Re: [PATCH v2 1/4] scsi: scsi_dh_alua: allow I/O in target port unavailable and standby states

From: Mauricio Faria de Oliveira
Date: Tue Jul 11 2017 - 11:32:43 EST

On 07/11/2017 06:18 AM, Hannes Reinecke wrote:

The whole_point_ of having device handlers is to_avoid_ I/O errors
during booting.

And the ALUA checker is prepared to handle this situation properly.
The directio checker of course doesn't know about this, but then no-one
expected the directio checker to work with ALUA.

I lacked that more holistic understanding. Thanks for explaining.

Now, for the sake of logging/debugging...

Any problem with patches 2 and 4?

Also, it seems the Unavailable/Standby states would not be logged
without a recheck from alua_check_sense(), since the only callers
of alua_rtpg_queue() are alua_activate() and alua_check[_sense]()
[the call from alua_check_vpd() is only in the initialization path].

Isn't there a point in scheduling a recheck once those conditions
are found in alua_check_sense() to get them logged? - since valid
path checkers won't go through that function.

(and it occurred to me that the state-change check of patch 3 can
be done there, simpler.)


Mauricio Faria de Oliveira
IBM Linux Technology Center