mgr/volumes: implement trash as a subvolume group

Signed-off-by: Venky Shankar <vshankar@redhat.com>

src/pybind/mgr/volumes/fs/operations/trash.py

@@ -0,0 +1,132 @@
+import os
+import uuid
+import logging
+from contextlib import contextmanager
+
+import cephfs
+
+from .template import GroupTemplate
+from ..fs_util import listdir
+from ..exception import VolumeException
+
+log = logging.getLogger(__name__)
+
+class Trash(GroupTemplate):
+    GROUP_NAME = "_deleting"
+
+    def __init__(self, fs, vol_spec):
+        self.fs = fs
+        self.vol_spec = vol_spec
+        self.groupname = Trash.GROUP_NAME
+
+    @property
+    def path(self):
+        return os.path.join(self.vol_spec.base_dir.encode('utf-8'), self.groupname.encode('utf-8'))
+
+    @property
+    def unique_trash_path(self):
+        """
+        return a unique trash directory entry path
+        """
+        return os.path.join(self.path, str(uuid.uuid4()).encode('utf-8'))
+
+    def _get_single_dir_entry(self, exclude_list=[]):
+        exclude_list.extend((b".", b".."))
+        try:
+            with self.fs.opendir(self.path) as d:
+                entry = self.fs.readdir(d)
+                while entry:
+                    if entry.d_name not in exclude_list and entry.is_dir():
+                        return entry.d_name
+                    entry = self.fs.readdir(d)
+            return None
+        except cephfs.Error as e:
+            raise VolumeException(-e.args[0], e.args[1])
+
+    def get_trash_entry(self, exclude_list):
+        """
+        get a trash entry excluding entries provided.
+
+        :praram exclude_list: entries to exclude
+        :return: trash entry
+        """
+        return self._get_single_dir_entry(exclude_list)
+
+    def purge(self, trash_entry, should_cancel):
+        """
+        purge a trash entry.
+
+        :praram trash_entry: the trash entry to purge
+        :praram should_cancel: callback to check if the purge should be aborted
+        :return: None
+        """
+        def rmtree(root_path):
+            log.debug("rmtree {0}".format(root_path))
+            try:
+                with self.fs.opendir(root_path) as dir_handle:
+                    d = self.fs.readdir(dir_handle)
+                    while d and not should_cancel():
+                        if d.d_name not in (b".", b".."):
+                            d_full = os.path.join(root_path, d.d_name)
+                            if d.is_dir():
+                                rmtree(d_full)
+                            else:
+                                self.fs.unlink(d_full)
+                        d = self.fs.readdir(dir_handle)
+            except cephfs.ObjectNotFound:
+                return
+            except cephfs.Error as e:
+                raise VolumeException(-e.args[0], e.args[1])
+            # remove the directory only if we were not asked to cancel
+            # (else we would fail to remove this anyway)
+            if not should_cancel():
+                self.fs.rmdir(root_path)
+
+        trashpath = os.path.join(self.path, trash_entry)
+        # catch any unlink errors
+        try:
+            rmtree(trashpath)
+        except cephfs.Error as e:
+            raise VolumeException(-e.args[0], e.args[1])
+
+    def dump(self, path):
+        """
+        move an filesystem entity to trash can.
+
+        :praram path: the filesystem path to be moved
+        :return: None
+        """
+        try:
+            self.fs.rename(path, self.unique_trash_path)
+        except cephfs.Error as e:
+            raise VolumeException(-e.args[0], e.args[1])
+
+def create_trashcan(fs, vol_spec):
+    """
+    create a trash can.
+
+    :param fs: ceph filesystem handle
+    :param vol_spec: volume specification
+    :return: None
+    """
+    trashcan = Trash(fs, vol_spec)
+    try:
+        fs.mkdirs(trashcan.path, 0o700)
+    except cephfs.Error as e:
+        raise VolumeException(-e.args[0], e.args[1])
+
+@contextmanager
+def open_trashcan(fs, vol_spec):
+    """
+    open a trash can. This API is to be used as a context manager.
+
+    :param fs: ceph filesystem handle
+    :param vol_spec: volume specification
+    :return: yields a trash can object (subclass of GroupTemplate)
+    """
+    trashcan = Trash(fs, vol_spec)
+    try:
+        fs.stat(trashcan.path)
+    except cephfs.Error as e:
+        raise VolumeException(-e.args[0], e.args[1])
+    yield trashcan