Re: [PATCH v2 5/7] scsi: scsi_debug: Add compression mode page for tapes

[John Meneghini <jmeneghi@redhat.com>]

Reviewed-by: John Meneghini <jmeneghi@redhat.com>
Tested-by: John Meneghini <jmeneghi@redhat.com>

On 2/13/25 4:26 AM, Kai Mäkisara wrote:
> Add support for compression mode page. The compression status
> is saved and returned. No UA is generated.
> 
> Signed-off-by: Kai Mäkisara <Kai.Makisara@kolumbus.fi>
> ---
>   drivers/scsi/scsi_debug.c | 33 +++++++++++++++++++++++++++++++++
>   1 file changed, 33 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index 29a9aea30d22..0a5cd35c41de 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -405,6 +405,7 @@ struct sdebug_dev_info {
>   	unsigned int tape_density;
>   	unsigned char tape_partition;
>   	unsigned char tape_nbr_partitions;
> +	unsigned char tape_dce;
>   	unsigned int tape_location[TAPE_MAX_PARTITIONS];
>   	unsigned int tape_eop[TAPE_MAX_PARTITIONS];
>   	struct tape_block *tape_blocks[TAPE_MAX_PARTITIONS];
> @@ -2843,6 +2844,20 @@ static int resp_partition_m_pg(unsigned char *p, int pcontrol, int target)
>   	return sizeof(partition_pg);
>   }
>   
> +static int resp_compression_m_pg(unsigned char *p, int pcontrol, int target,
> +	unsigned char dce)
> +{	/* Compression page for mode_sense (tape) */
> +	unsigned char compression_pg[] = {0x0f, 14, 0x40, 0, 0, 0, 0, 0,
> +		0, 0, 0, 0, 00, 00};
> +
> +	memcpy(p, compression_pg, sizeof(compression_pg));
> +	if (dce)
> +		p[2] |= 0x80;
> +	if (pcontrol == 1)
> +		memset(p + 2, 0, sizeof(compression_pg) - 2);
> +	return sizeof(compression_pg);
> +}
> +
>   /* PAGE_SIZE is more than necessary but provides room for future expansion. */
>   #define SDEBUG_MAX_MSENSE_SZ PAGE_SIZE
>   
> @@ -2983,6 +2998,12 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
>   		}
>   		offset += len;
>   		break;
> +	case 0xf:	/* Compression Mode Page (tape) */
> +		if (!is_tape)
> +			goto bad_pcode;
> +		len += resp_compression_m_pg(ap, pcontrol, target, devip->tape_dce);
> +		offset += len;
> +		break;
>   	case 0x11:	/* Partition Mode Page (tape) */
>   		if (!is_tape)
>   			goto bad_pcode;
> @@ -3143,6 +3164,14 @@ static int resp_mode_select(struct scsi_cmnd *scp,
>   			goto set_mode_changed_ua;
>   		}
>   		break;
> +	case 0xf:       /* Compression mode page */
> +		if (sdebug_ptype != TYPE_TAPE)
> +			goto bad_pcode;
> +		if ((arr[off + 2] & 0x40) != 0) {
> +			devip->tape_dce = (arr[off + 2] & 0x80) != 0;
> +			return 0;
> +		}
> +		break;
>   	case 0x1c:      /* Informational Exceptions Mode page */
>   		if (iec_m_pg[1] == arr[off + 1]) {
>   			memcpy(iec_m_pg + 2, arr + off + 2,
> @@ -3158,6 +3187,10 @@ static int resp_mode_select(struct scsi_cmnd *scp,
>   set_mode_changed_ua:
>   	set_bit(SDEBUG_UA_MODE_CHANGED, devip->uas_bm);
>   	return 0;
> +
> +bad_pcode:
> +	mk_sense_invalid_fld(scp, SDEB_IN_CDB, 2, 5);
> +	return check_condition_result;
>   }
>   
>   static int resp_temp_l_pg(unsigned char *arr)