NFSD: Fix NFSv4's PUTPUBFH operation

According to RFC 8881, all minor versions of NFSv4 support PUTPUBFH.

Replace the XDR decoder for PUTPUBFH with a "noop" since we no
longer want the minorversion check, and PUTPUBFH has no arguments to
decode. (Ideally nfsd4_decode_noop should really be called
nfsd4_decode_void).

PUTPUBFH should now behave just like PUTROOTFH.
Reported-by: Cedric Blancher <cedric.blancher@gmail.com>
Fixes: e1a90ebd ("NFSD: Combine decode operations for v4 and v4.1")
Cc: Dan Shelton <dan.f.shelton@gmail.com>
Cc: Roland Mainz <roland.mainz@nrubsig.org>
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4xdr.c

@@ -1245,14 +1245,6 @@ nfsd4_decode_putfh(struct nfsd4_compoundargs *argp, union nfsd4_op_u *u)
 	return nfs_ok;
 }
 
-static __be32
-nfsd4_decode_putpubfh(struct nfsd4_compoundargs *argp, union nfsd4_op_u *p)
-{
-	if (argp->minorversion == 0)
-		return nfs_ok;
-	return nfserr_notsupp;
-}
-
 static __be32
 nfsd4_decode_read(struct nfsd4_compoundargs *argp, union nfsd4_op_u *u)
 {
@@ -2374,7 +2366,7 @@ static const nfsd4_dec nfsd4_dec_ops[] = {
 	[OP_OPEN_CONFIRM]	= nfsd4_decode_open_confirm,
 	[OP_OPEN_DOWNGRADE]	= nfsd4_decode_open_downgrade,
 	[OP_PUTFH]		= nfsd4_decode_putfh,
-	[OP_PUTPUBFH]		= nfsd4_decode_putpubfh,
+	[OP_PUTPUBFH]		= nfsd4_decode_noop,
 	[OP_PUTROOTFH]		= nfsd4_decode_noop,
 	[OP_READ]		= nfsd4_decode_read,
 	[OP_READDIR]		= nfsd4_decode_readdir,