/* * Copyright (C) 2003 Sistina Software Limited. * Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved. * * This file is released under the GPL. */ #include "dm-bio-record.h" #include <linux/init.h> #include <linux/mempool.h> #include <linux/module.h> #include <linux/pagemap.h> #include <linux/slab.h> #include <linux/workqueue.h> #include <linux/device-mapper.h> #include <linux/dm-io.h> #include <linux/dm-dirty-log.h> #include <linux/dm-kcopyd.h> #include <linux/dm-region-hash.h> #define DM_MSG_PREFIX "raid1" #define MAX_RECOVERY 1 /* Maximum number of regions recovered in parallel. */ #define DM_IO_PAGES 64 #define DM_KCOPYD_PAGES 64 #define DM_RAID1_HANDLE_ERRORS 0x01 #define errors_handled(p) ((p)->features & DM_RAID1_HANDLE_ERRORS) static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped); /*----------------------------------------------------------------- * Mirror set structures. *---------------------------------------------------------------*/ enum dm_raid1_error { DM_RAID1_WRITE_ERROR, DM_RAID1_SYNC_ERROR, DM_RAID1_READ_ERROR }; struct mirror { struct mirror_set *ms; atomic_t error_count; unsigned long error_type; struct dm_dev *dev; sector_t offset; }; struct mirror_set { struct dm_target *ti; struct list_head list; uint64_t features; spinlock_t lock; /* protects the lists */ struct bio_list reads; struct bio_list writes; struct bio_list failures; struct dm_region_hash *rh; struct dm_kcopyd_client *kcopyd_client; struct dm_io_client *io_client; mempool_t *read_record_pool; /* recovery */ region_t nr_regions; int in_sync; int log_failure; atomic_t suspend; atomic_t default_mirror; /* Default mirror */ struct workqueue_struct *kmirrord_wq; struct work_struct kmirrord_work; struct timer_list timer; unsigned long timer_pending; struct work_struct trigger_event; unsigned nr_mirrors; struct mirror mirror[0]; }; static void wakeup_mirrord(void *context) { struct mirror_set *ms = context; queue_work(ms->kmirrord_wq, &ms->kmirrord_work); } static void delayed_wake_fn(unsigned long data) { struct mirror_set *ms = (struct mirror_set *) data; clear_bit(0, &ms->timer_pending); wakeup_mirrord(ms); } static void delayed_wake(struct mirror_set *ms) { if (test_and_set_bit(0, &ms->timer_pending)) return; ms->timer.expires = jiffies + HZ / 5; ms->timer.data = (unsigned long) ms; ms->timer.function = delayed_wake_fn; add_timer(&ms->timer); } static void wakeup_all_recovery_waiters(void *context) { wake_up_all(&_kmirrord_recovery_stopped); } static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw) { unsigned long flags; int should_wake = 0; struct bio_list *bl; bl = (rw == WRITE) ? &ms->writes : &ms->reads; spin_lock_irqsave(&ms->lock, flags); should_wake = !(bl->head); bio_list_add(bl, bio); spin_unlock_irqrestore(&ms->lock, flags); if (should_wake) wakeup_mirrord(ms); } static void dispatch_bios(void *context, struct bio_list *bio_list) { struct mirror_set *ms = context; struct bio *bio; while ((bio = bio_list_pop(bio_list))) queue_bio(ms, bio, WRITE); } #define MIN_READ_RECORDS 20 struct dm_raid1_read_record { struct mirror *m; struct dm_bio_details details; }; static struct kmem_cache *_dm_raid1_read_record_cache; /* * Every mirror should look like this one. */ #define DEFAULT_MIRROR 0 /* * This is yucky. We squirrel the mirror struct away inside * bi_next for read/write buffers. This is safe since the bh * doesn't get submitted to the lower levels of block layer. */ static struct mirror *bio_get_m(struct bio *bio) { return (struct mirror *) bio->bi_next; } static void bio_set_m(struct bio *bio, struct mirror *m) { bio->bi_next = (struct bio *) m; } static struct mirror *get_default_mirror(struct mirror_set *ms) { return &ms->mirror[atomic_read(&ms->default_mirror)]; } static void set_default_mirror(struct mirror *m) { struct mirror_set *ms = m->ms; struct mirror *m0 = &(ms->mirror[0]); atomic_set(&ms->default_mirror, m - m0); } /* fail_mirror * @m: mirror device to fail * @error_type: one of the enum's, DM_RAID1_*_ERROR * * If errors are being handled, record the type of * error encountered for this device. If this type * of error has already been recorded, we can return; * otherwise, we must signal userspace by triggering * an event. Additionally, if the device is the * primary device, we must choose a new primary, but * only if the mirror is in-sync. * * This function must not block. */ static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type) { struct mirror_set *ms = m->ms; struct mirror *new; /* * error_count is used for nothing more than a * simple way to tell if a device has encountered * errors. */ atomic_inc(&m->error_count); if (test_and_set_bit(error_type, &m->error_type)) return; if (!errors_handled(ms)) return; if (m != get_default_mirror(ms)) goto out; if (!ms->in_sync) { /* * Better to issue requests to same failing device * than to risk returning corrupt data. */ DMERR("Primary mirror (%s) failed while out-of-sync: " "Reads may fail.", m->dev->name); goto out; } for (new = ms->mirror; new < ms->mirror + ms->nr_mirrors; new++) if (!atomic_read(&new->error_count)) { set_default_mirror(new); break; } if (unlikely(new == ms->mirror + ms->nr_mirrors)) DMWARN("All sides of mirror have failed."); out: schedule_work(&ms->trigger_event); } /*----------------------------------------------------------------- * 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 long write_err, void *context) { struct dm_region *reg = context; struct mirror_set *ms = dm_rh_region_context(reg); int m, bit = 0; if (read_err) { /* Read error means the failure of default mirror. */ DMERR_LIMIT("Unable to read primary mirror during recovery"); fail_mirror(get_default_mirror(ms), DM_RAID1_SYNC_ERROR); } if (write_err) { DMERR_LIMIT("Write error during recovery (error = 0x%lx)", write_err); /* * Bits correspond to devices (excluding default mirror). * The default mirror cannot change during recovery. */ for (m = 0; m < ms->nr_mirrors; m++) { if (&ms->mirror[m] == get_default_mirror(ms)) continue; if (test_bit(bit, &write_err)) fail_mirror(ms->mirror + m, DM_RAID1_SYNC_ERROR); bit++; } } dm_rh_recovery_end(reg, !(read_err || write_err)); } static int recover(struct mirror_set *ms, struct dm_region *reg) { int r; unsigned i; struct dm_io_region from, to[DM_KCOPYD_MAX_REGIONS], *dest; struct mirror *m; unsigned long flags = 0; region_t key = dm_rh_get_region_key(reg); sector_t region_size = dm_rh_get_region_size(ms->rh); /* fill in the source */ m = get_default_mirror(ms); from.bdev = m->dev->bdev; from.sector = m->offset + dm_rh_region_to_sector(ms->rh, key); if (key == (ms->nr_regions - 1)) { /* * The final region may be smaller than * region_size. */ from.count = ms->ti->len & (region_size - 1); if (!from.count) from.count = region_size; } else from.count = region_size; /* fill in the destinations */ for (i = 0, dest = to; i < ms->nr_mirrors; i++) { if (&ms->mirror[i] == get_default_mirror(ms)) continue; m = ms->mirror + i; dest->bdev = m->dev->bdev; dest->sector = m->offset + dm_rh_region_to_sector(ms->rh, key); dest->count = from.count; dest++; } /* hand to kcopyd */ if (!errors_handled(ms)) set_bit(DM_KCOPYD_IGNORE_ERROR, &flags); r = dm_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) { struct dm_region *reg; struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); int r; /* * Start quiescing some regions. */ dm_rh_recovery_prepare(ms->rh); /* * Copy any already quiesced regions. */ while ((reg = dm_rh_recovery_start(ms->rh))) { r = recover(ms, reg); if (r) dm_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) { struct mirror *m = get_default_mirror(ms); do { if (likely(!atomic_read(&m->error_count))) return m; if (m-- == ms->mirror) m += ms->nr_mirrors; } while (m != get_default_mirror(ms)); return NULL; } static int default_ok(struct mirror *m) { struct mirror *default_mirror = get_default_mirror(m->ms); return !atomic_read(&default_mirror->error_count); } static int mirror_available(struct mirror_set *ms, struct bio *bio) { struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); region_t region = dm_rh_bio_to_region(ms->rh, bio); if (log->type->in_sync(log, region, 0)) return choose_mirror(ms, bio->bi_sector) ? 1 : 0; return 0; } /* * remap a buffer to a particular mirror. */ static sector_t map_sector(struct mirror *m, struct bio *bio) { return m->offset + (bio->bi_sector - m->ms->ti->begin); } static void map_bio(struct mirror *m, struct bio *bio) { bio->bi_bdev = m->dev->bdev; bio->bi_sector = map_sector(m, bio); } static void map_region(struct dm_io_region *io, struct mirror *m, struct bio *bio) { io->bdev = m->dev->bdev; io->sector = map_sector(m, bio); io->count = bio->bi_size >> 9; } /*----------------------------------------------------------------- * Reads *---------------------------------------------------------------*/ static void read_callback(unsigned long error, void *context) { struct bio *bio = context; struct mirror *m; m = bio_get_m(bio); bio_set_m(bio, NULL); if (likely(!error)) { bio_endio(bio, 0); return; } fail_mirror(m, DM_RAID1_READ_ERROR); if (likely(default_ok(m)) || mirror_available(m->ms, bio)) { DMWARN_LIMIT("Read failure on mirror device %s. " "Trying alternative device.", m->dev->name); queue_bio(m->ms, bio, bio_rw(bio)); return; } DMERR_LIMIT("Read failure on mirror device %s. Failing I/O.", m->dev->name); bio_endio(bio, -EIO); } /* Asynchronous read. */ static void read_async_bio(struct mirror *m, struct bio *bio) { struct dm_io_region io; struct dm_io_request io_req = { .bi_rw = READ, .mem.type = DM_IO_BVEC, .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx, .notify.fn = read_callback, .notify.context = bio, .client = m->ms->io_client, }; map_region(&io, m, bio); bio_set_m(bio, m); BUG_ON(dm_io(&io_req, 1, &io, NULL)); } static inline int region_in_sync(struct mirror_set *ms, region_t region, int may_block) { int state = dm_rh_get_state(ms->rh, region, may_block); return state == DM_RH_CLEAN || state == DM_RH_DIRTY; } 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 = dm_rh_bio_to_region(ms->rh, bio); m = get_default_mirror(ms); /* * We can only read balance if the region is in sync. */ if (likely(region_in_sync(ms, region, 1))) m = choose_mirror(ms, bio->bi_sector); else if (m && atomic_read(&m->error_count)) m = NULL; if (likely(m)) read_async_bio(m, bio); else bio_endio(bio, -EIO); } } /*----------------------------------------------------------------- * 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 i, ret = 0; struct bio *bio = (struct bio *) context; struct mirror_set *ms; int uptodate = 0; int should_wake = 0; unsigned long flags; ms = bio_get_m(bio)->ms; bio_set_m(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 (likely(!error)) goto out; for (i = 0; i < ms->nr_mirrors; i++) if (test_bit(i, &error)) fail_mirror(ms->mirror + i, DM_RAID1_WRITE_ERROR); else uptodate = 1; if (unlikely(!uptodate)) { DMERR("All replicated volumes dead, failing I/O"); /* None of the writes succeeded, fail the I/O. */ ret = -EIO; } else if (errors_handled(ms)) { /* * Need to raise event. Since raising * events can block, we need to do it in * the main thread. */ spin_lock_irqsave(&ms->lock, flags); if (!ms->failures.head) should_wake = 1; bio_list_add(&ms->failures, bio); spin_unlock_irqrestore(&ms->lock, flags); if (should_wake) wakeup_mirrord(ms); return; } out: bio_endio(bio, ret); } static void do_write(struct mirror_set *ms, struct bio *bio) { unsigned int i; struct dm_io_region io[ms->nr_mirrors], *dest = io; struct mirror *m; struct dm_io_request io_req = { .bi_rw = WRITE, .mem.type = DM_IO_BVEC, .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx, .notify.fn = write_callback, .notify.context = bio, .client = ms->io_client, }; for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++) map_region(dest++, m, bio); /* * Use default mirror because we only need it to retrieve the reference * to the mirror set in write_callback(). */ bio_set_m(bio, get_default_mirror(ms)); BUG_ON(dm_io(&io_req, ms->nr_mirrors, io, NULL)); } 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; struct bio_list requeue; struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); region_t region; if (!writes->head) return; /* * Classify each write. */ bio_list_init(&sync); bio_list_init(&nosync); bio_list_init(&recover); bio_list_init(&requeue); while ((bio = bio_list_pop(writes))) { region = dm_rh_bio_to_region(ms->rh, bio); if (log->type->is_remote_recovering && log->type->is_remote_recovering(log, region)) { bio_list_add(&requeue, bio); continue; } state = dm_rh_get_state(ms->rh, region, 1); switch (state) { case DM_RH_CLEAN: case DM_RH_DIRTY: this_list = &sync; break; case DM_RH_NOSYNC: this_list = &nosync; break; case DM_RH_RECOVERING: this_list = &recover; break; } bio_list_add(this_list, bio); } /* * Add bios that are delayed due to remote recovery * back on to the write queue */ if (unlikely(requeue.head)) { spin_lock_irq(&ms->lock); bio_list_merge(&ms->writes, &requeue); spin_unlock_irq(&ms->lock); } /* * Increment the pending counts for any regions that will * be written to (writes to recover regions are going to * be delayed). */ dm_rh_inc_pending(ms->rh, &sync); dm_rh_inc_pending(ms->rh, &nosync); ms->log_failure = dm_rh_flush(ms->rh) ? 1 : 0; /* * Dispatch io. */ if (unlikely(ms->log_failure)) { spin_lock_irq(&ms->lock); bio_list_merge(&ms->failures, &sync); spin_unlock_irq(&ms->lock); wakeup_mirrord(ms); } else while ((bio = bio_list_pop(&sync))) do_write(ms, bio); while ((bio = bio_list_pop(&recover))) dm_rh_delay(ms->rh, bio); while ((bio = bio_list_pop(&nosync))) { map_bio(get_default_mirror(ms), bio); generic_make_request(bio); } } static void do_failures(struct mirror_set *ms, struct bio_list *failures) { struct bio *bio; if (!failures->head) return; if (!ms->log_failure) { while ((bio = bio_list_pop(failures))) { ms->in_sync = 0; dm_rh_mark_nosync(ms->rh, bio, bio->bi_size, 0); } return; } /* * If the log has failed, unattempted writes are being * put on the failures list. We can't issue those writes * until a log has been marked, so we must store them. * * If a 'noflush' suspend is in progress, we can requeue * the I/O's to the core. This give userspace a chance * to reconfigure the mirror, at which point the core * will reissue the writes. If the 'noflush' flag is * not set, we have no choice but to return errors. * * Some writes on the failures list may have been * submitted before the log failure and represent a * failure to write to one of the devices. It is ok * for us to treat them the same and requeue them * as well. */ if (dm_noflush_suspending(ms->ti)) { while ((bio = bio_list_pop(failures))) bio_endio(bio, DM_ENDIO_REQUEUE); return; } if (atomic_read(&ms->suspend)) { while ((bio = bio_list_pop(failures))) bio_endio(bio, -EIO); return; } spin_lock_irq(&ms->lock); bio_list_merge(&ms->failures, failures); spin_unlock_irq(&ms->lock); delayed_wake(ms); } static void trigger_event(struct work_struct *work) { struct mirror_set *ms = container_of(work, struct mirror_set, trigger_event); dm_table_event(ms->ti->table); } /*----------------------------------------------------------------- * kmirrord *---------------------------------------------------------------*/ static void do_mirror(struct work_struct *work) { struct mirror_set *ms = container_of(work, struct mirror_set, kmirrord_work); struct bio_list reads, writes, failures; unsigned long flags; spin_lock_irqsave(&ms->lock, flags); reads = ms->reads; writes = ms->writes; failures = ms->failures; bio_list_init(&ms->reads); bio_list_init(&ms->writes); bio_list_init(&ms->failures); spin_unlock_irqrestore(&ms->lock, flags); dm_rh_update_states(ms->rh, errors_handled(ms)); do_recovery(ms); do_reads(ms, &reads); do_writes(ms, &writes); do_failures(ms, &failures); dm_table_unplug_all(ms->ti->table); } /*----------------------------------------------------------------- * Target functions *---------------------------------------------------------------*/ static struct mirror_set *alloc_context(unsigned int nr_mirrors, uint32_t region_size, struct dm_target *ti, struct dm_dirty_log *dl) { size_t len; struct mirror_set *ms = NULL; len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors); ms = kzalloc(len, GFP_KERNEL); if (!ms) { ti->error = "Cannot allocate mirror context"; return NULL; } 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; ms->log_failure = 0; atomic_set(&ms->suspend, 0); atomic_set(&ms->default_mirror, DEFAULT_MIRROR); ms->read_record_pool = mempool_create_slab_pool(MIN_READ_RECORDS, _dm_raid1_read_record_cache); if (!ms->read_record_pool) { ti->error = "Error creating mirror read_record_pool"; kfree(ms); return NULL; } ms->io_client = dm_io_client_create(DM_IO_PAGES); if (IS_ERR(ms->io_client)) { ti->error = "Error creating dm_io client"; mempool_destroy(ms->read_record_pool); kfree(ms); return NULL; } ms->rh = dm_region_hash_create(ms, dispatch_bios, wakeup_mirrord, wakeup_all_recovery_waiters, ms->ti->begin, MAX_RECOVERY, dl, region_size, ms->nr_regions); if (IS_ERR(ms->rh)) { ti->error = "Error creating dirty region hash"; dm_io_client_destroy(ms->io_client); mempool_destroy(ms->read_record_pool); 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); dm_io_client_destroy(ms->io_client); dm_region_hash_destroy(ms->rh); mempool_destroy(ms->read_record_pool); kfree(ms); } static int get_mirror(struct mirror_set *ms, struct dm_target *ti, unsigned int mirror, char **argv) { unsigned long long offset; if (sscanf(argv[1], "%llu", &offset) != 1) { ti->error = "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 = "Device lookup failure"; return -ENXIO; } ms->mirror[mirror].ms = ms; atomic_set(&(ms->mirror[mirror].error_count), 0); ms->mirror[mirror].error_type = 0; ms->mirror[mirror].offset = offset; return 0; } /* * Create dirty log: log_type #log_params <log_params> */ static struct dm_dirty_log *create_dirty_log(struct dm_target *ti, unsigned argc, char **argv, unsigned *args_used) { unsigned param_count; struct dm_dirty_log *dl; if (argc < 2) { ti->error = "Insufficient mirror log arguments"; return NULL; } if (sscanf(argv[1], "%u", ¶m_count) != 1) { ti->error = "Invalid mirror log argument count"; return NULL; } *args_used = 2 + param_count; if (argc < *args_used) { ti->error = "Insufficient mirror log arguments"; return NULL; } dl = dm_dirty_log_create(argv[0], ti, param_count, argv + 2); if (!dl) { ti->error = "Error creating mirror dirty log"; return NULL; } return dl; } static int parse_features(struct mirror_set *ms, unsigned argc, char **argv, unsigned *args_used) { unsigned num_features; struct dm_target *ti = ms->ti; *args_used = 0; if (!argc) return 0; if (sscanf(argv[0], "%u", &num_features) != 1) { ti->error = "Invalid number of features"; return -EINVAL; } argc--; argv++; (*args_used)++; if (num_features > argc) { ti->error = "Not enough arguments to support feature count"; return -EINVAL; } if (!strcmp("handle_errors", argv[0])) ms->features |= DM_RAID1_HANDLE_ERRORS; else { ti->error = "Unrecognised feature requested"; return -EINVAL; } (*args_used)++; return 0; } /* * Construct a mirror mapping: * * log_type #log_params <log_params> * #mirrors [mirror_path offset]{2,} * [#features <features>] * * log_type is "core" or "disk" * #log_params is between 1 and 3 * * If present, features must be "handle_errors". */ 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 dm_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 > DM_KCOPYD_MAX_REGIONS + 1) { ti->error = "Invalid number of mirrors"; dm_dirty_log_destroy(dl); return -EINVAL; } argv++, argc--; if (argc < nr_mirrors * 2) { ti->error = "Too few mirror arguments"; dm_dirty_log_destroy(dl); return -EINVAL; } ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl); if (!ms) { dm_dirty_log_destroy(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; ti->split_io = dm_rh_get_region_size(ms->rh); ms->kmirrord_wq = create_singlethread_workqueue("kmirrord"); if (!ms->kmirrord_wq) { DMERR("couldn't start kmirrord"); r = -ENOMEM; goto err_free_context; } INIT_WORK(&ms->kmirrord_work, do_mirror); init_timer(&ms->timer); ms->timer_pending = 0; INIT_WORK(&ms->trigger_event, trigger_event); r = parse_features(ms, argc, argv, &args_used); if (r) goto err_destroy_wq; argv += args_used; argc -= args_used; /* * Any read-balancing addition depends on the * DM_RAID1_HANDLE_ERRORS flag being present. * This is because the decision to balance depends * on the sync state of a region. If the above * flag is not present, we ignore errors; and * the sync state may be inaccurate. */ if (argc) { ti->error = "Too many mirror arguments"; r = -EINVAL; goto err_destroy_wq; } r = dm_kcopyd_client_create(DM_KCOPYD_PAGES, &ms->kcopyd_client); if (r) goto err_destroy_wq; wakeup_mirrord(ms); return 0; err_destroy_wq: destroy_workqueue(ms->kmirrord_wq); err_free_context: free_context(ms, ti, ms->nr_mirrors); return r; } static void mirror_dtr(struct dm_target *ti) { struct mirror_set *ms = (struct mirror_set *) ti->private; del_timer_sync(&ms->timer); flush_workqueue(ms->kmirrord_wq); flush_scheduled_work(); dm_kcopyd_client_destroy(ms->kcopyd_client); destroy_workqueue(ms->kmirrord_wq); free_context(ms, ti, ms->nr_mirrors); } /* * 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; struct dm_raid1_read_record *read_record = NULL; struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); if (rw == WRITE) { /* Save region for mirror_end_io() handler */ map_context->ll = dm_rh_bio_to_region(ms->rh, bio); queue_bio(ms, bio, rw); return DM_MAPIO_SUBMITTED; } r = log->type->in_sync(log, dm_rh_bio_to_region(ms->rh, bio), 0); if (r < 0 && r != -EWOULDBLOCK) return r; /* * If region is not in-sync queue the bio. */ if (!r || (r == -EWOULDBLOCK)) { if (rw == READA) return -EWOULDBLOCK; queue_bio(ms, bio, rw); return DM_MAPIO_SUBMITTED; } /* * The region is in-sync and we can perform reads directly. * Store enough information so we can retry if it fails. */ m = choose_mirror(ms, bio->bi_sector); if (unlikely(!m)) return -EIO; read_record = mempool_alloc(ms->read_record_pool, GFP_NOIO); if (likely(read_record)) { dm_bio_record(&read_record->details, bio); map_context->ptr = read_record; read_record->m = m; } map_bio(m, bio); return DM_MAPIO_REMAPPED; } 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; struct mirror *m = NULL; struct dm_bio_details *bd = NULL; struct dm_raid1_read_record *read_record = map_context->ptr; /* * We need to dec pending if this was a write. */ if (rw == WRITE) { dm_rh_dec(ms->rh, map_context->ll); return error; } if (error == -EOPNOTSUPP) goto out; if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio)) goto out; if (unlikely(error)) { if (!read_record) { /* * There wasn't enough memory to record necessary * information for a retry or there was no other * mirror in-sync. */ DMERR_LIMIT("Mirror read failed."); return -EIO; } m = read_record->m; DMERR("Mirror read failed from %s. Trying alternative device.", m->dev->name); fail_mirror(m, DM_RAID1_READ_ERROR); /* * A failed read is requeued for another attempt using an intact * mirror. */ if (default_ok(m) || mirror_available(ms, bio)) { bd = &read_record->details; dm_bio_restore(bd, bio); mempool_free(read_record, ms->read_record_pool); map_context->ptr = NULL; queue_bio(ms, bio, rw); return 1; } DMERR("All replicated volumes dead, failing I/O"); } out: if (read_record) { mempool_free(read_record, ms->read_record_pool); map_context->ptr = NULL; } return error; } static void mirror_presuspend(struct dm_target *ti) { struct mirror_set *ms = (struct mirror_set *) ti->private; struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); atomic_set(&ms->suspend, 1); /* * We must finish up all the work that we've * generated (i.e. recovery work). */ dm_rh_stop_recovery(ms->rh); wait_event(_kmirrord_recovery_stopped, !dm_rh_recovery_in_flight(ms->rh)); if (log->type->presuspend && log->type->presuspend(log)) /* FIXME: need better error handling */ DMWARN("log presuspend failed"); /* * Now that recovery is complete/stopped and the * delayed bios are queued, we need to wait for * the worker thread to complete. This way, * we know that all of our I/O has been pushed. */ flush_workqueue(ms->kmirrord_wq); } static void mirror_postsuspend(struct dm_target *ti) { struct mirror_set *ms = ti->private; struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); if (log->type->postsuspend && log->type->postsuspend(log)) /* FIXME: need better error handling */ DMWARN("log postsuspend failed"); } static void mirror_resume(struct dm_target *ti) { struct mirror_set *ms = ti->private; struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); atomic_set(&ms->suspend, 0); if (log->type->resume && log->type->resume(log)) /* FIXME: need better error handling */ DMWARN("log resume failed"); dm_rh_start_recovery(ms->rh); } /* * device_status_char * @m: mirror device/leg we want the status of * * We return one character representing the most severe error * we have encountered. * A => Alive - No failures * D => Dead - A write failure occurred leaving mirror out-of-sync * S => Sync - A sychronization failure occurred, mirror out-of-sync * R => Read - A read failure occurred, mirror data unaffected * * Returns: <char> */ static char device_status_char(struct mirror *m) { if (!atomic_read(&(m->error_count))) return 'A'; return (test_bit(DM_RAID1_WRITE_ERROR, &(m->error_type))) ? 'D' : (test_bit(DM_RAID1_SYNC_ERROR, &(m->error_type))) ? 'S' : (test_bit(DM_RAID1_READ_ERROR, &(m->error_type))) ? 'R' : 'U'; } static int mirror_status(struct dm_target *ti, status_type_t type, char *result, unsigned int maxlen) { unsigned int m, sz = 0; struct mirror_set *ms = (struct mirror_set *) ti->private; struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh); char buffer[ms->nr_mirrors + 1]; 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); buffer[m] = device_status_char(&(ms->mirror[m])); } buffer[m] = '\0'; DMEMIT("%llu/%llu 1 %s ", (unsigned long long)log->type->get_sync_count(log), (unsigned long long)ms->nr_regions, buffer); sz += log->type->status(log, type, result+sz, maxlen-sz); break; case STATUSTYPE_TABLE: sz = log->type->status(log, type, result, maxlen); DMEMIT("%d", ms->nr_mirrors); for (m = 0; m < ms->nr_mirrors; m++) DMEMIT(" %s %llu", ms->mirror[m].dev->name, (unsigned long long)ms->mirror[m].offset); if (ms->features & DM_RAID1_HANDLE_ERRORS) DMEMIT(" 1 handle_errors"); } return 0; } static struct target_type mirror_target = { .name = "mirror", .version = {1, 0, 20}, .module = THIS_MODULE, .ctr = mirror_ctr, .dtr = mirror_dtr, .map = mirror_map, .end_io = mirror_end_io, .presuspend = mirror_presuspend, .postsuspend = mirror_postsuspend, .resume = mirror_resume, .status = mirror_status, }; static int __init dm_mirror_init(void) { int r; _dm_raid1_read_record_cache = KMEM_CACHE(dm_raid1_read_record, 0); if (!_dm_raid1_read_record_cache) { DMERR("Can't allocate dm_raid1_read_record cache"); r = -ENOMEM; goto bad_cache; } r = dm_register_target(&mirror_target); if (r < 0) { DMERR("Failed to register mirror target"); goto bad_target; } return 0; bad_target: kmem_cache_destroy(_dm_raid1_read_record_cache); bad_cache: return r; } static void __exit dm_mirror_exit(void) { dm_unregister_target(&mirror_target); kmem_cache_destroy(_dm_raid1_read_record_cache); } /* 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");