Chuck Lever 1e091c3bbf svcrdma: Ignore source port when computing DRC hash
The DRC appears to be effectively empty after an RPC/RDMA transport
reconnect. The problem is that each connection uses a different
source port, which defeats the DRC hash.

Clients always have to disconnect before they send retransmissions
to reset the connection's credit accounting, thus every retransmit
on NFS/RDMA will miss the DRC.

An NFS/RDMA client's IP source port is meaningless for RDMA
transports. The transport layer typically sets the source port value
on the connection to a random ephemeral port. The server already
ignores it for the "secure port" check. See commit 16e4d93f6d
("NFSD: Ignore client's source port on RDMA transports").

The Linux NFS server's DRC resolves XID collisions from the same
source IP address by using the checksum of the first 200 bytes of
the RPC call header.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2019-06-19 16:40:40 -04:00
2019-05-26 16:49:19 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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