Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Improving Block Layer Tracepoints for Next-Generation Backup Systems

[Ming Lei <ming.lei@redhat.com>]

On Mon, Jan 13, 2025 at 11:01:30PM +0530, Vishnu ks wrote:
> Thanks everyone for the detailed technical feedback and clarifications
> - they've been extremely valuable in understanding the fundamental
> challenges and existing solutions.
> 
> I appreciate the points about md-cluster and DRBD's network RAID
> capabilities. While these are robust solutions for network-based
> replication, I'm particularly interested in the point-in-time recovery
> capability for scenarios like ransomware recovery, where being able to
> roll back to a specific point before encryption occurred would be
> valuable.
> 
> Regarding blk_filter - I've been exploring it since it was mentioned,
> and it indeed seems to be the right approach for what we're trying to
> achieve. However, I've found that many of our current requirements can
> actually be implemented using eBPF without additional kernel modules.
> I plan to create a detailed demonstration video to share my findings
> with this thread. Additionally, I'll be cleaning up and open-sourcing
> our replicator utility implementation for community feedback.
> 
> I would very much like to attend the LSF/MM/BPF summit to discuss
> these ideas in person and learn more about blk_filter and proper block
> layer fundamentals. Would it be possible for someone to help me with
> an invitation?

If one pair of bpf struct_ops are added for attaching to submit_bio()
and ->bi_end_io() in bio_endio(), lots of cases can be covered:

- blk filter

- bio interposer

- blk-snap

- easier IO trace

...

Then both bio and request based devices can be covered.

It shouldn't be hard to figure out generic bio/bvec kfuncs for helping block IO
bpf prog to do more valuable things & fun.

Thanks, 
Ming