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>
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