[LSF/MM/BPF TOPIC] NVMe Cancel support

[John Meneghini <jmeneghi@redhat.com>]

I am scheduled to present on the topic of NVMe Cancel support next week in the LSF/MM/BPF IO Track.

Here's an abstract for my talk.

The NVMe Cancel command was added to the NVMe spec with TP4097a back in the NVMe 2.0 time frame[1].

At that time I was working for a storage array company and was personally involved with the
effort to add support for this protocol into the storage array's controller.

After moving to Red Hat in the fall of 2021 I started working with my engineering
team at Red Hat to add support for TP4097a to the Linux host.

My talk next week will present the latest version of Red Hat's patches - which are based upon
our previous versions[2] submitted for comments - and discuss some of the obstacles
and challenges we've encountered during implementation.

Almost all of these obstacles have to do with testing.  We've had these patches working in our
lab for more than a year now, and we are happily able to send Cancel commands to the storage
array with no problems. However, these tests are not sufficient for upstream acceptance and we've
spent the last few months developing the nvmet patches needed to sufficiently test this feature
with a nvmet soft target..

I want to share those nvmet patches with the community and discuss what the possible next steps
could be to get this feature accepted upstream.

Many thanks to Chris Leech <cleech@redhat.com> and Maurizio Lombardi <mlombard@redhat.com> who
have done the lions share of this work.

[1] https://people.redhat.com/jmeneghi/LSFMM_2025/TP4097a_Abort_Enhancements_2021.07.26-Ratified.pdf
[2] https://lore.kernel.org/linux-nvme/20240912081510.171857-1-mlombard@redhat.com/

-- 
John A. Meneghini
Senior Principal Platform Storage Engineer
RHEL SST - Platform Storage Group
jmeneghi@redhat.com