[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <17995.59547.368508.202596@notabene.brown>
Date: Thu, 17 May 2007 15:31:07 +1000
From: Neil Brown <neilb@...e.de>
To: david@...g.hm, Jeff Zheng <Jeff.Zheng@...ace.com>,
Michal Piotrowski <michal.k.k.piotrowski@...il.com>,
Ingo Molnar <mingo@...e.hu>, linux-raid@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: RE: Software raid0 will crash the file-system, when each disk is
5TB
On Thursday May 17, neilb@...e.de wrote:
>
> 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.
Actually, it cannot be a problem with the 4*2.75T arrangement.
chuck << chunksize_bits
will not exceed the size of the underlying device *in*kilobytes*.
In that case that is 0xAE9EC800 which will git in a 32bit long.
We don't double it to make sectors until after we add
zone->dev_offset, which is "sector_t" and so 64bit arithmetic is used.
So I'm quite certain this bug will cause exactly the problems
experienced!!
>
> Jeff, can you try this patch?
Don't bother about the other tests I mentioned, just try this one.
Thanks.
NeilBrown
> Signed-off-by: Neil Brown <neilb@...e.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;
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists