From: t_jeang <devnull@localhost>
Date: Tue, 6 Jan 2009 12:06:01 +0000 (+0000)
Subject: imported patch CA-14804-fix-block-unplug-retries
X-Git-Tag: blk-fix-sysfs-remove-race
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=5d9a2dea49fa353e551bf7b35e5cb7a6107bc258;p=xenclient%2Fkernel.git

imported patch CA-14804-fix-block-unplug-retries
---

diff --git a/drivers/xen/blkback/xenbus.c b/drivers/xen/blkback/xenbus.c
index c48456d8..dfb54521 100644
--- a/drivers/xen/blkback/xenbus.c
+++ b/drivers/xen/blkback/xenbus.c
@@ -310,6 +310,30 @@ void blkback_close(blkif_t *blkif)
 	blkif->xenblkd = NULL;
 }
 
+static int xenbus_write_state(struct xenbus_device *dev,
+			      enum xenbus_state state)
+{
+	int err;
+	int current_state;
+
+	if (dev->state != state)
+		return xenbus_switch_state(dev, state);
+
+	err = xenbus_scanf(XBT_NIL, dev->nodename, "state", "%d",
+			   &current_state);
+	if (err != 1)
+		return 0;
+
+	err = xenbus_printf(XBT_NIL, dev->nodename, "state", "%d", state);
+	if (err) {
+		if (state != XenbusStateClosing) /* Avoid looping */
+			xenbus_dev_fatal(dev, err, "writing new state");
+		return err;
+	}
+
+	return 0;
+}
+
 static void start_shutdown(struct xenbus_watch *watch,
 			   const char **vec, unsigned int length)
 {
@@ -334,7 +358,7 @@ static void start_shutdown(struct xenbus_watch *watch,
 		return;
 	}
 
-	xenbus_switch_state(dev, XenbusStateClosing);
+	xenbus_write_state(dev, XenbusStateClosing);
 	
 	if (len == sizeof("force") - 1 && !memcmp(type, "force", len))
 		if (!kthread_remove(be))
diff --git a/drivers/xen/blktap/xenbus.c b/drivers/xen/blktap/xenbus.c
index 1150dfd3..9bf32164 100644
--- a/drivers/xen/blktap/xenbus.c
+++ b/drivers/xen/blktap/xenbus.c
@@ -353,6 +353,30 @@ void blktap_close(blkif_t *blkif)
 	blkif->xenblkd = NULL;
 }
 
+static int xenbus_write_state(struct xenbus_device *dev,
+			      enum xenbus_state state)
+{
+	int err;
+	int current_state;
+
+	if (dev->state != state)
+		return xenbus_switch_state(dev, state);
+
+	err = xenbus_scanf(XBT_NIL, dev->nodename, "state", "%d",
+			   &current_state);
+	if (err != 1)
+		return 0;
+
+	err = xenbus_printf(XBT_NIL, dev->nodename, "state", "%d", state);
+	if (err) {
+		if (state != XenbusStateClosing) /* Avoid looping */
+			xenbus_dev_fatal(dev, err, "writing new state");
+		return err;
+	}
+
+	return 0;
+}
+
 static void start_shutdown(struct xenbus_watch *watch,
 			   const char **vec, unsigned int length)
 {
@@ -377,7 +401,7 @@ static void start_shutdown(struct xenbus_watch *watch,
 		return;
 	}
 
-	xenbus_switch_state(dev, XenbusStateClosing);
+	xenbus_write_state(dev, XenbusStateClosing);
 
 	if (len == sizeof("force") - 1 && !memcmp(type, "force", len))
 		if (!kthread_remove(be))