diff options
| -rw-r--r-- | drivers/md/bcache/btree_iter.c | 32 | ||||
| -rw-r--r-- | drivers/md/bcache/dirent.c | 10 |
2 files changed, 31 insertions, 11 deletions
diff --git a/drivers/md/bcache/btree_iter.c b/drivers/md/bcache/btree_iter.c index 113cb8cd54de..42ac601be585 100644 --- a/drivers/md/bcache/btree_iter.c +++ b/drivers/md/bcache/btree_iter.c @@ -399,15 +399,34 @@ static void btree_iter_up(struct btree_iter *iter) btree_node_unlock(iter, iter->level++); } -static void verify_no_read_locks_held(struct btree_iter *iter) +static void btree_iter_verify_locking(struct btree_iter *iter) { #ifdef CONFIG_BCACHE_DEBUG struct btree_iter *linked; unsigned level; + /* + * Can't hold _any_ read locks (including in linked iterators) when + * taking intent locks, that leads to a fun deadlock involving write + * locks and journal reservations + * + * We could conceivably drop read locks, then retake them and if + * retaking fails then return -EINTR... but, let's keep things simple + * for now: + */ + for_each_linked_btree_iter(iter, linked) for (level = 0; level < BTREE_MAX_DEPTH; level++) BUG_ON(btree_node_read_locked(linked, level)); + + /* + * Also, we have to take intent locks on interior nodes before leaf + * nodes - verify that linked iterators don't have intent locks held at + * depths lower than where we're at: + */ + for_each_linked_btree_iter(iter, linked) + for (level = 0; level < iter->level; level++) + BUG_ON(btree_node_intent_locked(linked, level)); #endif } @@ -426,17 +445,8 @@ static int __must_check __bch_btree_iter_traverse(struct btree_iter *iter, if (!iter->nodes[iter->level]) return 0; - /* - * Can't hold _any_ read locks (including in linked iterators) when - * taking intent locks, that leads to a fun deadlock involving write - * locks and journal reservations - * - * We could conceivably drop read locks, then retake them and if - * retaking fails then return -EINTR... but, let's keep things simple - * for now: - */ if (iter->locks_want >= 0) - verify_no_read_locks_held(iter); + btree_iter_verify_locking(iter); retry: /* * If the current node isn't locked, go up until we have a locked node diff --git a/drivers/md/bcache/dirent.c b/drivers/md/bcache/dirent.c index e5ecc073825c..5f3f031c6b40 100644 --- a/drivers/md/bcache/dirent.c +++ b/drivers/md/bcache/dirent.c @@ -287,6 +287,16 @@ int bch_dirent_rename(struct cache_set *c, do { /* + * When taking intent locks, we have to take interior node locks + * before leaf node locks; if the second iter we traverse has + * locks_want > the first iter, we could end up taking an intent + * lock on an interior node after traversing the first iterator + * only took an intent lock on a leaf. + */ + src_iter.locks_want = dst_iter.locks_want = + max(src_iter.locks_want, dst_iter.locks_want); + + /* * Have to traverse lower btree nodes before higher - due to * lock ordering. */ |