[lxc-devel] [lxd/master] Fix ZFS refcounting issues

[stgraber on Github]

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From b588fe35c359eca860d5230919cb9818ed4d6dac Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Graber?= <stgraber at ubuntu.com>
Date: Wed, 11 May 2016 12:07:06 -0400
Subject: [PATCH] Fix ZFS refcounting issues
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Closes #1916
Closes #2013

Signed-off-by: Stéphane Graber <stgraber at ubuntu.com>
---
 lxd/storage_zfs.go | 61 ++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 48 insertions(+), 13 deletions(-)

diff --git a/lxd/storage_zfs.go b/lxd/storage_zfs.go
index 4d8d932..8386ed8 100644
--- a/lxd/storage_zfs.go
+++ b/lxd/storage_zfs.go
@@ -795,29 +795,64 @@ func (s *storageZfs) zfsDestroy(path string) error {
 
 func (s *storageZfs) zfsCleanup(path string) error {
 	if strings.HasPrefix(path, "deleted/") {
+		// Cleanup of filesystems kept for refcount reason
 		removablePath, err := s.zfsSnapshotRemovable(path, "")
 		if err != nil {
 			return err
 		}
 
+		// Confirm that there are no more clones
 		if removablePath {
-			subPath := strings.SplitN(path, "@", 2)[0]
-
-			origin, err := s.zfsGet(subPath, "origin")
-			if err != nil {
-				return err
-			}
-			origin = strings.TrimPrefix(origin, fmt.Sprintf("%s/", s.zfsPool))
-
-			err = s.zfsDestroy(subPath)
-			if err != nil {
-				return err
+			if strings.Contains(path, "@") {
+				// Cleanup snapshots
+				err = s.zfsDestroy(path)
+				if err != nil {
+					return err
+				}
+
+				// Check if the parent can now be deleted
+				subPath := strings.SplitN(path, "@", 2)[0]
+				snaps, err := s.zfsListSnapshots(subPath)
+				if err != nil {
+					return err
+				}
+
+				if len(snaps) == 0 {
+					err := s.zfsCleanup(subPath)
+					if err != nil {
+						return err
+					}
+				}
+			} else {
+				// Cleanup filesystems
+				origin, err := s.zfsGet(path, "origin")
+				if err != nil {
+					return err
+				}
+				origin = strings.TrimPrefix(origin, fmt.Sprintf("%s/", s.zfsPool))
+
+				err = s.zfsDestroy(path)
+				if err != nil {
+					return err
+				}
+
+				// Attempt to remove its parent
+				if origin != "-" {
+					err := s.zfsCleanup(origin)
+					if err != nil {
+						return err
+					}
+				}
 			}
 
-			s.zfsCleanup(origin)
-
 			return nil
 		}
+	} else if strings.HasPrefix(path, "containers") {
+		// Just remove the copy- snapshot for copies of active containers
+		err := s.zfsDestroy(path)
+		if err != nil {
+			return err
+		}
 	}
 
 	return nil