scsi: always assign block layer tags if enabled
Allow a driver to ask for block layer tags by setting .use_blk_tags in the
host template, in which case it will always see a valid value in
request->tag, similar to the behavior when using blk-mq. This means even
SCSI "untagged" commands will now have a tag, which is especially useful
when using a host-wide tag map.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index d6bd652..61a81bf 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -422,6 +422,11 @@
unsigned char present;
/*
+ * Let the block layer assigns tags to all commands.
+ */
+ unsigned use_blk_tags:1;
+
+ /*
* This specifies the mode that a LLD supports.
*/
unsigned supported_mode:2;