Re: Bug#402710: Loop mount of XFS on DVD-RW fails on Debian, works on SUSE

[Max Vozeler <max@nusquama.org>]

reassign 402710 linux-2.6
retitle 402710 Loop mount of XFS on DVD-RW fails on Debian, works on SUSE
thanks

Hi kernel team, hi Kosza,

This bug is about a problem Kosza experienced when trying to loop
mount an XFS filesystem stored on DVD-RW. This works correctly on
SUSE 10.0 but fails on Debian 2.6.17-2. Summarizing what I think
we have found out so far:

 - DVD has a fixed block size of 2048 bytes
 - mkfs.xfs created a filesystem with block size of 4096 bytes
 - Debian kernel (2.6.17) is unable to loop mount it from the DVD
 - SUSE 10.0 kernel (2.6.13 ?) is able to loop mount it
 - Encryption makes no difference

This suggests that an unknown difference exists between the SUSE
and Debian kernels. I'm not sure where to start looking for this;
perhaps someone on the kernel team can suggest how to continue.

If my understanding of the problem is correct, you should be able
to work around this problem by telling mkfs.xfs to create the
filesystem with a block size that matches the block size of the
DVD (something like mkfs.xfs -b 2048 /dev/loop0).

cheers,
Max