Merge lp:~renamer-developers/renamer/1395239-reflink into lp:renamer

[Tristan Seligmann]

[lp:~renamer-developers/renamer/1395239-reflink]

93. By Tristan Seligmann on 2014-11-22

Fix minor error in docstring.

[Jonathan Jacobs (jjacobs)]

Just one minor concern, as noted in the inline comments. Please merge after resolving it.

review: Approve

[lp:~renamer-developers/renamer/1395239-reflink]

94. By Tristan Seligmann on 2014-11-24

Say some stuff about ioctls.

=== modified file 'docs/manual.rst'
--- docs/manual.rst	2010-10-26 14:37:34 +0000
+++ docs/manual.rst	2014-11-24 09:37:32 +0000
@@ -49,6 +49,13 @@
     Create a symlink at the destination. The original file will not be moved
     but a symlink will be created at the new location.
 
+--reflink
+    Create a COW copy at the destination. The file will not occupy any
+    additional space on disk until the contents are modified. The destination
+    must be on the same filesystem as the source, and the underlying filesystem
+    must support the BTRFS_IOC_CLONE ioctl (as of this writing, only btrfs has
+    this support).
+
 -c file, --config=file
     Read configuration defaults from *file*. The default configuration is read
     from *~/.renamer/renamer.conf*. See the :ref:`CONFIGURATION` section for

=== modified file 'renamer/application.py'
--- renamer/application.py	2011-12-06 10:08:13 +0000
+++ renamer/application.py	2014-11-24 09:37:32 +0000
@@ -24,7 +24,8 @@
         ('one-file-system', 'x',  "Don't cross filesystems."),
         ('no-act',          'n',  'Perform a trial run with no changes made.'),
         ('link-src',        None, 'Create a symlink at the source.'),
-        ('link-dst',        None, 'Create a symlink at the destination.')]
+        ('link-dst',        None, 'Create a symlink at the destination.'),
+        ('reflink',         None, 'Create a COW copy at the destination.')]
 
 
     optParameters = [
@@ -194,7 +195,11 @@
             logging.msg('Skipping noop "%s"' % (src.path,), verbosity=2)
             return
 
-        if self.options['link-dst']:
+        if self.options['reflink']:
+            self.changeset.do(
+                self.changeset.newAction(u'reflink', src, dst),
+                self.options)
+        elif self.options['link-dst']:
             self.changeset.do(
                 self.changeset.newAction(u'symlink', src, dst),
                 self.options)

=== modified file 'renamer/plugins/actions.py'
--- renamer/plugins/actions.py	2010-10-16 17:39:21 +0000
+++ renamer/plugins/actions.py	2014-11-24 09:37:32 +0000
@@ -1,3 +1,5 @@
+from fcntl import ioctl
+
 from renamer import logging, util
 from renamer.plugin import RenamingAction
 
@@ -50,3 +52,46 @@
         if self.dst.islink():
             logging.msg('Symlink: Removing %s' % (self.dst.path,))
             self.dst.remove()
+
+
+# Should be:
+#  BTRFS_IOCTL_MAGIC = 0x94
+#  BTRFS_IOC_CLONE = ioctl.IOW(BTRFS_IOCTL_MAGIC, 9, INT)
+# but Python doesn't have these.
+BTRFS_IOC_CLONE = 0x40049409
+
+
+def _reflink(src, dest):
+    """
+    Make a COW copy of a file.
+
+    @type src: L{twisted.python.filepath.FilePath}
+    @param src: The source file.
+
+    @type dest: L{twisted.python.filepath.FilePath}
+    @param dest: The destination file.
+    """
+    with src.open('rb') as sfile:
+        with dest.open('wb') as dfile:
+            ioctl(dfile.fileno(), BTRFS_IOC_CLONE, sfile.fileno())
+
+
+
+class ReflinkAction(RenamingAction):
+    """
+    Reflink action.
+    """
+    name = 'reflink'
+
+
+    # IRenamingAction
+
+    def do(self, options):
+        self.prepare(self.dst, options)
+        logging.msg('Reflink: %s => %s' % (self.src.path, self.dst.path))
+        _reflink(self.src, self.dst)
+
+
+    def undo(self, options):
+        logging.msg('Reflink: Removing %s' % (self.dst.path,))
+        self.dst.remove()

=== modified file 'renamer/test/test_actions.py'
--- renamer/test/test_actions.py	2010-10-20 18:08:59 +0000
+++ renamer/test/test_actions.py	2014-11-24 09:37:32 +0000
@@ -1,5 +1,7 @@
+from errno import ENOTTY
+
 from twisted.python.filepath import FilePath
-from twisted.trial.unittest import TestCase
+from twisted.trial.unittest import TestCase, SkipTest
 
 from renamer import errors
 from renamer.application import Options
@@ -171,3 +173,58 @@
         """
         Undoing a symlink cannot raise L{renamer.errors.NoClobber}.
         """
+
+
+
+class ReflinkActionTests(_ActionTestMixin, TestCase):
+    """
+    Tests for L{renamer.plugin.actions.ReflinkAction}.
+    """
+    actionType = actions.ReflinkAction
+
+
+    def setUp(self):
+        p1 = FilePath(self.mktemp())
+        p2 = FilePath(self.mktemp())
+        p1.setContent('foo')
+        p2.setContent('bar')
+        try:
+            actions._reflink(p1, p2)
+        except IOError, e:
+            if e.errno == ENOTTY:
+                raise SkipTest('Not a btrfs filesystem')
+            raise
+        super(ReflinkActionTests, self).setUp()
+
+
+    def test_do(self):
+        self.src.setContent('content')
+
+        self.assertTrue(self.src.exists())
+        self.assertFalse(self.dst.exists())
+
+        action = self.createAction()
+        action.do(self.options)
+
+        self.assertEquals('content', self.src.getContent())
+        self.assertEquals('content', self.dst.getContent())
+
+
+    def test_undo(self):
+        self.src.touch()
+        self.dst.touch()
+
+        self.assertTrue(self.src.exists())
+        self.assertTrue(self.dst.exists())
+
+        action = self.createAction()
+        action.undo(self.options)
+
+        self.assertTrue(self.src.exists())
+        self.assertFalse(self.dst.exists())
+
+
+    def test_undoClobber(self):
+        """
+        Undoing a reflink copy cannot raise L{renamer.errors.NoClobber}.
+        """