RE: [RFC 16/16] lpfc: vmid: Introducing vmid in io path.

From: Muneendra Kumar M <muneendra.kumar@broadcom.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	James Smart <james.smart@broadcom.com>,
	Hannes Reinecke <hare@suse.de>,
	linux-block@vger.kernel.org, linux-scsi@vger.kernel.org
Cc: emilne@redhat.com, mkumar@redhat.com,
	Gaurav Srivastava <gaurav.srivastava@broadcom.com>,
	James Smart <jsmart2021@gmail.com>,
	Ming Lei <tom.leiming@gmail.com>, Tejun Heo <tj@kernel.org>
Subject: RE: [RFC 16/16] lpfc: vmid: Introducing vmid in io path.
Date: Wed, 12 Aug 2020 17:46:51 +0530	[thread overview]
Message-ID: <747480d2533f28e44dcd9a02f6398a60@mail.gmail.com> (raw)
In-Reply-To: <a4bf914b-c0ff-5876-890d-f1889308f6ea@redhat.com>

Hi Paolo/Tejun,
From the overall conversation the approach will be as below.
Please let me know if I miss anything or any issue with the same.

1)      blkcg will have a new field fc_app_id to store UUID /driver specific
information.
2)      scsi transport will provide a new interface(sysfs) as
register_vm_fabric
3)      As part of this interface user will provide the details of UUID and
the  open fd (cgroup associated
 info with VM) to the new interface.
4)      With VM provided cgroup info we need to find the associated blkcg
and needs to
update the UUID info in the fc_app_id.
5)      Once we update the fc_app_id  all the io’s issued from VM will have
the UUID info as part of blkcg.

If this approach is fine then I will make the necessary changes in my next
version.

Regards,
Muneendra.

-----Original Message-----
From: Paolo Bonzini [mailto:pbonzini@redhat.com]
Sent: Wednesday, August 12, 2020 1:25 PM
To: Muneendra Kumar M <muneendra.kumar@broadcom.com>; James Smart
<james.smart@broadcom.com>; Hannes Reinecke <hare@suse.de>;
linux-block@vger.kernel.org; linux-scsi@vger.kernel.org
Cc: emilne@redhat.com; mkumar@redhat.com; Gaurav Srivastava
<gaurav.srivastava@broadcom.com>; James Smart <jsmart2021@gmail.com>; Ming
Lei <tom.leiming@gmail.com>; Tejun Heo <tj@kernel.org>
Subject: Re: [RFC 16/16] lpfc: vmid: Introducing vmid in io path.

On 10/08/20 14:13, Muneendra Kumar M wrote:
> Agreed:
> So from the user we need to provide UUID and the cgroup associated
> info with VM to the kernel interface. Is this correct?

Yes.

> There is no issues with UUID  passing as one of the arg.
> Coming to the other cgroup associated VM here are the options which we
> can send
>
> 1)openfd:
> We need a utility which opens the cgroup path and pass the fd details
> to the interface.
> And we can use the cgroup_get_from_fd() utility to get the associated
> cgroup in the kernel.
> Dependent on utilty.

This looks good to me.

Paolo