Re: [PATCH v2 1/2] liveupdate: luo_file: allow keeping private_data from retrieve until finish

[Samiullah Khawaja]

On Tue, Nov 10, 2026 at 06:58:52PM +0100, Pratyush Yadav wrote:
> From: "Pratyush Yadav (Google)" <pratyush@xxxxxxxxxx>
>
> The private_data field of struct liveupdate_file_op_args lets file
> handlers keep runtime state that is not preserved. It is set by
> .preserve() and passed to the later outgoing callbacks, up to
> .unpreserve(). But in the new kernel, nothing set by .retrieve() is
> kept, and .can_finish() and .finish() always get a NULL private_data.
>
> Handlers might need to keep runtime state from retrieve until finish.
> For example, memfd will need to remember the folios it holds on to
> until finish so it can release them there.
>
> Save the private_data set by a successful .retrieve() in the luo_file,
> and pass it to .can_finish() and .finish(). The handler must free it in
> .finish().
>
> While at it, update a stale comment under struct
> liveupdate_file_op_args. There is no 'data', but there is
> 'serialized_data' and 'private_data'. Refer to them instead.
>
> Reviewed-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> Signed-off-by: Pratyush Yadav (Google) <pratyush@xxxxxxxxxx>
> ---
> include/linux/liveupdate.h   | 11 +++++++----
> kernel/liveupdate/luo_file.c | 11 ++++++++---
> 2 files changed, 15 insertions(+), 7 deletions(-)

Reviewed-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>