From 738f57c16a2bb527c705641f0fc1c68ff8cba72a Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Fri, 26 Aug 2016 15:59:19 +1000
Subject: xfs: disallow mounting of realtime + rmap filesystems

Since the kernel doesn't currently support the realtime rmapbt,
don't allow such filesystems to be mounted.  Support will appear
in a future release.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 24ef83e..fd6be45 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1574,9 +1574,16 @@ xfs_fs_fill_super(
 		}
 	}
 
-	if (xfs_sb_version_hasrmapbt(&mp->m_sb))
+	if (xfs_sb_version_hasrmapbt(&mp->m_sb)) {
+		if (mp->m_sb.sb_rblocks) {
+			xfs_alert(mp,
+	"EXPERIMENTAL reverse mapping btree not compatible with realtime device!");
+			error = -EINVAL;
+			goto out_filestream_unmount;
+		}
 		xfs_alert(mp,
 	"EXPERIMENTAL reverse mapping btree feature enabled. Use at your own risk!");
+	}
 
 	error = xfs_mountfs(mp);
 	if (error)
-- 
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