On Fri, Dec 10, 2010 at 14:02, Neil Brown <neilb@xxxxxxx> wrote:
> On Sat, 11 Dec 2010 07:43:05 +1100 Neil Brown <neilb@xxxxxxx> wrote:
>
>> >
>> > raid5: reshape_position too early for auto-recovery - aborting.
>>
>> Something must be going wrong with the math in raid5:
>>
>> if (mddev->delta_disks < 0
>> ? (here_new * mddev->new_chunk_sectors <=
>> here_old * mddev->chunk_sectors)
>> : (here_new * mddev->new_chunk_sectors >=
>> here_old * mddev->chunk_sectors)) {
>> /* Reading from the same stripe as writing to - bad */
>> printk(KERN_ERR "raid5: reshape_position too early for "
>> "auto-recovery - aborting.\n");
>> return -EINVAL;
>> }
>>
>> there 'here_new* new_chunk_size' must be over-flowing. So the size of the
>> array must only just fit into sector_t.
>> On and arm5 you would need to have CONFIG_LBD set - do you know if it is?
Looking at what I think are the relevant kirkwood kernel config, I
only see CONFIG_LBDAF here:
http://merkel.debian.org/~jurij/
Which upon further investigation is the new name of CONFIG_LBD. So, I
believe so.
>> I guess I need to make that code more robust when sector_t doesn't have lots
>> more bits that the size of the device...
>>
>> If you can compile your own kernel, you should be able to get it to work
>> easily. If not ... complain to whoever provided you with a kernel.
That'd be the nice folks working on debian squeeze.
> No ... I take that back. here_new is the result of dividing the
> reshape_position by chunk_sector times number of disks.
> So multiplying by chunk_sectors again is not going to cause an overflow.
>
> So I have no idea what if going on here.... maybe a compiler bug?
>
> If you compile your own kernel, I would put some printk's in
> drives/md/raid5.c just before the above code to see what the values of the
> variables are, and to see what the results of the multiplications will be.
I'm happy to try my own kernel, but first I think I'll try pulling the
disks and putting them on an x86 machine to see if its actually
platform related. If that works, I can keep the broken array around
for a bit to troubleshoot on. Thanks!
--
Phil
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