diff mbox series

[01/50] core: Introduce the blk_req() function

Message ID	20210514213356.5264-2-bvanassche@acm.org
State	Superseded
Headers	show Return-Path: <linux-scsi-owner@kernel.org> From: Bart Van Assche <bvanassche@acm.org> To: "Martin K . Petersen" <martin.petersen@oracle.com> Cc: linux-scsi@vger.kernel.org, Bart Van Assche <bvanassche@acm.org>, Christoph Hellwig <hch@lst.de>, Hannes Reinecke <hare@suse.de>, Ming Lei <ming.lei@redhat.com>, "James E.J. Bottomley" <jejb@linux.ibm.com> Subject: [PATCH 01/50] core: Introduce the blk_req() function Date: Fri, 14 May 2021 14:32:16 -0700 Message-Id: <20210514213356.5264-2-bvanassche@acm.org> In-Reply-To: <20210514213356.5264-1-bvanassche@acm.org> References: <20210514213356.5264-1-bvanassche@acm.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	[01/50] core: Introduce the blk_req() function \| expand [01/50] core: Introduce the blk_req() function [03/50] sd: Use blk_req() instead of scsi_cmnd.request [09/50] rdma/srp: Use blk_req() instead of scsi_cmnd.request [11/50] 53c700: Use blk_req() instead of scsi_cmnd.request [13/50] aacraid: Use blk_req() instead of scsi_cmnd.request [15/50] bnx2i: Use blk_req() instead of scsi_cmnd.request [17/50] cxlflash: Use blk_req() instead of scsi_cmnd.request [19/50] fnic: Use blk_req() instead of scsi_cmnd.request [21/50] hpsa: Use blk_req() instead of scsi_cmnd.request [25/50] libsas: Use blk_req() instead of scsi_cmnd.request [27/50] megaraid: Use blk_req() instead of scsi_cmnd.request [29/50] mvumi: Use blk_req() instead of scsi_cmnd.request [31/50] myrs: Use blk_req() instead of scsi_cmnd.request [33/50] qedf: Use blk_req() instead of scsi_cmnd.request [35/50] qla1280: Use blk_req() instead of scsi_cmnd.request [37/50] qla4xxx: Use blk_req() instead of scsi_cmnd.request [39/50] scsi_debug: Use blk_req() instead of scsi_cmnd.request [41/50] snic: Use blk_req() instead of scsi_cmnd.request [43/50] sun3_scsi: Use blk_req() instead of scsi_cmnd.request [45/50] ufs: Use blk_req() instead of scsi_cmnd.request [46/50] virtio_scsi: Use blk_req() instead of scsi_cmnd.request [48/50] tcm_loop: Use blk_req() instead of scsi_cmnd.request [50/50] core: Remove the request member from struct scsi_cmnd [02/50] core: Use blk_req() instead of scsi_cmnd.request [04/50] sr: Use blk_req() instead of scsi_cmnd.request [07/50] ata: Use blk_req() instead of scsi_cmnd.request [08/50] rdma/iser: Use blk_req() instead of scsi_cmnd.request [10/50] zfcp: Use blk_req() instead of scsi_cmnd.request [12/50] NCR5380: Use blk_req() instead of scsi_cmnd.request [14/50] advansys: Use blk_req() instead of scsi_cmnd.request [16/50] csiostor: Use blk_req() instead of scsi_cmnd.request [18/50] dpt_i2o: Use blk_req() instead of scsi_cmnd.request [20/50] hisi_sas: Use blk_req() instead of scsi_cmnd.request [22/50] ibmvfc: Use blk_req() instead of scsi_cmnd.request [24/50] ips: Use blk_req() instead of scsi_cmnd.request

Commit Message

Bart Van Assche May 14, 2021, 9:32 p.m. UTC

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@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 include/scsi/scsi_cmnd.h | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Christoph Hellwig May 15, 2021, 6:47 a.m. UTC | #1

> +/* Variant of blk_mq_rq_from_pdu() that verifies the type of its argument. */

> +static inline struct request *blk_req(struct scsi_cmnd *scmd)


Please don't use a blk_ prefix for a SCSI funtion.  Why not scsi_scmd_to_rq
or something like that?

Bart Van Assche May 17, 2021, 4:07 p.m. UTC | #2

On 5/14/21 11:47 PM, Christoph Hellwig wrote:
>> +/* Variant of blk_mq_rq_from_pdu() that verifies the type of its argument. */

>> +static inline struct request *blk_req(struct scsi_cmnd *scmd)

> 

> Please don't use a blk_ prefix for a SCSI funtion.  Why not scsi_scmd_to_rq

> or something like that?


Hi Christoph,

Thanks for having taken a look. I will rename that function into
scsi_cmd_to_rq().

Bart.

diff mbox series

Patch

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index fed024f4c02a..f5825be7ee76 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 *blk_req(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.