linux-kernel - Re: [RFC][PATCH] md: avoid fullsync if a faulty member missed a dirty transition

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Date:	Thu, 8 May 2008 16:11:53 -0400
From:	"Mike Snitzer" <snitzer@...il.com>
To:	"Neil Brown" <neilb@...e.de>
Cc:	linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
	paul.clements@...eleye.com
Subject: Re: [RFC][PATCH] md: avoid fullsync if a faulty member missed a dirty transition

On Thu, May 8, 2008 at 2:13 AM, Neil Brown <neilb@...e.de> wrote:
> On Tuesday May 6, snitzer@...il.com wrote:
>  >
>  > It looks like bitmap_update_sb()'s incrementing of events_cleared (on
>  > behalf of the local member) could be racing with the fact that the NBD
>  > member becomes faulty (whereby making the array degraded).  This
>  > allows the events_cleared to reflect a clean->dirty transition last
>  > occurred before the array became degraded.  My reasoning is: If it was
>  > a clean->dirty transition the bitmap still has the associated dirty
>  > bit set in the local member's bitmap, so using the bitmap to resync is
>  > valid.
>  >
>  > thanks,
>  > Mike
>
>  Thanks for persisting.  I think I understand what is going on now.
>
>  How about this patch?  It is similar to your, but instead of depending
>  on the odd/even state of the event counter, it directly checks the
>  clean/dirty state of the array.

Hi Neil,

Your revised patch works great and is obviously cleaner.

Thanks!

Tested-by: Mike Snitzer <snitzer@...il.com>
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