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Observed at Connectathon 2017. If a client has underestimated the size of a Write or Reply chunk, the Linux server writes as much payload data as it can, then it recognizes there was a problem and closes the connection without sending the transport header. This creates a couple of problems: <> The client never receives indication of the server-side failure, so it continues to retransmit the bad RPC. Forward progress on the transport is blocked. <> The reply payload pages are not moved out of the svc_rqst, thus they can be released by the RPC server before the RDMA Writes have completed. The new rdma_rw-ized helpers return a distinct error code when a Write/Reply chunk overrun occurs, so it's now easy for the caller (svc_rdma_sendto) to recognize this case. Instead of dropping the connection, post an RDMA_ERROR message. The client now sees an RDMA_ERROR and can properly terminate the RPC transaction. As part of the new logic, set up the same delayed release for these payload pages as would have occurred in the normal case. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.