linux-kernel - Re: [PATCH v5 00/11] blksnap - block devices snapshots module

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Message-ID: <20230612161911.GA1200@sol.localdomain>
Date:   Mon, 12 Jun 2023 09:19:11 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Sergei Shtepa <sergei.shtepa@...am.com>
Cc:     axboe@...nel.dk, hch@...radead.org, corbet@....net,
        snitzer@...nel.org, viro@...iv.linux.org.uk, brauner@...nel.org,
        dchinner@...hat.com, willy@...radead.org, dlemoal@...nel.org,
        linux@...ssschuh.net, jack@...e.cz, ming.lei@...hat.com,
        linux-block@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v5 00/11] blksnap - block devices snapshots module

On Mon, Jun 12, 2023 at 03:52:17PM +0200, Sergei Shtepa wrote:
> Hi all.
> 
> I am happy to offer a improved version of the Block Devices Snapshots
> Module. It allows to create non-persistent snapshots of any block devices.
> The main purpose of such snapshots is to provide backups of block devices.
> See more in Documentation/block/blksnap.rst.

How does blksnap interact with blk-crypto?

I.e., what happens if a bio with a ->bi_crypt_context set is submitted to a
block device that has blksnap active?

If you are unfamiliar with blk-crypto, please read
Documentation/block/inline-encryption.rst

It looks like blksnap hooks into the block layer directly, via the new
"blkfilter" mechanism.  I'm concerned that it might ignore ->bi_crypt_context
and write data to the disk in plaintext, when it is supposed to be encrypted.

- Eric