In the case of mapped security model, files are created with QEMU user
credentials and the client-user's credentials are saved in extended attributes.
Whereas in the case of passthrough security model, files on the
filesystem are directly created with client-user's credentials.
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>