scsi: add scsi_{get,put}_internal_cmd() helper

Add helper functions to allow LLDDs to allocate and free
internal commands.

Signed-off-by: Hannes Reinecke <hare@suse.de>

2 files changed, 44 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 702afc7523fda..ff6c9f876078e 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1953,6 +1953,47 @@ void scsi_mq_destroy_tags(struct Scsi_Host *shost)
 }
 
 /**
+ * scsi_get_internal_cmd - allocate an intenral SCSI command
+ * @sdev: SCSI device from which to allocate the command
+ * @data_direction: Data direction for the allocated command
+ * @op_flags: request allocation flags
+ *
+ * Allocates a SCSI command for internal LLDD use.
+ */
+struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev,
+					int data_direction, int op_flags)
+{
+	struct request *rq;
+	struct scsi_cmnd *scmd;
+	blk_mq_req_flags_t flags = 0;
+	unsigned int op = REQ_INTERNAL | op_flags;
+
+	op |= (data_direction == DMA_TO_DEVICE) ?
+		REQ_OP_DRV_OUT : REQ_OP_DRV_IN;
+	rq = blk_mq_alloc_request(sdev->request_queue, op, flags);
+	if (IS_ERR(rq))
+		return NULL;
+	scmd = blk_mq_rq_to_pdu(rq);
+	scmd->request = rq;
+	scmd->device = sdev;
+	return scmd;
+}
+EXPORT_SYMBOL_GPL(scsi_get_internal_cmd);
+
+/**
+ * scsi_put_internal_cmd - free an internal SCSI command
+ * @scmd: SCSI command to be freed
+ */
+void scsi_put_internal_cmd(struct scsi_cmnd *scmd)
+{
+	struct request *rq = blk_mq_rq_from_pdu(scmd);
+
+	if (blk_rq_is_internal(rq))
+		blk_mq_free_request(rq);
+}
+EXPORT_SYMBOL_GPL(scsi_put_internal_cmd);
+
+/**
  * scsi_device_from_queue - return sdev associated with a request_queue
  * @q: The request queue to return the sdev from
  *
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index b97e142a7ca92..03bf5eb9b4a9a 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -469,6 +469,9 @@ static inline int scsi_execute_req(struct scsi_device *sdev,
 	return scsi_execute(sdev, cmd, data_direction, buffer,
 		bufflen, NULL, sshdr, timeout, retries,  0, 0, resid);
 }
+struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev,
+					int data_direction, int op_flags);
+void scsi_put_internal_cmd(struct scsi_cmnd *scmd);
 extern void sdev_disable_disk_events(struct scsi_device *sdev);
 extern void sdev_enable_disk_events(struct scsi_device *sdev);
 extern int scsi_vpd_lun_id(struct scsi_device *, char *, size_t);