--- /dev/null
+/*
+ * Copyright (C) 2003 Sistina Software Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+#include "dm-bio-list.h"
+#include "dm-io.h"
+#include "dm-log.h"
+#include "kcopyd.h"
+
+#include <linux/ctype.h>
+#include <linux/init.h>
+#include <linux/mempool.h>
+#include <linux/module.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/vmalloc.h>
+#include <linux/workqueue.h>
+
+static struct workqueue_struct *_kmirrord_wq;
+static struct work_struct _kmirrord_work;
+
+static inline void wake(void)
+{
+ queue_work(_kmirrord_wq, &_kmirrord_work);
+}
+
+/*-----------------------------------------------------------------
+ * 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. 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. 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
+ * 'bhs_delayed' fields of the regions. This is used from irq
+ * context, so all other uses will have to suspend local irqs.
+ *---------------------------------------------------------------*/
+struct mirror_set;
+struct region_hash {
+ struct mirror_set *ms;
+ sector_t region_size;
+ unsigned region_shift;
+
+ /* holds persistent region state */
+ struct dirty_log *log;
+
+ /* hash table */
+ rwlock_t hash_lock;
+ mempool_t *region_pool;
+ unsigned int mask;
+ unsigned int nr_buckets;
+ struct list_head *buckets;
+
+ spinlock_t region_lock;
+ struct semaphore recovery_count;
+ struct list_head clean_regions;
+ struct list_head quiesced_regions;
+ struct list_head recovered_regions;
+};
+
+enum {
+ RH_CLEAN,
+ RH_DIRTY,
+ RH_NOSYNC,
+ RH_RECOVERING
+};
+
+struct region {
+ struct 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 inline region_t bio_to_region(struct region_hash *rh, struct bio *bio)
+{
+ return bio->bi_sector >> rh->region_shift;
+}
+
+static inline sector_t region_to_sector(struct region_hash *rh, region_t region)
+{
+ return region << rh->region_shift;
+}
+
+/* FIXME move this */
+static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw);
+
+static void *region_alloc(int gfp_mask, void *pool_data)
+{
+ return kmalloc(sizeof(struct region), gfp_mask);
+}
+
+static void region_free(void *element, void *pool_data)
+{
+ kfree(element);
+}
+
+#define MIN_REGIONS 64
+#define MAX_RECOVERY 1
+static int rh_init(struct region_hash *rh, struct mirror_set *ms,
+ struct dirty_log *log, sector_t region_size,
+ region_t nr_regions)
+{
+ unsigned int 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->ms = ms;
+ 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->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets));
+ if (!rh->buckets) {
+ DMERR("unable to allocate region hash memory");
+ return -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);
+ INIT_LIST_HEAD(&rh->clean_regions);
+ INIT_LIST_HEAD(&rh->quiesced_regions);
+ INIT_LIST_HEAD(&rh->recovered_regions);
+
+ rh->region_pool = mempool_create(MIN_REGIONS, region_alloc,
+ region_free, NULL);
+ if (!rh->region_pool) {
+ vfree(rh->buckets);
+ rh->buckets = NULL;
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void rh_exit(struct region_hash *rh)
+{
+ unsigned int h;
+ struct 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_destroy_dirty_log(rh->log);
+ if (rh->region_pool)
+ mempool_destroy(rh->region_pool);
+ vfree(rh->buckets);
+}
+
+#define RH_HASH_MULT 2654435387U
+
+static inline unsigned int rh_hash(struct region_hash *rh, region_t region)
+{
+ return (unsigned int) ((region * RH_HASH_MULT) >> 12) & rh->mask;
+}
+
+static struct region *__rh_lookup(struct region_hash *rh, region_t region)
+{
+ struct region *reg;
+
+ list_for_each_entry (reg, rh->buckets + rh_hash(rh, region), hash_list)
+ if (reg->key == region)
+ return reg;
+
+ return NULL;
+}
+
+static void __rh_insert(struct region_hash *rh, struct region *reg)
+{
+ unsigned int h = rh_hash(rh, reg->key);
+ list_add(®->hash_list, rh->buckets + h);
+}
+
+static struct region *__rh_alloc(struct region_hash *rh, region_t region)
+{
+ struct region *reg, *nreg;
+
+ read_unlock(&rh->hash_lock);
+ nreg = mempool_alloc(rh->region_pool, GFP_NOIO);
+ nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
+ RH_CLEAN : 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 == RH_CLEAN) {
+ spin_lock_irq(&rh->region_lock);
+ list_add(&nreg->list, &rh->clean_regions);
+ spin_unlock_irq(&rh->region_lock);
+ }
+ reg = nreg;
+ }
+ write_unlock_irq(&rh->hash_lock);
+ read_lock(&rh->hash_lock);
+
+ return reg;
+}
+
+static inline struct region *__rh_find(struct region_hash *rh, region_t region)
+{
+ struct region *reg;
+
+ reg = __rh_lookup(rh, region);
+ if (!reg)
+ reg = __rh_alloc(rh, region);
+
+ return reg;
+}
+
+static int rh_state(struct region_hash *rh, region_t region, int may_block)
+{
+ int r;
+ struct 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 RH_NOSYNC
+ */
+ return r == 1 ? RH_CLEAN : RH_NOSYNC;
+}
+
+static inline int rh_in_sync(struct region_hash *rh,
+ region_t region, int may_block)
+{
+ int state = rh_state(rh, region, may_block);
+ return state == RH_CLEAN || state == RH_DIRTY;
+}
+
+static void dispatch_bios(struct mirror_set *ms, struct bio_list *bio_list)
+{
+ struct bio *bio;
+
+ while ((bio = bio_list_pop(bio_list))) {
+ queue_bio(ms, bio, WRITE);
+ }
+}
+
+static void rh_update_states(struct region_hash *rh)
+{
+ struct region *reg, *next;
+
+ LIST_HEAD(clean);
+ LIST_HEAD(recovered);
+
+ /*
+ * Quickly grab the lists.
+ */
+ write_lock_irq(&rh->hash_lock);
+ spin_lock(&rh->region_lock);
+ if (!list_empty(&rh->clean_regions)) {
+ list_splice(&rh->clean_regions, &clean);
+ INIT_LIST_HEAD(&rh->clean_regions);
+
+ list_for_each_entry (reg, &clean, list) {
+ rh->log->type->clear_region(rh->log, reg->key);
+ list_del(®->hash_list);
+ }
+ }
+
+ if (!list_empty(&rh->recovered_regions)) {
+ list_splice(&rh->recovered_regions, &recovered);
+ INIT_LIST_HEAD(&rh->recovered_regions);
+
+ list_for_each_entry (reg, &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);
+ rh->log->type->complete_resync_work(rh->log, reg->key, 1);
+ dispatch_bios(rh->ms, ®->delayed_bios);
+ up(&rh->recovery_count);
+ mempool_free(reg, rh->region_pool);
+ }
+
+ if (!list_empty(&recovered))
+ rh->log->type->flush(rh->log);
+
+ list_for_each_entry_safe (reg, next, &clean, list)
+ mempool_free(reg, rh->region_pool);
+}
+
+static void rh_inc(struct region_hash *rh, region_t region)
+{
+ struct region *reg;
+
+ read_lock(&rh->hash_lock);
+ reg = __rh_find(rh, region);
+ if (reg->state == RH_CLEAN) {
+ rh->log->type->mark_region(rh->log, reg->key);
+
+ spin_lock_irq(&rh->region_lock);
+ reg->state = RH_DIRTY;
+ list_del_init(®->list); /* take off the clean list */
+ spin_unlock_irq(&rh->region_lock);
+ }
+
+ atomic_inc(®->pending);
+ read_unlock(&rh->hash_lock);
+}
+
+static void rh_inc_pending(struct region_hash *rh, struct bio_list *bios)
+{
+ struct bio *bio;
+
+ for (bio = bios->head; bio; bio = bio->bi_next)
+ rh_inc(rh, bio_to_region(rh, bio));
+}
+
+static void rh_dec(struct region_hash *rh, region_t region)
+{
+ unsigned long flags;
+ struct region *reg;
+ int should_wake = 0;
+
+ read_lock(&rh->hash_lock);
+ reg = __rh_lookup(rh, region);
+ read_unlock(&rh->hash_lock);
+
+ if (atomic_dec_and_test(®->pending)) {
+ spin_lock_irqsave(&rh->region_lock, flags);
+ if (reg->state == RH_RECOVERING) {
+ list_add_tail(®->list, &rh->quiesced_regions);
+ } else {
+ reg->state = RH_CLEAN;
+ list_add(®->list, &rh->clean_regions);
+ }
+ spin_unlock_irqrestore(&rh->region_lock, flags);
+ should_wake = 1;
+ }
+
+ if (should_wake)
+ wake();
+}
+
+/*
+ * Starts quiescing a region in preparation for recovery.
+ */
+static int __rh_recovery_prepare(struct region_hash *rh)
+{
+ int r;
+ struct region *reg;
+ region_t region;
+
+ /*
+ * 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 = RH_RECOVERING;
+
+ /* Already quiesced ? */
+ if (atomic_read(®->pending))
+ list_del_init(®->list);
+
+ else {
+ list_del_init(®->list);
+ list_add(®->list, &rh->quiesced_regions);
+ }
+ spin_unlock_irq(&rh->region_lock);
+
+ return 1;
+}
+
+static void rh_recovery_prepare(struct region_hash *rh)
+{
+ while (!down_trylock(&rh->recovery_count))
+ if (__rh_recovery_prepare(rh) <= 0) {
+ up(&rh->recovery_count);
+ break;
+ }
+}
+
+/*
+ * Returns any quiesced regions.
+ */
+static struct region *rh_recovery_start(struct region_hash *rh)
+{
+ struct region *reg = NULL;
+
+ spin_lock_irq(&rh->region_lock);
+ if (!list_empty(&rh->quiesced_regions)) {
+ reg = list_entry(rh->quiesced_regions.next,
+ struct region, list);
+ list_del_init(®->list); /* remove from the quiesced list */
+ }
+ spin_unlock_irq(&rh->region_lock);
+
+ return reg;
+}
+
+/* FIXME: success ignored for now */
+static void rh_recovery_end(struct region *reg, int success)
+{
+ struct region_hash *rh = reg->rh;
+
+ spin_lock_irq(&rh->region_lock);
+ list_add(®->list, ®->rh->recovered_regions);
+ spin_unlock_irq(&rh->region_lock);
+
+ wake();
+}
+
+static void rh_flush(struct region_hash *rh)
+{
+ rh->log->type->flush(rh->log);
+}
+
+static void rh_delay(struct region_hash *rh, struct bio *bio)
+{
+ struct region *reg;
+
+ read_lock(&rh->hash_lock);
+ reg = __rh_find(rh, bio_to_region(rh, bio));
+ bio_list_add(®->delayed_bios, bio);
+ read_unlock(&rh->hash_lock);
+}
+
+static void rh_stop_recovery(struct region_hash *rh)
+{
+ int i;
+
+ /* wait for any recovering regions */
+ for (i = 0; i < MAX_RECOVERY; i++)
+ down(&rh->recovery_count);
+}
+
+static void rh_start_recovery(struct region_hash *rh)
+{
+ int i;
+
+ for (i = 0; i < MAX_RECOVERY; i++)
+ up(&rh->recovery_count);
+
+ wake();
+}
+
+/*-----------------------------------------------------------------
+ * Mirror set structures.
+ *---------------------------------------------------------------*/
+struct mirror {
+ atomic_t error_count;
+ struct dm_dev *dev;
+ sector_t offset;
+};
+
+struct mirror_set {
+ struct dm_target *ti;
+ struct list_head list;
+ struct region_hash rh;
+ struct kcopyd_client *kcopyd_client;
+
+ spinlock_t lock; /* protects the next two lists */
+ struct bio_list reads;
+ struct bio_list writes;
+
+ /* recovery */
+ region_t nr_regions;
+ int in_sync;
+
+ unsigned int nr_mirrors;
+ struct mirror mirror[0];
+};
+
+/*
+ * Every mirror should look like this one.
+ */
+#define DEFAULT_MIRROR 0
+
+/*
+ * This is yucky. We squirrel the mirror_set struct away inside
+ * bi_next for write buffers. This is safe since the bh
+ * doesn't get submitted to the lower levels of block layer.
+ */
+static struct mirror_set *bio_get_ms(struct bio *bio)
+{
+ return (struct mirror_set *) bio->bi_next;
+}
+
+static void bio_set_ms(struct bio *bio, struct mirror_set *ms)
+{
+ bio->bi_next = (struct bio *) ms;
+}
+
+/*-----------------------------------------------------------------
+ * Recovery.
+ *
+ * When a mirror is first activated we may find that some regions
+ * are in the no-sync state. We have to recover these by
+ * recopying from the default mirror to all the others.
+ *---------------------------------------------------------------*/
+static void recovery_complete(int read_err, unsigned int write_err,
+ void *context)
+{
+ struct region *reg = (struct region *) context;
+
+ /* FIXME: better error handling */
+ rh_recovery_end(reg, read_err || write_err);
+}
+
+static int recover(struct mirror_set *ms, struct region *reg)
+{
+ int r;
+ unsigned int i;
+ struct io_region from, to[ms->nr_mirrors - 1], *dest;
+ struct mirror *m;
+ unsigned long flags = 0;
+
+ /* fill in the source */
+ m = ms->mirror + DEFAULT_MIRROR;
+ from.bdev = m->dev->bdev;
+ from.sector = m->offset + region_to_sector(reg->rh, reg->key);
+ if (reg->key == (ms->nr_regions - 1)) {
+ /*
+ * The final region may be smaller than
+ * region_size.
+ */
+ from.count = ms->ti->len & (reg->rh->region_size - 1);
+ if (!from.count)
+ from.count = reg->rh->region_size;
+ } else
+ from.count = reg->rh->region_size;
+
+ /* fill in the destinations */
+ for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
+ if (i == DEFAULT_MIRROR)
+ continue;
+
+ m = ms->mirror + i;
+ dest->bdev = m->dev->bdev;
+ dest->sector = m->offset + region_to_sector(reg->rh, reg->key);
+ dest->count = from.count;
+ dest++;
+ }
+
+ /* hand to kcopyd */
+ set_bit(KCOPYD_IGNORE_ERROR, &flags);
+ r = kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to, flags,
+ recovery_complete, reg);
+
+ return r;
+}
+
+static void do_recovery(struct mirror_set *ms)
+{
+ int r;
+ struct region *reg;
+ struct dirty_log *log = ms->rh.log;
+
+ /*
+ * Start quiescing some regions.
+ */
+ rh_recovery_prepare(&ms->rh);
+
+ /*
+ * Copy any already quiesced regions.
+ */
+ while ((reg = rh_recovery_start(&ms->rh))) {
+ r = recover(ms, reg);
+ if (r)
+ rh_recovery_end(reg, 0);
+ }
+
+ /*
+ * Update the in sync flag.
+ */
+ if (!ms->in_sync &&
+ (log->type->get_sync_count(log) == ms->nr_regions)) {
+ /* the sync is complete */
+ dm_table_event(ms->ti->table);
+ ms->in_sync = 1;
+ }
+}
+
+/*-----------------------------------------------------------------
+ * Reads
+ *---------------------------------------------------------------*/
+static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
+{
+ /* FIXME: add read balancing */
+ return ms->mirror + DEFAULT_MIRROR;
+}
+
+/*
+ * remap a buffer to a particular mirror.
+ */
+static void map_bio(struct mirror_set *ms, struct mirror *m, struct bio *bio)
+{
+ bio->bi_bdev = m->dev->bdev;
+ bio->bi_sector = m->offset + (bio->bi_sector - ms->ti->begin);
+}
+
+static void do_reads(struct mirror_set *ms, struct bio_list *reads)
+{
+ region_t region;
+ struct bio *bio;
+ struct mirror *m;
+
+ while ((bio = bio_list_pop(reads))) {
+ region = bio_to_region(&ms->rh, bio);
+
+ /*
+ * We can only read balance if the region is in sync.
+ */
+ if (rh_in_sync(&ms->rh, region, 0))
+ m = choose_mirror(ms, bio->bi_sector);
+ else
+ m = ms->mirror + DEFAULT_MIRROR;
+
+ map_bio(ms, m, bio);
+ generic_make_request(bio);
+ }
+}
+
+/*-----------------------------------------------------------------
+ * Writes.
+ *
+ * We do different things with the write io depending on the
+ * state of the region that it's in:
+ *
+ * SYNC: increment pending, use kcopyd to write to *all* mirrors
+ * RECOVERING: delay the io until recovery completes
+ * NOSYNC: increment pending, just write to the default mirror
+ *---------------------------------------------------------------*/
+static void write_callback(unsigned long error, void *context)
+{
+ unsigned int i;
+ int uptodate = 1;
+ struct bio *bio = (struct bio *) context;
+ struct mirror_set *ms;
+
+ ms = bio_get_ms(bio);
+ bio_set_ms(bio, NULL);
+
+ /*
+ * NOTE: We don't decrement the pending count here,
+ * instead it is done by the targets endio function.
+ * This way we handle both writes to SYNC and NOSYNC
+ * regions with the same code.
+ */
+
+ if (error) {
+ /*
+ * only error the io if all mirrors failed.
+ * FIXME: bogus
+ */
+ uptodate = 0;
+ for (i = 0; i < ms->nr_mirrors; i++)
+ if (!test_bit(i, &error)) {
+ uptodate = 1;
+ break;
+ }
+ }
+ bio_endio(bio, bio->bi_size, 0);
+}
+
+static void do_write(struct mirror_set *ms, struct bio *bio)
+{
+ unsigned int i;
+ struct io_region io[ms->nr_mirrors];
+ struct mirror *m;
+
+ for (i = 0; i < ms->nr_mirrors; i++) {
+ m = ms->mirror + i;
+
+ io[i].bdev = m->dev->bdev;
+ io[i].sector = m->offset + (bio->bi_sector - ms->ti->begin);
+ io[i].count = bio->bi_size >> 9;
+ }
+
+ bio_set_ms(bio, ms);
+ dm_io_async_bvec(ms->nr_mirrors, io, WRITE,
+ bio->bi_io_vec + bio->bi_idx,
+ write_callback, bio);
+}
+
+static void do_writes(struct mirror_set *ms, struct bio_list *writes)
+{
+ int state;
+ struct bio *bio;
+ struct bio_list sync, nosync, recover, *this_list = NULL;
+
+ if (!writes->head)
+ return;
+
+ /*
+ * Classify each write.
+ */
+ bio_list_init(&sync);
+ bio_list_init(&nosync);
+ bio_list_init(&recover);
+
+ while ((bio = bio_list_pop(writes))) {
+ state = rh_state(&ms->rh, bio_to_region(&ms->rh, bio), 1);
+ switch (state) {
+ case RH_CLEAN:
+ case RH_DIRTY:
+ this_list = &sync;
+ break;
+
+ case RH_NOSYNC:
+ this_list = &nosync;
+ break;
+
+ case RH_RECOVERING:
+ this_list = &recover;
+ break;
+ }
+
+ bio_list_add(this_list, bio);
+ }
+
+ /*
+ * Increment the pending counts for any regions that will
+ * be written to (writes to recover regions are going to
+ * be delayed).
+ */
+ rh_inc_pending(&ms->rh, &sync);
+ rh_inc_pending(&ms->rh, &nosync);
+ rh_flush(&ms->rh);
+
+ /*
+ * Dispatch io.
+ */
+ while ((bio = bio_list_pop(&sync)))
+ do_write(ms, bio);
+
+ while ((bio = bio_list_pop(&recover)))
+ rh_delay(&ms->rh, bio);
+
+ while ((bio = bio_list_pop(&nosync))) {
+ map_bio(ms, ms->mirror + DEFAULT_MIRROR, bio);
+ generic_make_request(bio);
+ }
+}
+
+/*-----------------------------------------------------------------
+ * kmirrord
+ *---------------------------------------------------------------*/
+static LIST_HEAD(_mirror_sets);
+static DECLARE_RWSEM(_mirror_sets_lock);
+
+static void do_mirror(struct mirror_set *ms)
+{
+ struct bio_list reads, writes;
+
+ spin_lock(&ms->lock);
+ reads = ms->reads;
+ writes = ms->writes;
+ bio_list_init(&ms->reads);
+ bio_list_init(&ms->writes);
+ spin_unlock(&ms->lock);
+
+ rh_update_states(&ms->rh);
+ do_recovery(ms);
+ do_reads(ms, &reads);
+ do_writes(ms, &writes);
+}
+
+static void do_work(void *ignored)
+{
+ struct mirror_set *ms;
+
+ down_read(&_mirror_sets_lock);
+ list_for_each_entry (ms, &_mirror_sets, list)
+ do_mirror(ms);
+ up_read(&_mirror_sets_lock);
+}
+
+/*-----------------------------------------------------------------
+ * Target functions
+ *---------------------------------------------------------------*/
+static struct mirror_set *alloc_context(unsigned int nr_mirrors,
+ sector_t region_size,
+ struct dm_target *ti,
+ struct dirty_log *dl)
+{
+ size_t len;
+ struct mirror_set *ms = NULL;
+
+ if (array_too_big(sizeof(*ms), sizeof(ms->mirror[0]), nr_mirrors))
+ return NULL;
+
+ len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
+
+ ms = kmalloc(len, GFP_KERNEL);
+ if (!ms) {
+ ti->error = "dm-mirror: Cannot allocate mirror context";
+ return NULL;
+ }
+
+ memset(ms, 0, len);
+ spin_lock_init(&ms->lock);
+
+ ms->ti = ti;
+ ms->nr_mirrors = nr_mirrors;
+ ms->nr_regions = dm_div_up(ti->len, region_size);
+ ms->in_sync = 0;
+
+ if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) {
+ ti->error = "dm-mirror: Error creating dirty region hash";
+ kfree(ms);
+ return NULL;
+ }
+
+ return ms;
+}
+
+static void free_context(struct mirror_set *ms, struct dm_target *ti,
+ unsigned int m)
+{
+ while (m--)
+ dm_put_device(ti, ms->mirror[m].dev);
+
+ rh_exit(&ms->rh);
+ kfree(ms);
+}
+
+static inline int _check_region_size(struct dm_target *ti, sector_t size)
+{
+ return !(size % (PAGE_SIZE >> 9) || (size & (size - 1)) ||
+ size > ti->len);
+}
+
+static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
+ unsigned int mirror, char **argv)
+{
+ sector_t offset;
+
+ if (sscanf(argv[1], SECTOR_FORMAT, &offset) != 1) {
+ ti->error = "dm-mirror: Invalid offset";
+ return -EINVAL;
+ }
+
+ if (dm_get_device(ti, argv[0], offset, ti->len,
+ dm_table_get_mode(ti->table),
+ &ms->mirror[mirror].dev)) {
+ ti->error = "dm-mirror: Device lookup failure";
+ return -ENXIO;
+ }
+
+ ms->mirror[mirror].offset = offset;
+
+ return 0;
+}
+
+static int add_mirror_set(struct mirror_set *ms)
+{
+ down_write(&_mirror_sets_lock);
+ list_add_tail(&ms->list, &_mirror_sets);
+ up_write(&_mirror_sets_lock);
+ wake();
+
+ return 0;
+}
+
+static void del_mirror_set(struct mirror_set *ms)
+{
+ down_write(&_mirror_sets_lock);
+ list_del(&ms->list);
+ up_write(&_mirror_sets_lock);
+}
+
+/*
+ * Create dirty log: log_type #log_params <log_params>
+ */
+static struct dirty_log *create_dirty_log(struct dm_target *ti,
+ unsigned int argc, char **argv,
+ unsigned int *args_used)
+{
+ unsigned int param_count;
+ struct dirty_log *dl;
+
+ if (argc < 2) {
+ ti->error = "dm-mirror: Insufficient mirror log arguments";
+ return NULL;
+ }
+
+ if (sscanf(argv[1], "%u", ¶m_count) != 1) {
+ ti->error = "dm-mirror: Invalid mirror log argument count";
+ return NULL;
+ }
+
+ *args_used = 2 + param_count;
+
+ if (argc < *args_used) {
+ ti->error = "dm-mirror: Insufficient mirror log arguments";
+ return NULL;
+ }
+
+ dl = dm_create_dirty_log(argv[0], ti, param_count, argv + 2);
+ if (!dl) {
+ ti->error = "dm-mirror: Error creating mirror dirty log";
+ return NULL;
+ }
+
+ if (!_check_region_size(ti, dl->type->get_region_size(dl))) {
+ ti->error = "dm-mirror: Invalid region size";
+ dm_destroy_dirty_log(dl);
+ return NULL;
+ }
+
+ return dl;
+}
+
+/*
+ * Construct a mirror mapping:
+ *
+ * log_type #log_params <log_params>
+ * #mirrors [mirror_path offset]{2,}
+ *
+ * For now, #log_params = 1, log_type = "core"
+ *
+ */
+#define DM_IO_PAGES 64
+static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+ int r;
+ unsigned int nr_mirrors, m, args_used;
+ struct mirror_set *ms;
+ struct dirty_log *dl;
+
+ dl = create_dirty_log(ti, argc, argv, &args_used);
+ if (!dl)
+ return -EINVAL;
+
+ argv += args_used;
+ argc -= args_used;
+
+ if (!argc || sscanf(argv[0], "%u", &nr_mirrors) != 1 ||
+ nr_mirrors < 2) {
+ ti->error = "dm-mirror: Invalid number of mirrors";
+ dm_destroy_dirty_log(dl);
+ return -EINVAL;
+ }
+
+ argv++, argc--;
+
+ if (argc != nr_mirrors * 2) {
+ ti->error = "dm-mirror: Wrong number of mirror arguments";
+ dm_destroy_dirty_log(dl);
+ return -EINVAL;
+ }
+
+ ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl);
+ if (!ms) {
+ dm_destroy_dirty_log(dl);
+ return -ENOMEM;
+ }
+
+ /* Get the mirror parameter sets */
+ for (m = 0; m < nr_mirrors; m++) {
+ r = get_mirror(ms, ti, m, argv);
+ if (r) {
+ free_context(ms, ti, m);
+ return r;
+ }
+ argv += 2;
+ argc -= 2;
+ }
+
+ ti->private = ms;
+
+ r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
+ if (r) {
+ free_context(ms, ti, ms->nr_mirrors);
+ return r;
+ }
+
+ add_mirror_set(ms);
+ return 0;
+}
+
+static void mirror_dtr(struct dm_target *ti)
+{
+ struct mirror_set *ms = (struct mirror_set *) ti->private;
+
+ del_mirror_set(ms);
+ kcopyd_client_destroy(ms->kcopyd_client);
+ free_context(ms, ti, ms->nr_mirrors);
+}
+
+static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
+{
+ int should_wake = 0;
+ struct bio_list *bl;
+
+ bl = (rw == WRITE) ? &ms->writes : &ms->reads;
+ spin_lock(&ms->lock);
+ should_wake = !(bl->head);
+ bio_list_add(bl, bio);
+ spin_unlock(&ms->lock);
+
+ if (should_wake)
+ wake();
+}
+
+/*
+ * Mirror mapping function
+ */
+static int mirror_map(struct dm_target *ti, struct bio *bio,
+ union map_info *map_context)
+{
+ int r, rw = bio_rw(bio);
+ struct mirror *m;
+ struct mirror_set *ms = ti->private;
+
+ map_context->ll = bio->bi_sector >> ms->rh.region_shift;
+
+ if (rw == WRITE) {
+ queue_bio(ms, bio, rw);
+ return 0;
+ }
+
+ r = ms->rh.log->type->in_sync(ms->rh.log,
+ bio_to_region(&ms->rh, bio), 0);
+ if (r < 0 && r != -EWOULDBLOCK)
+ return r;
+
+ if (r == -EWOULDBLOCK) /* FIXME: ugly */
+ r = 0;
+
+ /*
+ * We don't want to fast track a recovery just for a read
+ * ahead. So we just let it silently fail.
+ * FIXME: get rid of this.
+ */
+ if (!r && rw == READA)
+ return -EIO;
+
+ if (!r) {
+ /* Pass this io over to the daemon */
+ queue_bio(ms, bio, rw);
+ return 0;
+ }
+
+ m = choose_mirror(ms, bio->bi_sector);
+ if (!m)
+ return -EIO;
+
+ map_bio(ms, m, bio);
+ return 1;
+}
+
+static int mirror_end_io(struct dm_target *ti, struct bio *bio,
+ int error, union map_info *map_context)
+{
+ int rw = bio_rw(bio);
+ struct mirror_set *ms = (struct mirror_set *) ti->private;
+ region_t region = map_context->ll;
+
+ /*
+ * We need to dec pending if this was a write.
+ */
+ if (rw == WRITE)
+ rh_dec(&ms->rh, region);
+
+ return 0;
+}
+
+static void mirror_suspend(struct dm_target *ti)
+{
+ struct mirror_set *ms = (struct mirror_set *) ti->private;
+ struct dirty_log *log = ms->rh.log;
+ rh_stop_recovery(&ms->rh);
+ if (log->type->suspend && log->type->suspend(log))
+ /* FIXME: need better error handling */
+ DMWARN("log suspend failed");
+}
+
+static void mirror_resume(struct dm_target *ti)
+{
+ struct mirror_set *ms = (struct mirror_set *) ti->private;
+ struct dirty_log *log = ms->rh.log;
+ if (log->type->resume && log->type->resume(log))
+ /* FIXME: need better error handling */
+ DMWARN("log resume failed");
+ rh_start_recovery(&ms->rh);
+}
+
+static int mirror_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned int maxlen)
+{
+ char buffer[32];
+ unsigned int m, sz = 0;
+ struct mirror_set *ms = (struct mirror_set *) ti->private;
+
+#define EMIT(x...) sz += ((sz >= maxlen) ? \
+ 0 : scnprintf(result + sz, maxlen - sz, x))
+
+ switch (type) {
+ case STATUSTYPE_INFO:
+ EMIT("%d ", ms->nr_mirrors);
+
+ for (m = 0; m < ms->nr_mirrors; m++) {
+ format_dev_t(buffer, ms->mirror[m].dev->bdev->bd_dev);
+ EMIT("%s ", buffer);
+ }
+
+ EMIT(SECTOR_FORMAT "/" SECTOR_FORMAT,
+ ms->rh.log->type->get_sync_count(ms->rh.log),
+ ms->nr_regions);
+ break;
+
+ case STATUSTYPE_TABLE:
+ EMIT("%s 1 " SECTOR_FORMAT " %d ",
+ ms->rh.log->type->name, ms->rh.region_size,
+ ms->nr_mirrors);
+
+ for (m = 0; m < ms->nr_mirrors; m++) {
+ format_dev_t(buffer, ms->mirror[m].dev->bdev->bd_dev);
+ EMIT("%s " SECTOR_FORMAT " ",
+ buffer, ms->mirror[m].offset);
+ }
+ }
+
+ return 0;
+}
+
+static struct target_type mirror_target = {
+ .name = "mirror",
+ .version = {1, 0, 1},
+ .module = THIS_MODULE,
+ .ctr = mirror_ctr,
+ .dtr = mirror_dtr,
+ .map = mirror_map,
+ .end_io = mirror_end_io,
+ .suspend = mirror_suspend,
+ .resume = mirror_resume,
+ .status = mirror_status,
+};
+
+static int __init dm_mirror_init(void)
+{
+ int r;
+
+ r = dm_dirty_log_init();
+ if (r)
+ return r;
+
+ _kmirrord_wq = create_workqueue("kmirrord");
+ if (!_kmirrord_wq) {
+ DMERR("couldn't start kmirrord");
+ dm_dirty_log_exit();
+ return r;
+ }
+ INIT_WORK(&_kmirrord_work, do_work, NULL);
+
+ r = dm_register_target(&mirror_target);
+ if (r < 0) {
+ DMERR("%s: Failed to register mirror target",
+ mirror_target.name);
+ dm_dirty_log_exit();
+ destroy_workqueue(_kmirrord_wq);
+ }
+
+ return r;
+}
+
+static void __exit dm_mirror_exit(void)
+{
+ int r;
+
+ r = dm_unregister_target(&mirror_target);
+ if (r < 0)
+ DMERR("%s: unregister failed %d", mirror_target.name, r);
+
+ destroy_workqueue(_kmirrord_wq);
+ dm_dirty_log_exit();
+}
+
+/* Module hooks */
+module_init(dm_mirror_init);
+module_exit(dm_mirror_exit);
+
+MODULE_DESCRIPTION(DM_NAME " mirror target");
+MODULE_AUTHOR("Joe Thornber");
+MODULE_LICENSE("GPL");
git://git.onelab.eu / linux-2.6.git / blobdiff