Re: ext2 on a CD-RW

[Peter Osterlund <petero2@telia.com>]

Arjan van de Ven <arjanv@redhat.com> writes:

> On Fri, 2004-01-02 at 02:30, Peter Osterlund wrote:
> 
> > The packet writing code has the restriction that a bio must not span a
> > packet boundary. (A packet is 32*2048 bytes.) If the page when mapped
> > to disk starts 2kb before a packet boundary, merge_bvec_fn therefore
> > returns 2048, which is less than len, which is 4096 if the whole page
> > is mapped, so the bio_add_page() call fails.
> 
> devicemapper has similar restrictions for raid0 format; in that case
> it's device-mappers job to split the page/bio. Just as it is UDF's task
> to do the same I suspect...

Old versions of the packet writing code did just that, but Jens told
me that bio splitting was evil, so when the merge_bvec_fn
functionality was added to the kernel, I started to use it.

        http://lists.suse.com/archive/packet-writing/2002-Aug/0044.html

If merge_bvec_fn is not supposed to be able to handle the need of the
packet writing code, I can certainly resurrect my bio splitting code.

Btw, for some reason, this bug is not triggered when using the UDF
filesystem on a CDRW. I've only seen it with the ext2 filesystem.

-- 
Peter Osterlund - petero2@telia.com
http://w1.894.telia.com/~u89404340