[LTP] bcachefs fails to mount loop device on kernel

[Petr Vorel]

> 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