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| author | Bart Van Assche <bvanassche@acm.org> | 2021-08-09 16:03:04 -0700 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2021-08-11 22:25:36 -0400 |
| commit | 51f3a478892873337c54068d1185bcd797000a52 (patch) | |
| tree | 2dfb7deb4b8dc178f4a799bdc4151bfe71254108 | |
| parent | 10163cee1f06fc2e17bcf7bbc2982337202d1d5c (diff) | |
| download | linux-51f3a478892873337c54068d1185bcd797000a52.tar.bz2 | |
scsi: core: Introduce the scsi_cmd_to_rq() function
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.
Link: https://lore.kernel.org/r/20210809230355.8186-2-bvanassche@acm.org
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
| -rw-r--r-- | include/scsi/scsi_cmnd.h | 6 |
1 files changed, 6 insertions, 0 deletions
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. |