Re: [PATCH v6 1/7] block: Introduce the flag QUEUE_FLAG_NO_ZONE_WRITE_LOCK

[Bart Van Assche <bvanassche@acm.org>]

On 8/8/23 15:27, Jens Axboe wrote:
> I don't think setting that flag by default makes a lot of sense, if the
> device in question isn't zoned. Maybe have variants of BLK_ZONED_* which
> has a locked and unlocked variant for each where it applies? Perhaps
> have the lock flag be common between them so you can check them in the
> same way? That'd keep the fact that it's zoned and if it needs locking
> in the same spot, rather than scatter them in two spots.

Hi Jens,

That's an interesting suggestion but there is a complication: the zone type
is set by different code than the code that decides whether or not locking
is required. For SCSI devices the zone type is set from inside
drivers/scsi/sd.c or drivers/scsi/sd_zbc.c while the locking requirements
come from the SCSI LLD (drivers/ufs/core/ufshcd.c). Additionally, the code
for converting between model type and model string in scsi_debug.c would
look weird if BLK_ZONED_* is split into locked and unlocked variants. See
also the zbc_model_strs_*[] arrays and the sdeb_zbc_model_str() function.

It should be possible to move the flag that indicates whether or not zone
locking is required into struct queue_limits next to "enum blk_zoned_model
zoned;". If nobody objects I will select this alternative.

Thanks,

Bart.