[RFC PATCH 0/4] union mounts: In-kernel copyup v1

[Valerie Aurora <vaurora@redhat.com>]

Well, not really v1, but gotta start numbering somewhere. :)

This is a proof of concept implementation of in-kernel copyup for
union mounts.  It implements copy up of files on chown(), which is in
some ways harder than rename() or link() because it doesn't lookup the
parent separately.

The idea behind this version is to keep the <mnt,dentry> pair of the
parent directory of the chown() target around in case we need to copy
it up.  If we do need to copy up, we already have the path of the
directory for the topmost file system, instead of having to look it up
again.

Valerie Aurora (4):
  VFS: Split inode_permission() and create path_permission()
  VFS: create user_path_and_parent()
  union-mount: In-kernel copyup routines
  union-mount: Implement chown()

 fs/namei.c            |  125 +++++++++++++++++++++++++++++++----
 fs/open.c             |   33 ++++++++--
 fs/union.c            |  172 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h    |    1 +
 include/linux/namei.h |    2 +
 include/linux/union.h |    2 +
 6 files changed, 315 insertions(+), 20 deletions(-)