Btrfs: fix race when updating existing ref head
PATCH 1/1 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 <[email protected]>
--- fs/btrfs/delayed-ref.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
fs/btrfs/delayed-ref.c +1 -1
@@ -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); }
Signature · 1 line
1.7.9.5