Re: [PATCH 3/4] scsi: Internally retry scsi_execute commands

[Mike Christie <michael.christie@oracle.com>]

On 8/11/22 12:02 PM, Martin Wilck wrote:
> On Thu, 2022-08-11 at 11:15 -0500, Mike Christie wrote:
>>>
>>> I don't think it's _that_ speficic. (retries < allowed) is the
>>> default
>>> case, at least for the first failure. REQ_FAILFAST_DEV has very few
>>> users except for the device handlers, and NEEDS_RETRY is a rather
>>> frequently used disposition.
>> I'm saying it's really specific because we only hit this code
>> path that is causing issues when scsi_check_sense returns
>> NEEDS_RETRY.
> 
> What about the other cases in scsi_decide_disposition() that jump to
> maybe_retry?

Ok one exception to what I wrote. DID_TIMEOUT hits the
blk_rq_is_passthrough test of course :)

The rest hit that check condition check and are retried like normal IO:

scsi_noretry_cmd()
.....

	switch (host_byte(scmd->result)) {
...

        if (!scsi_status_is_check_condition(scmd->result))
                return false;

We get to that blk_rq_is_passthrough for DID_TIME_OUT because it
has a goto to bypass the above test. The other host errors we return
false above and retry.