Re: [PATCH v3 4/6] scsi: scsi_debug: Enforce physical block alignment of zoned writes

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] scsi: scsi_debug: ZBC write physical block boundary check ignores lowest_aligned
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commit 6fe3c0eff911c1b4e6a4a33707f2eb37306c8d19
Author: Niklas Cassel <cassel@kernel.org>

scsi: scsi_debug: Enforce physical block alignment of zoned writes

This commit enforces the requirement from ZBC-3 that write commands to
sequential write required zones must end on a physical block boundary.
It does this by adding a check in check_zbc_access_params() to ensure
the transfer length aligns with the physical block size.

> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index 41c8d958f4458..64f32d97455d6 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -3980,6 +3980,16 @@ static int check_zbc_access_params(struct scsi_cmnd *scp,
[ ... ]
> +		/*
> +		 * Writes must end on a physical block boundary, that is, the
> +		 * transfer length must be a multiple of the physical block
> +		 * size.
> +		 */
> +		if (!IS_ALIGNED(lba + num, 1U << sdebug_physblk_exp)) {

[Severity: Medium]
Does this alignment check ignore the physical block offset?

If a ZBC device is configured with lowest_aligned > 0 (for example
zbc=managed, physblk_exp > 0, lowest_aligned > 0), valid write commands
to sequential required zones where the ending LBA perfectly aligns with
the advertised physical block boundary (meaning lba + num - lowest_aligned
is a multiple of the physical block size) will be rejected with an ILLEGAL
REQUEST (UNALIGNED WRITE COMMAND) sense key. This breaks device emulation
and fails valid I/O. Invalid writes might also be accepted, violating the
ZBC-3 standard.

Should this check subtract sdebug_lowest_aligned to compute the correct
physical block boundary as required by SBC-5?

> +			mk_sense_buffer(scp, ILLEGAL_REQUEST,
> +					UNALIGNED_WRITE_COMMAND);
> +			return check_condition_result;
> +		}
>  	}
>  
>  	/* Handle implicit open of closed and empty zones */

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Sashiko AI review · https://sashiko.dev/#/patchset/20260917125445.1376493-8-cassel@kernel.org?part=4