CA-30778-blkback-backend-bound-sysfs.diff

CA-30778: Bind sysfs create/remove to backend init/exit

Moves the per-backend sysfs create/remove code into backend
init/exit. Attribute existence bound to guest ring connection state
does not seem to serve any particular purpose, and keeping
backend_changed() small makes later extensions, such as switching the
physical node in VBD paused state, more straightforward.

diff -r 336053aae576 drivers/xen/blkback/xenbus.c
--- a/drivers/xen/blkback/xenbus.c	Wed Jul 15 17:20:14 2009 -0700
+++ b/drivers/xen/blkback/xenbus.c	Wed Jul 15 17:23:19 2009 -0700
@@ -194,7 +194,7 @@
 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
 VBD_SHOW(mode, "%s\n", be->mode);
 
-int xenvbd_sysfs_addif(struct xenbus_device *dev)
+static int xenvbd_sysfs_addif(struct xenbus_device *dev)
 {
 	int error;
 	struct backend_info *be = dev->dev.driver_data;
@@ -221,7 +221,7 @@
 	return error;
 }
 
-void xenvbd_sysfs_delif(struct xenbus_device *dev)
+static void xenvbd_sysfs_delif(struct xenbus_device *dev)
 {
 	struct backend_info *be = dev->dev.driver_data;
 	if (be->group_added == 0)
@@ -341,8 +341,6 @@
 	blkif->be->major = 0;
 	blkif->be->minor = 0;
 	blkif->remove_requested = 0;
-	if (blkif->be->dev)
-		xenvbd_sysfs_delif(blkif->be->dev);
 
 	up(&blkback_dev_sem);
 
@@ -516,6 +514,12 @@
 	/* setup back pointer */
 	be->blkif->be = be;
 
+	err = xenvbd_sysfs_addif(dev);
+	if (err) {
+		xenbus_dev_fatal(dev, err, "creating sysfs entries");
+		goto fail;
+	}
+
 	err = xenbus_watch_path2(dev, dev->nodename, "physical-device",
 				 &be->backend_watch, backend_changed);
 	if (err)
@@ -673,14 +677,6 @@
 		if (err)
 			return;
 
-		err = xenvbd_sysfs_addif(dev);
-		if (err) {
-			vbd_free(&be->blkif->vbd);
-			be->major = be->minor = 0;
-			xenbus_dev_fatal(dev, err, "creating sysfs entries");
-			return;
-		}
-
 		/* We're potentially connected now */
 		update_blkif_status(be->blkif);
 	}