Re: [PATCH RFC 00/24] scsi: enable reserved commands for LLDDs

[John Garry <john.garry@huawei.com>]

On 23/08/2019 14:26, John Garry wrote:
>>
>> quite some drivers use internal commands for various purposes, most
>> commonly sending TMFs or querying the HBA status.
>> While these commands use the same submission mechanism than normal
>> I/O commands, they will not be counted as outstanding commands,
>> requiring those drivers to implement their own mechanism to figure
>> out outstanding commands.
>> This patchset enables the use of reserved tags for the SCSI midlayer,
>> enabling LLDDs to rely on the block layer for tracking outstanding
>> commands.
>> More importantly, it allows LLDD to request a valid tag from the block
>> layer without having to implement some tracking mechanism within the
>> driver. This removes quite some hacks which were required for some
>> drivers (eg. fnic or snic).
>>
>> As usual, comments and reviews are welcome.
>>
> 
Hi Hannes,

JFYI, I have rebased this series to 5.6-rc4 here:

https://github.com/hisilicon/kernel-dev/tree/private-topic-sas-5.6-resv-commands-v1

I am interested in enabling this for libsas and associated HBAs, so 
there are some patches on top for that.

No review comments have been addressed, apart from removing "block: 
disable elevator for reserved tags"

Please let me know your plan for this series.

Thanks,
John

> 
> I was wondering if you have any plans to progress this series?
> 
> I don't mind helping out...
> 
> Cheers,
> John
> 
>> Hannes Reinecke (24):
>>   block: disable elevator for reserved tags
>>   scsi: add scsi_{get,put}_reserved_cmd()
>>   scsi: add 'nr_reserved_cmds' field to the SCSI host template
>>   csiostor: use reserved command for LUN reset
>>   scsi: add scsi_cmd_from_priv()
>>   virtio_scsi: use reserved commands for TMF
>>   scsi: add host tagset busy iterator
>>   fnic: use reserved commands
>>   fnic: use scsi_host_tagset_busy_iter() to traverse commands
>>   scsi: allocate separate queue for reserved commands
>>   scsi: add scsi_host_get_reserved_cmd()
>>   hpsa: move hpsa_hba_inquiry after scsi_add_host()
>>   hpsa: use reserved commands