Re: [PATCH] md/raid5:When exec md_wait_for_blocked_rdev in ops_run_io,we must atomic_inc(&rdev->nr_pending).

[NeilBrown <neilb@suse.de>]

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On Mon, 11 Jun 2012 11:23:56 +0800 majianpeng <majianpeng@gmail.com> wrote:

> In ops_run_io(), if call md_wait_for_blocked_rdev which it dec
> nr_pending, the rdev->nr_pending will dec again in else-statement.
> So the nr_penging is error and we can't remove this device.
> 
> Signed-off-by: majianpeng <majianpeng@gmail.com>
> ---
>  drivers/md/raid5.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index d267672..995b2de 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -607,6 +607,12 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
>  					md_check_recovery(conf->mddev);
>  				}
>  				md_wait_for_blocked_rdev(rdev, conf->mddev);
> +				/*
> +				 * Because md_wait_for_blocked_rdev will dec
> +				 * nr_pending,we must add.The real dec is in
> +				 * else statement.
> +				 */
> +				atomic_inc(&rdev->nr_pending);
>  			} else {
>  				/* Acknowledged bad block - skip the write */
>  				rdev_dec_pending(rdev, conf->mddev);

Thanks for catching this.

I have moved the 'atomic_inc' to before 'md_wait_for_blocked_rdev'
to make sure that the nr_pending count never goes to zero, and I tidied
up the comment a little.

Thanks,
NeilBrown


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