Current code set new file/directory's initial ACL in a non-atomic
manner.
Client first sends request to MDS to create new file/directory, then set
the initial ACL after the new file/directory is successfully created.

The fix is include the initial ACL in create/mkdir/mknod MDS requests.
So MDS can handle creating file/directory and setting the initial ACL in
one request.
Signed-off-by: Yan, Zheng <zyan@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>