Btrfs: fix race between balance and unused block group deletion

[linux-drm-fsl-dcu.git] / fs / btrfs / extent-tree.c

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 38b76cc02f486db1e9d7f887860aba8137d61205..1c2bd1723e40ce8d1390223daf2bf4a7871ac051 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -9889,6 +9889,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
                }
                spin_unlock(&fs_info->unused_bgs_lock);
 
+               mutex_lock(&root->fs_info->delete_unused_bgs_mutex);
+
                /* Don't want to race with allocators so take the groups_sem */
                down_write(&space_info->groups_sem);
                spin_lock(&block_group->lock);
@@ -9983,6 +9985,7 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
 end_trans:
                btrfs_end_transaction(trans, root);
 next:
+               mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
                btrfs_put_block_group(block_group);
                spin_lock(&fs_info->unused_bgs_lock);
        }