linux-kernel - Re: [PATCH v6 06/20] liveupdate: luo_file: implement file systems callbacks

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Message-ID: <aRyvG308oNRVzuN7@google.com>
Date: Tue, 18 Nov 2025 17:38:35 +0000
From: David Matlack <dmatlack@...gle.com>
To: Pasha Tatashin <pasha.tatashin@...een.com>
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Subject: Re: [PATCH v6 06/20] liveupdate: luo_file: implement file systems
 callbacks

On 2025-11-15 06:33 PM, Pasha Tatashin wrote:
> This patch implements the core mechanism for managing preserved
> files throughout the live update lifecycle. It provides the logic to
> invoke the file handler callbacks (preserve, unpreserve, freeze,
> unfreeze, retrieve, and finish) at the appropriate stages.
> 
> During the reboot phase, luo_file_freeze() serializes the final
> metadata for each file (handler compatible string, token, and data
> handle) into a memory region preserved by KHO. In the new kernel,
> luo_file_deserialize() reconstructs the in-memory file list from this
> data, preparing the session for retrieval.
> 
> Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>

> +int liveupdate_register_file_handler(struct liveupdate_file_handler *h);

Should there be a way to unregister a file handler?

If VFIO is built as module then I think it  would need to be able to
unregister its file handler when the module is unloaded to avoid leaking
pointers to its text in LUO.