Re: [patch 03/10 v3] raid5: add a per-stripe lock

[Shaohua Li <shli@xxxxxxxxxx>]

On Mon, Jul 02, 2012 at 10:50:46AM +1000, NeilBrown wrote:
> On Mon, 25 Jun 2012 15:24:50 +0800 Shaohua Li <shli@xxxxxxxxxx> wrote:
> 
> > Add a per-stripe lock to protect stripe specific data, like dev->read,
> > written, ... The purpose is to reduce lock contention of conf->device_lock.
> > 
> > Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
> 
> I had hoped to avoid having a per-stripe lock again, but it does look like it
> is needed.
> However I don't like the way you have split up these three patches - it makes
> them a little hard to review.
> 
> I would like to see one patch which converts the bi_phys_segments access to
> be atomic and also removes all the spin_lock calls that were just for
> protecting that.
> 
> Then another patch which adds the new stripe_lock, clearly documenting
> exactly what is protects (not just "like dev->read" but an explicit list)
> and also removes any spin_lock of device_lock that is no longer needed.
> 
> Then I could see what is being added and what is being removed all in the one
> patch and I can be sure that they balance.

reworked the patch 3-5 to two patches as you suggested, and sent to you. please check.

Thanks,
Shaohua
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