Re: [PATCH] sd_zbc: Write unlock zone from sd_uninit_cmnd()

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Bart,

On 8/9/17 00:07, Bart Van Assche wrote:
> On Tue, 2017-08-08 at 13:17 +0900, Damien Le Moal wrote:
>> Releasing the write lock of a zone when the write commnand that
>                                                     ^^^^^^^^
>                                                     command?
>> acquired the lock completes can cause deadlocks with scsi-mq due to
>> potential queue reordering if the lock owning request is requeued and
>> not executed.
> 
> Please note that even with scsi-sq requeueing can cause request reordering.

I am painfully aware of this fact... I will update the commit message to
reflect this.

>> Since sd_uninit_cmnd() is always called when a request is requeued,
>> call sd_zbc_write_unlock_zone() from that function for write requests
>> that acquired a zone lock. Acquisition of a zone lock by a write command
>> is indicated using the new command flag SCMD_ZONE_WRITE_LOCK.
> 
> Hello Damien,
> 
> Since this patch differs slightly from the version that was posted a few
> days ago, should a "v2" label have been added to the subject and should a
> changelog have been included? Anyway:

Yes, forgot to do that. Reposting.

> Reviewed-by: Bart Van Assche <bart.vanassche@xxxxxxx>

Thanks.

-- 
Damien Le Moal,
Western Digital



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