[SCSI] zfcp: Make queue_depth adjustable

zfcp did always set the queue_depth for SCSI devices to 32, not
allowing to change this. Introduce a kernel parameter zfcp.queue_depth
and the change_queue_depth callback to allow changing the queue_depth
when it is required.

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/s390/scsi/zfcp_scsi.c b/drivers/s390/scsi/zfcp_scsi.c
index e8fbeaeb5fbf..7d0da230eb63 100644
--- a/drivers/s390/scsi/zfcp_scsi.c
+++ b/drivers/s390/scsi/zfcp_scsi.c
@@ -12,6 +12,10 @@
 #include "zfcp_ext.h"
 #include <asm/atomic.h>
 
+static unsigned int default_depth = 32;
+module_param_named(queue_depth, default_depth, uint, 0600);
+MODULE_PARM_DESC(queue_depth, "Default queue depth for new SCSI devices");
+
 /* Find start of Sense Information in FCP response unit*/
 char *zfcp_get_fcp_sns_info_ptr(struct fcp_rsp_iu *fcp_rsp_iu)
 {
@@ -24,6 +28,12 @@ char *zfcp_get_fcp_sns_info_ptr(struct fcp_rsp_iu *fcp_rsp_iu)
         return fcp_sns_info_ptr;
 }
 
+static int zfcp_scsi_change_queue_depth(struct scsi_device *sdev, int depth)
+{
+        scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
+        return sdev->queue_depth;
+}
+
 static void zfcp_scsi_slave_destroy(struct scsi_device *sdpnt)
 {
         struct zfcp_unit *unit = (struct zfcp_unit *) sdpnt->hostdata;
@@ -34,7 +44,7 @@ static void zfcp_scsi_slave_destroy(struct scsi_device *sdpnt)
 static int zfcp_scsi_slave_configure(struct scsi_device *sdp)
 {
         if (sdp->tagged_supported)
-                scsi_adjust_queue_depth(sdp, MSG_SIMPLE_TAG, 32);
+                scsi_adjust_queue_depth(sdp, MSG_SIMPLE_TAG, default_depth);
         else
                 scsi_adjust_queue_depth(sdp, 0, 1);
         return 0;
@@ -647,6 +657,7 @@ struct zfcp_data zfcp_data = {
                 .name                    = "zfcp",
                 .module                  = THIS_MODULE,
                 .proc_name               = "zfcp",
+                .change_queue_depth      = zfcp_scsi_change_queue_depth,
                 .slave_alloc             = zfcp_scsi_slave_alloc,
                 .slave_configure         = zfcp_scsi_slave_configure,
                 .slave_destroy           = zfcp_scsi_slave_destroy,