Re: [PATCH] - filesystem corruption on soft RAID5 in 2.4.0+

[Edward <edward@namesys.com>]

Neil Brown wrote:
> 
> There have been assorted reports of filesystem corruption on raid5 in
> 2.4.0, and I have finally got a patch - see below.
> I don't know if it addresses everybody's problems, but it fixed a very
> really problem that is very reproducable.
> 
> The problem is that parity can be calculated wrongly when doing a
> read-modify-write update cycle.  If you have a fully functional, you
> wont notice this problem as the parity block is never used to return
> data.  But if you have a degraded array, you will get corruption very
> quickly.
> So I think this will solve the reported corruption with ext2fs, as I
> think they were mostly on degradred arrays.  I have no idea whether it
> will address the reiserfs problems as I don't think anybody reporting
> those problems described their array.
 
But we deal with a fully functional one. 
Nevertheless this patch fixed reiserfs corruption..
Thanks.
Edward.

> 
> In any case, please apply, and let me know of any further problems.
> 
> --- ./drivers/md/raid5.c        2001/01/21 04:01:57     1.1
> +++ ./drivers/md/raid5.c        2001/01/21 20:36:05     1.2
> @@ -714,6 +714,11 @@
>                 break;
>         }
>         spin_unlock_irq(&conf->device_lock);
> +       if (count>1) {
> +               xor_block(count, bh_ptr);
> +               count = 1;
> +       }
> +
>         for (i = disks; i--;)
>                 if (chosen[i]) {
>                         struct buffer_head *bh = sh->bh_cache[i];
-
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