docker-btrfs.patch

--- docker/daemon/graphdriver/btrfs/btrfs.go    2016-03-09 12:13:24.000000000 -0800
+++ docker/daemon/graphdriver/btrfs/btrfs.go    2016-04-17 04:34:27.188376720 -0700
@@ -7,6 +7,10 @@ package btrfs
 #include <dirent.h>
 #include <btrfs/ioctl.h>
 #include <btrfs/ctree.h>
+
+static void set_name_btrfs_ioctl_vol_args_v2(struct btrfs_ioctl_vol_args_v2* btrfs_struct, const char* value) {
+    snprintf(btrfs_struct->name, BTRFS_SUBVOL_NAME_MAX, "%s", value);
+}
 */
 import "C"
 
@@ -160,9 +164,10 @@ func subvolSnapshot(src, dest, name stri
 
        var args C.struct_btrfs_ioctl_vol_args_v2
        args.fd = C.__s64(getDirFd(srcDir))
-       for i, c := range []byte(name) {
-               args.name[i] = C.char(c)
-       }
+
+       var cs = C.CString(name)
+       C.set_name_btrfs_ioctl_vol_args_v2(&args, cs)
+       C.free(unsafe.Pointer(cs))
 
        _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(destDir), C.BTRFS_IOC_SNAP_CREATE_V2,
                uintptr(unsafe.Pointer(&args)))