Re: CVS commit: src/sys

[Andrew Doran <ad%netbsd.org@localhost>]

On Sun, Jan 04, 2009 at 06:33:50PM +1100, matthew green wrote:

> 
>    
>    Module Name:       src
>    Committed By:      reinoud
>    Date:              Tue Dec 30 19:38:36 UTC 2008
>    
>    Modified Files:
>       src/sys/dev/scsipi: cd.c
>       src/sys/kern: subr_disk_mbr.c
>       src/sys/sys: disklabel.h
>    
>    Log Message:
>    Add ISO partition detection enabling auto-detection of iso9660 and UDF
>    partitions on optical media like CD/DVD/BD but also on all other media if
>    there is no NetBSD disklabel or MBR label.
>    
>    Also fix cd's readdisklabel arguments so the ioctl's arrive at the right
>    device (!) and update its default label to make more sense.
[...]
> and this change just scares me, that you commited it without
> fixing the underlying bug or talking about it with anyone 
> else that i can see:
> 
> !       a.bp = geteblk(2 * (int)lp->d_secsize);
> -
> !       /*
> !        * XXX somehow memory is getting corrupted on 2048 byte sectors if its
> !        * just 2 times 2048!! It even reads only 2048 bytes max in one go on
> !        * optical media.
> !        */
> !
> !       a.bp = geteblk(3 * (int)lp->d_secsize);

This is the second time in recent months you've hammered in a hack around
I/O buffers. Hacks like this are unacceptable because you have left it for
someone else to come along and untangle the resulting mess later. This
change could sit for years because noone but you knows why it is needed.

Please diagnose problems and fix them properly. If you run into a brick wall
diagnosing a problem, ask for assistance with debugging it.

Andrew