NFSD: MKNOD should return NFSERR_BADTYPE instead of NFSERR_INVAL

A late paragraph of RFC 1813 Section 3.3.11 states:

| ... if the server does not support the target type or the
| target type is illegal, the error, NFS3ERR_BADTYPE, should
| be returned. Note that NF3REG, NF3DIR, and NF3LNK are
| illegal types for MKNOD.

The Linux NFS server incorrectly returns NFSERR_INVAL in these
cases.

Signed-off-by: Chuck Lever <[e-mail]>
Signed-off-by: J. Bruce Fields <[e-mail]>

fs/nfsd/nfs3proc.c

···
 	fh_copy(&resp->dirfh, &argp->fh);
 	fh_init(&resp->fh, NFS3_FHSIZE);
 
-	if (argp->ftype == 0 || argp->ftype >= NF3BAD) {
-		resp->status = nfserr_inval;
-		goto out;
-	}
 	if (argp->ftype == NF3CHR || argp->ftype == NF3BLK) {
 		rdev = MKDEV(argp->major, argp->minor);
 		if (MAJOR(rdev) != argp->major ||
···
 			goto out;
 		}
 	} else if (argp->ftype != NF3SOCK && argp->ftype != NF3FIFO) {
-		resp->status = nfserr_inval;
+		resp->status = nfserr_badtype;
 		goto out;
 	}