From ac277c6a8a39bc50f891a3477625330c276bd7f5 Mon Sep 17 00:00:00 2001
From: Goldwyn Rodrigues <rgoldwyn@suse.com>
Date: Mon, 21 Dec 2015 10:50:59 +1100
Subject: md-cluster: Avoid the resync ping-pong

If a RESYNCING message with (0,0) has been sent before, do not send it
again. This avoids a resync ping pong between the nodes. We read
the bitmap lockresource's LVB to figure out the previous value
of the RESYNCING message.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
index d6a1126..e57bbfe 100644
--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -882,8 +882,16 @@ static int resync_start(struct mddev *mddev)
 static int resync_info_update(struct mddev *mddev, sector_t lo, sector_t hi)
 {
 	struct md_cluster_info *cinfo = mddev->cluster_info;
+	struct resync_info ri;
 	struct cluster_msg cmsg = {0};
 
+	/* do not send zero again, if we have sent before */
+	if (hi == 0) {
+		memcpy(&ri, cinfo->bitmap_lockres->lksb.sb_lvbptr, sizeof(struct resync_info));
+		if (le64_to_cpu(ri.hi) == 0)
+			return 0;
+	}
+
 	add_resync_info(cinfo->bitmap_lockres, lo, hi);
 	/* Re-acquire the lock to refresh LVB */
 	dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW);
-- 
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