diff --git a/man/man8/xfs_admin.8 b/man/man8/xfs_admin.8
index e07fc3d..3a9175c 100644
--- a/man/man8/xfs_admin.8
+++ b/man/man8/xfs_admin.8
@@ -170,6 +170,12 @@
 This upgrade can fail if any AG has less than 1% free space remaining.
 The filesystem cannot be downgraded after this feature is enabled.
 This feature was added to Linux 3.16.
+.TP 0.4i
+.B reflink
+Enable sharing of file data blocks.
+This upgrade can fail if any AG has less than 2% free space remaining.
+The filesystem cannot be downgraded after this feature is enabled.
+This feature was added to Linux 4.9.
 .RE
 .TP
 .BI \-U " uuid"
diff --git a/repair/globals.c b/repair/globals.c
index 3ea5fd8..07a15dd 100644
--- a/repair/globals.c
+++ b/repair/globals.c
@@ -54,6 +54,7 @@
 bool	add_nrext64;
 bool	add_exchrange;		/* add file content exchange support */
 bool	add_finobt;		/* add free inode btrees */
+bool	add_reflink;		/* add reference count btrees */
 
 /* misc status variables */
 
diff --git a/repair/globals.h b/repair/globals.h
index 9f9ecb2..c5114b5 100644
--- a/repair/globals.h
+++ b/repair/globals.h
@@ -95,6 +95,7 @@
 extern bool	add_nrext64;
 extern bool	add_exchrange;		/* add file content exchange support */
 extern bool	add_finobt;		/* add free inode btrees */
+extern bool	add_reflink;		/* add reference count btrees */
 
 /* misc status variables */
 
diff --git a/repair/phase2.c b/repair/phase2.c
index 2931db8..a013d6c 100644
--- a/repair/phase2.c
+++ b/repair/phase2.c
@@ -198,7 +198,7 @@
 		exit(0);
 	}
 
-	if (!xfs_has_reflink(mp)) {
+	if (!xfs_has_reflink(mp) && !add_reflink) {
 		printf(
 	_("File exchange-range feature cannot be added without reflink.\n"));
 		exit(0);
@@ -232,6 +232,33 @@
 	return true;
 }
 
+static bool
+set_reflink(
+	struct xfs_mount	*mp,
+	struct xfs_sb		*new_sb)
+{
+	if (xfs_has_reflink(mp)) {
+		printf(_("Filesystem already supports reflink.\n"));
+		exit(0);
+	}
+
+	if (!xfs_has_crc(mp)) {
+		printf(
+	_("Reflink feature only supported on V5 filesystems.\n"));
+		exit(0);
+	}
+
+	if (xfs_has_realtime(mp)) {
+		printf(_("Reflink feature not supported with realtime.\n"));
+		exit(0);
+	}
+
+	printf(_("Adding reflink support to filesystem.\n"));
+	new_sb->sb_features_ro_compat |= XFS_SB_FEAT_RO_COMPAT_REFLINK;
+	new_sb->sb_features_incompat |= XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR;
+	return true;
+}
+
 struct check_state {
 	struct xfs_sb		sb;
 	uint64_t		features;
@@ -401,6 +428,8 @@
 {
 	if (xfs_has_finobt(mp) && !(old->features & XFS_FEAT_FINOBT))
 		return true;
+	if (xfs_has_reflink(mp) && !(old->features & XFS_FEAT_REFLINK))
+		return true;
 	return false;
 }
 
@@ -480,6 +509,8 @@
 		dirty |= set_exchrange(mp, &new_sb);
 	if (add_finobt)
 		dirty |= set_finobt(mp, &new_sb);
+	if (add_reflink)
+		dirty |= set_reflink(mp, &new_sb);
 	if (!dirty)
 		return;
 
diff --git a/repair/rmap.c b/repair/rmap.c
index 553c7a6..97591e1 100644
--- a/repair/rmap.c
+++ b/repair/rmap.c
@@ -58,7 +58,7 @@
 rmap_needs_work(
 	struct xfs_mount	*mp)
 {
-	return xfs_has_reflink(mp) ||
+	return xfs_has_reflink(mp) || add_reflink ||
 	       xfs_has_rmapbt(mp);
 }
 
@@ -1515,7 +1515,7 @@
 	int				i;
 	int				error;
 
-	if (!xfs_has_reflink(mp))
+	if (!xfs_has_reflink(mp) || add_reflink)
 		return;
 	if (refcbt_suspect) {
 		if (no_modify && agno == 0)
diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
index 95c12ce..0b5ad61 100644
--- a/repair/xfs_repair.c
+++ b/repair/xfs_repair.c
@@ -71,6 +71,7 @@
 	CONVERT_NREXT64,
 	CONVERT_EXCHRANGE,
 	CONVERT_FINOBT,
+	CONVERT_REFLINK,
 	C_MAX_OPTS,
 };
 
@@ -81,6 +82,7 @@
 	[CONVERT_NREXT64]	= "nrext64",
 	[CONVERT_EXCHRANGE]	= "exchange",
 	[CONVERT_FINOBT]	= "finobt",
+	[CONVERT_REFLINK]	= "reflink",
 	[C_MAX_OPTS]		= NULL,
 };
 
@@ -382,6 +384,15 @@
 		_("-c finobt only supports upgrades\n"));
 					add_finobt = true;
 					break;
+				case CONVERT_REFLINK:
+					if (!val)
+						do_abort(
+		_("-c reflink requires a parameter\n"));
+					if (strtol(val, NULL, 0) != 1)
+						do_abort(
+		_("-c reflink only supports upgrades\n"));
+					add_reflink = true;
+					break;
 				default:
 					unknown('c', val);
 					break;