Re: [PATCH v4 03/10] scsi: scsi_debug: Take the zone metadata lock before the data lock

[Damien Le Moal <dlemoal@kernel.org>]

On 2026/09/18 13:29, Niklas Cassel wrote:
> resp_comp_write() takes the data lock and then the zone metadata lock.
> Every other command that takes both takes them the other way round:
> resp_write_dt0(), resp_write_scat(), resp_write_same() and
> resp_write_tape() take the metadata lock and then call
> do_device_access(), which takes the data lock.
> 
> Two commands that take the same two locks in opposite orders can
> deadlock against each other, so a COMPARE AND WRITE and any other write
> to the same store can hang one another.
> 
> Take the locks in the same order as everywhere else, and release them in
> the reverse of that order.
> 
> Correct the comment above map_region() while here. The provisioning map
> is covered by the metadata lock rather than by the data lock, which is
> why resp_unmap() takes only the metadata lock while unmap_region()
> clears map bits.
> 
> Assisted-by: LLM
> Fixes: 84f3a3c01d70 ("scsi: scsi_debug: Atomic write support")
> Signed-off-by: Niklas Cassel <cassel@kernel.org>

Looks good.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

-- 
Damien Le Moal
Western Digital Research