nfsd: Lower NFSv4.1 callback message size limit
The maximum size of a backchannel message on RPC-over-RDMA depends
on the connection's inline threshold. Today that threshold is
typically 1024 bytes, making the maximum message size 996 bytes.
The Linux server's CREATE_SESSION operation checks that the size
of callback Calls can be as large as 1044 bytes, to accommodate
RPCSEC_GSS. Thus CREATE_SESSION fails if a client advertises the
true message size maximum of 996 bytes.
But the server's backchannel currently does not support RPCSEC_GSS.
The actual maximum size it needs is much smaller. It is safe to
reduce the limit to enable NFSv4.1 on RDMA backchannel operation.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/net/sunrpc/auth_unix.c b/net/sunrpc/auth_unix.c
index 548240d..0d3dd36 100644
--- a/net/sunrpc/auth_unix.c
+++ b/net/sunrpc/auth_unix.c
@@ -23,8 +23,6 @@
};
#define uc_uid uc_base.cr_uid
-#define UNX_WRITESLACK (21 + XDR_QUADLEN(UNX_MAXNODENAME))
-
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
@@ -228,8 +226,8 @@
static
struct rpc_auth unix_auth = {
- .au_cslack = UNX_WRITESLACK,
- .au_rslack = 2, /* assume AUTH_NULL verf */
+ .au_cslack = UNX_CALLSLACK,
+ .au_rslack = NUL_REPLYSLACK,
.au_ops = &authunix_ops,
.au_flavor = RPC_AUTH_UNIX,
.au_count = ATOMIC_INIT(0),