/* * Copyright (C) 2003 Sistina Software Limited. * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved. * * This file is released under the GPL. */ #include #include #include #include #include #include #include #include "dm.h" #define DM_MSG_PREFIX "region hash" /*----------------------------------------------------------------- * Region hash * * The mirror splits itself up into discrete regions. Each * region can be in one of three states: clean, dirty, * nosync. There is no need to put clean regions in the hash. * * In addition to being present in the hash table a region _may_ * be present on one of three lists. * * clean_regions: Regions on this list have no io pending to * them, they are in sync, we are no longer interested in them, * they are dull. dm_rh_update_states() will remove them from the * hash table. * * quiesced_regions: These regions have been spun down, ready * for recovery. rh_recovery_start() will remove regions from * this list and hand them to kmirrord, which will schedule the * recovery io with kcopyd. * * recovered_regions: Regions that kcopyd has successfully * recovered. dm_rh_update_states() will now schedule any delayed * io, up the recovery_count, and remove the region from the * hash. * * There are 2 locks: * A rw spin lock 'hash_lock' protects just the hash table, * this is never held in write mode from interrupt context, * which I believe means that we only have to disable irqs when * doing a write lock. * * An ordinary spin lock 'region_lock' that protects the three * lists in the region_hash, with the 'state', 'list' and * 'delayed_bios' fields of the regions. This is used from irq * context, so all other uses will have to suspend local irqs. *---------------------------------------------------------------*/ struct dm_region_hash { uint32_t region_size; unsigned region_shift; /* holds persistent region state */ struct dm_dirty_log *log; /* hash table */ rwlock_t hash_lock; mempool_t *region_pool; unsigned mask; unsigned nr_buckets; unsigned prime; unsigned shift; struct list_head *buckets; unsigned max_recovery; /* Max # of regions to recover in parallel */ spinlock_t region_lock; atomic_t recovery_in_flight; struct semaphore recovery_count; struct list_head clean_regions; struct list_head quiesced_regions; struct list_head recovered_regions; struct list_head failed_recovered_regions; /* * If there was a flush failure no regions can be marked clean. */ int flush_failure; void *context; sector_t target_begin; /* Callback function to schedule bios writes */ void (*dispatch_bios)(void *context, struct bio_list *bios); /* Callback function to wakeup callers worker thread. */ void (*wakeup_workers)(void *context); /* Callback function to wakeup callers recovery waiters. */ void (*wakeup_all_recovery_waiters)(void *context); }; struct dm_region { struct dm_region_hash *rh; /* FIXME: can we get rid of this ? */ region_t key; int state; struct list_head hash_list; struct list_head list; atomic_t pending; struct bio_list delayed_bios; }; /* * Conversion fns */ static region_t dm_rh_sector_to_region(struct dm_region_hash *rh, sector_t sector) { return sector >> rh->region_shift; } sector_t dm_rh_region_to_sector(struct dm_region_hash *rh, region_t region) { return region << rh->region_shift; } EXPORT_SYMBOL_GPL(dm_rh_region_to_sector); region_t dm_rh_bio_to_region(struct dm_region_hash *rh, struct bio *bio) { return dm_rh_sector_to_region(rh, bio->bi_iter.bi_sector - rh->target_begin); } EXPORT_SYMBOL_GPL(dm_rh_bio_to_region); void *dm_rh_region_context(struct dm_region *reg) { return reg->rh->context; } EXPORT_SYMBOL_GPL(dm_rh_region_context); region_t dm_rh_get_region_key(struct dm_region *reg) { return reg->key; } EXPORT_SYMBOL_GPL(dm_rh_get_region_key); sector_t dm_rh_get_region_size(struct dm_region_hash *rh) { return rh->region_size; } EXPORT_SYMBOL_GPL(dm_rh_get_region_size); /* * FIXME: shall we pass in a structure instead of all these args to * dm_region_hash_create()???? */ #define RH_HASH_MULT 2654435387U #define RH_HASH_SHIFT 12 #define MIN_REGIONS 64 struct dm_region_hash *dm_region_hash_create( void *context, void (*dispatch_bios)(void *context, struct bio_list *bios), void (*wakeup_workers)(void *context), void (*wakeup_all_recovery_waiters)(void *context), sector_t target_begin, unsigned max_recovery, struct dm_dirty_log *log, uint32_t region_size, region_t nr_regions) { struct dm_region_hash *rh; unsigned nr_buckets, max_buckets; size_t i; /* * Calculate a suitable number of buckets for our hash * table. */ max_buckets = nr_regions >> 6; for (nr_buckets = 128u; nr_buckets < max_buckets; nr_buckets <<= 1) ; nr_buckets >>= 1; rh = kmalloc(sizeof(*rh), GFP_KERNEL); if (!rh) { DMERR("unable to allocate region hash memory"); return ERR_PTR(-ENOMEM); } rh->context = context; rh->dispatch_bios = dispatch_bios; rh->wakeup_workers = wakeup_workers; rh->wakeup_all_recovery_waiters = wakeup_all_recovery_waiters; rh->target_begin = target_begin; rh->max_recovery = max_recovery; rh->log = log; rh->region_size = region_size; rh->region_shift = ffs(region_size) - 1; rwlock_init(&rh->hash_lock); rh->mask = nr_buckets - 1; rh->nr_buckets = nr_buckets; rh->shift = RH_HASH_SHIFT; rh->prime = RH_HASH_MULT; rh->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets)); if (!rh->buckets) { DMERR("unable to allocate region hash bucket memory"); kfree(rh); return ERR_PTR(-ENOMEM); } for (i = 0; i < nr_buckets; i++) INIT_LIST_HEAD(rh->buckets + i); spin_lock_init(&rh->region_lock); sema_init(&rh->recovery_count, 0); atomic_set(&rh->recovery_in_flight, 0); INIT_LIST_HEAD(&rh->clean_regions); INIT_LIST_HEAD(&rh->quiesced_regions); INIT_LIST_HEAD(&rh->recovered_regions); INIT_LIST_HEAD(&rh->failed_recovered_regions); rh->flush_failure = 0; rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS, sizeof(struct dm_region)); if (!rh->region_pool) { vfree(rh->buckets); kfree(rh); rh = ERR_PTR(-ENOMEM); } return rh; } EXPORT_SYMBOL_GPL(dm_region_hash_create); void dm_region_hash_destroy(struct dm_region_hash *rh) { unsigned h; struct dm_region *reg, *nreg; BUG_ON(!list_empty(&rh->quiesced_regions)); for (h = 0; h < rh->nr_buckets; h++) { list_for_each_entry_safe(reg, nreg, rh->buckets + h, hash_list) { BUG_ON(atomic_read(®->pending)); mempool_free(reg, rh->region_pool); } } if (rh->log) dm_dirty_log_destroy(rh->log); if (rh->region_pool) mempool_destroy(rh->region_pool); vfree(rh->buckets); kfree(rh); } EXPORT_SYMBOL_GPL(dm_region_hash_destroy); struct dm_dirty_log *dm_rh_dirty_log(struct dm_region_hash *rh) { return rh->log; } EXPORT_SYMBOL_GPL(dm_rh_dirty_log); static unsigned rh_hash(struct dm_region_hash *rh, region_t region) { return (unsigned) ((region * rh->prime) >> rh->shift) & rh->mask; } static struct dm_region *__rh_lookup(struct dm_region_hash *rh, region_t region) { struct dm_region *reg; struct list_head *bucket = rh->buckets + rh_hash(rh, region); list_for_each_entry(reg, bucket, hash_list) if (reg->key == region) return reg; return NULL; } static void __rh_insert(struct dm_region_hash *rh, struct dm_region *reg) { list_add(®->hash_list, rh->buckets + rh_hash(rh, reg->key)); } static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region) { struct dm_region *reg, *nreg; nreg = mempool_alloc(rh->region_pool, GFP_ATOMIC); if (unlikely(!nreg)) nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL); nreg->state = rh->log->type->in_sync(rh->log, region, 1) ? DM_RH_CLEAN : DM_RH_NOSYNC; nreg->rh = rh; nreg->key = region; INIT_LIST_HEAD(&nreg->list); atomic_set(&nreg->pending, 0); bio_list_init(&nreg->delayed_bios); write_lock_irq(&rh->hash_lock); reg = __rh_lookup(rh, region); if (reg) /* We lost the race. */ mempool_free(nreg, rh->region_pool); else { __rh_insert(rh, nreg); if (nreg->state == DM_RH_CLEAN) { spin_lock(&rh->region_lock); list_add(&nreg->list, &rh->clean_regions); spin_unlock(&rh->region_lock); } reg = nreg; } write_unlock_irq(&rh->hash_lock); return reg; } static struct dm_region *__rh_find(struct dm_region_hash *rh, region_t region) { struct dm_region *reg; reg = __rh_lookup(rh, region); if (!reg) { read_unlock(&rh->hash_lock); reg = __rh_alloc(rh, region); read_lock(&rh->hash_lock); } return reg; } int dm_rh_get_state(struct dm_region_hash *rh, region_t region, int may_block) { int r; struct dm_region *reg; read_lock(&rh->hash_lock); reg = __rh_lookup(rh, region); read_unlock(&rh->hash_lock); if (reg) return reg->state; /* * The region wasn't in the hash, so we fall back to the * dirty log. */ r = rh->log->type->in_sync(rh->log, region, may_block); /* * Any error from the dirty log (eg. -EWOULDBLOCK) gets * taken as a DM_RH_NOSYNC */ return r == 1 ? DM_RH_CLEAN : DM_RH_NOSYNC; } EXPORT_SYMBOL_GPL(dm_rh_get_state); static void complete_resync_work(struct dm_region *reg, int success) { struct dm_region_hash *rh = reg->rh; rh->log->type->set_region_sync(rh->log, reg->key, success); /* * Dispatch the bios before we call 'wake_up_all'. * This is important because if we are suspending, * we want to know that recovery is complete and * the work queue is flushed. If we wake_up_all * before we dispatch_bios (queue bios and call wake()), * then we risk suspending before the work queue * has been properly flushed. */ rh->dispatch_bios(rh->context, ®->delayed_bios); if (atomic_dec_and_test(&rh->recovery_in_flight)) rh->wakeup_all_recovery_waiters(rh->context); up(&rh->recovery_count); } /* dm_rh_mark_nosync * @ms * @bio * * The bio was written on some mirror(s) but failed on other mirror(s). * We can successfully endio the bio but should avoid the region being * marked clean by setting the state DM_RH_NOSYNC. * * This function is _not_ safe in interrupt context! */ void dm_rh_mark_nosync(struct dm_region_hash *rh, struct bio *bio) { unsigned long flags; struct dm_dirty_log *log = rh->log; struct dm_region *reg; region_t region = dm_rh_bio_to_region(rh, bio); int recovering = 0; if (bio->bi_rw & REQ_FLUSH) { rh->flush_failure = 1; return; } if (bio->bi_rw & REQ_DISCARD) return; /* We must inform the log that the sync count has changed. */ log->type->set_region_sync(log, region, 0); read_lock(&rh->hash_lock); reg = __rh_find(rh, region); read_unlock(&rh->hash_lock); /* region hash entry should exist because write was in-flight */ BUG_ON(!reg); BUG_ON(!list_empty(®->list)); spin_lock_irqsave(&rh->region_lock, flags); /* * Possible cases: * 1) DM_RH_DIRTY * 2) DM_RH_NOSYNC: was dirty, other preceding writes failed * 3) DM_RH_RECOVERING: flushing pending writes * Either case, the region should have not been connected to list. */ recovering = (reg->state == DM_RH_RECOVERING); reg->state = DM_RH_NOSYNC; BUG_ON(!list_empty(®->list)); spin_unlock_irqrestore(&rh->region_lock, flags); if (recovering) complete_resync_work(reg, 0); } EXPORT_SYMBOL_GPL(dm_rh_mark_nosync); void dm_rh_update_states(struct dm_region_hash *rh, int errors_handled) { struct dm_region *reg, *next; LIST_HEAD(clean); LIST_HEAD(recovered); LIST_HEAD(failed_recovered); /* * Quickly grab the lists. */ write_lock_irq(&rh->hash_lock); spin_lock(&rh->region_lock); if (!list_empty(&rh->clean_regions)) { list_splice_init(&rh->clean_regions, &clean); list_for_each_entry(reg, &clean, list) list_del(®->hash_list); } if (!list_empty(&rh->recovered_regions)) { list_splice_init(&rh->recovered_regions, &recovered); list_for_each_entry(reg, &recovered, list) list_del(®->hash_list); } if (!list_empty(&rh->failed_recovered_regions)) { list_splice_init(&rh->failed_recovered_regions, &failed_recovered); list_for_each_entry(reg, &failed_recovered, list) list_del(®->hash_list); } spin_unlock(&rh->region_lock); write_unlock_irq(&rh->hash_lock); /* * All the regions on the recovered and clean lists have * now been pulled out of the system, so no need to do * any more locking. */ list_for_each_entry_safe(reg, next, &recovered, list) { rh->log->type->clear_region(rh->log, reg->key); complete_resync_work(reg, 1); mempool_free(reg, rh->region_pool); } list_for_each_entry_safe(reg, next, &failed_recovered, list) { complete_resync_work(reg, errors_handled ? 0 : 1); mempool_free(reg, rh->region_pool); } list_for_each_entry_safe(reg, next, &clean, list) { rh->log->type->clear_region(rh->log, reg->key); mempool_free(reg, rh->region_pool); } rh->log->type->flush(rh->log); } EXPORT_SYMBOL_GPL(dm_rh_update_states); static void rh_inc(struct dm_region_hash *rh, region_t region) { struct dm_region *reg; read_lock(&rh->hash_lock); reg = __rh_find(rh, region); spin_lock_irq(&rh->region_lock); atomic_inc(®->pending); if (reg->state == DM_RH_CLEAN) { reg->state = DM_RH_DIRTY; list_del_init(®->list); /* take off the clean list */ spin_unlock_irq(&rh->region_lock); rh->log->type->mark_region(rh->log, reg->key); } else spin_unlock_irq(&rh->region_lock); read_unlock(&rh->hash_lock); } void dm_rh_inc_pending(struct dm_region_hash *rh, struct bio_list *bios) { struct bio *bio; for (bio = bios->head; bio; bio = bio->bi_next) { if (bio->bi_rw & (REQ_FLUSH | REQ_DISCARD)) continue; rh_inc(rh, dm_rh_bio_to_region(rh, bio)); } } EXPORT_SYMBOL_GPL(dm_rh_inc_pending); void dm_rh_dec(struct dm_region_hash *rh, region_t region) { unsigned long flags; struct dm_region *reg; int should_wake = 0; read_lock(&rh->hash_lock); reg = __rh_lookup(rh, region); read_unlock(&rh->hash_lock); spin_lock_irqsave(&rh->region_lock, flags); if (atomic_dec_and_test(®->pending)) { /* * There is no pending I/O for this region. * We can move the region to corresponding list for next action. * At this point, the region is not yet connected to any list. * * If the state is DM_RH_NOSYNC, the region should be kept off * from clean list. * The hash entry for DM_RH_NOSYNC will remain in memory * until the region is recovered or the map is reloaded. */ /* do nothing for DM_RH_NOSYNC */ if (unlikely(rh->flush_failure)) { /* * If a write flush failed some time ago, we * don't know whether or not this write made it * to the disk, so we must resync the device. */ reg->state = DM_RH_NOSYNC; } else if (reg->state == DM_RH_RECOVERING) { list_add_tail(®->list, &rh->quiesced_regions); } else if (reg->state == DM_RH_DIRTY) { reg->state = DM_RH_CLEAN; list_add(®->list, &rh->clean_regions); } should_wake = 1; } spin_unlock_irqrestore(&rh->region_lock, flags); if (should_wake) rh->wakeup_workers(rh->context); } EXPORT_SYMBOL_GPL(dm_rh_dec); /* * Starts quiescing a region in preparation for recovery. */ static int __rh_recovery_prepare(struct dm_region_hash *rh) { int r; region_t region; struct dm_region *reg; /* * Ask the dirty log what's next. */ r = rh->log->type->get_resync_work(rh->log, ®ion); if (r <= 0) return r; /* * Get this region, and start it quiescing by setting the * recovering flag. */ read_lock(&rh->hash_lock); reg = __rh_find(rh, region); read_unlock(&rh->hash_lock); spin_lock_irq(&rh->region_lock); reg->state = DM_RH_RECOVERING; /* Already quiesced ? */ if (atomic_read(®->pending)) list_del_init(®->list); else list_move(®->list, &rh->quiesced_regions); spin_unlock_irq(&rh->region_lock); return 1; } void dm_rh_recovery_prepare(struct dm_region_hash *rh) { /* Extra reference to avoid race with dm_rh_stop_recovery */ atomic_inc(&rh->recovery_in_flight); while (!down_trylock(&rh->recovery_count)) { atomic_inc(&rh->recovery_in_flight); if (__rh_recovery_prepare(rh) <= 0) { atomic_dec(&rh->recovery_in_flight); up(&rh->recovery_count); break; } } /* Drop the extra reference */ if (atomic_dec_and_test(&rh->recovery_in_flight)) rh->wakeup_all_recovery_waiters(rh->context); } EXPORT_SYMBOL_GPL(dm_rh_recovery_prepare); /* * Returns any quiesced regions. */ struct dm_region *dm_rh_recovery_start(struct dm_region_hash *rh) { struct dm_region *reg = NULL; spin_lock_irq(&rh->region_lock); if (!list_empty(&rh->quiesced_regions)) { reg = list_entry(rh->quiesced_regions.next, struct dm_region, list); list_del_init(®->list); /* remove from the quiesced list */ } spin_unlock_irq(&rh->region_lock); return reg; } EXPORT_SYMBOL_GPL(dm_rh_recovery_start); void dm_rh_recovery_end(struct dm_region *reg, int success) { struct dm_region_hash *rh = reg->rh; spin_lock_irq(&rh->region_lock); if (success) list_add(®->list, ®->rh->recovered_regions); else list_add(®->list, ®->rh->failed_recovered_regions); spin_unlock_irq(&rh->region_lock); rh->wakeup_workers(rh->context); } EXPORT_SYMBOL_GPL(dm_rh_recovery_end); /* Return recovery in flight count. */ int dm_rh_recovery_in_flight(struct dm_region_hash *rh) { return atomic_read(&rh->recovery_in_flight); } EXPORT_SYMBOL_GPL(dm_rh_recovery_in_flight); int dm_rh_flush(struct dm_region_hash *rh) { return rh->log->type->flush(rh->log); } EXPORT_SYMBOL_GPL(dm_rh_flush); void dm_rh_delay(struct dm_region_hash *rh, struct bio *bio) { struct dm_region *reg; read_lock(&rh->hash_lock); reg = __rh_find(rh, dm_rh_bio_to_region(rh, bio)); bio_list_add(®->delayed_bios, bio); read_unlock(&rh->hash_lock); } EXPORT_SYMBOL_GPL(dm_rh_delay); void dm_rh_stop_recovery(struct dm_region_hash *rh) { int i; /* wait for any recovering regions */ for (i = 0; i < rh->max_recovery; i++) down(&rh->recovery_count); } EXPORT_SYMBOL_GPL(dm_rh_stop_recovery); void dm_rh_start_recovery(struct dm_region_hash *rh) { int i; for (i = 0; i < rh->max_recovery; i++) up(&rh->recovery_count); rh->wakeup_workers(rh->context); } EXPORT_SYMBOL_GPL(dm_rh_start_recovery); MODULE_DESCRIPTION(DM_NAME " region hash"); MODULE_AUTHOR("Joe Thornber/Heinz Mauelshagen "); MODULE_LICENSE("GPL");