rpc_mkpipe sets the S_IFSOCK mode bit when it creates a
inode but does not create a true socket inode. So when other parts
of the kernel (i.e. the SELinux code in the-mm kernel) use
S_ISSOCK() to see if the inode is a socket, the macro returns true,
but the expected socket inode container structure is really
an rpc_inode container which obviously causes problems...

This patch simply change the S_IFSOCK mode bit to
S_IFIFO which eliminates the problem.

steved.