From: Chris Lalancette <clalance@redhat.com>
Date: Thu, 17 Jul 2008 17:27:51 +0200
Subject: [xen] rename blktap kernel threads to blktap.dom.blkname
Message-id: 487F64F7.5020504@redhat.com
O-Subject: [RHEL5.3 PATCH 1/7]: Rename blktap kernel threads to [blktap.dom.blkname] v2
Bugzilla: 250104
RH-Acked-by: Stephen Tweedie <sct@redhat.com>
RH-Acked-by: Bill Burns <bburns@redhat.com>
RH-Acked-by: Don Dutile <ddutile@redhat.com>

This patch just renames the blktap kernel  threads from the [xvda] that they
were before to [blktap.domid.blkname], for more useful debugging.  From
xen-3.1-testing.hg c/s 13325

diff --git a/drivers/xen/blkback/xenbus.c b/drivers/xen/blkback/xenbus.c
index f1ab227..05a8bb1 100644
--- a/drivers/xen/blkback/xenbus.c
+++ b/drivers/xen/blkback/xenbus.c
@@ -43,9 +43,30 @@ static int connect_ring(struct backend_info *);
 static void backend_changed(struct xenbus_watch *, const char **,
 			    unsigned int);
 
+static int blkback_name(blkif_t *blkif, char *buf)
+{
+	char *devpath, *devname;
+	struct xenbus_device *dev = blkif->be->dev;
+
+	devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
+	if (IS_ERR(devpath)) 
+		return PTR_ERR(devpath);
+	
+	if ((devname = strstr(devpath, "/dev/")) != NULL)
+		devname += strlen("/dev/");
+	else
+		devname  = devpath;
+
+	snprintf(buf, TASK_COMM_LEN, "blkback.%d.%s", blkif->domid, devname);
+	kfree(devpath);
+	
+	return 0;
+}
+
 static void update_blkif_status(blkif_t *blkif)
 { 
 	int err;
+	char name[TASK_COMM_LEN];
 
 	/* Not ready to connect? */
 	if (!blkif->irq || !blkif->vbd.bdev)
@@ -60,10 +81,13 @@ static void update_blkif_status(blkif_t *blkif)
 	if (blkif->be->dev->state != XenbusStateConnected)
 		return;
 
-	blkif->xenblkd = kthread_run(blkif_schedule, blkif,
-				     "xvd %d %02x:%02x",
-				     blkif->domid,
-				     blkif->be->major, blkif->be->minor);
+	err = blkback_name(blkif, name);
+	if (err) {
+		xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
+		return;
+	}
+
+	blkif->xenblkd = kthread_run(blkif_schedule, blkif, name);
 	if (IS_ERR(blkif->xenblkd)) {
 		err = PTR_ERR(blkif->xenblkd);
 		blkif->xenblkd = NULL;
diff --git a/drivers/xen/blktap/xenbus.c b/drivers/xen/blktap/xenbus.c
index 29b5af9..58a79e7 100644
--- a/drivers/xen/blktap/xenbus.c
+++ b/drivers/xen/blktap/xenbus.c
@@ -92,9 +92,30 @@ static long get_id(const char *str)
         return simple_strtol(num, NULL, 10);
 }				
 
+static int blktap_name(blkif_t *blkif, char *buf)
+{
+	char *devpath, *devname;
+	struct xenbus_device *dev = blkif->be->dev;
+
+	devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
+	if (IS_ERR(devpath)) 
+		return PTR_ERR(devpath);
+	
+	if ((devname = strstr(devpath, "/dev/")) != NULL)
+		devname += strlen("/dev/");
+	else
+		devname  = devpath;
+
+	snprintf(buf, TASK_COMM_LEN, "blktap.%d.%s", blkif->domid, devname);
+	kfree(devpath);
+	
+	return 0;
+}
+
 static void tap_update_blkif_status(blkif_t *blkif)
 { 
 	int err;
+	char name[TASK_COMM_LEN];
 
 	/* Not ready to connect? */
 	if(!blkif->irq || !blkif->sectors) {
@@ -110,10 +131,13 @@ static void tap_update_blkif_status(blkif_t *blkif)
 	if (blkif->be->dev->state != XenbusStateConnected)
 		return;
 
-	blkif->xenblkd = kthread_run(tap_blkif_schedule, blkif,
-				     "xvd %d",
-				     blkif->domid);
+	err = blktap_name(blkif, name);
+	if (err) {
+		xenbus_dev_error(blkif->be->dev, err, "get blktap dev name");
+		return;
+	}
 
+	blkif->xenblkd = kthread_run(tap_blkif_schedule, blkif, name);
 	if (IS_ERR(blkif->xenblkd)) {
 		err = PTR_ERR(blkif->xenblkd);
 		blkif->xenblkd = NULL;