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From:   Daniil Lunev <dlunev@chromium.org>
Date:   Thu, 9 Jun 2022 10:22:01 +1000
Message-ID: <CAONX=-ck0kfSpZhu8vBstmen1U++rzn0_HcntiWAWKE8FP+1UA@mail.gmail.com>
Subject: Re: [PATCH v4 0/2] Prevent re-use of FUSE superblock after force unmount
To:     miklos@szeredi.hu, viro@zeniv.linux.org.uk, tytso@mit.edu
Cc:     linux-kernel@vger.kernel.org, fuse-devel@lists.sourceforge.net,
        Daniil Lunev <dlunev@google.com>,
        linux-fsdevel@vger.kernel.org, hch@infradead.org
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Hi Miklos and Alexander,
Do you have any more concerns or comments regarding the patchset or do
you think we can proceed with it?
--Daniil

On Wed, Jun 1, 2022 at 11:11 AM Daniil Lunev <dlunev@chromium.org> wrote:
>
> Force unmount of fuse severes the connection between FUSE driver and its
> userspace counterpart. However, open file handles will prevent the
> superblock from being reclaimed. An attempt to remount the filesystem at
> the same endpoint will try re-using the superblock, if still present.
> Since the superblock re-use path doesn't go through the fs-specific
> superblock setup code, its state in FUSE case is already disfunctional,
> and that will prevent the mount from succeeding.
>
> Changes in v4:
> - Simplify condition according to Christoph Hellwig's comments.
>
> Changes in v3:
> - Back to state tracking from v1
> - Use s_iflag to mark superblocked ignored
> - Only unregister private bdi in retire, without freeing
>
> Changes in v2:
> - Remove super from list of superblocks instead of using a flag
>
> Daniil Lunev (2):
>   fs/super: function to prevent super re-use
>   FUSE: Retire superblock on force unmount
>
>  fs/fuse/inode.c    |  7 +++++--
>  fs/super.c         | 28 ++++++++++++++++++++++++++--
>  include/linux/fs.h |  2 ++
>  3 files changed, 33 insertions(+), 4 deletions(-)
>
> --
> 2.31.0
>