btrfs: Remove extra reference count bumps in btrfs_compare_trees

When the 2 comparison trees roots are initialised they are private to
the function and already have reference counts of 1 each. There is no
need to further increment the reference count since the cloned buffers
are already accessed via struct btrfs_path. Eventually the 2 paths used
for comparison are going to be released, effectively disposing of the
cloned buffers.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.c

@@ -5388,7 +5388,6 @@ int btrfs_compare_trees(struct btrfs_root *left_root,
 		ret = -ENOMEM;
 		goto out;
 	}
-	extent_buffer_get(left_path->nodes[left_level]);
 
 	right_level = btrfs_header_level(right_root->commit_root);
 	right_root_level = right_level;
@@ -5399,7 +5398,6 @@ int btrfs_compare_trees(struct btrfs_root *left_root,
 		ret = -ENOMEM;
 		goto out;
 	}
-	extent_buffer_get(right_path->nodes[right_level]);
 	up_read(&fs_info->commit_root_sem);
 
 	if (left_level == 0)