diff options
Diffstat (limited to 'libbcachefs/btree_cache.c')
| -rw-r--r-- | libbcachefs/btree_cache.c | 30 |
1 files changed, 12 insertions, 18 deletions
diff --git a/libbcachefs/btree_cache.c b/libbcachefs/btree_cache.c index 2c9c3c18..e9df7e82 100644 --- a/libbcachefs/btree_cache.c +++ b/libbcachefs/btree_cache.c @@ -595,12 +595,13 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c, struct btree_cache *bc = &c->btree_cache; struct btree *b; + BUG_ON(level + 1 >= BTREE_MAX_DEPTH); /* * Parent node must be locked, else we could read in a btree node that's * been freed: */ - BUG_ON(!btree_node_locked(iter, level + 1)); - BUG_ON(level >= BTREE_MAX_DEPTH); + if (!bch2_btree_node_relock(iter, level + 1)) + return ERR_PTR(-EINTR); b = bch2_btree_node_mem_alloc(c); if (IS_ERR(b)) @@ -623,13 +624,9 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c, } /* - * If the btree node wasn't cached, we can't drop our lock on - * the parent until after it's added to the cache - because - * otherwise we could race with a btree_split() freeing the node - * we're trying to lock. + * Unlock before doing IO: * - * But the deadlock described below doesn't exist in this case, - * so it's safe to not drop the parent lock until here: + * XXX: ideally should be dropping all btree node locks here */ if (btree_node_read_locked(iter, level + 1)) btree_node_unlock(iter, level + 1); @@ -666,16 +663,11 @@ struct btree *bch2_btree_node_get(struct bch_fs *c, struct btree_iter *iter, struct btree *b; struct bset_tree *t; - /* - * XXX: locking optimization - * - * we can make the locking looser here - caller can drop lock on parent - * node before locking child node (and potentially blocking): we just - * have to have bch2_btree_node_fill() call relock on the parent and - * return -EINTR if that fails - */ - EBUG_ON(!btree_node_locked(iter, level + 1)); EBUG_ON(level >= BTREE_MAX_DEPTH); + + b = btree_node_mem_ptr(k); + if (b) + goto lock_node; retry: b = btree_cache_find(bc, k); if (unlikely(!b)) { @@ -693,6 +685,7 @@ retry: if (IS_ERR(b)) return b; } else { +lock_node: /* * There's a potential deadlock with splits and insertions into * interior nodes we have to avoid: @@ -739,6 +732,7 @@ retry: } } + /* XXX: waiting on IO with btree locks held: */ wait_on_bit_io(&b->flags, BTREE_NODE_read_in_flight, TASK_UNINTERRUPTIBLE); @@ -753,7 +747,7 @@ retry: } /* avoid atomic set bit if it's not needed: */ - if (btree_node_accessed(b)) + if (!btree_node_accessed(b)) set_btree_node_accessed(b); if (unlikely(btree_node_read_error(b))) { |