Re: [PATCH v3 3/6] scsi: scsi_debug: Advance the write pointer over the data written

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

On 2026/09/17 19:54, Niklas Cassel wrote:
> resp_write_dt0() and resp_write_scat() advance the write pointer of a
> sequential write required zone by the transfer length of the command
> before looking at what do_device_access() returned. It does not always
> move that much data: it returns -1 when the data direction of the
> command does not match the operation, and a short byte count when the
> data-out buffer is smaller than the transfer length, both of which an
> initiator can produce with SG_IO. The first terminates the command, the
> second completes it with GOOD status and a residual.
> 
> The zone state then describes more data than is on the medium, and a
> write at the position where the data really ends is terminated with
> UNALIGNED WRITE COMMAND, because the write pointer has moved beyond it.
> The zone has to be reset before it can be written to again.
> 
> Advance the write pointer over the data that was written instead. As
> do_device_access() does not write a partial physical block, what it
> reports is a whole number of physical blocks, so the write pointer is
> left on a physical block boundary, which is where a write can end.
> 
> resp_write_same() does not need the same treatment, as it writes with
> memmove() and cannot fail part way through.
> 
> Assisted-by: LLM
> Fixes: f0d1cf9378bd ("scsi: scsi_debug: Add ZBC zone commands")
> Signed-off-by: Niklas Cassel <cassel@kernel.org>

OK. So you read my mind :)

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

-- 
Damien Le Moal
Western Digital Research