Filipe David Borba Manana
2014-Mar-14 20:55 UTC
[PATCH] Btrfs: fix race when updating existing ref head
While we update an existing ref head's extent_op, we're not holding its spinlock, so while we're updating its extent_op contents (key, flags) we can have a task running __btrfs_run_delayed_refs() that holds the ref head's lock and sets its extent_op to NULL right after the task updating the ref head just checked its extent_op was not NULL. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> --- fs/btrfs/delayed-ref.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 2502ba5..3129964 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -495,6 +495,7 @@ update_existing_head_ref(struct btrfs_delayed_ref_node *existing, ref = btrfs_delayed_node_to_head(update); BUG_ON(existing_ref->is_data != ref->is_data); + spin_lock(&existing_ref->lock); if (ref->must_insert_reserved) { /* if the extent was freed and then * reallocated before the delayed ref @@ -536,7 +537,6 @@ update_existing_head_ref(struct btrfs_delayed_ref_node *existing, * only need the lock for this case cause we could be processing it * currently, for refs we just added we know we're a-ok. */ - spin_lock(&existing_ref->lock); existing->ref_mod += update->ref_mod; spin_unlock(&existing_ref->lock); } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html