RE: Software raid0 will crash the file-system, when each disk is 5TB

Neil Brown
2007-05-17T05:03:58Z

On Wednesday May 16, david@lang.hm wrote:
> On Thu, 17 May 2007, Neil Brown wrote:
>
> > On Thursday May 17, Jeff.Zheng@endace.com wrote:
> >>
> >>> The only difference of any significance between the working
> >>> and non-working configurations is that in the non-working,
> >>> the component devices are larger than 2Gig, and hence have
> >>> sector offsets greater than 32 bits.
> >>
> >> Do u mean 2T here?, but in both configuartion, the component devices are
> >> larger than 2T (2.25T&5.5T).
> >
> > Yes, I meant 2T, and yes, the components are always over 2T.
>
> 2T decimal or 2T binary?
>

Either. The smallest as actually 2.75T (typo above).
Precisely it was
2929641472 kilobytes
or
5859282944 sectors
or
0x15D3D9000 sectors.

So it is over 32bits already...

Uhm, I just noticed something.
'chunk' is unsigned long, and when it gets shifted up, we might lose
bits. That could still happen with the 4*2.75T arrangement, but is
much more likely in the 2*5.5T arrangement.

Jeff, can you try this patch?

Thanks.
NeilBrown

Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
./drivers/md/raid0.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff .prev/drivers/md/raid0.c ./drivers/md/raid0.c
--- .prev/drivers/md/raid0.c 2007-05-17 10:33:30.000000000 +1000
+++ ./drivers/md/raid0.c 2007-05-17 15:02:15.000000000 +1000
@@ -475,7 +475,7 @@ static int raid0_make_request (request_q
x = block >> chunksize_bits;
tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
}
- rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
+ rsect = ((((sector_t)chunk << chunksize_bits) + zone->dev_offset)<<1)
+ sect_in_chunk;

bio->bi_bdev = tmp_dev->bdev;