1 files changed, 704 insertions, 0 deletions

diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c
new file mode 100644
index 000000000000..59f8d9df9e1a
--- /dev/null
+++ b/drivers/md/dm-region-hash.c
@@ -0,0 +1,704 @@
+/*
+ * 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/vmalloc.h>
+
+#include "dm.h"
+#include "dm-bio-list.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;
+
+        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_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->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(&reg->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(&reg->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);
+
+        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, &reg->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
+ * @done
+ * @error
+ *
+ * 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 done, int error)
+{
+        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;
+
+        /* 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(&reg->list));
+
+        spin_lock_irqsave(&rh->region_lock, flags);
+        /*
+         * Possible cases:
+         *   1) DM_RH_DIRTY
+         *   2) DM_RH_NOSYNC: was dirty, other preceeding 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(&reg->list));
+        spin_unlock_irqrestore(&rh->region_lock, flags);
+
+        bio_endio(bio, error);
+        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(&reg->hash_list);
+        }
+
+        if (!list_empty(&rh->recovered_regions)) {
+                list_splice_init(&rh->recovered_regions, &recovered);
+
+                list_for_each_entry(reg, &recovered, list)
+                        list_del(&reg->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(&reg->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(&reg->pending);
+
+        if (reg->state == DM_RH_CLEAN) {
+                reg->state = DM_RH_DIRTY;
+                list_del_init(&reg->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)
+                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(&reg->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 (reg->state == DM_RH_RECOVERING) {
+                        list_add_tail(&reg->list, &rh->quiesced_regions);
+                } else if (reg->state == DM_RH_DIRTY) {
+                        reg->state = DM_RH_CLEAN;
+                        list_add(&reg->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, &region);
+        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(&reg->pending))
+                list_del_init(&reg->list);
+        else
+                list_move(&reg->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(&reg->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(&reg->list, &reg->rh->recovered_regions);
+        else {
+                reg->state = DM_RH_NOSYNC;
+                list_add(&reg->list, &reg->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(&reg->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");