mnt: Factor out unhash_mnt from detach_mnt and umount_tree
mnt: Factor out unhash_mnt from detach_mnt and umount_tree

Create a function unhash_mnt that contains the common code between
detach_mnt and umount_tree, and use unhash_mnt in place of the common
code.  This add a unncessary list_del_init(mnt->mnt_child) into
umount_tree but given that mnt_child is already empty this extra
line is a noop.

Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <8a741aa8cbd77ebc4a56ddb528ce9fd15d42f034@xmission.com>

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