On Wed, May 31, 2023 at 04:27:30PM +0000, Martin Wilck wrote:
> On Wed, 2023-05-24 at 18:21 -0500, Benjamin Marzinski wrote:
> > need_switch_pathgroup() only checks if the currently used pathgroup
> > is
> > not the highest priority pathgroup. If it isn't, all multipathd does
> > is
> > instruct the kernel to switch to the correct pathgroup. However, the
> > kernel treats the pathgroups as if they were ordered by priority.
> > When
> > the kernel runs out of paths to use in the currently selected
> > pathgroup,
> > it will start checking the pathgroups in order until it finds one
> > with
> > usable paths.
> >
> > need_switch_pathgroup() should also check if the pathgroups are out
> > of
> > order, and if so, multipathd should reload the map to reorder them
> > correctly.
> >
> > Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
> > ---
> > libmultipath/libmultipath.version | 5 ++++
> > libmultipath/switchgroup.c | 27 ++++++++++++++++++++++
> > libmultipath/switchgroup.h | 1 +
> > multipathd/main.c | 38 +++++++++++++++++++++--------
> > --
> > 4 files changed, 59 insertions(+), 12 deletions(-)
> >
> > diff --git a/libmultipath/libmultipath.version
> > b/libmultipath/libmultipath.version
> > index 8f72c452..38074699 100644
> > --- a/libmultipath/libmultipath.version
> > +++ b/libmultipath/libmultipath.version
> > @@ -237,3 +237,8 @@ global:
> > local:
> > *;
> > };
> > +
> > +LIBMULTIPATH_19.1.0 {
> > +global:
> > + path_groups_in_order;
> > +} LIBMULTIPATH_19.0.0;
> > diff --git a/libmultipath/switchgroup.c b/libmultipath/switchgroup.c
> > index b1e1f39b..b1180839 100644
> > --- a/libmultipath/switchgroup.c
> > +++ b/libmultipath/switchgroup.c
> > @@ -7,6 +7,33 @@
> > #include "structs.h"
> > #include "switchgroup.h"
> >
> > +bool path_groups_in_order(struct multipath *mpp)
> > +{
> > + int i;
> > + struct pathgroup *pgp;
> > + bool seen_marginal_pg = false;
> > + int last_prio = INT_MAX;
> > +
> > + if (VECTOR_SIZE(mpp->pg) < 2)
> > + return true;
> > +
> > + vector_foreach_slot(mpp->pg, pgp, i) {
> > + /* skip pgs with PRIO_UNDEF, since this is likely
> > temporary */
> > + if (!pgp->paths || pgp->priority == PRIO_UNDEF)
> > + continue;
> > + if (pgp->marginal && !seen_marginal_pg) {
> > + last_prio = INT_MAX;
> > + continue;
> > + }
> > + if (seen_marginal_pg && !pgp->marginal)
> > + return false;
> > + if (pgp->priority > last_prio)
> > + return false;
> > + last_prio = pgp->priority;
> > + }
> > + return true;
> > +}
> > +
> > void path_group_prio_update(struct pathgroup *pgp)
> > {
> > int i;
> > diff --git a/libmultipath/switchgroup.h b/libmultipath/switchgroup.h
> > index 9365e2e2..43dbb6c9 100644
> > --- a/libmultipath/switchgroup.h
> > +++ b/libmultipath/switchgroup.h
> > @@ -1,2 +1,3 @@
> > void path_group_prio_update (struct pathgroup * pgp);
> > int select_path_group (struct multipath * mpp);
> > +bool path_groups_in_order(struct multipath *mpp);
> > diff --git a/multipathd/main.c b/multipathd/main.c
> > index e7c272ad..2ea7c76b 100644
> > --- a/multipathd/main.c
> > +++ b/multipathd/main.c
> > @@ -396,7 +396,7 @@ void put_multipath_config(__attribute__((unused))
> > void *arg)
> > }
> >
> > static int
> > -need_switch_pathgroup (struct multipath * mpp, int refresh)
> > +need_switch_pathgroup (struct multipath * mpp, int refresh, bool
> > *need_reload)
> > {
> > struct pathgroup * pgp;
> > struct path * pp;
> > @@ -404,6 +404,7 @@ need_switch_pathgroup (struct multipath * mpp,
> > int refresh)
> > struct config *conf;
> > int bestpg;
> >
> > + *need_reload = false;
> > if (!mpp)
> > return 0;
> >
> > @@ -430,10 +431,9 @@ need_switch_pathgroup (struct multipath * mpp,
> > int refresh)
> > return 0;
> >
> > mpp->bestpg = bestpg;
> > - if (mpp->bestpg != mpp->nextpg)
> > - return 1;
> > + *need_reload = !path_groups_in_order(mpp);
>
> This will start another loop over the path groups. Can we just
> integrate the path_groups_in_order() logic into the loop right here?
>
Sure
-Ben
>
>
> >
> > - return 0;
> > + return (*need_reload || mpp->bestpg != mpp->nextpg);
> > }
> >
> > static void
> > @@ -1982,20 +1982,26 @@ ghost_delay_tick(struct vectors *vecs)
> > }
> >
> > static void
> > -deferred_failback_tick (vector mpvec)
> > +deferred_failback_tick (struct vectors *vecs)
> > {
> > struct multipath * mpp;
> > unsigned int i;
> > + bool need_reload;
> >
> > - vector_foreach_slot (mpvec, mpp, i) {
> > + vector_foreach_slot (vecs->mpvec, mpp, i) {
> > /*
> > * deferred failback getting sooner
> > */
> > if (mpp->pgfailback > 0 && mpp->failback_tick > 0) {
> > mpp->failback_tick--;
> >
> > - if (!mpp->failback_tick &&
> > need_switch_pathgroup(mpp, 1))
> > - switch_pathgroup(mpp);
> > + if (!mpp->failback_tick &&
> > + need_switch_pathgroup(mpp, 1,
> > &need_reload)) {
> > + if (need_reload)
> > + reload_and_sync_map(mpp,
> > vecs, 0);
> > + else
> > + switch_pathgroup(mpp);
> > + }
> > }
> > }
> > }
> > @@ -2579,6 +2585,7 @@ check_path (struct vectors * vecs, struct path
> > * pp, unsigned int ticks)
> > int prio_changed = update_prio(pp, new_path_up);
> > bool need_refresh = (!new_path_up && prio_changed &&
> > pp->priority != PRIO_UNDEF);
> > + bool need_reload;
> >
> > if (prio_changed &&
> > pp->mpp->pgpolicyfn == (pgpolicyfn
> > *)group_by_prio &&
> > @@ -2586,15 +2593,22 @@ check_path (struct vectors * vecs, struct
> > path * pp, unsigned int ticks)
> > condlog(2, "%s: path priorities changed.
> > reloading",
> > pp->mpp->alias);
> > reload_and_sync_map(pp->mpp, vecs,
> > !new_path_up);
> > - } else if (need_switch_pathgroup(pp->mpp,
> > need_refresh)) {
> > + } else if (need_switch_pathgroup(pp->mpp,
> > need_refresh,
> > + &need_reload)) {
> > if (pp->mpp->pgfailback > 0 &&
> > (new_path_up || pp->mpp->failback_tick <=
> > 0))
> > pp->mpp->failback_tick =
> > pp->mpp->pgfailback + 1;
> > else if (pp->mpp->pgfailback == -
> > FAILBACK_IMMEDIATE ||
> > (chkr_new_path_up &&
> > - followover_should_failback(pp)))
> > - switch_pathgroup(pp->mpp);
> > + followover_should_failback(pp))) {
> > + if (need_reload)
> > + reload_and_sync_map(pp->mpp,
> > vecs,
> > +
> > !need_refresh &&
> > +
> > !new_path_up);
> > + else
> > + switch_pathgroup(pp->mpp);
> > + }
> > }
> > }
> > return 1;
> > @@ -2720,7 +2734,7 @@ unlock:
> > pthread_cleanup_push(cleanup_lock, &vecs->lock);
> > lock(&vecs->lock);
> > pthread_testcancel();
> > - deferred_failback_tick(vecs->mpvec);
> > + deferred_failback_tick(vecs);
> > retry_count_tick(vecs->mpvec);
> > missing_uev_wait_tick(vecs);
> > ghost_delay_tick(vecs);
>
>
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