| Message ID | 20240713060506.2015463-13-bmarzins@redhat.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | christophe varoqui |
| Headers | show |
| Series | path checker refactor and misc fixes | expand |
On Sat, 2024-07-13 at 02:04 -0400, Benjamin Marzinski wrote: > Move the code to sync the mpp device state into a helper function and > add a counter to to make sure that the device is synced at least once > every max_checkint secs. This makes sure that multipath devices with > no > paths will still get synced with the kernel. Also, if multiple paths > are checked in the same loop, the multipath device will only be > synced > with the kernel once, since every time the mpp is synced in any code > path, mpp->sync_tick is reset. > > The code still syncs the mpp before updating the path state for two > main reasons. > > 1. Sometimes multipathd leaves the mpp with a garbage state. Future > patches will fix most of these cases, but the code intentially > does not remove the mpp is resyncing fails while checking paths. > But this does leave the mpp with a garbage state. > > 2. The kernel chages the multipath state independently of multipathd. > If > the kernel fails a path, a uevent will arrive shortly. But the > kernel > doesn't provide any notification when it switches the active > path group or if it ends up picking a different one than > multipathd > selected. Multipathd needs to know the actual current pathgroup to > know when it should be switching them. > > Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> > --- > libmultipath/configure.c | 1 + > libmultipath/structs.h | 2 ++ > libmultipath/structs_vec.c | 5 +++ > multipathd/main.c | 64 +++++++++++++++++++++++++----------- > -- > 4 files changed, 50 insertions(+), 22 deletions(-) > > > diff --git a/multipathd/main.c b/multipathd/main.c > index fbd253ca..179fec24 100644 > --- a/multipathd/main.c > +++ b/multipathd/main.c > @@ -2342,6 +2342,37 @@ check_path_state(struct path *pp) > return newstate; > } > > +static void > +do_check_mpp(struct vectors * vecs, struct multipath *mpp) > +{ > + int i, ret; > + struct path *pp; > + > + mpp->is_checked = true; > + ret = update_multipath_strings(mpp, vecs->pathvec); > + if (ret != DMP_OK) { > + condlog(1, "%s: %s", mpp->alias, ret == > DMP_NOT_FOUND ? > + "device not found" : > + "couldn't synchronize with kernel state"); > + vector_foreach_slot (mpp->paths, pp, i) > + pp->dmstate = PSTATE_UNDEF; > + return; > + } > + set_no_path_retry(mpp); > +} > + > +static void > +check_mpp(struct vectors * vecs, struct multipath *mpp, unsigned int > ticks) > +{ > + if (mpp->sync_tick) > + mpp->sync_tick -= (mpp->sync_tick > ticks) ? ticks : > + mpp->sync_tick; > + if (mpp->sync_tick) > + return; > + > + do_check_mpp(vecs, mpp); > +} > + > /* > * Returns '1' if the path has been checked and '0' otherwise > */ > @@ -2356,7 +2387,6 @@ check_path (struct vectors * vecs, struct path > * pp, unsigned int ticks) > unsigned int checkint, max_checkint; > struct config *conf; > int marginal_pathgroups, marginal_changed = 0; > - int ret; > bool need_reload; > > if (pp->initialized == INIT_REMOVED) > @@ -2395,26 +2425,6 @@ check_path (struct vectors * vecs, struct path > * pp, unsigned int ticks) > pp->tick = 1; > return 0; > } > - /* > - * Synchronize with kernel state > - */ > - ret = update_multipath_strings(pp->mpp, vecs->pathvec); > - if (ret != DMP_OK) { > - if (ret == DMP_NOT_FOUND) { > - /* multipath device missing. Likely removed > */ > - condlog(1, "%s: multipath device '%s' not > found", > - pp->dev, pp->mpp ? pp->mpp->alias : > ""); > - return 0; > - } else > - condlog(1, "%s: Couldn't synchronize with > kernel state", > - pp->dev); > - pp->dmstate = PSTATE_UNDEF; > - } > - /* if update_multipath_strings orphaned the path, quit early > */ > - if (!pp->mpp) > - return 0; > - set_no_path_retry(pp->mpp); > - > if (pp->recheck_wwid == RECHECK_WWID_ON && > (newstate == PATH_UP || newstate == PATH_GHOST) && > ((pp->state != PATH_UP && pp->state != PATH_GHOST) || > @@ -2424,7 +2434,12 @@ check_path (struct vectors * vecs, struct path > * pp, unsigned int ticks) > handle_path_wwid_change(pp, vecs); > return 0; > } > - > + if (!pp->mpp->is_checked) { > + do_check_mpp(vecs, pp->mpp); > + /* if update_multipath_strings orphaned the path, > quit early */ > + if (!pp->mpp) > + return 0; > + } > if ((newstate != PATH_UP && newstate != PATH_GHOST && > newstate != PATH_PENDING) && (pp->state == > PATH_DELAYED)) { > /* If path state become failed again cancel path > delay state */ > @@ -2752,12 +2767,17 @@ checkerloop (void *ap) > while (checker_state != CHECKER_FINISHED) { > unsigned int paths_checked = 0, i; > struct timespec chk_start_time; > + struct multipath *mpp; > > pthread_cleanup_push(cleanup_lock, &vecs- > >lock); > lock(&vecs->lock); > pthread_testcancel(); > + vector_foreach_slot(vecs->mpvec, mpp, i) > + mpp->is_checked = false; Why is this not done inside the "if (checker_state == CHECKER_STARTING) code path? Martin > get_monotonic_time(&chk_start_time); > if (checker_state == CHECKER_STARTING) { > + vector_foreach_slot(vecs->mpvec, > mpp, i) > + check_mpp(vecs, mpp, ticks); > vector_foreach_slot(vecs->pathvec, > pp, i) > pp->is_checked = false; > checker_state = CHECKER_RUNNING;
On Mon, Jul 15, 2024 at 06:23:53PM +0200, Martin Wilck wrote: > On Sat, 2024-07-13 at 02:04 -0400, Benjamin Marzinski wrote: > > Move the code to sync the mpp device state into a helper function and > > add a counter to to make sure that the device is synced at least once > > every max_checkint secs. This makes sure that multipath devices with > > no > > paths will still get synced with the kernel. Also, if multiple paths > > are checked in the same loop, the multipath device will only be > > synced > > with the kernel once, since every time the mpp is synced in any code > > path, mpp->sync_tick is reset. > > > > The code still syncs the mpp before updating the path state for two > > main reasons. > > > > 1. Sometimes multipathd leaves the mpp with a garbage state. Future > > patches will fix most of these cases, but the code intentially > > does not remove the mpp is resyncing fails while checking paths. > > But this does leave the mpp with a garbage state. > > > > 2. The kernel chages the multipath state independently of multipathd. > > If > > the kernel fails a path, a uevent will arrive shortly. But the > > kernel > > doesn't provide any notification when it switches the active > > path group or if it ends up picking a different one than > > multipathd > > selected. Multipathd needs to know the actual current pathgroup to > > know when it should be switching them. > > > > Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> > > --- > > libmultipath/configure.c | 1 + > > libmultipath/structs.h | 2 ++ > > libmultipath/structs_vec.c | 5 +++ > > multipathd/main.c | 64 +++++++++++++++++++++++++----------- > > -- > > 4 files changed, 50 insertions(+), 22 deletions(-) > > > > > > diff --git a/multipathd/main.c b/multipathd/main.c > > index fbd253ca..179fec24 100644 > > --- a/multipathd/main.c > > +++ b/multipathd/main.c > > @@ -2752,12 +2767,17 @@ checkerloop (void *ap) > > while (checker_state != CHECKER_FINISHED) { > > unsigned int paths_checked = 0, i; > > struct timespec chk_start_time; > > + struct multipath *mpp; > > > > pthread_cleanup_push(cleanup_lock, &vecs- > > >lock); > > lock(&vecs->lock); > > pthread_testcancel(); > > + vector_foreach_slot(vecs->mpvec, mpp, i) > > + mpp->is_checked = false; > > Why is this not done inside the "if (checker_state == CHECKER_STARTING) > code path? Since we slept here, there was more time for something to change in a way where we needed to resync the state. Also, like I mention in the comments, there are places where we fail in some function that is updating the mpp state and don't resync it with the kernel. I'm fairly sure (but not totally certain) future patches catch all of these except for failing to update the state in the checker function itself. (We've never removed the multipath device for failing to resync its state in the check_path(), unlike failures when responding to an event or after reloading the device. This makes sense to me. Since we're doing these resyncs in check_path() routinely, not because we think something has changed, it seems reasonable to assume that nothing has changed if we fail to resync). Clearing is_checked here doesn't guarantee that we will resync the mpp. Only that we will resync if we need to check one of its paths, after the interruption. When we switch to checking paths by mpp later, this will never happen, except in corner cases. -Ben > Martin > > > > get_monotonic_time(&chk_start_time); > > if (checker_state == CHECKER_STARTING) { > > + vector_foreach_slot(vecs->mpvec, > > mpp, i) > > + check_mpp(vecs, mpp, ticks); > > vector_foreach_slot(vecs->pathvec, > > pp, i) > > pp->is_checked = false; > > checker_state = CHECKER_RUNNING;
diff --git a/libmultipath/configure.c b/libmultipath/configure.c index b4de863c..34158e31 100644 --- a/libmultipath/configure.c +++ b/libmultipath/configure.c @@ -358,6 +358,7 @@ int setup_map(struct multipath *mpp, char **params, struct vectors *vecs) sysfs_set_scsi_tmo(conf, mpp); marginal_pathgroups = conf->marginal_pathgroups; + mpp->sync_tick = conf->max_checkint; pthread_cleanup_pop(1); if (!mpp->features || !mpp->hwhandler || !mpp->selector) { diff --git a/libmultipath/structs.h b/libmultipath/structs.h index 3b91e39c..002eeae1 100644 --- a/libmultipath/structs.h +++ b/libmultipath/structs.h @@ -453,6 +453,8 @@ struct multipath { int ghost_delay; int ghost_delay_tick; int queue_mode; + unsigned int sync_tick; + bool is_checked; uid_t uid; gid_t gid; mode_t mode; diff --git a/libmultipath/structs_vec.c b/libmultipath/structs_vec.c index 731b1bce..60360c76 100644 --- a/libmultipath/structs_vec.c +++ b/libmultipath/structs_vec.c @@ -505,10 +505,15 @@ update_multipath_table (struct multipath *mpp, vector pathvec, int flags) char __attribute__((cleanup(cleanup_charp))) *params = NULL; char __attribute__((cleanup(cleanup_charp))) *status = NULL; unsigned long long size = mpp->size; + struct config *conf; if (!mpp) return r; + conf = get_multipath_config(); + mpp->sync_tick = conf->max_checkint; + put_multipath_config(conf); + r = libmp_mapinfo(DM_MAP_BY_NAME | MAPINFO_MPATH_ONLY, (mapid_t) { .str = mpp->alias }, (mapinfo_t) { diff --git a/multipathd/main.c b/multipathd/main.c index fbd253ca..179fec24 100644 --- a/multipathd/main.c +++ b/multipathd/main.c @@ -2342,6 +2342,37 @@ check_path_state(struct path *pp) return newstate; } +static void +do_check_mpp(struct vectors * vecs, struct multipath *mpp) +{ + int i, ret; + struct path *pp; + + mpp->is_checked = true; + ret = update_multipath_strings(mpp, vecs->pathvec); + if (ret != DMP_OK) { + condlog(1, "%s: %s", mpp->alias, ret == DMP_NOT_FOUND ? + "device not found" : + "couldn't synchronize with kernel state"); + vector_foreach_slot (mpp->paths, pp, i) + pp->dmstate = PSTATE_UNDEF; + return; + } + set_no_path_retry(mpp); +} + +static void +check_mpp(struct vectors * vecs, struct multipath *mpp, unsigned int ticks) +{ + if (mpp->sync_tick) + mpp->sync_tick -= (mpp->sync_tick > ticks) ? ticks : + mpp->sync_tick; + if (mpp->sync_tick) + return; + + do_check_mpp(vecs, mpp); +} + /* * Returns '1' if the path has been checked and '0' otherwise */ @@ -2356,7 +2387,6 @@ check_path (struct vectors * vecs, struct path * pp, unsigned int ticks) unsigned int checkint, max_checkint; struct config *conf; int marginal_pathgroups, marginal_changed = 0; - int ret; bool need_reload; if (pp->initialized == INIT_REMOVED) @@ -2395,26 +2425,6 @@ check_path (struct vectors * vecs, struct path * pp, unsigned int ticks) pp->tick = 1; return 0; } - /* - * Synchronize with kernel state - */ - ret = update_multipath_strings(pp->mpp, vecs->pathvec); - if (ret != DMP_OK) { - if (ret == DMP_NOT_FOUND) { - /* multipath device missing. Likely removed */ - condlog(1, "%s: multipath device '%s' not found", - pp->dev, pp->mpp ? pp->mpp->alias : ""); - return 0; - } else - condlog(1, "%s: Couldn't synchronize with kernel state", - pp->dev); - pp->dmstate = PSTATE_UNDEF; - } - /* if update_multipath_strings orphaned the path, quit early */ - if (!pp->mpp) - return 0; - set_no_path_retry(pp->mpp); - if (pp->recheck_wwid == RECHECK_WWID_ON && (newstate == PATH_UP || newstate == PATH_GHOST) && ((pp->state != PATH_UP && pp->state != PATH_GHOST) || @@ -2424,7 +2434,12 @@ check_path (struct vectors * vecs, struct path * pp, unsigned int ticks) handle_path_wwid_change(pp, vecs); return 0; } - + if (!pp->mpp->is_checked) { + do_check_mpp(vecs, pp->mpp); + /* if update_multipath_strings orphaned the path, quit early */ + if (!pp->mpp) + return 0; + } if ((newstate != PATH_UP && newstate != PATH_GHOST && newstate != PATH_PENDING) && (pp->state == PATH_DELAYED)) { /* If path state become failed again cancel path delay state */ @@ -2752,12 +2767,17 @@ checkerloop (void *ap) while (checker_state != CHECKER_FINISHED) { unsigned int paths_checked = 0, i; struct timespec chk_start_time; + struct multipath *mpp; pthread_cleanup_push(cleanup_lock, &vecs->lock); lock(&vecs->lock); pthread_testcancel(); + vector_foreach_slot(vecs->mpvec, mpp, i) + mpp->is_checked = false; get_monotonic_time(&chk_start_time); if (checker_state == CHECKER_STARTING) { + vector_foreach_slot(vecs->mpvec, mpp, i) + check_mpp(vecs, mpp, ticks); vector_foreach_slot(vecs->pathvec, pp, i) pp->is_checked = false; checker_state = CHECKER_RUNNING;
Move the code to sync the mpp device state into a helper function and add a counter to to make sure that the device is synced at least once every max_checkint secs. This makes sure that multipath devices with no paths will still get synced with the kernel. Also, if multiple paths are checked in the same loop, the multipath device will only be synced with the kernel once, since every time the mpp is synced in any code path, mpp->sync_tick is reset. The code still syncs the mpp before updating the path state for two main reasons. 1. Sometimes multipathd leaves the mpp with a garbage state. Future patches will fix most of these cases, but the code intentially does not remove the mpp is resyncing fails while checking paths. But this does leave the mpp with a garbage state. 2. The kernel chages the multipath state independently of multipathd. If the kernel fails a path, a uevent will arrive shortly. But the kernel doesn't provide any notification when it switches the active path group or if it ends up picking a different one than multipathd selected. Multipathd needs to know the actual current pathgroup to know when it should be switching them. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> --- libmultipath/configure.c | 1 + libmultipath/structs.h | 2 ++ libmultipath/structs_vec.c | 5 +++ multipathd/main.c | 64 +++++++++++++++++++++++++------------- 4 files changed, 50 insertions(+), 22 deletions(-)