nfs41: V2 adjust max_rqst_sz, max_resp_sz w.r.t to rsize, wsize

The v4.1 client should take into account the desired rsize, wsize when
negotiating the max size in CREATE_SESSION. Accordingly, it should use
rsize, wsize that are smaller than the session negotiated values.
Signed-off-by: NAlexandros Batsakis <batsakis@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/client.c

@@ -1260,10 +1260,20 @@ static int nfs4_set_client(struct nfs_server *server,
 static void nfs4_session_set_rwsize(struct nfs_server *server)
 {
 #ifdef CONFIG_NFS_V4_1
+	struct nfs4_session *sess;
+	u32 server_resp_sz;
+	u32 server_rqst_sz;
+
 	if (!nfs4_has_session(server->nfs_client))
 		return;
-	server->rsize = server->nfs_client->cl_session->fc_attrs.max_resp_sz;
-	server->wsize = server->nfs_client->cl_session->fc_attrs.max_rqst_sz;
+	sess = server->nfs_client->cl_session;
+	server_resp_sz = sess->fc_attrs.max_resp_sz - nfs41_maxread_overhead;
+	server_rqst_sz = sess->fc_attrs.max_rqst_sz - nfs41_maxwrite_overhead;
+
+	if (server->rsize > server_resp_sz)
+		server->rsize = server_resp_sz;
+	if (server->wsize > server_rqst_sz)
+		server->wsize = server_rqst_sz;
 #endif /* CONFIG_NFS_V4_1 */
 }
 

fs/nfs/internal.h

@@ -191,6 +191,10 @@ extern __be32 *nfs3_decode_dirent(__be32 *, struct nfs_entry *, int);
 #ifdef CONFIG_NFS_V4
 extern __be32 *nfs4_decode_dirent(__be32 *p, struct nfs_entry *entry, int plus);
 #endif
+#ifdef CONFIG_NFS_V4_1
+extern const u32 nfs41_maxread_overhead;
+extern const u32 nfs41_maxwrite_overhead;
+#endif
 
 /* nfs4proc.c */
 extern void nfs4_restart_rpc(struct rpc_task *, const struct nfs_client *,

fs/nfs/nfs4proc.c

@@ -4862,13 +4862,16 @@ int nfs4_proc_destroy_session(struct nfs4_session *session)
 int nfs4_init_session(struct nfs_server *server)
 {
 	struct nfs_client *clp = server->nfs_client;
+	struct nfs4_session *session;
 	int ret;
 
 	if (!nfs4_has_session(clp))
 		return 0;
 
-	clp->cl_session->fc_attrs.max_rqst_sz = server->wsize;
-	clp->cl_session->fc_attrs.max_resp_sz = server->rsize;
+	session = clp->cl_session;
+	session->fc_attrs.max_rqst_sz = server->wsize + nfs41_maxwrite_overhead;
+	session->fc_attrs.max_resp_sz = server->rsize + nfs41_maxread_overhead;
+
 	ret = nfs4_recover_expired_lease(server);
 	if (!ret)
 		ret = nfs4_check_client_ready(clp);

fs/nfs/nfs4xdr.c

@@ -46,6 +46,7 @@
 #include <linux/proc_fs.h>
 #include <linux/kdev_t.h>
 #include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/msg_prot.h>
 #include <linux/nfs.h>
 #include <linux/nfs4.h>
 #include <linux/nfs_fs.h>
@@ -677,6 +678,19 @@ static int nfs4_stat_to_errno(int);
 					 decode_sequence_maxsz + \
 					 decode_putrootfh_maxsz + \
 					 decode_fsinfo_maxsz)
+
+const u32 nfs41_maxwrite_overhead = ((RPC_MAX_HEADER_WITH_AUTH +
+				      compound_encode_hdr_maxsz +
+				      encode_sequence_maxsz +
+				      encode_putfh_maxsz +
+				      encode_getattr_maxsz) *
+				     XDR_UNIT);
+
+const u32 nfs41_maxread_overhead = ((RPC_MAX_HEADER_WITH_AUTH +
+				     compound_decode_hdr_maxsz +
+				     decode_sequence_maxsz +
+				     decode_putfh_maxsz) *
+				    XDR_UNIT);
 #endif /* CONFIG_NFS_V4_1 */
 
 static const umode_t nfs_type2fmt[] = {