From: t_jeang <devnull@localhost>
Date: Tue, 6 Jan 2009 12:06:01 +0000 (+0000)
Subject: imported patch CA-15586-blkback-close-bdev
X-Git-Tag: CA-14804-fix-block-unplug-retries
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=a7dd7ea8a1a24d92d86f1d37b2279d7f6b620f82;p=xenclient%2Fkernel.git

imported patch CA-15586-blkback-close-bdev
---

diff --git a/drivers/xen/blkback/common.h b/drivers/xen/blkback/common.h
index 53911bff..dbfd1beb 100644
--- a/drivers/xen/blkback/common.h
+++ b/drivers/xen/blkback/common.h
@@ -48,7 +48,11 @@
 	pr_debug("(file=%s, line=%d) " _f,	\
 		 __FILE__ , __LINE__ , ## _a )
 
-#define WPRINTK(fmt, args...) printk(KERN_WARNING "blk_tap: " fmt, ##args)
+#define WPRINTK(fmt, args...)					\
+do {								\
+	if (printk_ratelimit())					\
+		printk(KERN_WARNING "blk_back: " fmt, ##args);	\
+} while(0)
 
 struct vbd {
 	blkif_vdev_t   handle;      /* what the domain refers to this vbd as */
diff --git a/drivers/xen/blkback/xenbus.c b/drivers/xen/blkback/xenbus.c
index dfb54521..be42a4a4 100644
--- a/drivers/xen/blkback/xenbus.c
+++ b/drivers/xen/blkback/xenbus.c
@@ -298,7 +298,9 @@ static int blkback_remove(struct xenbus_device *dev)
 void blkback_close(blkif_t *blkif)
 {
 	blkif_disconnect(blkif);
-	vbd_sync(&blkif->vbd);
+	vbd_free(&blkif->vbd);
+	blkif->be->major = 0;
+	blkif->be->minor = 0;
 	blkif->remove_requested = 0;
 
 	down(&blkback_dev_sem);
@@ -442,6 +444,71 @@ fail:
 	return err;
 }
 
+static int blkback_open_bdev(struct backend_info *be)
+{
+	int err;
+	char *p;
+	long handle;
+	int cdrom = 0;
+	unsigned major;
+	unsigned minor;
+	char *device_type;
+	struct xenbus_device *dev = be->dev;
+
+	if (be->blkif->vbd.bdev) {
+		xenbus_dev_fatal(dev, -EINVAL, "attempting invalid vbd open");
+		return -EINVAL;
+	}
+
+	err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
+			   &major, &minor);
+	if (err != 2) {
+		xenbus_dev_fatal(dev, err, "reading physical-device");
+		return err;
+	}
+
+	if ((be->major || be->minor) &&
+	    ((be->major != major) || (be->minor != minor))) {
+		printk(KERN_WARNING
+		       "blkback: changing physical device (from %x:%x to "
+		       "%x:%x) not supported.\n", be->major, be->minor,
+		       major, minor);
+		xenbus_dev_fatal(dev, err, "invalid physical-device change");
+		return -EINVAL;
+	}
+
+	if (!be->mode) {
+		be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
+		if (IS_ERR(be->mode)) {
+			err = PTR_ERR(be->mode);
+			be->mode = NULL;
+			xenbus_dev_fatal(dev, err, "reading mode");
+			return err;
+		}
+	}
+
+	device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
+	if (!IS_ERR(device_type)) {
+		cdrom = strcmp(device_type, "cdrom") == 0;
+		kfree(device_type);
+	}
+
+	/* Front end dir is a number, which is used as the handle. */
+	p = strrchr(dev->otherend, '/') + 1;
+	handle = simple_strtoul(p, NULL, 0);
+
+	err = vbd_create(be->blkif, handle, major, minor,
+			 (NULL == strchr(be->mode, 'w')), cdrom);
+	if (err) {
+		xenbus_dev_fatal(dev, err, "creating vbd structure");
+		return err;
+	}
+
+	be->major = major;
+	be->minor = minor;
+
+	return 0;
+}
 
 /**
  * Callback received when the hotplug scripts have placed the physical-device
@@ -457,8 +524,6 @@ static void backend_changed(struct xenbus_watch *watch,
 	struct backend_info *be
 		= container_of(watch, struct backend_info, backend_watch);
 	struct xenbus_device *dev = be->dev;
-	int cdrom = 0;
-	char *device_type;
 
 	DPRINTK("");
 
@@ -484,6 +549,11 @@ static void backend_changed(struct xenbus_watch *watch,
 		return;
 	}
 
+	if (be->mode) {
+		kfree(be->mode);
+		be->mode = NULL;
+	}
+
 	be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
 	if (IS_ERR(be->mode)) {
 		err = PTR_ERR(be->mode);
@@ -492,28 +562,10 @@ static void backend_changed(struct xenbus_watch *watch,
 		return;
 	}
 
-	device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
-	if (!IS_ERR(device_type)) {
-		cdrom = strcmp(device_type, "cdrom") == 0;
-		kfree(device_type);
-	}
-
 	if (be->major == 0 && be->minor == 0) {
-		/* Front end dir is a number, which is used as the handle. */
-
-		char *p = strrchr(dev->otherend, '/') + 1;
-		long handle = simple_strtoul(p, NULL, 0);
-
-		be->major = major;
-		be->minor = minor;
-
-		err = vbd_create(be->blkif, handle, major, minor,
-				 (NULL == strchr(be->mode, 'w')), cdrom);
-		if (err) {
-			be->major = be->minor = 0;
-			xenbus_dev_fatal(dev, err, "creating vbd structure");
+		err = blkback_open_bdev(be);
+		if (err)
 			return;
-		}
 
 		err = xenvbd_sysfs_addif(dev);
 		if (err) {
@@ -558,10 +610,18 @@ static void frontend_changed(struct xenbus_device *dev,
 		/* Ensure we connect even when two watches fire in 
 		   close successsion and we miss the intermediate value 
 		   of frontend_state. */
-		if (dev->state != XenbusStateConnected && dev->state != XenbusStateClosing) {
+		if (dev->state != XenbusStateConnected &&
+		    dev->state != XenbusStateClosing) {
 			err = connect_ring(be);
 			if (err)
 				break;
+
+			if (!be->blkif->vbd.bdev) {
+				err = blkback_open_bdev(be);
+				if (err)
+					break;
+			}
+
 			update_blkif_status(be->blkif);
 		}