[SCSI] add shared tag map helpers
This patch adds support for sharing tag maps at the host level
(i.e. either every queue [LUN] has its own tag map or there's a single
one for the entire host). This formulation is primarily intended to
help single issue queue hardware, like the aic7xxx
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index b3dd90f..39c6f8c 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -16,6 +16,7 @@
struct Scsi_Host;
struct scsi_host_cmd_pool;
struct scsi_transport_template;
+struct blk_queue_tags;
/*
@@ -466,6 +467,12 @@
struct scsi_transport_template *transportt;
/*
+ * area to keep a shared tag map (if needed, will be
+ * NULL if not)
+ */
+ struct blk_queue_tag *bqt;
+
+ /*
* The following two fields are protected with host_lock;
* however, eh routines can safely access during eh processing
* without acquiring the lock.