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UPSTREAM: scsi: core: Introduce the scsi_cmd_to_rq() function

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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>
Bug: 204438323
(cherry picked from commit 51f3a47889)
Signed-off-by: Bart Van Assche <bvanassche@google.com>
Change-Id: Iba5551cbb5d80daaab10dbbdb302aac7892ea442
This commit is contained in:
Bart Van Assche
2021-08-09 16:03:04 -07:00
committed by Bart Van Assche
parent 7da289ada7
commit 435df62d65
2 changed files with 18 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
include/scsi/scsi_cmnd.h
View File

@@ -150,6 +150,12 @@ struct scsi_cmnd {
ANDROID_KABI_RESERVE(4);
};
/* 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.
@@ -162,7 +168,9 @@ static inline void *scsi_cmd_priv(struct scsi_cmnd *cmd)
/* make sure not to use it with passthrough commands */
static inline struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
{
return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
struct request *rq = scsi_cmd_to_rq(cmd);
return *(struct scsi_driver **)rq->rq_disk->private_data;
}
extern void scsi_finish_command(struct scsi_cmnd *cmd);

16
include/scsi/scsi_device.h
View File

@@ -271,13 +271,15 @@ sdev_prefix_printk(const char *, const struct scsi_device *, const char *,
__printf(3, 4) void
scmd_printk(const char *, const struct scsi_cmnd *, const char *, ...);
#define scmd_dbg(scmd, fmt, a...) \
do { \
if ((scmd)->request->rq_disk) \
sdev_dbg((scmd)->device, "[%s] " fmt, \
(scmd)->request->rq_disk->disk_name, ##a);\
else \
sdev_dbg((scmd)->device, fmt, ##a); \
#define scmd_dbg(scmd, fmt, a...) \
do { \
struct request *__rq = scsi_cmd_to_rq((scmd)); \
\
if (__rq->rq_disk) \
sdev_dbg((scmd)->device, "[%s] " fmt, \
__rq->rq_disk->disk_name, ##a); \
else \
sdev_dbg((scmd)->device, fmt, ##a); \
} while (0)
enum scsi_target_state {