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authorFilipe Manana <fdmanana@gmail.com>2014-03-14 21:55:01 +0100
committerChris Mason <clm@fb.com>2014-03-21 01:15:28 +0100
commit21543baddcdbaa49db5ac8766ae564381e7c64d9 (patch)
tree4ce8aee02deb8ed2d37ef08fe7b2bf2ef66eec24 /fs/btrfs
parentbtrfs: Add trace for btrfs_workqueue alloc/destroy (diff)
downloadlinux-21543baddcdbaa49db5ac8766ae564381e7c64d9.tar.xz
linux-21543baddcdbaa49db5ac8766ae564381e7c64d9.zip
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> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/delayed-ref.c2
1 files changed, 1 insertions, 1 deletions
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);
}