Re: [LSF/MM/BPF RFC PATCH 00/13]

[Leon Romanovsky <leon@kernel.org>]

On Wed, May 27, 2026 at 02:44:08PM +0200, Haris Iqbal wrote:
> On Tue, May 12, 2026 at 12:34 PM Leon Romanovsky <leon@kernel.org> wrote:
> >
> > On Tue, May 05, 2026 at 09:46:12AM +0200, Md Haris Iqbal wrote:
> > > Following a conversation with Bart yesterday, I am sending the RMR+BRMR
> > > code through patch for easier review.
> > >
> > > The patches apply over the for-next branch of the block tree over commit
> > > 07dfa981ca3
> > >
> > > For context,
> > > RMR (Reliable Multicast over RTRS) is a kernel module that provides
> > > active-active block-level replication over RDMA. It guarantees delivery
> > > of IO to a group of storage nodes and handles resynchronization of data
> > > directly between storage nodes without involving the compute client.
> > >
> > > BRMR (Block device over RMR) sits on top of RMR and exposes a standard
> > > Linux block device (/dev/brmrX) backed by an RMR pool. Together, RMR and
> > > BRMR provide a single-hop replication and resynchronization solution for
> > > RDMA-connected storage clusters.
> > >
> > > My session is on Wednesday, at 12 in the storage room (Istanbul).
> >
> > To summarize the discussion:
> >
> > 1. Move as much logic as possible into the block layer; RDMA should serve
> >    strictly as a transport.
> > 2. Identify another in‑kernel user of this functionality, and add support for
> >    it if required. At least accommodate potential users elsewhere in the
> >    kernel.
> 
> Thanks for the summary Leon.
> 
> The main logic which handles multicast/replication legs, missed I/O
> tracking, re-synchronization, etc are the core parts of RMR.
> If we move those to a separate module, there won't be much left in
> RMR. RMR already uses RTRS from the RDMA subsystem as transport.
> 
> Having said that, I am not against moving RMR out of the RDMA layer.
> It can serve as a reliable replication service/library for any other
> user in the kernel to use.
> Which subsystem (block or something else) would be a better fit then,
> can be discussed.
> 
> PS: Would this be a good candidate for a session/discussion in the upcoming LPC?

Probably yes.

Thanks

> 
> >
> > Thanks