tree b27cd472257302edfd6689e98b9991fa7d648ae0
parent 820f9f147dcce2602eefd9b575bbbd9ea14f0953
author Eric W. Biederman <ebiederm@xmission.com> 1419392223 -0600
committer Eric W. Biederman <ebiederm@xmission.com> 1428597595 -0500

mnt: Honor MNT_LOCKED when detaching mounts

Modify umount(MNT_DETACH) to keep mounts in the hash table that are
locked to their parent mounts, when the parent is lazily unmounted.

In mntput_no_expire detach the children from the hash table, depending
on mnt_pin_kill in cleanup_mnt to decrement the mnt_count of the children.

In __detach_mounts if there are any mounts that have been unmounted
but still are on the list of mounts of a mountpoint, remove their
children from the mount hash table and those children to the unmounted
list so they won't linger potentially indefinitely waiting for their
final mntput, now that the mounts serve no purpose.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>