On Fri, Jan 24, 2020 at 9:47 PM Jack Wang <jinpuwang@xxxxxxxxx> wrote:
>
> Hi all,
>
> Here is v8 of the RTRS (former IBTRS) RDMA Transport Library and the
> corresponding RNBD (former IBNBD) RDMA Network Block Device, which includes
> changes to address comments from the community.
>
> Introduction
> -------------
>
> RTRS (RDMA Transport) is a reliable high speed transport library
> which allows for establishing connection between client and server
> machines via RDMA. It is based on RDMA-CM, so expect also to support RoCE
> and iWARP, but we mainly tested in IB environment. It is optimized to
> transfer (read/write) IO blocks in the sense that it follows the BIO
> semantics of providing the possibility to either write data from a
> scatter-gather list to the remote side or to request ("read") data
> transfer from the remote side into a given set of buffers.
>
> RTRS is multipath capable and provides I/O fail-over and load-balancing
> functionality, i.e. in RTRS terminology, an RTRS path is a set of RDMA
> connections and particular path is selected according to the load-balancing
> policy. It can be used for other components beside RNBD.
>
> Module parameter always_invalidate is introduced for the security problem
> discussed in LPC RDMA MC 2019. When always_invalidate=Y, on the server side we
> invalidate each rdma buffer before we hand it over to RNBD server and
> then pass it to the block layer. A new rkey is generated and registered for the
> buffer after it returns back from the block layer and RNBD server.
> The new rkey is sent back to the client along with the IO result.
> The procedure is the default behaviour of the driver. This invalidation and
> registration on each IO causes performance drop of up to 20%. A user of the
> driver may choose to load the modules with this mechanism switched off
> (always_invalidate=N), if he understands and can take the risk of a malicious
> client being able to corrupt memory of a server it is connected to. This might
> be a reasonable option in a scenario where all the clients and all the servers
> are located within a secure datacenter.
>
> RNBD (RDMA Network Block Device) is a pair of kernel modules
> (client and server) that allow for remote access of a block device on
> the server over RTRS protocol. After being mapped, the remote block
> devices can be accessed on the client side as local block devices.
> Internally RNBD uses RTRS as an RDMA transport library.
>
> Commits for kernel can be found here:
> https://github.com/ionos-enterprise/ibnbd/commits/linux-5.5-rc6-ibnbd-v7
Sorry, forgot to update the link:
https://github.com/ionos-enterprise/ibnbd/tree/linux-5.5-rc7-ibnbd-v8
