Re: [PATCH v9 03/13] nvme: Added a newsysfs attribute appid_store

From: Benjamin Block <bblock@linux.ibm.com>
To: Muneendra Kumar M <muneendra.kumar@broadcom.com>
Cc: Benjamin Block <lkml@mageta.org>,
	linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
	tj@kernel.org, linux-nvme@lists.infradead.org, hare@suse.de,
	jsmart2021@gmail.com, emilne@redhat.com, mkumar@redhat.com,
	Steffen Maier <maier@linux.ibm.com>
Subject: Re: [PATCH v9 03/13] nvme: Added a newsysfs attribute appid_store
Date: Tue, 20 Apr 2021 13:09:08 +0200	[thread overview]
Message-ID: <YH62VB+SVfnG+GoI@t480-pf1aa2c2.linux.ibm.com> (raw)
In-Reply-To: <a6497bd924795a5a9279b893b0d83baf@mail.gmail.com>

On Tue, Apr 20, 2021 at 12:24:41PM +0530, Muneendra Kumar M wrote:
> Hi Benjamin,
> 
> >> ---
> >>  drivers/nvme/host/fc.c | 73
> >> +++++++++++++++++++++++++++++++++++++++++-
> >>  1 file changed, 72 insertions(+), 1 deletion(-)
> 
> > Hmm, I wonder why only NVMe-FC? Or is this just for the moment? We also
> > have the FC transport class for SCSI; I assume this could feed the same
> > IDs into the LLDs.
>
> At present it supports only for SCSI-FC .

It does? By adding it to the implementation under `drivers/nvme/host/`?
I am confused.

I see it adds the sysfs-attribute to `nvme_fc_attrs`, how would that be
added to a FC Host that does not have a NVMe 'personality'? I was
assuming this only ever appears under `/sys/class/fc` if the LLDD
registers itself with the NVMe subsystem (presumably via
`nvme_fc_register_localport()`).

zFCP, for example, does not do that, but we do implement the SCSI FC
transport class in `drivers/scsi/scsi_transport_fc.c`.

> In future we are adding the support for NVMe-FC
> But to make it generic and avoid duplication we added this under
> /sys/class/fc .
> 
> Ewan was mentioning that at some point there is a plan  to decouple
> the FC transport somewhat so that there is a layer that represents the
> FC stuff regardless of the FC4 type (SCSI, NVMe). When we have this
> layer we can move the things accordingly.
> 

-- 
Best Regards, Benjamin Block  / Linux on IBM Z Kernel Development / IBM Systems
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