Re: [PATCH 06/18] scsi: Make scsi_ioctl_reset() pass the request queue pointer to blk_rq_init()

Hannes Reinecke
2017-05-22T12:56:20Z

On 05/22/2017 02:48 PM, hch@lst.de wrote:
> On Mon, May 22, 2017 at 10:46:10AM +0200, Hannes Reinecke wrote:
>>> That seems to be overkill to me for the few drivers. And I suspect
>>> most of them would be better off now even using blk-mq private tags
>>> (which we'd have to implement for the legacy path first or just
>>> kill it off) but just not expose a tag per host to the scsi and block
>>> layers and set that aside.
>>>
>> IE not using blk-mq private tags for EH? Hmm.
>> But then we'd need a SCSI-internal mechanism to get one of them. I
>> really would want to avoid having each driver to implement it's own
>> mechanism on how to get a TMF tag; that sort of thing only leads to
>> copy-and-paste errors.
>> Ok; will be looking into it.
>
> No, we don't. The driver simply sets a tag aside and doesn't expose
> it to the block layer. Similar to what smartpqi already does for LUN
> resets and AENs, mpt3sas does for the ioctl tags and NVMe does for AERs.
> Personally I feel a bit uncomfortable by setting aside just one tag for
TMFs; this assumes we'll never be sending LUN resets to devices in parallel.

But maybe this is a discussion for another time, if and when we finally
move to that.

Cheers,

Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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