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Date:   Tue, 13 Dec 2022 12:50:28 -0800
From:   Eric Biggers <ebiggers@kernel.org>
To:     Andrey Albershteyn <aalbersh@redhat.com>
Cc:     linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH 00/11] fs-verity support for XFS
Message-ID: <Y5jllLwXlfB7BzTz@sol.localdomain>
References: <20221213172935.680971-1-aalbersh@redhat.com>
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On Tue, Dec 13, 2022 at 06:29:24PM +0100, Andrey Albershteyn wrote:
> Not yet implemented:
> - No pre-fetching of Merkle tree pages in the
>   read_merkle_tree_page()

This would be helpful, but not essential.

> - No marking of already verified Merkle tree pages (each read, the
>   whole tree is verified).

This is essential to have, IMO.

You *could* do what btrfs does, where it caches the Merkle tree pages in the
inode's page cache past i_size, even though btrfs stores the Merkle tree
separately from the file data on-disk.

However, I'd guess that the other XFS developers would have an adversion to that
approach, even though it would not affect the on-disk storage.

The alternatives would be to create a separate in-memory-only inode for the
cache, or to build a custom cache with its own shrinker.

- Eric