Re: [PATCH v4 2/5] ata: libata-scsi: refactor ata_scsi_report_supported_opcodes()

[Hannes Reinecke <hare@suse.de>]

On 7/3/26 10:51 AM, Damien Le Moal wrote:
> ata_scsi_report_supported_opcodes() is very limited in functionality as it
> lacks support for the all command format and also does not handle
> correctly commands that have a service action.
> 
> In preparation for adding these missing features, refactor how
> ata_scsi_report_supported_opcodes() operates to make modifications and
> extensions easier. To do so, introduce the array of supported commands
> ata_supported_cmds. This array entries are of type struct ata_scsi_cmd.
> This structure stores the operation code, CDB length, and the service
> action of a supported SCSI command that libata SAT can translate or
> emulate. Since some service actions (e.g. ZI_REPORT_ZONES) can have a
> value of 0, the field sa_valid of struct ata_scsi_cmd is used to indicate
> if the sa field is valid, or if it should be ignored.
> 
> The helper function ata_scsi_get_supported_cmd() is implemented to search
> for a particular command by opcode in this array. This function is used in
> ata_scsi_cmd_is_supported() together with a struct ata_scsi_cmd_support to
> check based on the target device features if the specified command is
> supported.
> 
> ata_scsi_cmd_is_supported() is used as the main function in
> ata_scsi_report_supported_opcodes() to determine if a particular command
> is supported and fill the command reply rbuf as needed. In the case of a
> command that is not supported, the support field is set to 1 as specified
> in SPC, indicating that the command is not supported.
> 
> Of note is that the old ata_scsi_report_supported_opcodes() code did not
> handle the VARIABLE_LENGTH_CMD/ATA_32 command which is supported and
> translated by libata-scsi. The ata_supported_cmds array includes this
> command. As commented in the code, WRITE_SAME_16 is left out of the array
> of supported command ata_scsi_write_same_xlat() prevents the use of this
> command as a passthrough command.
> 
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> ---
>   drivers/ata/libata-scsi.c | 197 ++++++++++++++++++++++++++++----------
>   1 file changed, 145 insertions(+), 52 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@kernel.org>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
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