Refactor voljournal to aid reuse with CephFS

and to also inmprove the code reuse in rbd itself.

Signed-off-by: ShyamsundarR <srangana@redhat.com>

pkg/rbd/rbd_journal.go

@@ -0,0 +1,307 @@
+/*
+Copyright 2019 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package rbd
+
+import (
+	"fmt"
+
+	"github.com/ceph/ceph-csi/pkg/util"
+
+	"github.com/pkg/errors"
+	"k8s.io/klog"
+)
+
+func validateNonEmptyField(field, fieldName, structName string) error {
+	if field == "" {
+		return fmt.Errorf("value '%s' in '%s' structure cannot be empty", fieldName, structName)
+	}
+
+	return nil
+}
+
+func validateRbdSnap(rbdSnap *rbdSnapshot) error {
+	var err error
+
+	if err = validateNonEmptyField(rbdSnap.RequestName, "RequestName", "rbdSnapshot"); err != nil {
+		return err
+	}
+
+	if err = validateNonEmptyField(rbdSnap.Monitors, "Monitors", "rbdSnapshot"); err != nil {
+		return err
+	}
+
+	if err = validateNonEmptyField(rbdSnap.AdminID, "AdminID", "rbdSnapshot"); err != nil {
+		return err
+	}
+
+	if err = validateNonEmptyField(rbdSnap.Pool, "Pool", "rbdSnapshot"); err != nil {
+		return err
+	}
+
+	if err = validateNonEmptyField(rbdSnap.RbdImageName, "RbdImageName", "rbdSnapshot"); err != nil {
+		return err
+	}
+
+	if err = validateNonEmptyField(rbdSnap.ClusterID, "ClusterID", "rbdSnapshot"); err != nil {
+		return err
+	}
+
+	return err
+}
+
+func validateRbdVol(rbdVol *rbdVolume) error {
+	var err error
+
+	if err = validateNonEmptyField(rbdVol.RequestName, "RequestName", "rbdVolume"); err != nil {
+		return err
+	}
+
+	if err = validateNonEmptyField(rbdVol.Monitors, "Monitors", "rbdVolume"); err != nil {
+		return err
+	}
+
+	if err = validateNonEmptyField(rbdVol.AdminID, "AdminID", "rbdVolume"); err != nil {
+		return err
+	}
+
+	if err = validateNonEmptyField(rbdVol.Pool, "Pool", "rbdVolume"); err != nil {
+		return err
+	}
+
+	if err = validateNonEmptyField(rbdVol.ClusterID, "ClusterID", "rbdVolume"); err != nil {
+		return err
+	}
+
+	if rbdVol.VolSize == 0 {
+		return errors.New("value 'VolSize' in 'rbdVolume' structure cannot be 0")
+	}
+
+	return err
+}
+
+/*
+checkSnapExists, and its counterpart checkVolExists, function checks if the passed in rbdSnapshot
+or rbdVolume exists on the backend.
+
+**NOTE:** These functions manipulate the rados omaps that hold information regarding
+volume names as requested by the CSI drivers. Hence, these need to be invoked only when the
+respective CSI driver generated snapshot or volume name based locks are held, as otherwise racy
+access to these omaps may end up leaving them in an inconsistent state.
+
+These functions need enough information about cluster and pool (ie, Monitors, Pool, IDs filled in)
+to operate. They further require that the RequestName element of the structure have a valid value
+to operate on and determine if the said RequestName already exists on the backend.
+
+These functions populate the snapshot or the image name, its attributes and the CSI snapshot/volume
+ID for the same when successful.
+
+These functions also cleanup omap reservations that are stale. I.e when omap entries exist and
+backing images or snapshots are missing, or one of the omaps exist and the next is missing. This is
+because, the order of omap creation and deletion are inverse of each other, and protected by the
+request name lock, and hence any stale omaps are leftovers from incomplete transactions and are
+hence safe to garbage collect.
+*/
+func checkSnapExists(rbdSnap *rbdSnapshot, credentials map[string]string) (bool, error) {
+	err := validateRbdSnap(rbdSnap)
+	if err != nil {
+		return false, err
+	}
+
+	key, err := getKey(rbdSnap.AdminID, credentials)
+	if err != nil {
+		return false, err
+	}
+
+	snapUUID, err := snapJournal.CheckReservation(rbdSnap.Monitors, rbdSnap.AdminID, key, rbdSnap.Pool,
+		rbdSnap.RequestName, rbdSnap.RbdImageName)
+	if err != nil {
+		return false, err
+	}
+	if snapUUID == "" {
+		return false, nil
+	}
+	rbdSnap.RbdSnapName = snapJournal.NamingPrefix() + snapUUID
+
+	// Fetch on-disk image attributes
+	err = updateSnapWithImageInfo(rbdSnap, credentials)
+	if err != nil {
+		if _, ok := err.(ErrSnapNotFound); ok {
+			err = snapJournal.UndoReservation(rbdSnap.Monitors, rbdSnap.AdminID, key, rbdSnap.Pool,
+				rbdSnap.RbdSnapName, rbdSnap.RequestName)
+			return false, err
+		}
+		return false, err
+	}
+
+	// found a snapshot already available, process and return its information
+	rbdSnap.SnapID, err = util.GenerateVolID(rbdSnap.Monitors, rbdSnap.AdminID, key, rbdSnap.Pool,
+		rbdSnap.ClusterID, snapUUID, volIDVersion)
+	if err != nil {
+		return false, err
+	}
+
+	klog.V(4).Infof("found existing snap (%s) with snap name (%s) for request (%s)",
+		rbdSnap.SnapID, rbdSnap.RbdSnapName, rbdSnap.RequestName)
+
+	return true, nil
+}
+
+/*
+Check comment on checkSnapExists, to understand how this function behaves
+
+**NOTE:** These functions manipulate the rados omaps that hold information regarding
+volume names as requested by the CSI drivers. Hence, these need to be invoked only when the
+respective CSI snapshot or volume name based locks are held, as otherwise racy access to these
+omaps may end up leaving the omaps in an inconsistent state.
+*/
+func checkVolExists(rbdVol *rbdVolume, credentials map[string]string) (bool, error) {
+	err := validateRbdVol(rbdVol)
+	if err != nil {
+		return false, err
+	}
+
+	key, err := getKey(rbdVol.AdminID, credentials)
+	if err != nil {
+		return false, err
+	}
+
+	imageUUID, err := volJournal.CheckReservation(rbdVol.Monitors, rbdVol.AdminID, key, rbdVol.Pool,
+		rbdVol.RequestName, "")
+	if err != nil {
+		return false, err
+	}
+	if imageUUID == "" {
+		return false, nil
+	}
+	rbdVol.RbdImageName = volJournal.NamingPrefix() + imageUUID
+
+	// NOTE: Return volsize should be on-disk volsize, not request vol size, so
+	// save it for size checks before fetching image data
+	requestSize := rbdVol.VolSize
+	// Fetch on-disk image attributes and compare against request
+	err = updateVolWithImageInfo(rbdVol, credentials)
+	if err != nil {
+		if _, ok := err.(ErrImageNotFound); ok {
+			err = volJournal.UndoReservation(rbdVol.Monitors, rbdVol.AdminID, key, rbdVol.Pool,
+				rbdVol.RbdImageName, rbdVol.RequestName)
+			return false, err
+		}
+		return false, err
+	}
+
+	// size checks
+	if rbdVol.VolSize < requestSize {
+		err = fmt.Errorf("image with the same name (%s) but with different size already exists",
+			rbdVol.RbdImageName)
+		return false, ErrVolNameConflict{rbdVol.RbdImageName, err}
+	}
+	// TODO: We should also ensure image features and format is the same
+
+	// found a volume already available, process and return it!
+	rbdVol.VolID, err = util.GenerateVolID(rbdVol.Monitors, rbdVol.AdminID, key, rbdVol.Pool,
+		rbdVol.ClusterID, imageUUID, volIDVersion)
+	if err != nil {
+		return false, err
+	}
+
+	klog.V(4).Infof("found existng volume (%s) with image name (%s) for request (%s)",
+		rbdVol.VolID, rbdVol.RbdImageName, rbdVol.RequestName)
+
+	return true, nil
+}
+
+// reserveSnap is a helper routine to request a rbdSnapshot name reservation and generate the
+// volume ID for the generated name
+func reserveSnap(rbdSnap *rbdSnapshot, credentials map[string]string) error {
+	key, err := getKey(rbdSnap.AdminID, credentials)
+	if err != nil {
+		return err
+	}
+
+	snapUUID, err := snapJournal.ReserveName(rbdSnap.Monitors, rbdSnap.AdminID, key, rbdSnap.Pool,
+		rbdSnap.RequestName, rbdSnap.RbdImageName)
+	if err != nil {
+		return err
+	}
+
+	rbdSnap.SnapID, err = util.GenerateVolID(rbdSnap.Monitors, rbdSnap.AdminID, key, rbdSnap.Pool,
+		rbdSnap.ClusterID, snapUUID, volIDVersion)
+	if err != nil {
+		return err
+	}
+
+	rbdSnap.RbdSnapName = snapJournal.NamingPrefix() + snapUUID
+
+	klog.V(4).Infof("generated Volume ID (%s) and image name (%s) for request name (%s)",
+		rbdSnap.SnapID, rbdSnap.RbdImageName, rbdSnap.RequestName)
+
+	return nil
+}
+
+// reserveVol is a helper routine to request a rbdVolume name reservation and generate the
+// volume ID for the generated name
+func reserveVol(rbdVol *rbdVolume, credentials map[string]string) error {
+	key, err := getKey(rbdVol.AdminID, credentials)
+	if err != nil {
+		return err
+	}
+
+	imageUUID, err := volJournal.ReserveName(rbdVol.Monitors, rbdVol.AdminID, key, rbdVol.Pool,
+		rbdVol.RequestName, "")
+	if err != nil {
+		return err
+	}
+
+	rbdVol.VolID, err = util.GenerateVolID(rbdVol.Monitors, rbdVol.AdminID, key, rbdVol.Pool,
+		rbdVol.ClusterID, imageUUID, volIDVersion)
+	if err != nil {
+		return err
+	}
+
+	rbdVol.RbdImageName = volJournal.NamingPrefix() + imageUUID
+
+	klog.V(4).Infof("generated Volume ID (%s) and image name (%s) for request name (%s)",
+		rbdVol.VolID, rbdVol.RbdImageName, rbdVol.RequestName)
+
+	return nil
+}
+
+// undoSnapReservation is a helper routine to undo a name reservation for rbdSnapshot
+func undoSnapReservation(rbdSnap *rbdSnapshot, credentials map[string]string) error {
+	key, err := getKey(rbdSnap.AdminID, credentials)
+	if err != nil {
+		return err
+	}
+
+	err = snapJournal.UndoReservation(rbdSnap.Monitors, rbdSnap.AdminID, key, rbdSnap.Pool,
+		rbdSnap.RbdSnapName, rbdSnap.RequestName)
+
+	return err
+}
+
+// undoVolReservation is a helper routine to undo a name reservation for rbdVolume
+func undoVolReservation(rbdVol *rbdVolume, credentials map[string]string) error {
+	key, err := getKey(rbdVol.AdminID, credentials)
+	if err != nil {
+		return err
+	}
+
+	err = volJournal.UndoReservation(rbdVol.Monitors, rbdVol.AdminID, key, rbdVol.Pool,
+		rbdVol.RbdImageName, rbdVol.RequestName)
+
+	return err
+}