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?
>
> 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.
>
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.
NeilBrown
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