Add a queue_depth file so that the multipath dynamic queue depth can be
looked up from per-path gendisk (scsi_disk) directory.

Signed-off-by: John Garry <[email protected]>
---
 drivers/scsi/sd.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index ee604f9f8cd20..f416457b5a08f 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -4049,9 +4049,27 @@ static ssize_t sd_mpath_numa_nodes_show(struct device 
*dev,
 }
 static DEVICE_ATTR(mpath_numa_nodes, 0444, sd_mpath_numa_nodes_show, NULL);
 
+static ssize_t sd_mpath_queue_depth_show(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       struct gendisk *gd = dev_to_disk(dev);
+       struct scsi_disk *sdkp = gd->private_data;
+       struct scsi_device *sdev = sdkp->device;
+       struct sd_mpath_disk *sd_mpath_disk = sdkp->sd_mpath_disk;
+       struct scsi_mpath_head *scsi_mpath_head = 
sd_mpath_disk->scsi_mpath_head;
+       struct Scsi_Host *shost = sdev->host;
+
+       if (!mpath_qd_iopolicy(&scsi_mpath_head->iopolicy))
+               return 0;
+
+       return sysfs_emit(buf, "%d\n", atomic_read(&shost->mpath_nr_active));
+}
+static DEVICE_ATTR(mpath_queue_depth, 0444, sd_mpath_queue_depth_show, NULL);
+
 static struct attribute *sd_mpath_dev_attrs[] = {
        &dev_attr_mpath_dev.attr,
        &dev_attr_mpath_numa_nodes.attr,
+       &dev_attr_mpath_queue_depth.attr,
        NULL
 };
 
-- 
2.43.5


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