From: Jonathan Brassow <jbrassow@redhat.com>
Subject: [PATCH RHEL 5.1] bz235039 unconditionalize log flush
Date: Tue, 08 May 2007 13:22:10 -0500
Bugzilla: 235039
Message-Id: <1178648531.10582.23.camel@hydrogen.msp.redhat.com>
Changelog: [md] unconditionalize log flush


 brassow

RHEL5

Bug 235039: conditionalized flush causes clear region requests...

If you suspend/dtr a mirror, clear region requests are not flushed
to disk.  This means that the next time a [cluster] mirror is started,
those regions will be incorrectly assumed to be not in-sync.

The culprit is in rh_update_states:
        if (!list_empty(&recovered))
                rh->log->type->flush(rh->log);

The conditional should be removed.  Note that this does not cause
extra disk activity, since the (disk) log checks for lc->touched.

Index: linux-rhel5/drivers/md/dm-raid1.c
===================================================================
--- linux-rhel5.orig/drivers/md/dm-raid1.c
+++ linux-rhel5/drivers/md/dm-raid1.c
@@ -437,8 +437,11 @@ static void rh_update_states(struct regi
 		mempool_free(reg, rh->region_pool);
 	}
 
-	if (!list_empty(&recovered))
-		rh->log->type->flush(rh->log);
+	/*
+	 * If the log implementation is good, it will only
+	 * flush (to disk) if it is necessary.
+	 */
+	rh->log->type->flush(rh->log);
 
 	list_for_each_entry_safe (reg, next, &clean, list)
 		mempool_free(reg, rh->region_pool);