- cleanup/add missing stuff to struct smbXsrv_open*
  - create_guid, application_guid..., file_name
    desired_access, granted_access, share_mode

- replace get_gen_count() by smbXsrv_open_hash()
  smbXsrv_open_hash() should calculate the jenkins hash
  over global->open_persistent_id global->open_volatile_id
  and global->open_time
  - in long run we should replace fsp->fh->gen_id with a dynamic
    blob

- add NTSTATUS SMB_VFS_DURABLE_COOKIE(fsp, mem_ctx, &cookie_blob);
  vfs_default => NT_STATUS_NOT_IMPLEMENTED
  vfs_simple_durable => blob = data_blob(fsp->file_id + fsp->fh->gen_id)

- add NTSTATUS SMB_VFS_DURABLE_REOPEN(fsp, cookie_blob);
  vfs_default => NT_STATUS_NOT_SUPPORTED
  vfs_simple_durable => what we have currently...

- or three functions:
   // called at open when durable is requested:
   NTSTATUS SMB_VFS_DURABLE_COOKIE(fsp, mem_ctx, &cookie_blob);
   // maybe pass persistent or resilient...
   NTSTATUS SMB_VFS_DURABLE_COOKIE(fsp, in_flags, mem_ctx, &cookie_blob, &out_flags);
   // called at disconnect:
   NTSTATUS SMB_VFS_DURABLE_DISCONNECT(fsp, mem_ctx, old_cookie_blob, &new_cookie_blob);
   // called at durable reconnect:
   NTSTATUS SMB_VFS_DURABLE_RECONNECT(fsp, cookie_blob);

- remove file_find_fd()
  - in oplocks_linux use a global linked list of
    struct linux_oplock_fd_mapping {
           struct linux_oplock_fd_mapping *prev, *next;
           int fd;
           struct files_struct *fsp;
    };
  - in smb_Dir_destructor() -- I don't know yet...