btrfs: fix compiling with CONFIG_BTRFS_DEBUG enabled.

Merging in the free space tree deleted a variable needed when
CONFIG_BTRFS_DEBUG=y

Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 0617cb73669dda8206ebc070f2cfb7d8a49ee6b6..83fc61db0e4522b2453791e689d30a85e1ea33b5 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -543,11 +543,13 @@ static noinline void caching_thread(struct btrfs_work *work)
        struct btrfs_block_group_cache *block_group;
        struct btrfs_fs_info *fs_info;
        struct btrfs_caching_control *caching_ctl;
+       struct btrfs_root *extent_root;
        int ret;
 
        caching_ctl = container_of(work, struct btrfs_caching_control, work);
        block_group = caching_ctl->block_group;
        fs_info = block_group->fs_info;
+       extent_root = fs_info->extent_root;
 
        mutex_lock(&caching_ctl->mutex);
        down_read(&fs_info->commit_root_sem);