From 21543baddcdbaa49db5ac8766ae564381e7c64d9 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Fri, 14 Mar 2014 20:55:01 +0000 Subject: [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 Signed-off-by: Chris Mason --- 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 2502ba5a3ac0..31299646024d 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); } -- 2.39.2