NFSD: Clean up nfsd4_encode_layoutcommit()

Adopt the use of conventional XDR utility functions. Restructure
the encoder to better align with the XDR definition of the result.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4proc.c

@@ -2357,10 +2357,10 @@ nfsd4_layoutcommit(struct svc_rqst *rqstp,
 	mutex_unlock(&ls->ls_mutex);
 
 	if (new_size > i_size_read(inode)) {
-		lcp->lc_size_chg = 1;
+		lcp->lc_size_chg = true;
 		lcp->lc_newsize = new_size;
 	} else {
-		lcp->lc_size_chg = 0;
+		lcp->lc_size_chg = false;
 	}
 
 	nfserr = ops->proc_layoutcommit(inode, lcp);

fs/nfsd/nfs4xdr.c

@@ -4914,20 +4914,15 @@ nfsd4_encode_layoutcommit(struct nfsd4_compoundres *resp, __be32 nfserr,
 {
 	struct nfsd4_layoutcommit *lcp = &u->layoutcommit;
 	struct xdr_stream *xdr = resp->xdr;
-	__be32 *p;
 
-	p = xdr_reserve_space(xdr, 4);
-	if (!p)
-		return nfserr_resource;
-	*p++ = cpu_to_be32(lcp->lc_size_chg);
-	if (lcp->lc_size_chg) {
-		p = xdr_reserve_space(xdr, 8);
-		if (!p)
-			return nfserr_resource;
-		p = xdr_encode_hyper(p, lcp->lc_newsize);
-	}
-
-	return 0;
+	/* ns_sizechanged */
+	nfserr = nfsd4_encode_bool(xdr, lcp->lc_size_chg);
+	if (nfserr != nfs_ok)
+		return nfserr;
+	if (lcp->lc_size_chg)
+		/* ns_size */
+		return nfsd4_encode_length4(xdr, lcp->lc_newsize);
+	return nfs_ok;
 }
 
 static __be32

fs/nfsd/xdr4.h

@@ -618,7 +618,7 @@ struct nfsd4_layoutcommit {
 	u32			lc_layout_type;	/* request */
 	u32			lc_up_len;	/* layout length */
 	void			*lc_up_layout;	/* decoded by callback */
-	u32			lc_size_chg;	/* boolean for response */
+	bool			lc_size_chg;	/* response */
 	u64			lc_newsize;	/* response */
 };