[PATCH 17/24] scsi: sd: add sd_mpath_{start,end}_command()

[John Garry]

These do the same as nvme_mpath_{start,end}_request()

Signed-off-by: John Garry <john.g.garry at oracle.com>
---
 drivers/scsi/sd.c             | 55 +++++++++++++++++++++++++++++++++++
 include/scsi/scsi_cmnd.h      |  5 ++++
 include/scsi/scsi_multipath.h |  1 +
 3 files changed, 61 insertions(+)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 222e28ed44e9b..845d392456549 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1546,6 +1546,57 @@ static void sd_uninit_command(struct scsi_cmnd *SCpnt)
 		mempool_free(rq->special_vec.bv_page, sd_page_pool);
 }
 
+#ifdef CONFIG_SCSI_MULTIPATH
+static void sd_mpath_start_command(struct scsi_cmnd *scmd)
+{
+	struct request *req = scsi_cmd_to_rq(scmd);
+	struct scsi_disk *sdkp = scsi_disk(req->q->disk);
+	struct sd_mpath_disk *sd_mpath_disk = sdkp->sd_mpath_disk;
+	struct mpath_disk *mpath_disk = sd_mpath_disk->mpath_disk;
+	struct scsi_device *sdev = scmd->device;
+	struct mpath_head *mpath_head = mpath_disk->mpath_head;
+	struct scsi_mpath_head *scsi_mpath_head = mpath_head->drvdata;
+	struct gendisk *disk = mpath_disk->disk;
+
+	if (mpath_qd_iopolicy(&scsi_mpath_head->iopolicy) &&
+	    !(scmd->flags & SCMD_MPATH_CNT_ACTIVE)) {
+		struct scsi_mpath_device *scsi_mpath_dev = sdev->scsi_mpath_dev;
+
+		atomic_inc(&scsi_mpath_dev->nr_active);
+		scmd->flags |= SCMD_MPATH_CNT_ACTIVE;
+	}
+
+	if (!blk_queue_io_stat(disk->queue) || blk_rq_is_passthrough(req) ||
+	    (scmd->flags & SCMD_MPATH_IO_STATS))
+		return;
+
+	scmd->flags |= SCMD_MPATH_IO_STATS;
+	scmd->start_time = bdev_start_io_acct(disk->part0, req_op(req),
+						      jiffies);
+}
+
+static void sd_mpath_end_command(struct scsi_cmnd *scmd)
+{
+	struct request *req = scsi_cmd_to_rq(scmd);
+	struct scsi_disk *sdkp = scsi_disk(req->q->disk);
+	struct sd_mpath_disk *sd_mpath_disk = sdkp->sd_mpath_disk;
+	struct mpath_disk *mpath_disk = sd_mpath_disk->mpath_disk;
+	struct scsi_device *sdev = scmd->device;
+
+	if (scmd->flags & SCMD_MPATH_CNT_ACTIVE) {
+		struct scsi_mpath_device *scsi_mpath_dev = sdev->scsi_mpath_dev;
+
+		atomic_dec_if_positive(&scsi_mpath_dev->nr_active);
+	}
+
+	if (!(scmd->flags & SCMD_MPATH_IO_STATS))
+		return;
+	bdev_end_io_acct(mpath_disk->disk->part0, req_op(req),
+			 blk_rq_bytes(req) >> SECTOR_SHIFT,
+			 scmd->start_time);
+}
+#endif
+
 static bool sd_need_revalidate(struct gendisk *disk, struct scsi_disk *sdkp)
 {
 	if (sdkp->device->removable || sdkp->write_prot) {
@@ -4468,6 +4519,10 @@ static struct scsi_driver sd_template = {
 	.resume			= sd_resume,
 	.init_command		= sd_init_command,
 	.uninit_command		= sd_uninit_command,
+	#ifdef CONFIG_SCSI_MULTIPATH
+	.mpath_start_cmd	= sd_mpath_start_command,
+	.mpath_end_cmd		= sd_mpath_end_command,
+	#endif
 	.done			= sd_done,
 	.eh_action		= sd_eh_action,
 	.eh_reset		= sd_eh_reset,
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 8ecfb94049db5..c6571a36e577b 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -60,6 +60,8 @@ struct scsi_pointer {
 #define SCMD_FAIL_IF_RECOVERING	(1 << 4)
 /* flags preserved across unprep / reprep */
 #define SCMD_PRESERVED_FLAGS	(SCMD_INITIALIZED | SCMD_FAIL_IF_RECOVERING)
+#define SCMD_MPATH_IO_STATS	(1 << 5)
+#define SCMD_MPATH_CNT_ACTIVE	(1 << 6)
 
 /* for scmd->state */
 #define SCMD_STATE_COMPLETE	0
@@ -139,6 +141,9 @@ struct scsi_cmnd {
 					 * to release this memory.  (The memory
 					 * obtained by scsi_malloc is guaranteed
 					 * to be at an address < 16Mb). */
+	#ifdef CONFIG_SCSI_MULTIPATH
+	unsigned long		start_time;
+	#endif
 
 	int result;		/* Status code from lower level driver */
 };
diff --git a/include/scsi/scsi_multipath.h b/include/scsi/scsi_multipath.h
index cb63c6536b854..2011447f482d6 100644
--- a/include/scsi/scsi_multipath.h
+++ b/include/scsi/scsi_multipath.h
@@ -36,6 +36,7 @@ struct scsi_mpath_device {
 	struct mpath_device	mpath_device;
 	struct scsi_device 	*sdev;
 	int			index;
+	atomic_t		nr_active;
 	struct scsi_mpath_head	*scsi_mpath_head;
 
 	char			device_id_str[SCSI_MPATH_DEVICE_ID_LEN];
-- 
2.43.5