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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	[thread overview]
Message-ID: <20210514213356.5264-2-bvanassche@acm.org> (raw)
In-Reply-To: <20210514213356.5264-1-bvanassche@acm.org>

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(+)

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.

  reply	other threads:[~2021-05-14 21:34 UTC|newest]

Thread overview: 81+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-14 21:32 [PATCH 00/50] Remove the request pointer from struct scsi_cmnd Bart Van Assche
2021-05-14 21:32 ` Bart Van Assche [this message]
2021-05-15  6:47   ` [PATCH 01/50] core: Introduce the blk_req() function Christoph Hellwig
2021-05-17 16:07     ` Bart Van Assche
2021-05-14 21:32 ` [PATCH 02/50] core: Use blk_req() instead of scsi_cmnd.request Bart Van Assche
2021-05-14 21:32 ` [PATCH 03/50] sd: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 04/50] sr: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 05/50] scsi_transport_fc: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 06/50] scsi_transport_spi: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 07/50] ata: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 08/50] rdma/iser: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 09/50] rdma/srp: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 10/50] zfcp: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 11/50] 53c700: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 12/50] NCR5380: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 13/50] aacraid: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 14/50] advansys: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 15/50] bnx2i: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 16/50] csiostor: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 17/50] cxlflash: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 18/50] dpt_i2o: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 19/50] fnic: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 20/50] hisi_sas: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 21/50] hpsa: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 22/50] ibmvfc: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 23/50] ibmvscsi: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 24/50] ips: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 25/50] libsas: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 26/50] lpfc: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 27/50] megaraid: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 28/50] mpt3sas: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 29/50] mvumi: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 30/50] myrb: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 31/50] myrs: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 32/50] ncr53c8xx: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 33/50] qedf: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 34/50] qedi: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 35/50] qla1280: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 36/50] qla2xxx: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 37/50] qla4xxx: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 38/50] qlogicpti: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 39/50] scsi_debug: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 40/50] smartpqi: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 41/50] snic: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 42/50] stex: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 43/50] sun3_scsi: " Bart Van Assche
2021-05-14 21:32 ` [PATCH 44/50] sym53c8xx: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 45/50] ufs: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 46/50] virtio_scsi: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 47/50] xen-scsifront: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 48/50] tcm_loop: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 49/50] usb-storage: " Bart Van Assche
2021-05-15 15:09   ` Alan Stern
2021-05-14 21:33 ` [PATCH 50/50] core: Remove the request member from struct scsi_cmnd Bart Van Assche
2021-05-14 21:33 ` [PATCH 00/50] Remove the request pointer " Bart Van Assche
2021-05-14 21:33 ` [PATCH 01/50] core: Introduce the blk_req() function Bart Van Assche
2021-05-14 21:33 ` [PATCH 02/50] core: Use blk_req() instead of scsi_cmnd.request Bart Van Assche
2021-05-14 21:33 ` [PATCH 03/50] sd: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 04/50] sr: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 05/50] scsi_transport_fc: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 06/50] scsi_transport_spi: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 07/50] ata: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 08/50] rdma/iser: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 09/50] rdma/srp: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 10/50] zfcp: " Bart Van Assche
2021-05-17 17:29   ` Benjamin Block
2021-05-14 21:33 ` [PATCH 11/50] 53c700: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 12/50] NCR5380: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 13/50] aacraid: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 14/50] advansys: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 15/50] bnx2i: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 16/50] csiostor: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 17/50] cxlflash: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 18/50] dpt_i2o: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 19/50] fnic: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 20/50] hisi_sas: " Bart Van Assche
2021-05-17  9:49   ` John Garry
2021-05-14 21:33 ` [PATCH 21/50] hpsa: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 22/50] ibmvfc: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 23/50] ibmvscsi: " Bart Van Assche
2021-05-14 21:33 ` [PATCH 24/50] ips: " Bart Van Assche

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