IB/srp: Add change_queue_depth and change_queue_type support

Currently, it's not possible to change queue depth for a device behind
SRP host. Sometimes, we need to adjust queue_depth for performance
reason (eg storage busy, we need lower queue_depth to avoid running
into SCSI error handler), so this patch add support for SRP driver.

Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
Tested-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 6aa660d188a3..a8f8d0b8a777 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -46,6 +46,7 @@
 #include <scsi/scsi.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_dbg.h>
+#include <scsi/scsi_tcq.h>
 #include <scsi/srp.h>
 #include <scsi/scsi_transport_srp.h>
 
@@ -1882,6 +1883,57 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
         return 0;
 }
 
+/**
+ * srp_change_queue_type - changing device queue tag type
+ * @sdev: scsi device struct
+ * @tag_type: requested tag type
+ *
+ * Returns queue tag type.
+ */
+static int
+srp_change_queue_type(struct scsi_device *sdev, int tag_type)
+{
+        if (sdev->tagged_supported) {
+                scsi_set_tag_type(sdev, tag_type);
+                if (tag_type)
+                        scsi_activate_tcq(sdev, sdev->queue_depth);
+                else
+                        scsi_deactivate_tcq(sdev, sdev->queue_depth);
+        } else
+                tag_type = 0;
+
+        return tag_type;
+}
+
+/**
+ * srp_change_queue_depth - setting device queue depth
+ * @sdev: scsi device struct
+ * @qdepth: requested queue depth
+ * @reason: SCSI_QDEPTH_DEFAULT/SCSI_QDEPTH_QFULL/SCSI_QDEPTH_RAMP_UP
+ * (see include/scsi/scsi_host.h for definition)
+ *
+ * Returns queue depth.
+ */
+static int
+srp_change_queue_depth(struct scsi_device *sdev, int qdepth, int reason)
+{
+        struct Scsi_Host *shost = sdev->host;
+        int max_depth;
+        if (reason == SCSI_QDEPTH_DEFAULT || reason == SCSI_QDEPTH_RAMP_UP) {
+                max_depth = shost->can_queue;
+                if (!sdev->tagged_supported)
+                        max_depth = 1;
+                if (qdepth > max_depth)
+                        qdepth = max_depth;
+                scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), qdepth);
+        } else if (reason == SCSI_QDEPTH_QFULL)
+                scsi_track_queue_full(sdev, qdepth);
+        else
+                return -EOPNOTSUPP;
+
+        return sdev->queue_depth;
+}
+
 static int srp_send_tsk_mgmt(struct srp_target_port *target,
                              u64 req_tag, unsigned int lun, u8 func)
 {
@@ -2173,6 +2225,8 @@ static struct scsi_host_template srp_template = {
         .slave_configure                = srp_slave_configure,
         .info                           = srp_target_info,
         .queuecommand                   = srp_queuecommand,
+        .change_queue_depth             = srp_change_queue_depth,
+        .change_queue_type              = srp_change_queue_type,
         .eh_abort_handler               = srp_abort,
         .eh_device_reset_handler        = srp_reset_device,
         .eh_host_reset_handler          = srp_reset_host,