On 11/16/18 10:14 AM, Christoph Hellwig wrote:

On Thu, Nov 15, 2018 at 12:46:05PM -0500, Mike Snitzer wrote:

quoted

Whether or not ANA is present is a choice of the target implementation;
the host (and whether it supports multipathing) has _zero_ influence on
this.  If the target declares a path as 'inaccessible' the path _is_
inaccessible to the host.  As such, ANA support should be functional
even if native multipathing is not.

Introduce ability to always re-read ANA log page as required due to ANA
error and make current ANA state available via sysfs -- even if native
multipathing is disabled on the host (e.g. nvme_core.multipath=N).

The first part I could see, but I still want to make it conditional
in some way as nvme is going into deeply embedded setups, and I don't
want to carry the weight of the ANA code around for everyone.

Can you clarify this a bit?
We _do_ have the NVME multipath config option to deconfigure the whole 
thing during compile time; that isn't influenced with this patch.
So are you worried about the size of the ANA implementation itself?
Or are you worried about the size of the ANA structures?

The second I fundamentally disagree with.  And even if you found agreement
it would have to be in a separate patch as it is a separate feature.

Why? Where's the problem with re-reading the ANA log pages if we get an 
event indicating that we should?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
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