[PATCH RFC v2 06/24] scsi: add scsi_cmd_from_priv()

[John Garry]

From: Hannes Reinecke <hare@xxxxxxxx>

Add a functon to retrieve the scsi_cmnd structure from the driver
private allocation data.

Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
---
 include/scsi/scsi_cmnd.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 82a4499539b3..c73280b3706d 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -153,6 +153,16 @@ static inline void *scsi_cmd_priv(struct scsi_cmnd *cmd)
 	return cmd + 1;
 }
 
+/*
+ * Return the scsi_cmnd structure located before the driver
+ * private allocation. Only works if cmd_size is set in the
+ * host template.
+ */
+static inline struct scsi_cmnd *scsi_cmd_from_priv(void *priv)
+{
+	return priv - sizeof(struct scsi_cmnd);
+}
+
 /* make sure not to use it with passthrough commands */
 static inline struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
 {
-- 
2.17.1