SUNRPC: Use only rpcbind v2 for AF_INET requests

Some server vendors support the higher versions of rpcbind only for
AF_INET6.  The kernel doesn't need to use v3 or v4 for AF_INET anyway,
so change the kernel's rpcbind client to query AF_INET servers over
rpcbind v2 only.

This has a few interesting benefits:

1. If the rpcbind request is going over TCP, and the server doesn't
   support rpcbind versions 3 or 4, the client reduces by two the number
   of ephemeral ports left in TIME_WAIT for each rpcbind request.  This
   will help during NFS mount storms.

2. The rpcbind interaction with servers that don't support rpcbind
   versions 3 or 4 will use less network traffic.  Also helpful
   during mount storms.

3. We can eliminate the kernel build option that controls whether the
   kernel's rpcbind client uses rpcbind version 3 and 4 for AF_INET
   servers.  Less complicated kernel configuration...

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 0 insertions, 21 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index 1c16de9611e9..0ce72dcd6b96 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -1799,27 +1799,6 @@ config SUNRPC_XPRT_RDMA
 
           If unsure, say N.
 
-config SUNRPC_BIND34
-        bool "Support for rpcbind versions 3 & 4 (EXPERIMENTAL)"
-        depends on SUNRPC && EXPERIMENTAL
-        default n
-        help
-          RPC requests over IPv6 networks require support for larger
-          addresses when performing an RPC bind.  Sun added support for
-          IPv6 addressing by creating two new versions of the rpcbind
-          protocol (RFC 1833).
-
-          This option enables support in the kernel RPC client for
-          querying rpcbind servers via versions 3 and 4 of the rpcbind
-          protocol.  The kernel automatically falls back to version 2
-          if a remote rpcbind service does not support versions 3 or 4.
-          By themselves, these new versions do not provide support for
-          RPC over IPv6, but the new protocol versions are necessary to
-          support it.
-
-          If unsure, say N to get traditional behavior (version 2 rpcbind
-          requests only).
-
 config RPCSEC_GSS_KRB5
         tristate "Secure RPC: Kerberos V mechanism (EXPERIMENTAL)"
         depends on SUNRPC && EXPERIMENTAL