--- /dev/null
+/*
+ * Copyright (C) 2003 Sistina Software Limited.
+ * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/dm-dirty-log.h>
+#include <linux/dm-region-hash.h>
+
+#include <linux/ctype.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+#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 <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff