NFSD: Clean up nfsd4_encode_layoutreturn()

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/nfs4layouts.c

@@ -515,11 +515,11 @@ nfsd4_return_file_layouts(struct svc_rqst *rqstp,
 	if (!list_empty(&ls->ls_layouts)) {
 		if (found)
 			nfs4_inc_and_copy_stateid(&lrp->lr_sid, &ls->ls_stid);
-		lrp->lrs_present = 1;
+		lrp->lrs_present = true;
 	} else {
 		trace_nfsd_layoutstate_unhash(&ls->ls_stid.sc_stateid);
 		nfs4_unhash_stid(&ls->ls_stid);
-		lrp->lrs_present = 0;
+		lrp->lrs_present = false;
 	}
 	spin_unlock(&ls->ls_lock);
 
@@ -539,7 +539,7 @@ nfsd4_return_client_layouts(struct svc_rqst *rqstp,
 	struct nfs4_layout *lp, *t;
 	LIST_HEAD(reaplist);
 
-	lrp->lrs_present = 0;
+	lrp->lrs_present = false;
 
 	spin_lock(&clp->cl_lock);
 	list_for_each_entry_safe(ls, n, &clp->cl_lo_states, ls_perclnt) {

fs/nfsd/nfs4xdr.c

@@ -4931,15 +4931,15 @@ nfsd4_encode_layoutreturn(struct nfsd4_compoundres *resp, __be32 nfserr,
 {
 	struct nfsd4_layoutreturn *lrp = &u->layoutreturn;
 	struct xdr_stream *xdr = resp->xdr;
-	__be32 *p;
 
-	p = xdr_reserve_space(xdr, 4);
-	if (!p)
-		return nfserr_resource;
-	*p++ = cpu_to_be32(lrp->lrs_present);
+	/* lrs_present */
+	nfserr = nfsd4_encode_bool(xdr, lrp->lrs_present);
+	if (nfserr != nfs_ok)
+		return nfserr;
 	if (lrp->lrs_present)
+		/* lrs_stateid */
 		return nfsd4_encode_stateid4(xdr, &lrp->lr_sid);
-	return 0;
+	return nfs_ok;
 }
 #endif /* CONFIG_NFSD_PNFS */
 

fs/nfsd/xdr4.h

@@ -630,7 +630,7 @@ struct nfsd4_layoutreturn {
 	u32			lrf_body_len;	/* request */
 	void			*lrf_body;	/* request */
 	stateid_t		lr_sid;		/* request/response */
-	u32			lrs_present;	/* response */
+	bool			lrs_present;	/* response */
 };
 
 struct nfsd4_fallocate {