[PATCH tty-next 0/6] Minor devpts cleanups, fixes and enhancments

[ebiederm@xmission.com (Eric W. Biederman)]

Greg please apply the following patches to tty-next.  If tty-next is not
the proper tree please let me know and I will take these patches through
my user namespace tree.

The follow patches perform a few small cleanups and one enhancement to
devpts, with a net decrease in code size.

The big achievement from a code maintenance point of view is being able
to use mount_nodev in devpts_mount.

The only really significant bug fix is handling the very unlikely case
when kzalloc fails in new_pts_fs_info called from devpts_fill_super and
s_fs_info is NULL when devpts_kill_sb is called from deactivate_locked
super.

The final patch is an enhancment to use the fsuid and fsgid of the mounter
of devpts as the owner of /dev/pts/ptmx.  This is a feature that has
been asked for by users of user namespaces a couple of times, so that
they are not required to have uid 0 mapped into a user namespace to use
devpts.

Eric

fs/devpts/inode.c | 71 ++++++++++++++++++++-----------------------------------
 1 file changed, 26 insertions(+), 45 deletions(-)

Eric W. Biederman (6):
      devpts: Move parse_mount_options into fill_super
      devpts: Move the creation of /dev/pts/ptmx into fill_super
      devpts: Simplify devpts_mount by using mount_nodev
      devpts: Make devpts_kill_sb safe if fsi is NULL
      devpts: Remove sync_filesystems
      devpts: Change the owner of /dev/pts/ptmx to the mounter of /dev/pts