diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 11697a8b2a1d..c2a437416227 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -399,6 +399,7 @@ xrep_calc_rtgroup_resblks(
 	struct xfs_mount		*mp = sc->mp;
 	struct xfs_scrub_metadata	*sm = sc->sm;
 	uint64_t			usedlen;
+	xfs_extlen_t			refcbt_sz = 0;
 	xfs_extlen_t			rmapbt_sz = 0;
 
 	if (!(sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR))
@@ -411,13 +412,27 @@ xrep_calc_rtgroup_resblks(
 	usedlen = xfs_rtbxlen_to_blen(mp, xfs_rtgroup_extents(mp, sm->sm_agno));
 	ASSERT(usedlen <= XFS_MAX_RGBLOCKS);
 
+	if (xfs_has_reflink(mp))
+		refcbt_sz = xfs_rtrefcountbt_calc_size(mp, usedlen);
+
 	if (xfs_has_rmapbt(mp))
 		rmapbt_sz = xfs_rtrmapbt_calc_size(mp, usedlen);
 
-	trace_xrep_calc_rtgroup_resblks_btsize(mp, sm->sm_agno, usedlen,
-			rmapbt_sz);
+	/*
+	 * Guess how many blocks we need to rebuild the rmapbt.  For
+	 * non-reflink filesystems we can't have more records than used blocks.
+	 * However, with reflink it's possible to have more than one rmap
+	 * record per rtgroup block.  We don't know how many rmaps there could
+	 * be in the rtgroup, so we start off with what we hope is an generous
+	 * over-estimation.
+	 */
+	if (refcbt_sz > 0 && rmapbt_sz > 0)
+		rmapbt_sz *= 2;
 
-	return rmapbt_sz;
+	trace_xrep_calc_rtgroup_resblks_btsize(mp, sm->sm_agno, usedlen,
+			rmapbt_sz, refcbt_sz);
+
+	return max(rmapbt_sz, refcbt_sz);
 }
 #endif /* CONFIG_XFS_RT */
 
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index 0f5adc293962..cb85f75ce101 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -2376,25 +2376,29 @@ TRACE_EVENT(xrep_calc_ag_resblks_btsize,
 #ifdef CONFIG_XFS_RT
 TRACE_EVENT(xrep_calc_rtgroup_resblks_btsize,
 	TP_PROTO(struct xfs_mount *mp, xfs_rgnumber_t rgno,
-		 xfs_rgblock_t usedlen, xfs_rgblock_t rmapbt_sz),
-	TP_ARGS(mp, rgno, usedlen, rmapbt_sz),
+		 xfs_rgblock_t usedlen, xfs_rgblock_t rmapbt_sz,
+		 xfs_rgblock_t refcbt_sz),
+	TP_ARGS(mp, rgno, usedlen, rmapbt_sz, refcbt_sz),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(xfs_rgnumber_t, rgno)
 		__field(xfs_rgblock_t, usedlen)
 		__field(xfs_rgblock_t, rmapbt_sz)
+		__field(xfs_rgblock_t, refcbt_sz)
 	),
 	TP_fast_assign(
 		__entry->dev = mp->m_super->s_dev;
 		__entry->rgno = rgno;
 		__entry->usedlen = usedlen;
 		__entry->rmapbt_sz = rmapbt_sz;
+		__entry->refcbt_sz = refcbt_sz;
 	),
-	TP_printk("dev %d:%d rgno 0x%x usedlen %u rmapbt %u",
+	TP_printk("dev %d:%d rgno 0x%x usedlen %u rmapbt %u refcountbt %u",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->rgno,
 		  __entry->usedlen,
-		  __entry->rmapbt_sz)
+		  __entry->rmapbt_sz,
+		  __entry->refcbt_sz)
 );
 #endif /* CONFIG_XFS_RT */