vfs: spread struct mount - mount group id handling

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/pnode.c b/fs/pnode.c
index ae5b1bd..a824a09 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -83,7 +83,7 @@
 			peer_mnt = NULL;
 	}
 	if (IS_MNT_SHARED(mnt) && list_empty(&mnt->mnt_share))
-		mnt_release_group_id(mnt);
+		mnt_release_group_id(real_mount(mnt));
 
 	list_del_init(&mnt->mnt_share);
 	mnt->mnt_group_id = 0;