--- /dev/null
+/*
+ * 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_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_FLUSH_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 bio_list holds; /* bios are waiting until suspend */
+
+ struct dm_region_hash *rh;
+ struct dm_kcopyd_client *kcopyd_client;
+ struct dm_io_client *io_client;
+
+ /* recovery */
+ region_t nr_regions;
+ int in_sync;
+ int log_failure;
+ int leg_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];
+};
+
+DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(raid1_resync_throttle,
+ "A percentage of time allocated for raid resynchronization");
+
+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);
+}
+
+struct dm_raid1_bio_record {
+ struct mirror *m;
+ /* if details->bi_bdev == NULL, details were not saved */
+ struct dm_bio_details details;
+ region_t write_region;
+};
+
+/*
+ * 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);
+}
+
+static struct mirror *get_valid_mirror(struct mirror_set *ms)
+{
+ struct mirror *m;
+
+ for (m = ms->mirror; m < ms->mirror + ms->nr_mirrors; m++)
+ if (!atomic_read(&m->error_count))
+ return m;
+
+ return NULL;
+}
+
+/* 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;
+
+ ms->leg_failure = 1;
+
+ /*
+ * 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;
+ }
+
+ new = get_valid_mirror(ms);
+ if (new)
+ set_default_mirror(new);
+ else
+ DMWARN("All sides of mirror have failed.");
+
+out:
+ schedule_work(&ms->trigger_event);
+}
+
+static int mirror_flush(struct dm_target *ti)
+{
+ struct mirror_set *ms = ti->private;
+ unsigned long error_bits;
+
+ unsigned int i;
+ struct dm_io_region io[ms->nr_mirrors];
+ struct mirror *m;
+ struct dm_io_request io_req = {
+ .bi_rw = WRITE_FLUSH,
+ .mem.type = DM_IO_KMEM,
+ .mem.ptr.addr = NULL,
+ .client = ms->io_client,
+ };
+
+ for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++) {
+ io[i].bdev = m->dev->bdev;
+ io[i].sector = 0;
+ io[i].count = 0;
+ }
+
+ error_bits = -1;
+ dm_io(&io_req, ms->nr_mirrors, io, &error_bits);
+ if (unlikely(error_bits != 0)) {
+ for (i = 0; i < ms->nr_mirrors; i++)
+ if (test_bit(i, &error_bits))
+ fail_mirror(ms->mirror + i,
+ DM_RAID1_FLUSH_ERROR);
+ return -EIO;
+ }
+
+ return 0;
+}
+
+/*-----------------------------------------------------------------
+ * 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_iter.bi_sector) ? 1 : 0;
+
+ return 0;
+}
+
+/*
+ * remap a buffer to a particular mirror.
+ */
+static sector_t map_sector(struct mirror *m, struct bio *bio)
+{
+ if (unlikely(!bio->bi_iter.bi_size))
+ return 0;
+ return m->offset + dm_target_offset(m->ms->ti, bio->bi_iter.bi_sector);
+}
+
+static void map_bio(struct mirror *m, struct bio *bio)
+{
+ bio->bi_bdev = m->dev->bdev;
+ bio->bi_iter.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_sectors(bio);
+}
+
+static void hold_bio(struct mirror_set *ms, struct bio *bio)
+{
+ /*
+ * Lock is required to avoid race condition during suspend
+ * process.
+ */
+ spin_lock_irq(&ms->lock);
+
+ if (atomic_read(&ms->suspend)) {
+ spin_unlock_irq(&ms->lock);
+
+ /*
+ * If device is suspended, complete the bio.
+ */
+ if (dm_noflush_suspending(ms->ti))
+ bio_endio(bio, DM_ENDIO_REQUEUE);
+ else
+ bio_endio(bio, -EIO);
+ return;
+ }
+
+ /*
+ * Hold bio until the suspend is complete.
+ */
+ bio_list_add(&ms->holds, bio);
+ spin_unlock_irq(&ms->lock);
+}
+
+/*-----------------------------------------------------------------
+ * 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_BIO,
+ .mem.ptr.bio = bio,
+ .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_iter.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 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)) {
+ bio_endio(bio, ret);
+ return;
+ }
+
+ /*
+ * If the bio is discard, return an error, but do not
+ * degrade the array.
+ */
+ if (bio->bi_rw & REQ_DISCARD) {
+ bio_endio(bio, -EOPNOTSUPP);
+ return;
+ }
+
+ for (i = 0; i < ms->nr_mirrors; i++)
+ if (test_bit(i, &error))
+ fail_mirror(ms->mirror + i, DM_RAID1_WRITE_ERROR);
+
+ /*
+ * 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);
+}
+
+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 | (bio->bi_rw & WRITE_FLUSH_FUA),
+ .mem.type = DM_IO_BIO,
+ .mem.ptr.bio = bio,
+ .notify.fn = write_callback,
+ .notify.context = bio,
+ .client = ms->io_client,
+ };
+
+ if (bio->bi_rw & REQ_DISCARD) {
+ io_req.bi_rw |= REQ_DISCARD;
+ io_req.mem.type = DM_IO_KMEM;
+ io_req.mem.ptr.addr = NULL;
+ }
+
+ 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))) {
+ if ((bio->bi_rw & REQ_FLUSH) ||
+ (bio->bi_rw & REQ_DISCARD)) {
+ bio_list_add(&sync, bio);
+ continue;
+ }
+
+ 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);
+ delayed_wake(ms);
+ }
+
+ /*
+ * 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);
+
+ /*
+ * If the flush fails on a previous call and succeeds here,
+ * we must not reset the log_failure variable. We need
+ * userspace interaction to do that.
+ */
+ ms->log_failure = dm_rh_flush(ms->rh) ? 1 : ms->log_failure;
+
+ /*
+ * Dispatch io.
+ */
+ if (unlikely(ms->log_failure) && errors_handled(ms)) {
+ 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))) {
+ if (unlikely(ms->leg_failure) && errors_handled(ms)) {
+ spin_lock_irq(&ms->lock);
+ bio_list_add(&ms->failures, bio);
+ spin_unlock_irq(&ms->lock);
+ wakeup_mirrord(ms);
+ } else {
+ 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 (likely(!failures->head))
+ return;
+
+ /*
+ * If the log has failed, unattempted writes are being
+ * put on the holds 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.
+ */
+ while ((bio = bio_list_pop(failures))) {
+ if (!ms->log_failure) {
+ ms->in_sync = 0;
+ dm_rh_mark_nosync(ms->rh, bio);
+ }
+
+ /*
+ * If all the legs are dead, fail the I/O.
+ * If we have been told to handle errors, hold the bio
+ * and wait for userspace to deal with the problem.
+ * Otherwise pretend that the I/O succeeded. (This would
+ * be wrong if the failed leg returned after reboot and
+ * got replicated back to the good legs.)
+ */
+ if (!get_valid_mirror(ms))
+ bio_endio(bio, -EIO);
+ else if (errors_handled(ms))
+ hold_bio(ms, bio);
+ else
+ bio_endio(bio, 0);
+ }
+}
+
+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);
+}
+
+/*-----------------------------------------------------------------
+ * 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);
+ bio_list_init(&ms->reads);
+ bio_list_init(&ms->writes);
+ bio_list_init(&ms->failures);
+ bio_list_init(&ms->holds);
+
+ 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;
+ ms->leg_failure = 0;
+ atomic_set(&ms->suspend, 0);
+ atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
+
+ ms->io_client = dm_io_client_create();
+ if (IS_ERR(ms->io_client)) {
+ ti->error = "Error creating dm_io client";
+ 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);
+ 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);
+ kfree(ms);
+}
+
+static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
+ unsigned int mirror, char **argv)
+{
+ unsigned long long offset;
+ char dummy;
+
+ if (sscanf(argv[1], "%llu%c", &offset, &dummy) != 1) {
+ ti->error = "Invalid offset";
+ return -EINVAL;
+ }
+
+ if (dm_get_device(ti, argv[0], 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;
+ char dummy;
+
+ if (argc < 2) {
+ ti->error = "Insufficient mirror log arguments";
+ return NULL;
+ }
+
+ if (sscanf(argv[1], "%u%c", ¶m_count, &dummy) != 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, mirror_flush, 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;
+ char dummy;
+
+ *args_used = 0;
+
+ if (!argc)
+ return 0;
+
+ if (sscanf(argv[0], "%u%c", &num_features, &dummy) != 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;
+ char dummy;
+
+ 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%c", &nr_mirrors, &dummy) != 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;
+
+ r = dm_set_target_max_io_len(ti, dm_rh_get_region_size(ms->rh));
+ if (r)
+ goto err_free_context;
+
+ ti->num_flush_bios = 1;
+ ti->num_discard_bios = 1;
+ ti->per_bio_data_size = sizeof(struct dm_raid1_bio_record);
+ ti->discard_zeroes_data_unsupported = true;
+
+ ms->kmirrord_wq = alloc_workqueue("kmirrord", WQ_MEM_RECLAIM, 0);
+ 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;
+ }
+
+ ms->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle);
+ if (IS_ERR(ms->kcopyd_client)) {
+ r = PTR_ERR(ms->kcopyd_client);
+ 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_work(&ms->trigger_event);
+ 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)
+{
+ int r, rw = bio_rw(bio);
+ struct mirror *m;
+ struct mirror_set *ms = ti->private;
+ struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
+ struct dm_raid1_bio_record *bio_record =
+ dm_per_bio_data(bio, sizeof(struct dm_raid1_bio_record));
+
+ bio_record->details.bi_bdev = NULL;
+
+ if (rw == WRITE) {
+ /* Save region for mirror_end_io() handler */
+ bio_record->write_region = 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_iter.bi_sector);
+ if (unlikely(!m))
+ return -EIO;
+
+ dm_bio_record(&bio_record->details, bio);
+ bio_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)
+{
+ 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_bio_record *bio_record =
+ dm_per_bio_data(bio, sizeof(struct dm_raid1_bio_record));
+
+ /*
+ * We need to dec pending if this was a write.
+ */
+ if (rw == WRITE) {
+ if (!(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD)))
+ dm_rh_dec(ms->rh, bio_record->write_region);
+ return error;
+ }
+
+ if (error == -EOPNOTSUPP)
+ goto out;
+
+ if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
+ goto out;
+
+ if (unlikely(error)) {
+ if (!bio_record->details.bi_bdev) {
+ /*
+ * 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 = bio_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 = &bio_record->details;
+
+ dm_bio_restore(bd, bio);
+ bio_record->details.bi_bdev = NULL;
+
+ atomic_inc(&bio->bi_remaining);
+
+ queue_bio(ms, bio, rw);
+ return DM_ENDIO_INCOMPLETE;
+ }
+ DMERR("All replicated volumes dead, failing I/O");
+ }
+
+out:
+ bio_record->details.bi_bdev = 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);
+
+ struct bio_list holds;
+ struct bio *bio;
+
+ atomic_set(&ms->suspend, 1);
+
+ /*
+ * Process bios in the hold list to start recovery waiting
+ * for bios in the hold list. After the process, no bio has
+ * a chance to be added in the hold list because ms->suspend
+ * is set.
+ */
+ spin_lock_irq(&ms->lock);
+ holds = ms->holds;
+ bio_list_init(&ms->holds);
+ spin_unlock_irq(&ms->lock);
+
+ while ((bio = bio_list_pop(&holds)))
+ hold_bio(ms, bio);
+
+ /*
+ * 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_FLUSH_ERROR, &(m->error_type))) ? 'F' :
+ (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 void mirror_status(struct dm_target *ti, status_type_t type,
+ unsigned status_flags, char *result, unsigned 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");
+ }
+}
+
+static int mirror_iterate_devices(struct dm_target *ti,
+ iterate_devices_callout_fn fn, void *data)
+{
+ struct mirror_set *ms = ti->private;
+ int ret = 0;
+ unsigned i;
+
+ for (i = 0; !ret && i < ms->nr_mirrors; i++)
+ ret = fn(ti, ms->mirror[i].dev,
+ ms->mirror[i].offset, ti->len, data);
+
+ return ret;
+}
+
+static struct target_type mirror_target = {
+ .name = "mirror",
+ .version = {1, 13, 2},
+ .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,
+ .iterate_devices = mirror_iterate_devices,
+};
+
+static int __init dm_mirror_init(void)
+{
+ int r;
+
+ r = dm_register_target(&mirror_target);
+ if (r < 0) {
+ DMERR("Failed to register mirror target");
+ goto bad_target;
+ }
+
+ return 0;
+
+bad_target:
+ return r;
+}
+
+static void __exit dm_mirror_exit(void)
+{
+ dm_unregister_target(&mirror_target);
+}
+
+/* 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");
Code Review / kvmfornfv.git / blobdiff