[PATCH] xfs: disallow mounting of realtime + rmap filesystems

["Darrick J. Wong" <darrick.wong@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
 fs/xfs/xfs_super.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

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)