From: Coly Li colyli@suse.de
mainline inclusion from mainline-v5.7-rc1 commit 8e7102273f597dbb38af43da874f8c123f8e6dbe category: performance bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=327 CVE: NA
When registering a cache device, bch_btree_check() is called to check all btree nodes, to make sure the btree is consistent and not corrupted.
bch_btree_check() is recursively executed in a single thread, when there are a lot of data cached and the btree is huge, it may take very long time to check all the btree nodes. In my testing, I observed it took around 50 minutes to finish bch_btree_check().
When checking the bcache btree nodes, the cache set is not running yet, and indeed the whole tree is in read-only state, it is safe to create multiple threads to check the btree in parallel.
This patch tries to create multiple threads, and each thread tries to one-by-one check the sub-tree indexed by a key from the btree root node. The parallel thread number depends on how many keys in the btree root node. At most BCH_BTR_CHKTHREAD_MAX (64) threads can be created, but in practice is should be min(cpu-number/2, root-node-keys-number).
Signed-off-by: Coly Li colyli@suse.de Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: qinghaixiang xuweiqhx@163.com Signed-off-by: Xu Wei xuwei56@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com Reviewed-by: Li Ruilin liruilin4@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/md/bcache/btree.c | 224 +++++++++++++++++++++++++++----------- drivers/md/bcache/btree.h | 85 +++++++++++++++ 2 files changed, 246 insertions(+), 63 deletions(-)
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index f7c76efc97cdc..24e70ee342f0d 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -101,65 +101,6 @@
#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); @@ -1949,13 +1890,170 @@ static int bch_btree_check_recurse(struct btree *b, struct btree_op *op) return ret; }
+static int bch_btree_check_thread(void *arg) +{ + int ret; + struct btree_check_info *info = arg; + struct btree_check_state *check_state = info->state; + struct cache_set *c = check_state->c; + struct btree_iter iter; + struct bkey *k, *p; + int cur_idx, prev_idx, skip_nr; + + k = p = NULL; + cur_idx = prev_idx = 0; + ret = 0; + + /* root node keys are checked before thread created */ + bch_btree_iter_init(&c->root->keys, &iter, NULL); + k = bch_btree_iter_next_filter(&iter, &c->root->keys, bch_ptr_bad); + WARN_ON(!k); + + p = k; + while (k) { + /* + * Fetch a root node key index, skip the keys which + * should be fetched by other threads, then check the + * sub-tree indexed by the fetched key. + */ + spin_lock(&check_state->idx_lock); + cur_idx = check_state->key_idx; + check_state->key_idx++; + spin_unlock(&check_state->idx_lock); + + skip_nr = cur_idx - prev_idx; + + while (skip_nr) { + k = bch_btree_iter_next_filter(&iter, + &c->root->keys, + bch_ptr_bad); + if (k) + p = k; + else { + /* + * No more keys to check in root node, + * current checking threads are enough, + * stop creating more. + */ + atomic_set(&check_state->enough, 1); + /* Update check_state->enough earlier */ + smp_mb(); + goto out; + } + skip_nr--; + cond_resched(); + } + + if (p) { + struct btree_op op; + + btree_node_prefetch(c->root, p); + c->gc_stats.nodes++; + bch_btree_op_init(&op, 0); + ret = btree(check_recurse, p, c->root, &op); + if (ret) + goto out; + } + p = NULL; + prev_idx = cur_idx; + cond_resched(); + } + +out: + info->result = ret; + /* update check_state->started among all CPUs */ + smp_mb(); + if (atomic_dec_and_test(&check_state->started)) + wake_up(&check_state->wait); + + return ret; +} + +static int bch_btree_chkthread_nr(void) +{ + int n = num_online_cpus() / 2; + + if (n == 0) + n = 1; + else if (n > BCH_BTR_CHKTHREAD_MAX) + n = BCH_BTR_CHKTHREAD_MAX; + + return n; +} + int bch_btree_check(struct cache_set *c) { - struct btree_op op; + int ret = 0; + int i; + struct bkey *k = NULL; + struct btree_iter iter; + struct btree_check_state *check_state; + char name[32];
- bch_btree_op_init(&op, SHRT_MAX); + /* check and mark root node keys */ + for_each_key_filter(&c->root->keys, k, &iter, bch_ptr_invalid) + bch_initial_mark_key(c, c->root->level, k); + + bch_initial_mark_key(c, c->root->level + 1, &c->root->key); + + if (c->root->level == 0) + return 0; + + check_state = kzalloc(sizeof(struct btree_check_state), GFP_KERNEL); + if (!check_state) + return -ENOMEM;
- return btree_root(check_recurse, c, &op); + check_state->c = c; + check_state->total_threads = bch_btree_chkthread_nr(); + check_state->key_idx = 0; + spin_lock_init(&check_state->idx_lock); + atomic_set(&check_state->started, 0); + atomic_set(&check_state->enough, 0); + init_waitqueue_head(&check_state->wait); + + /* + * Run multiple threads to check btree nodes in parallel, + * if check_state->enough is non-zero, it means current + * running check threads are enough, unncessary to create + * more. + */ + for (i = 0; i < check_state->total_threads; i++) { + /* fetch latest check_state->enough earlier */ + smp_mb(); + if (atomic_read(&check_state->enough)) + break; + + check_state->infos[i].result = 0; + check_state->infos[i].state = check_state; + snprintf(name, sizeof(name), "bch_btrchk[%u]", i); + atomic_inc(&check_state->started); + + check_state->infos[i].thread = + kthread_run(bch_btree_check_thread, + &check_state->infos[i], + name); + if (IS_ERR(check_state->infos[i].thread)) { + pr_err("fails to run thread bch_btrchk[%d]\n", i); + for (--i; i >= 0; i--) + kthread_stop(check_state->infos[i].thread); + ret = -ENOMEM; + goto out; + } + } + + wait_event_interruptible(check_state->wait, + atomic_read(&check_state->started) == 0); + + for (i = 0; i < check_state->total_threads; i++) { + if (check_state->infos[i].result) { + ret = check_state->infos[i].result; + goto out; + } + } + +out: + kfree(check_state); + return ret; }
void bch_initial_gc_finish(struct cache_set *c) @@ -2416,7 +2514,7 @@ int __bch_btree_map_nodes(struct btree_op *op, struct cache_set *c, 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, +int bch_btree_map_keys_recurse(struct btree *b, struct btree_op *op, struct bkey *from, btree_map_keys_fn *fn, int flags) { diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h index 8bcca2beca986..42954927abd09 100644 --- a/drivers/md/bcache/btree.h +++ b/drivers/md/bcache/btree.h @@ -222,6 +222,25 @@ struct btree_op { unsigned int insert_collision:1; };
+struct btree_check_state; +struct btree_check_info { + struct btree_check_state *state; + struct task_struct *thread; + int result; +}; + +#define BCH_BTR_CHKTHREAD_MAX 64 +struct btree_check_state { + struct cache_set *c; + int total_threads; + int key_idx; + spinlock_t idx_lock; + atomic_t started; + atomic_t enough; + wait_queue_head_t wait; + struct btree_check_info infos[BCH_BTR_CHKTHREAD_MAX]; +}; + static inline void bch_btree_op_init(struct btree_op *op, int write_lock_level) { memset(op, 0, sizeof(struct btree_op)); @@ -266,12 +285,78 @@ void bch_initial_gc_finish(struct cache_set *c); void bch_moving_gc(struct cache_set *c, bool only_move_dirty); int bch_btree_check(struct cache_set *c); void bch_initial_mark_key(struct cache_set *c, int level, struct bkey *k); +typedef int (btree_map_keys_fn)(struct btree_op *op, struct btree *b, + struct bkey *k); +int bch_btree_map_keys(struct btree_op *op, struct cache_set *c, + struct bkey *from, btree_map_keys_fn *fn, int flags); +int bch_btree_map_keys_recurse(struct btree *b, struct btree_op *op, + struct bkey *from, btree_map_keys_fn *fn, + int flags);
static inline void wake_up_gc(struct cache_set *c) { wake_up(&c->gc_wait); }
+/* + * 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; \ +}) + #define MAP_DONE 0 #define MAP_CONTINUE 1