On Thu, Mar 18, 2010 at 12:42:46PM +0000, M.S.Colclough wrote:
> I find that some CD/drive combinations fail to mount. The problem seems
> to be raid probing at the end of the device, which some combinations
> don't mind, but for which others yield a scsi I/O error. This is with
> 2.17.1, using the provided libblkid.
>
> Thus "mount /dev/sr0 /mnt" and blkid -p -u raid /dev/sr0 fail but
> "mount -t iso9660 /dev/sr0 /mnt" and "blkid -p -u noraid /dev/sr0" are OK.
>
> The errors start (for some disks) when the *raid_member reads at offsets
> that are at or maybe beyond the written part of the disk.
>
> Where to fix this? Some callers just rely blindly on mount, which used
> to be OK with a less enthusiastic libblkid.
>
> Typical debug:
> [1] ddf_raid_member:
> call probefunc()
> buffer read: off=534103552 len=40
>
> (/sys/class/block/sr2/size * 512 = 534104064)
534104064 - 534103552 = 512
I don't see a problem, it reads 40 bytes from the last sector from
the device. Try:
# blockdev --getsize64 /dev/sr0
and, try read the last sector by dd(1):
# dd if=/dev/sr0 of=/dev/null skip=$(( $(blockdev --getsz /dev/sr0) - 1 )) bs=512
It seems like kernel last-sector-bug (see Google for more details).
What version of kernel are you running?
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
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