Index: sys/amd64/linux/linux_dummy.c
===================================================================
--- sys/amd64/linux/linux_dummy.c
+++ sys/amd64/linux/linux_dummy.c
@@ -144,8 +144,6 @@
 DUMMY(membarrier);
 /* Linux 4.4: */
 DUMMY(mlock2);
-/* Linux 4.5: */
-DUMMY(copy_file_range);
 /* Linux 4.6: */
 DUMMY(preadv2);
 DUMMY(pwritev2);
Index: sys/amd64/linux32/linux32_dummy.c
===================================================================
--- sys/amd64/linux32/linux32_dummy.c
+++ sys/amd64/linux32/linux32_dummy.c
@@ -148,8 +148,6 @@
 DUMMY(membarrier);
 /* Linux 4.4: */
 DUMMY(mlock2);
-/* Linux 4.5: */
-DUMMY(copy_file_range);
 /* Linux 4.6: */
 DUMMY(preadv2);
 DUMMY(pwritev2);
Index: sys/arm64/linux/linux_dummy.c
===================================================================
--- sys/arm64/linux/linux_dummy.c
+++ sys/arm64/linux/linux_dummy.c
@@ -142,8 +142,6 @@
 DUMMY(membarrier);
 /* Linux 4.4: */
 DUMMY(mlock2);
-/* Linux 4.5: */
-DUMMY(copy_file_range);
 /* Linux 4.6: */
 DUMMY(preadv2);
 DUMMY(pwritev2);
Index: sys/compat/linux/linux_file.c
===================================================================
--- sys/compat/linux/linux_file.c
+++ sys/compat/linux/linux_file.c
@@ -1565,3 +1565,42 @@
 	return (kern_posix_fallocate(td, args->fd, args->offset,
 	    args->len));
 }
+
+int
+linux_copy_file_range(struct thread *td, struct linux_copy_file_range_args
+    *args)
+{
+	l_loff_t inoff, outoff, *inoffp, *outoffp;
+	int error, flags;
+
+	/* copy_file_range(2) on Linux doesn't define any flags (yet), so is the
+	 * native implementation.  Enforce it. */
+	if (args->flags != 0) {
+		linux_msg(td, "copy_file_range unsupported flags 0x%x",
+		    args->flags);
+		return (EINVAL);
+	}
+	flags = 0;
+	inoffp = outoffp = NULL;
+	if (args->off_in != NULL) {
+		error = copyin(args->off_in, &inoff, sizeof(l_loff_t));
+		if (error != 0)
+			return (error);
+		inoffp = &inoff;
+	}
+	if (args->off_out != NULL) {
+		error = copyin(args->off_out, &outoff, sizeof(l_loff_t));
+		if (error != 0)
+			return (error);
+		outoffp = &outoff;
+	}
+
+	error = kern_copy_file_range(td, args->fd_in, inoffp, args->fd_out,
+	    outoffp, args->len, flags);
+	if (error == 0 && args->off_in != NULL)
+		error = copyout(inoffp, args->off_in, sizeof(l_loff_t));
+	if (error == 0 && args->off_out != NULL)
+		error = copyout(outoffp, args->off_out, sizeof(l_loff_t));
+	return (error);
+}
+
Index: sys/i386/linux/linux_dummy.c
===================================================================
--- sys/i386/linux/linux_dummy.c
+++ sys/i386/linux/linux_dummy.c
@@ -144,8 +144,6 @@
 DUMMY(membarrier);
 /* Linux 4.4: */
 DUMMY(mlock2);
-/* Linux 4.5: */
-DUMMY(copy_file_range);
 /* Linux 4.6: */
 DUMMY(preadv2);
 DUMMY(pwritev2);