diff options
Diffstat (limited to 'drivers/md/dm-raid1.c')
| -rw-r--r-- | drivers/md/dm-raid1.c | 1269 |
1 files changed, 1269 insertions, 0 deletions
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c new file mode 100644 index 000000000000..6e3cf7e13451 --- /dev/null +++ b/drivers/md/dm-raid1.c @@ -0,0 +1,1269 @@ +/* + * 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; + uint32_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(unsigned int __nocast 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, uint32_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(&rh->region_lock); + list_add(&nreg->list, &rh->clean_regions); + spin_unlock(&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[KCOPYD_MAX_REGIONS], *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[KCOPYD_MAX_REGIONS+1]; + 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, + uint32_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_sector_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, uint32_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,} + * + * log_type is "core" or "disk" + * #log_params is between 1 and 3 + */ +#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 || nr_mirrors > KCOPYD_MAX_REGIONS + 1) { + 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_postsuspend(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) +{ + unsigned int m, sz; + struct mirror_set *ms = (struct mirror_set *) ti->private; + + sz = ms->rh.log->type->status(ms->rh.log, type, result, maxlen); + + switch (type) { + case STATUSTYPE_INFO: + DMEMIT("%d ", ms->nr_mirrors); + for (m = 0; m < ms->nr_mirrors; m++) + DMEMIT("%s ", ms->mirror[m].dev->name); + + DMEMIT(SECTOR_FORMAT "/" SECTOR_FORMAT, + ms->rh.log->type->get_sync_count(ms->rh.log), + ms->nr_regions); + break; + + case STATUSTYPE_TABLE: + DMEMIT("%d ", ms->nr_mirrors); + for (m = 0; m < ms->nr_mirrors; m++) + DMEMIT("%s " SECTOR_FORMAT " ", + ms->mirror[m].dev->name, 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, + .postsuspend = mirror_postsuspend, + .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"); |