, end) >= 0)
break;
cond_resched();
}
}
return 0;
}
void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf,
struct bkey *end)
{
struct bkey start = buf->last_scanned;
struct btree_op op;
bch_btree_op_init_stack(&op);
cond_resched();
btree_root(refill_keybuf, c, &op, buf, end);
closure_sync(&op.cl);
pr_debug("found %s keys from %llu:%llu to %llu:%llu",
RB_EMPTY_ROOT(&buf->keys) ? "no" :
array_freelist_empty(&buf->freelist) ? "some" : "a few",
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)
{
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);
}
return ret;
}
void bch_keybuf_init(struct keybuf *buf, keybuf_pred_fn *fn)
{
buf->key_predicate = fn;
buf->last_scanned = MAX_KEY;
buf->keys = RB_ROOT;
spin_lock_init(&buf->lock);
array_allocator_init(&buf->freelist);
}
void bch_btree_exit(void)
{
if (btree_io_wq)
destroy_workqueue(btree_io_wq);
if (bch_gc_wq)
destroy_workqueue(bch_gc_wq);
}
int __init bch_btree_init(void)
{
if (!(bch_gc_wq = create_singlethread_workqueue("bch_btree_gc")) ||
!(btree_io_wq = create_singlethread_workqueue("bch_btree_io")))
return -ENOMEM;
return 0;
}
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