[PATCH] Btrfs: remove ourselves from the cluster list under lock

[PATCH] Btrfs: remove ourselves from the cluster list under lock

[Josef Bacik]

A user was reporting weird warnings from btrfs_put_delayed_ref() and I noticed
that we were doing this list_del_init() on our head ref outside of
delayed_refs->lock.  This is a problem if we have people still on the list, we
could end up modifying old pointers and such.  Fix this by removing us from the
list before we do our run_delayed_ref on our head ref.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
---
 fs/btrfs/extent-tree.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 4c89566..95c6539 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2440,6 +2440,8 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
 			default:
 				WARN_ON(1);
 			}
+		} else {
+			list_del_init(&locked_ref->cluster);
 		}
 		spin_unlock(&delayed_refs->lock);
 
@@ -2462,7 +2464,6 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
 		 * list before we release it.
 		 */
 		if (btrfs_delayed_ref_is_head(ref)) {
-			list_del_init(&locked_ref->cluster);
 			btrfs_delayed_ref_unlock(locked_ref);
 			locked_ref = NULL;
 		}
-- 
1.7.7.6

Re: [PATCH] Btrfs: remove ourselves from the cluster list under lock

[Miao Xie]

On 	thu, 22 Aug 2013 17:04:59 -0400, Josef Bacik wrote:
> A user was reporting weird warnings from btrfs_put_delayed_ref() and I noticed
> that we were doing this list_del_init() on our head ref outside of
> delayed_refs->lock.  This is a problem if we have people still on the list, we
> could end up modifying old pointers and such.  Fix this by removing us from the
> list before we do our run_delayed_ref on our head ref.  Thanks,

Looks good.

Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>

> 
> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
> ---
>  fs/btrfs/extent-tree.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 4c89566..95c6539 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -2440,6 +2440,8 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
>  			default:
>  				WARN_ON(1);
>  			}
> +		} else {
> +			list_del_init(&locked_ref->cluster);
>  		}
>  		spin_unlock(&delayed_refs->lock);
>  
> @@ -2462,7 +2464,6 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
>  		 * list before we release it.
>  		 */
>  		if (btrfs_delayed_ref_is_head(ref)) {
> -			list_del_init(&locked_ref->cluster);
>  			btrfs_delayed_ref_unlock(locked_ref);
>  			locked_ref = NULL;
>  		}
>