On 8/10/21 1:03 AM, Bart Van Assche wrote:
The 'request' member of struct scsi_cmnd is superfluous. The struct request and struct scsi_cmnd data structures are adjacent and hence the request pointer can be derived easily from a scsi_cmnd pointer. Introduce a helper function that performs that conversion in a type-safe way. This patch is the first step towards removing the request member from struct scsi_cmnd. Making that change has the following advantages: - This is a performance optimization since adding an offset to a pointer takes less time than dereferencing a pointer. - struct scsi_cmnd becomes smaller. Cc: Christoph Hellwig <hch@xxxxxx> Cc: Hannes Reinecke <hare@xxxxxxx> Cc: Ming Lei <ming.lei@xxxxxxxxxx> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx> --- include/scsi/scsi_cmnd.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h index 90da9617d28a..e76278ea1fee 100644 --- a/include/scsi/scsi_cmnd.h +++ b/include/scsi/scsi_cmnd.h @@ -146,6 +146,12 @@ struct scsi_cmnd { unsigned int extra_len; /* length of alignment and padding */ };+/* Variant of blk_mq_rq_from_pdu() that verifies the type of its argument. */+static inline struct request *scsi_cmd_to_rq(struct scsi_cmnd *scmd) +{ + return blk_mq_rq_from_pdu(scmd); +} + /* * Return the driver private allocation behind the command. * Only works if cmd_size is set in the host template.
Reviewed-by: Hannes Reinecke <hare@xxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@xxxxxxx +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
