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Date: Wed, 24 Jan 2024 22:07:38 +0100
From: Petr Vorel <pvorel@suse.cz>
To: Thomas Bertschinger <tahbertschinger@gmail.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>,
	Brian Foster <bfoster@redhat.com>, linux-bcachefs@vger.kernel.org,
	linux-kernel@vger.kernel.org, ltp@lists.linux.it
Subject: Re: bcachefs fails to mount loop device on kernel
Message-ID: <20240124210738.GA352616@pevik>
Reply-To: Petr Vorel <pvorel@suse.cz>
References: <20240124200032.GA343522@pevik>
 <20240124205149.GA268968@fedora-laptop>
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In-Reply-To: <20240124205149.GA268968@fedora-laptop>

> On Wed, Jan 24, 2024 at 09:00:32PM +0100, Petr Vorel wrote:
> > Hi all,

> > bcachefs fails to mount loop device on kernel on both 6.7 and 6.8.0-rc1.
> > Is mounting loop even supported?

> > [...]

> > bcachefs mount /dev/loop0 /mnt
> > => Unknown command mount

> What version of the bcachefs CLI tool are you using? Is it distribution
> provided or did you build it yourself?

Official openSUSE Tumbleweed package:

$ rpm -qf $(which bcachefs)
bcachefs-tools-1.4.0-1.1.x86_64

BTW this was found with LTP, which has 2 APIs: C API, which uses mount(2)
which works well and shell API which uses mount (which uses bcachefs) and here
it fails.

Kind regards,
Petr

> The mount command has been implemented in Rust for a while (since
> 28f703cc256f "Rust now integrated into bcachefs binary") and if building
> without Rust support (BCACHEFS_NO_RUST defined), that command won't be
> included in the binary.

> In more recent versions of bcachefs-tools, building without Rust is not
> supported at all.

> I don't think this has anything to do with loop devices specifically.

> - Thomas Bertschinger