Btrfs: only add roots if necessary in find_parent_nodes()
Btrfs: only add roots if necessary in find_parent_nodes()

find_all_leafs() dosen't need add all roots actually, add roots only
if we need, this can avoid unnecessary ulist dance.

Signed-off-by: Wang Shilong <a6ffe7a539d70ea74089829fdeeb6c8d6acce33c@cn.fujitsu.com>
Signed-off-by: Josef Bacik <631dfb3d07694fdcf26abc7aac2c6c2b641f8bde@fb.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs