commit 31672ff60e405795cad70d6d7888ac011f5373ce
Author: Christine Caulfield <ccaulfie@redhat.com>
Date:   Thu Oct 1 14:14:17 2009 +0000

    Stop clvmd from automatically doing lock conversions. Now, if a lock
    is granted at one mode and an attempt to convert it wthout the LCK_CONVERT
    flag set then it will return errno=EBUSY.
    
    This fixes a pretty bad bug in which an LV could be activated exclusively on
    one node and lvchange -ay on another would convert it to shared!
    
    It might break some things in other areas, but I doubt it.

Index: LVM2.2.02.39/daemons/clvmd/lvm-functions.c
===================================================================
--- LVM2.2.02.39.orig/daemons/clvmd/lvm-functions.c	2010-01-15 18:45:15.000000000 +0800
+++ LVM2.2.02.39/daemons/clvmd/lvm-functions.c	2010-01-15 18:53:21.000000000 +0800
@@ -141,10 +141,11 @@
 {
 	static char buf[128];
 
-	sprintf(buf, "0x%x (%s%s%s)", flags,
+	sprintf(buf, "0x%x (%s%s%s%s)", flags,
 		flags & LCK_PARTIAL_MODE	  ? "PARTIAL " : "",
 		flags & LCK_MIRROR_NOSYNC_MODE	  ? "MIRROR_NOSYNC " : "",
-		flags & LCK_DMEVENTD_MONITOR_MODE ? "DMEVENTD_MONITOR " : "");
+		flags & LCK_DMEVENTD_MONITOR_MODE ? "DMEVENTD_MONITOR " : "",
+		flags & LCK_CONVERT ? "CONVERT " : "");
 
 	return buf;
 }
@@ -190,16 +191,26 @@
 	int saved_errno;
 	struct lv_info *lvi;
 
-	flags &= LKF_NOQUEUE;	/* Only LKF_NOQUEUE is valid here */
+	/* Mask off invalid options */
+	flags &= LKF_NOQUEUE | LKF_CONVERT;
 
 	pthread_mutex_lock(&lv_hash_lock);
 	lvi = dm_hash_lookup(lv_hash, resource);
 	pthread_mutex_unlock(&lv_hash_lock);
+
+	if (lvi && lvi->lock_mode == mode) {
+		DEBUGLOG("hold_lock, lock mode %d already held\n", mode);
+		return 0;
+	}
+
+	if (lvi && !(flags & LKF_CONVERT)) {
+		errno = EBUSY;
+		return -1;
+	}
 	if (lvi) {
 		/* Already exists - convert it */
 		status =
-		    sync_lock(resource, mode, LKF_CONVERT | flags,
-			      &lvi->lock_id);
+		    sync_lock(resource, mode, flags, &lvi->lock_id);
 		saved_errno = errno;
 		if (!status)
 			lvi->lock_mode = mode;
@@ -215,7 +226,7 @@
 			return -1;
 
 		lvi->lock_mode = mode;
-		status = sync_lock(resource, mode, flags, &lvi->lock_id);
+		status = sync_lock(resource, mode, flags & ~LKF_CONVERT, &lvi->lock_id);
 		saved_errno = errno;
 		if (status) {
 			free(lvi);
@@ -296,9 +307,13 @@
 		mode = LKM_EXMODE;
 	}
 
-	/* Try to get the lock if it's a clustered volume group */
+	/* Try to get the lock if it's a clustered volume group
+	 * Use lock conversion only if requested, to prevent implicit conversion
+	 * of exclusive lock to shared one during activation.
+	 */
+
 	if (lock_flags & LCK_CLUSTER_VG) {
-		status = hold_lock(resource, mode, LKF_NOQUEUE);
+		status = hold_lock(resource, mode, LKF_NOQUEUE | (lock_flags & LCK_CONVERT?LKF_CONVERT:0));
 		if (status) {
 			/* Return an LVM-sensible error for this.
 			 * Forcing EIO makes the upper level return this text
@@ -477,12 +492,13 @@
 	/* Nearly all the stuff happens cluster-wide. Apart from SUSPEND. Here we get the
 	   lock out on this node (because we are the node modifying the metadata)
 	   before suspending cluster-wide.
+	   LKF_CONVERT is used always, local node is going to modify metadata
 	 */
 	if (command == LCK_LV_SUSPEND) {
 		DEBUGLOG("pre_lock_lv: resource '%s', cmd = %s, flags = %s\n",
 			 resource, decode_locking_cmd(command), decode_flags(lock_flags));
 
-		if (hold_lock(resource, LKM_PWMODE, LKF_NOQUEUE))
+		if (hold_lock(resource, LKM_PWMODE, LKF_NOQUEUE | LKF_CONVERT))
 			return errno;
 	}
 	return 0;
@@ -514,7 +530,7 @@
 				return EIO;
 
 			if (lvi.exists) {
-				if (hold_lock(resource, LKM_CRMODE, 0))
+				if (hold_lock(resource, LKM_CRMODE, LKF_CONVERT))
 					return errno;
 			} else {
 				if (hold_unlock(resource))
Index: LVM2.2.02.39/lib/locking/locking.h
===================================================================
--- LVM2.2.02.39.orig/lib/locking/locking.h	2008-05-10 03:26:58.000000000 +0800
+++ LVM2.2.02.39/lib/locking/locking.h	2010-01-15 18:45:15.000000000 +0800
@@ -86,6 +86,7 @@
 #define LCK_PARTIAL_MODE	0x00000001U	/* Running in partial mode */
 #define LCK_MIRROR_NOSYNC_MODE	0x00000002U	/* Mirrors don't require sync */
 #define LCK_DMEVENTD_MONITOR_MODE	0x00000004U	/* Register with dmeventd */
+#define LCK_CONVERT                 0x00000008U /* Convert existing lock */
 
 /*
  * Special cases of VG locks.