Merge remote-tracking branch 'qubesos/pr/9'

* qubesos/pr/9:
  cp --reflink=auto to speed up clone/backup/restore on btrfs

core/backup.py

@@ -1992,7 +1992,7 @@ def backup_restore_do(restore_info,
                                          backup_dir)
 
         # We prefer to use Linux's cp, because it nicely handles sparse files
-        cp_retcode = subprocess.call(["cp", "-rp", backup_src_dir, dst_dir])
+        cp_retcode = subprocess.call(["cp", "-rp", "--reflink=auto", backup_src_dir, dst_dir])
         if cp_retcode != 0:
             raise QubesException(
                 "*** Error while copying file {0} to {1}".format(backup_src_dir,
@@ -2224,7 +2224,7 @@ def backup_restore_do(restore_info,
                           home_dir + '/' + restore_home_backupdir + '/' + f)
             if format_version == 1:
                 subprocess.call(
-                    ["cp", "-nrp", backup_dom0_home_dir + '/' + f, home_file])
+                    ["cp", "-nrp", "--reflink=auto", backup_dom0_home_dir + '/' + f, home_file])
             elif format_version >= 2:
                 shutil.move(backup_dom0_home_dir + '/' + f, home_file)
         retcode = subprocess.call(['sudo', 'chown', '-R', local_user, home_dir])

core/storage/__init__.py

@@ -79,7 +79,7 @@ class QubesVmStorage(object):
         # TODO: Windows support
 
         # We prefer to use Linux's cp, because it nicely handles sparse files
-        retcode = subprocess.call (["cp", source, destination])
+        retcode = subprocess.call (["cp", "--reflink=auto", source, destination])
         if retcode != 0:
             raise IOError ("Error while copying {0} to {1}".\
                            format(source, destination))