On Mon, Aug 28, 2023 at 10:04 AM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote: > > From: Yu Kuai <yukuai3@xxxxxxxxxx> > > Advantages for new apis: > - reconfig_mutex is not required; > - the weird logical that suspend array hold 'reconfig_mutex' for > mddev_check_recovery() to update superblock is not needed; > - the specail handling, 'pers->prepare_suspend', for raid456 is not > needed; > - It's safe to be called at any time once mddev is allocated, and it's > designed to be used from slow path where array configuration is changed; > > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> > --- > drivers/md/md.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++-- > drivers/md/md.h | 3 ++ > 2 files changed, 86 insertions(+), 2 deletions(-) > > diff --git a/drivers/md/md.c b/drivers/md/md.c > index 7fa311a14317..6236e2e395c1 100644 > --- a/drivers/md/md.c > +++ b/drivers/md/md.c > @@ -443,12 +443,22 @@ void mddev_suspend(struct mddev *mddev) > lockdep_is_held(&mddev->reconfig_mutex)); > > WARN_ON_ONCE(thread && current == thread->tsk); > - if (mddev->suspended++) > + > + /* can't concurrent with __mddev_suspend() and __mddev_resume() */ > + mutex_lock(&mddev->suspend_mutex); > + if (mddev->suspended++) { > + mutex_unlock(&mddev->suspend_mutex); > return; > + } > + > wake_up(&mddev->sb_wait); > set_bit(MD_ALLOW_SB_UPDATE, &mddev->flags); > percpu_ref_kill(&mddev->active_io); > > + /* > + * TODO: cleanup 'pers->prepare_suspend after all callers are replaced > + * by __mddev_suspend(). > + */ > if (mddev->pers && mddev->pers->prepare_suspend) > mddev->pers->prepare_suspend(mddev); > > @@ -459,14 +469,21 @@ void mddev_suspend(struct mddev *mddev) > del_timer_sync(&mddev->safemode_timer); > /* restrict memory reclaim I/O during raid array is suspend */ > mddev->noio_flag = memalloc_noio_save(); > + > + mutex_unlock(&mddev->suspend_mutex); > } > EXPORT_SYMBOL_GPL(mddev_suspend); > > void mddev_resume(struct mddev *mddev) > { > lockdep_assert_held(&mddev->reconfig_mutex); > - if (--mddev->suspended) > + > + /* can't concurrent with __mddev_suspend() and __mddev_resume() */ > + mutex_lock(&mddev->suspend_mutex); > + if (--mddev->suspended) { > + mutex_unlock(&mddev->suspend_mutex); > return; > + } > > /* entred the memalloc scope from mddev_suspend() */ > memalloc_noio_restore(mddev->noio_flag); > @@ -477,9 +494,72 @@ void mddev_resume(struct mddev *mddev) > set_bit(MD_RECOVERY_NEEDED, &mddev->recovery); > md_wakeup_thread(mddev->thread); > md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */ > + > + mutex_unlock(&mddev->suspend_mutex); > } > EXPORT_SYMBOL_GPL(mddev_resume); > > +void __mddev_suspend(struct mddev *mddev) > +{ > + > + /* > + * hold reconfig_mutex to wait for normal io will deadlock, because > + * other context can't update super_block, and normal io can rely on > + * updating super_block. > + */ > + lockdep_assert_not_held(&mddev->reconfig_mutex); > + > + mutex_lock(&mddev->suspend_mutex); > + > + if (mddev->suspended) { > + WRITE_ONCE(mddev->suspended, mddev->suspended + 1); > + mutex_unlock(&mddev->suspend_mutex); > + return; > + } > + > + percpu_ref_kill(&mddev->active_io); > + wait_event(mddev->sb_wait, percpu_ref_is_zero(&mddev->active_io)); > + > + /* > + * For raid456, io might be waiting for reshape to make progress, > + * allow new reshape to start while waiting for io to be done to > + * prevent deadlock. > + */ > + WRITE_ONCE(mddev->suspended, mddev->suspended + 1); It changes the order of setting suspended and checking active_io. suspended is used to stop I/O. Now it checks active_io first and then adds suspended, if the i/o doesn't stop, it looks like active_io can't be 0. So it will stuck at waiting active_io to be 0? Best Regards Xiao > + > + del_timer_sync(&mddev->safemode_timer); > + /* restrict memory reclaim I/O during raid array is suspend */ > + mddev->noio_flag = memalloc_noio_save(); > + > + mutex_unlock(&mddev->suspend_mutex); > +} > +EXPORT_SYMBOL_GPL(__mddev_suspend); > + > +void __mddev_resume(struct mddev *mddev) > +{ > + lockdep_assert_not_held(&mddev->reconfig_mutex); > + > + mutex_lock(&mddev->suspend_mutex); > + WRITE_ONCE(mddev->suspended, mddev->suspended - 1); > + if (mddev->suspended) { > + mutex_unlock(&mddev->suspend_mutex); > + return; > + } > + > + /* entred the memalloc scope from __mddev_suspend() */ > + memalloc_noio_restore(mddev->noio_flag); > + > + percpu_ref_resurrect(&mddev->active_io); > + wake_up(&mddev->sb_wait); > + > + set_bit(MD_RECOVERY_NEEDED, &mddev->recovery); > + md_wakeup_thread(mddev->thread); > + md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */ > + > + mutex_unlock(&mddev->suspend_mutex); > +} > +EXPORT_SYMBOL_GPL(__mddev_resume); > + > /* > * Generic flush handling for md > */ > @@ -667,6 +747,7 @@ int mddev_init(struct mddev *mddev) > mutex_init(&mddev->open_mutex); > mutex_init(&mddev->reconfig_mutex); > mutex_init(&mddev->sync_mutex); > + mutex_init(&mddev->suspend_mutex); > mutex_init(&mddev->bitmap_info.mutex); > INIT_LIST_HEAD(&mddev->disks); > INIT_LIST_HEAD(&mddev->all_mddevs); > diff --git a/drivers/md/md.h b/drivers/md/md.h > index fb3b123f16dd..1103e6b08ad9 100644 > --- a/drivers/md/md.h > +++ b/drivers/md/md.h > @@ -316,6 +316,7 @@ struct mddev { > unsigned long sb_flags; > > int suspended; > + struct mutex suspend_mutex; > struct percpu_ref active_io; > int ro; > int sysfs_active; /* set when sysfs deletes > @@ -811,6 +812,8 @@ extern void md_rdev_clear(struct md_rdev *rdev); > extern void md_handle_request(struct mddev *mddev, struct bio *bio); > extern void mddev_suspend(struct mddev *mddev); > extern void mddev_resume(struct mddev *mddev); > +extern void __mddev_suspend(struct mddev *mddev); > +extern void __mddev_resume(struct mddev *mddev); > > extern void md_reload_sb(struct mddev *mddev, int raid_disk); > extern void md_update_sb(struct mddev *mddev, int force); > -- > 2.39.2 > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel