Re: [PATCH v2 08/14] multipathd: don't call reload_and_sync_map() from deferred_failback_tick()

[Benjamin Marzinski <bmarzins@redhat.com>]

On Wed, Dec 11, 2024 at 11:59:03PM +0100, Martin Wilck wrote:
> Instead, move the call inside the existing loop over vecs->mpvec and call
> reload_and_sync_map() from checker_finished(). Note that we can't simply
> put the call deferred_failback_tick() in the "if" condition, because we
> need to adjust the ticks even if update_mpp_prio() returns true. For
> consistency, use separate bool variables for each condition that would
> necessitate a reload.
> 
> Signed-off-by: Martin Wilck <mwilck@suse.com>
> ---
>  multipathd/main.c | 39 ++++++++++++++-------------------------
>  1 file changed, 14 insertions(+), 25 deletions(-)
> 
> diff --git a/multipathd/main.c b/multipathd/main.c
> index b045f8b..b1f0f81 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -2076,32 +2076,20 @@ ghost_delay_tick(struct vectors *vecs)
>  	}
>  }
>  
> -static void
> -deferred_failback_tick (struct vectors *vecs)
> +static bool deferred_failback_tick(struct multipath *mpp)
>  {
> -	struct multipath * mpp;
> -	int i;
>  	bool need_reload;
>  
> -	vector_foreach_slot (vecs->mpvec, mpp, i) {
> -		/*
> -		 * deferred failback getting sooner
> -		 */
> -		if (mpp->pgfailback > 0 && mpp->failback_tick > 0) {
> -			mpp->failback_tick--;
> +	if (mpp->pgfailback <= 0 || mpp->failback_tick <= 0)
> +		return false;
>  
> -			if (!mpp->failback_tick &&
> -			    need_switch_pathgroup(mpp, &need_reload)) {
> -				if (need_reload) {
> -					if (reload_and_sync_map(mpp, vecs) == 2) {
> -						/* multipath device removed */
> -						i--;
> -					}
> -				} else
> -					switch_pathgroup(mpp);
> -			}
> -		}
> -	}
> +	mpp->failback_tick--;
> +	if (!mpp->failback_tick &&
> +	    need_switch_pathgroup(mpp, &need_reload) &&
> +	    need_reload)
> +		return true;
> +	else

If (!mpp->failback_tick && need_switch_pathgroup(mpp, &need_reload) is
true by need_reload isn't, don't we still need to call
switch_pathgroup(mpp);

-Ben

> +		return false;
>  }
>  
>  static void
> @@ -2973,11 +2961,13 @@ static void checker_finished(struct vectors *vecs, unsigned int ticks)
>  	int i;
>  
>  	vector_foreach_slot(vecs->mpvec, mpp, i) {
> -		bool inconsistent;
> +		bool inconsistent, prio_reload, failback_reload;
>  
>  		sync_mpp(vecs, mpp, ticks);
>  		inconsistent = mpp->need_reload;
> -		if (update_mpp_prio(mpp) || inconsistent)
> +		prio_reload = update_mpp_prio(mpp);
> +		failback_reload = deferred_failback_tick(mpp);
> +		if (prio_reload || failback_reload || inconsistent)
>  			if (reload_and_sync_map(mpp, vecs) == 2) {
>  				/* multipath device deleted */
>  				i--;
> @@ -2990,7 +2980,6 @@ static void checker_finished(struct vectors *vecs, unsigned int ticks)
>  		if (inconsistent)
>  			mpp->sync_tick = 1;
>  	}
> -	deferred_failback_tick(vecs);
>  	retry_count_tick(vecs->mpvec);
>  	missing_uev_wait_tick(vecs);
>  	ghost_delay_tick(vecs);
> -- 
> 2.47.0