libbtrfsutil: add btrfs_util_create_snapshot()

Thanks to subvolume iterators, we can also implement recursive snapshot
fairly easily.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

5 files changed, 126 insertions, 0 deletions

diff --git a/libbtrfsutil/python/btrfsutilpy.h b/libbtrfsutil/python/btrfsutilpy.h
index 79ac2eec..59c7e994 100644
--- a/libbtrfsutil/python/btrfsutilpy.h
+++ b/libbtrfsutil/python/btrfsutilpy.h
@@ -73,6 +73,7 @@ PyObject *set_subvolume_read_only(PyObject *self, PyObject *args, PyObject *kwds
 PyObject *get_default_subvolume(PyObject *self, PyObject *args, PyObject *kwds);
 PyObject *set_default_subvolume(PyObject *self, PyObject *args, PyObject *kwds);
 PyObject *create_subvolume(PyObject *self, PyObject *args, PyObject *kwds);
+PyObject *create_snapshot(PyObject *self, PyObject *args, PyObject *kwds);
 
 void add_module_constants(PyObject *m);
 
diff --git a/libbtrfsutil/python/module.c b/libbtrfsutil/python/module.c
index 9a237142..3f0f6170 100644
--- a/libbtrfsutil/python/module.c
+++ b/libbtrfsutil/python/module.c
@@ -216,6 +216,17 @@ static PyMethodDef btrfsutil_methods[] = {
 	 "path -- string, bytes, or path-like object\n"
 	 "async -- create the subvolume without waiting for it to commit to\n"
 	 "disk and return the transaction ID"},
+	{"create_snapshot", (PyCFunction)create_snapshot,
+	 METH_VARARGS | METH_KEYWORDS,
+	 "create_snapshot(source, path, recursive=False, read_only=False, async=False)\n\n"
+	 "Create a new snapshot.\n\n"
+	 "Arguments:\n"
+	 "source -- string, bytes, path-like object, or open file descriptor\n"
+	 "path -- string, bytes, or path-like object\n"
+	 "recursive -- also snapshot child subvolumes\n"
+	 "read_only -- create a read-only snapshot\n"
+	 "async -- create the subvolume without waiting for it to commit to\n"
+	 "disk and return the transaction ID"},
 	{},
 };
 
diff --git a/libbtrfsutil/python/subvolume.c b/libbtrfsutil/python/subvolume.c
index 6c384583..a158ade7 100644
--- a/libbtrfsutil/python/subvolume.c
+++ b/libbtrfsutil/python/subvolume.c
@@ -349,6 +349,55 @@ PyObject *create_subvolume(PyObject *self, PyObject *args, PyObject *kwds)
 		Py_RETURN_NONE;
 }
 
+PyObject *create_snapshot(PyObject *self, PyObject *args, PyObject *kwds)
+{
+	static char *keywords[] = {
+		"source", "path", "recursive", "read_only", "async",
+		"qgroup_inherit", NULL,
+	};
+	struct path_arg src = {.allow_fd = true}, dst = {.allow_fd = false};
+	enum btrfs_util_error err;
+	int recursive = 0, read_only = 0, async = 0;
+	int flags = 0;
+	QgroupInherit *inherit = NULL;
+	uint64_t transid;
+
+	if (!PyArg_ParseTupleAndKeywords(args, kwds, "O&O&|pppO!:create_snapshot",
+					 keywords, &path_converter, &src,
+					 &path_converter, &dst, &recursive,
+					 &read_only, &async,
+					 &QgroupInherit_type, &inherit))
+		return NULL;
+
+	if (recursive)
+		flags |= BTRFS_UTIL_CREATE_SNAPSHOT_RECURSIVE;
+	if (read_only)
+		flags |= BTRFS_UTIL_CREATE_SNAPSHOT_READ_ONLY;
+
+	if (src.path) {
+		err = btrfs_util_create_snapshot(src.path, dst.path, flags,
+						 async ? &transid : NULL,
+						 inherit ? inherit->inherit : NULL);
+	} else {
+		err = btrfs_util_create_snapshot_fd(src.fd, dst.path, flags,
+						    async ? &transid : NULL,
+						    inherit ? inherit->inherit : NULL);
+	}
+	if (err) {
+		SetFromBtrfsUtilErrorWithPaths(err, &src, &dst);
+		path_cleanup(&src);
+		path_cleanup(&dst);
+		return NULL;
+	}
+
+	path_cleanup(&src);
+	path_cleanup(&dst);
+	if (async)
+		return PyLong_FromUnsignedLongLong(transid);
+	else
+		Py_RETURN_NONE;
+}
+
 typedef struct {
 	PyObject_HEAD
 	struct btrfs_util_subvolume_iterator *iter;
diff --git a/libbtrfsutil/python/tests/test_qgroup.py b/libbtrfsutil/python/tests/test_qgroup.py
index 19e6b05a..74fc46b6 100644
--- a/libbtrfsutil/python/tests/test_qgroup.py
+++ b/libbtrfsutil/python/tests/test_qgroup.py
@@ -31,6 +31,16 @@ class TestQgroup(BtrfsTestCase):
 
         btrfsutil.create_subvolume(subvol, qgroup_inherit=inherit)
 
+    def test_snapshot_inherit(self):
+        subvol = os.path.join(self.mountpoint, 'subvol')
+        snapshot = os.path.join(self.mountpoint, 'snapshot')
+
+        inherit = btrfsutil.QgroupInherit()
+        inherit.add_group(5)
+
+        btrfsutil.create_subvolume(subvol)
+        btrfsutil.create_snapshot(subvol, snapshot, qgroup_inherit=inherit)
+
 
 class TestQgroupInherit(unittest.TestCase):
     def test_new(self):
diff --git a/libbtrfsutil/python/tests/test_subvolume.py b/libbtrfsutil/python/tests/test_subvolume.py
index b43beca7..2951154e 100644
--- a/libbtrfsutil/python/tests/test_subvolume.py
+++ b/libbtrfsutil/python/tests/test_subvolume.py
@@ -129,6 +129,13 @@ class TestSubvolume(BtrfsTestCase):
         self.assertEqual(info.stime, 0)
         self.assertEqual(info.rtime, 0)
 
+        subvol_uuid = info.uuid
+        snapshot = os.path.join(self.mountpoint, 'snapshot')
+        btrfsutil.create_snapshot(subvol, snapshot)
+
+        info = btrfsutil.subvolume_info(snapshot)
+        self.assertEqual(info.parent_uuid, subvol_uuid)
+
         # TODO: test received_uuid, stransid, rtransid, stime, and rtime
 
         for arg in self.path_or_fd(self.mountpoint):
@@ -215,6 +222,54 @@ class TestSubvolume(BtrfsTestCase):
         self.assertTrue(os.WIFEXITED(wstatus))
         self.assertEqual(os.WEXITSTATUS(wstatus), 0)
 
+    def test_create_snapshot(self):
+        subvol = os.path.join(self.mountpoint, 'subvol')
+
+        btrfsutil.create_subvolume(subvol)
+        os.mkdir(os.path.join(subvol, 'dir'))
+
+        for i, arg in enumerate(self.path_or_fd(subvol)):
+            with self.subTest(type=type(arg)):
+                snapshots_dir = os.path.join(self.mountpoint, 'snapshots{}'.format(i))
+                os.mkdir(snapshots_dir)
+                snapshot = os.path.join(snapshots_dir, 'snapshot')
+
+                btrfsutil.create_snapshot(subvol, snapshot + '1')
+                self.assertTrue(btrfsutil.is_subvolume(snapshot + '1'))
+                self.assertTrue(os.path.exists(os.path.join(snapshot + '1', 'dir')))
+
+                btrfsutil.create_snapshot(subvol, (snapshot + '2').encode())
+                self.assertTrue(btrfsutil.is_subvolume(snapshot + '2'))
+                self.assertTrue(os.path.exists(os.path.join(snapshot + '2', 'dir')))
+
+                if HAVE_PATH_LIKE:
+                    btrfsutil.create_snapshot(subvol, PurePath(snapshot + '3'))
+                    self.assertTrue(btrfsutil.is_subvolume(snapshot + '3'))
+                    self.assertTrue(os.path.exists(os.path.join(snapshot + '3', 'dir')))
+
+        nested_subvol = os.path.join(subvol, 'nested')
+        more_nested_subvol = os.path.join(nested_subvol, 'more_nested')
+        btrfsutil.create_subvolume(nested_subvol)
+        btrfsutil.create_subvolume(more_nested_subvol)
+        os.mkdir(os.path.join(more_nested_subvol, 'nested_dir'))
+
+        snapshot = os.path.join(self.mountpoint, 'snapshot')
+
+        btrfsutil.create_snapshot(subvol, snapshot + '1')
+        # Dummy subvolume.
+        self.assertEqual(os.stat(os.path.join(snapshot + '1', 'nested')).st_ino, 2)
+        self.assertFalse(os.path.exists(os.path.join(snapshot + '1', 'nested', 'more_nested')))
+
+        btrfsutil.create_snapshot(subvol, snapshot + '2', recursive=True)
+        self.assertTrue(os.path.exists(os.path.join(snapshot + '2', 'nested/more_nested/nested_dir')))
+
+        transid = btrfsutil.create_snapshot(subvol, snapshot + '3', recursive=True, async=True)
+        self.assertTrue(os.path.exists(os.path.join(snapshot + '3', 'nested/more_nested/nested_dir')))
+        self.assertGreater(transid, 0)
+
+        btrfsutil.create_snapshot(subvol, snapshot + '4', read_only=True)
+        self.assertTrue(btrfsutil.get_subvolume_read_only(snapshot + '4'))
+
     def test_subvolume_iterator(self):
         pwd = os.getcwd()
         try: