nfs: enable localio for non-pNFS IO

Try a local open of the file being written to, and if it succeeds,
then use localio to issue IO.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

fs/nfs/pagelist.c

@@ -958,6 +958,12 @@ static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 	nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 	ret = nfs_generic_pgio(desc, hdr);
 	if (ret == 0) {
+		struct nfs_client *clp = NFS_SERVER(hdr->inode)->nfs_client;
+
+		struct nfsd_file *localio =
+			nfs_local_open_fh(clp, hdr->cred,
+					  hdr->args.fh, hdr->args.context->mode);
+
 		if (NFS_SERVER(hdr->inode)->nfs_client->cl_minorversion)
 			task_flags = RPC_TASK_MOVEABLE;
 		ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
@@ -967,7 +973,7 @@ static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 					desc->pg_rpc_callops,
 					desc->pg_ioflags,
 					RPC_TASK_CRED_NOREF | task_flags,
-					NULL);
+					localio);
 	}
 	return ret;
 }

fs/nfs/write.c

@@ -1796,6 +1796,7 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how,
 		struct nfs_commit_info *cinfo)
 {
 	struct nfs_commit_data	*data;
+	struct nfsd_file *localio;
 	unsigned short task_flags = 0;
 
 	/* another commit raced with us */
@@ -1812,9 +1813,12 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how,
 	nfs_init_commit(data, head, NULL, cinfo);
 	if (NFS_SERVER(inode)->nfs_client->cl_minorversion)
 		task_flags = RPC_TASK_MOVEABLE;
+
+	localio = nfs_local_open_fh(NFS_SERVER(inode)->nfs_client, data->cred,
+				    data->args.fh, data->context->mode);
 	return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
 				   data->mds_ops, how,
-				   RPC_TASK_CRED_NOREF | task_flags, NULL);
+				   RPC_TASK_CRED_NOREF | task_flags, localio);
 }
 
 /*