1 files changed, 576 insertions, 88 deletions

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 31123d4a6b9c..edc057f5cdcc 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -6,6 +6,7 @@
 
 #include "dm.h"
 #include "dm-bio-list.h"
+#include "dm-bio-record.h"
 #include "dm-io.h"
 #include "dm-log.h"
 #include "kcopyd.h"
@@ -20,6 +21,7 @@
 #include <linux/vmalloc.h>
 #include <linux/workqueue.h>
 #include <linux/log2.h>
+#include <linux/hardirq.h>
 
 #define DM_MSG_PREFIX "raid1"
 #define DM_IO_PAGES 64
@@ -113,9 +115,16 @@ struct region {
 /*-----------------------------------------------------------------
  * 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;
+        uint32_t error_type;
         struct dm_dev *dev;
         sector_t offset;
 };
@@ -127,21 +136,25 @@ struct mirror_set {
         struct kcopyd_client *kcopyd_client;
         uint64_t features;
 
-        spinlock_t lock;        /* protects the next two lists */
+        spinlock_t lock;        /* protects the lists */
         struct bio_list reads;
         struct bio_list writes;
+        struct bio_list failures;
 
         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;
 
-        struct mirror *default_mirror;  /* Default mirror */
+        atomic_t default_mirror;        /* Default mirror */
 
         struct workqueue_struct *kmirrord_wq;
         struct work_struct kmirrord_work;
+        struct work_struct trigger_event;
 
         unsigned int nr_mirrors;
         struct mirror mirror[0];
@@ -362,6 +375,16 @@ static void complete_resync_work(struct region *reg, int success)
         struct region_hash *rh = reg->rh;
 
         rh->log->type->set_region_sync(rh->log, reg->key, success);
+
+        /*
+         * Dispatch the bios before we call 'wake_up_all'.
+         * This is important because if we are suspending,
+         * we want to know that recovery is complete and
+         * the work queue is flushed.  If we wake_up_all
+         * before we dispatch_bios (queue bios and call wake()),
+         * then we risk suspending before the work queue
+         * has been properly flushed.
+         */
         dispatch_bios(rh->ms, &reg->delayed_bios);
         if (atomic_dec_and_test(&rh->recovery_in_flight))
                 wake_up_all(&_kmirrord_recovery_stopped);
@@ -626,24 +649,101 @@ static void rh_start_recovery(struct region_hash *rh)
         wake(rh->ms);
 }
 
+#define MIN_READ_RECORDS 20
+struct dm_raid1_read_record {
+        struct mirror *m;
+        struct dm_bio_details details;
+};
+
 /*
  * 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
+ * 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_set *bio_get_ms(struct bio *bio)
+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 (struct mirror_set *) bio->bi_next;
+        return &ms->mirror[atomic_read(&ms->default_mirror)];
 }
 
-static void bio_set_ms(struct bio *bio, struct mirror_set *ms)
+static void set_default_mirror(struct mirror *m)
 {
-        bio->bi_next = (struct bio *) ms;
+        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;
+
+        if (!errors_handled(ms))
+                return;
+
+        /*
+         * 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 (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);
 }
 
 /*-----------------------------------------------------------------
@@ -656,15 +756,32 @@ static void bio_set_ms(struct bio *bio, struct mirror_set *ms)
 static void recovery_complete(int read_err, unsigned int write_err,
                               void *context)
 {
-        struct region *reg = (struct region *) context;
+        struct region *reg = (struct region *)context;
+        struct mirror_set *ms = reg->rh->ms;
+        int m, bit = 0;
 
-        if (read_err)
+        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)
+        if (write_err) {
                 DMERR_LIMIT("Write error during recovery (error = 0x%x)",
                             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++;
+                }
+        }
 
         rh_recovery_end(reg, !(read_err || write_err));
 }
@@ -678,7 +795,7 @@ static int recover(struct mirror_set *ms, struct region *reg)
         unsigned long flags = 0;
 
         /* fill in the source */
-        m = ms->default_mirror;
+        m = get_default_mirror(ms);
         from.bdev = m->dev->bdev;
         from.sector = m->offset + region_to_sector(reg->rh, reg->key);
         if (reg->key == (ms->nr_regions - 1)) {
@@ -694,7 +811,7 @@ static int recover(struct mirror_set *ms, struct region *reg)
 
         /* fill in the destinations */
         for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
-                if (&ms->mirror[i] == ms->default_mirror)
+                if (&ms->mirror[i] == get_default_mirror(ms))
                         continue;
 
                 m = ms->mirror + i;
@@ -748,17 +865,105 @@ static void do_recovery(struct mirror_set *ms)
  *---------------------------------------------------------------*/
 static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
 {
-        /* FIXME: add read balancing */
-        return ms->default_mirror;
+        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)
+{
+        region_t region = bio_to_region(&ms->rh, bio);
+
+        if (ms->rh.log->type->in_sync(ms->rh.log, region, 0))
+                return choose_mirror(ms,  bio->bi_sector) ? 1 : 0;
+
+        return 0;
 }
 
 /*
  * remap a buffer to a particular mirror.
  */
-static void map_bio(struct mirror_set *ms, struct mirror *m, struct bio *bio)
+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 = m->offset + (bio->bi_sector - ms->ti->begin);
+        bio->bi_sector = map_sector(m, bio);
+}
+
+static void map_region(struct 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 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);
+        (void) dm_io(&io_req, 1, &io, NULL);
 }
 
 static void do_reads(struct mirror_set *ms, struct bio_list *reads)
@@ -769,17 +974,20 @@ static void do_reads(struct mirror_set *ms, struct bio_list *reads)
 
         while ((bio = bio_list_pop(reads))) {
                 region = bio_to_region(&ms->rh, bio);
+                m = get_default_mirror(ms);
 
                 /*
                  * We can only read balance if the region is in sync.
                  */
-                if (rh_in_sync(&ms->rh, region, 1))
+                if (likely(rh_in_sync(&ms->rh, region, 1)))
                         m = choose_mirror(ms, bio->bi_sector);
-                else
-                        m = ms->default_mirror;
+                else if (m && atomic_read(&m->error_count))
+                        m = NULL;
 
-                map_bio(ms, m, bio);
-                generic_make_request(bio);
+                if (likely(m))
+                        read_async_bio(m, bio);
+                else
+                        bio_endio(bio, -EIO);
         }
 }
 
@@ -793,15 +1001,70 @@ static void do_reads(struct mirror_set *ms, struct bio_list *reads)
  * RECOVERING:  delay the io until recovery completes
  * NOSYNC:      increment pending, just write to the default mirror
  *---------------------------------------------------------------*/
+
+/* __bio_mark_nosync
+ * @ms
+ * @bio
+ * @done
+ * @error
+ *
+ * The bio was written on some mirror(s) but failed on other mirror(s).
+ * We can successfully endio the bio but should avoid the region being
+ * marked clean by setting the state RH_NOSYNC.
+ *
+ * This function is _not_ safe in interrupt context!
+ */
+static void __bio_mark_nosync(struct mirror_set *ms,
+                              struct bio *bio, unsigned done, int error)
+{
+        unsigned long flags;
+        struct region_hash *rh = &ms->rh;
+        struct dirty_log *log = ms->rh.log;
+        struct region *reg;
+        region_t region = bio_to_region(rh, bio);
+        int recovering = 0;
+
+        /* We must inform the log that the sync count has changed. */
+        log->type->set_region_sync(log, region, 0);
+        ms->in_sync = 0;
+
+        read_lock(&rh->hash_lock);
+        reg = __rh_find(rh, region);
+        read_unlock(&rh->hash_lock);
+
+        /* region hash entry should exist because write was in-flight */
+        BUG_ON(!reg);
+        BUG_ON(!list_empty(&reg->list));
+
+        spin_lock_irqsave(&rh->region_lock, flags);
+        /*
+         * Possible cases:
+         *   1) RH_DIRTY
+         *   2) RH_NOSYNC: was dirty, other preceeding writes failed
+         *   3) RH_RECOVERING: flushing pending writes
+         * Either case, the region should have not been connected to list.
+         */
+        recovering = (reg->state == RH_RECOVERING);
+        reg->state = RH_NOSYNC;
+        BUG_ON(!list_empty(&reg->list));
+        spin_unlock_irqrestore(&rh->region_lock, flags);
+
+        bio_endio(bio, error);
+        if (recovering)
+                complete_resync_work(reg, 0);
+}
+
 static void write_callback(unsigned long error, void *context)
 {
-        unsigned int i;
-        int uptodate = 1;
+        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_ms(bio);
-        bio_set_ms(bio, NULL);
+        ms = bio_get_m(bio)->ms;
+        bio_set_m(bio, NULL);
 
         /*
          * NOTE: We don't decrement the pending count here,
@@ -809,26 +1072,42 @@ static void write_callback(unsigned long error, void *context)
          * 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 (error) {
+        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)) {
                 /*
-                 * only error the io if all mirrors failed.
-                 * FIXME: bogus
+                 * Need to raise event.  Since raising
+                 * events can block, we need to do it in
+                 * the main thread.
                  */
-                uptodate = 0;
-                for (i = 0; i < ms->nr_mirrors; i++)
-                        if (!test_bit(i, &error)) {
-                                uptodate = 1;
-                                break;
-                        }
+                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)
+                        wake(ms);
+                return;
         }
-        bio_endio(bio, 0);
+out:
+        bio_endio(bio, ret);
 }
 
 static void do_write(struct mirror_set *ms, struct bio *bio)
 {
         unsigned int i;
-        struct io_region io[KCOPYD_MAX_REGIONS+1];
+        struct io_region io[ms->nr_mirrors], *dest = io;
         struct mirror *m;
         struct dm_io_request io_req = {
                 .bi_rw = WRITE,
@@ -839,15 +1118,14 @@ static void do_write(struct mirror_set *ms, struct bio *bio)
                 .client = ms->io_client,
         };
 
-        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;
-        }
+        for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++)
+                map_region(dest++, m, bio);
 
-        bio_set_ms(bio, ms);
+        /*
+         * 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));
 
         (void) dm_io(&io_req, ms->nr_mirrors, io, NULL);
 }
@@ -900,43 +1178,125 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
         /*
          * Dispatch io.
          */
-        if (unlikely(ms->log_failure))
+        if (unlikely(ms->log_failure)) {
+                spin_lock_irq(&ms->lock);
+                bio_list_merge(&ms->failures, &sync);
+                spin_unlock_irq(&ms->lock);
+        } else
                 while ((bio = bio_list_pop(&sync)))
-                        bio_endio(bio, -EIO);
-        else while ((bio = bio_list_pop(&sync)))
-                do_write(ms, bio);
+                        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->default_mirror, bio);
+                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)))
+                        __bio_mark_nosync(ms, 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);
+
+        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)
+static int _do_mirror(struct work_struct *work)
 {
         struct mirror_set *ms =container_of(work, struct mirror_set,
                                             kmirrord_work);
-        struct bio_list reads, writes;
+        struct bio_list reads, writes, failures;
+        unsigned long flags;
 
-        spin_lock(&ms->lock);
+        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);
-        spin_unlock(&ms->lock);
+        bio_list_init(&ms->failures);
+        spin_unlock_irqrestore(&ms->lock, flags);
 
         rh_update_states(&ms->rh);
         do_recovery(ms);
         do_reads(ms, &reads);
         do_writes(ms, &writes);
+        do_failures(ms, &failures);
+
+        return (ms->failures.head) ? 1 : 0;
 }
 
+static void do_mirror(struct work_struct *work)
+{
+        /*
+         * If _do_mirror returns 1, we give it
+         * another shot.  This helps for cases like
+         * 'suspend' where we call flush_workqueue
+         * and expect all work to be finished.  If
+         * a failure happens during a suspend, we
+         * couldn't issue a 'wake' because it would
+         * not be honored.  Therefore, we return '1'
+         * from _do_mirror, and retry here.
+         */
+        while (_do_mirror(work))
+                schedule();
+}
+
+
 /*-----------------------------------------------------------------
  * Target functions
  *---------------------------------------------------------------*/
@@ -965,11 +1325,23 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
         ms->nr_mirrors = nr_mirrors;
         ms->nr_regions = dm_sector_div_up(ti->len, region_size);
         ms->in_sync = 0;
-        ms->default_mirror = &ms->mirror[DEFAULT_MIRROR];
+        ms->log_failure = 0;
+        atomic_set(&ms->suspend, 0);
+        atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
+
+        len = sizeof(struct dm_raid1_read_record);
+        ms->read_record_pool = mempool_create_kmalloc_pool(MIN_READ_RECORDS,
+                                                           len);
+        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;
         }
@@ -977,6 +1349,7 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
         if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) {
                 ti->error = "Error creating dirty region hash";
                 dm_io_client_destroy(ms->io_client);
+                mempool_destroy(ms->read_record_pool);
                 kfree(ms);
                 return NULL;
         }
@@ -992,6 +1365,7 @@ static void free_context(struct mirror_set *ms, struct dm_target *ti,
 
         dm_io_client_destroy(ms->io_client);
         rh_exit(&ms->rh);
+        mempool_destroy(ms->read_record_pool);
         kfree(ms);
 }
 
@@ -1019,6 +1393,8 @@ static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
         }
 
         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;
@@ -1171,6 +1547,7 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                 goto err_free_context;
         }
         INIT_WORK(&ms->kmirrord_work, do_mirror);
+        INIT_WORK(&ms->trigger_event, trigger_event);
 
         r = parse_features(ms, argc, argv, &args_used);
         if (r)
@@ -1220,14 +1597,15 @@ static void mirror_dtr(struct dm_target *ti)
 
 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(&ms->lock);
+        spin_lock_irqsave(&ms->lock, flags);
         should_wake = !(bl->head);
         bio_list_add(bl, bio);
-        spin_unlock(&ms->lock);
+        spin_unlock_irqrestore(&ms->lock, flags);
 
         if (should_wake)
                 wake(ms);
@@ -1242,10 +1620,11 @@ 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;
-
-        map_context->ll = bio_to_region(&ms->rh, bio);
+        struct dm_raid1_read_record *read_record = NULL;
 
         if (rw == WRITE) {
+                /* Save region for mirror_end_io() handler */
+                map_context->ll = bio_to_region(&ms->rh, bio);
                 queue_bio(ms, bio, rw);
                 return DM_MAPIO_SUBMITTED;
         }
@@ -1255,28 +1634,34 @@ static int mirror_map(struct dm_target *ti, struct bio *bio,
         if (r < 0 && r != -EWOULDBLOCK)
                 return r;
 
-        if (r == -EWOULDBLOCK)  /* FIXME: ugly */
-                r = DM_MAPIO_SUBMITTED;
-
         /*
-         * 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 region is not in-sync queue the bio.
          */
-        if (!r && rw == READA)
-                return -EIO;
+        if (!r || (r == -EWOULDBLOCK)) {
+                if (rw == READA)
+                        return -EWOULDBLOCK;
 
-        if (!r) {
-                /* Pass this io over to the daemon */
                 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 (!m)
+        if (unlikely(!m))
                 return -EIO;
 
-        map_bio(ms, m, bio);
+        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;
 }
 
@@ -1285,71 +1670,173 @@ static int mirror_end_io(struct dm_target *ti, struct bio *bio,
 {
         int rw = bio_rw(bio);
         struct mirror_set *ms = (struct mirror_set *) ti->private;
-        region_t region = map_context->ll;
+        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)
-                rh_dec(&ms->rh, region);
+        if (rw == WRITE) {
+                rh_dec(&ms->rh, map_context->ll);
+                return error;
+        }
 
-        return 0;
+        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 from %s.",
+                                    m->dev->name);
+                        return -EIO;
+                }
+                DMERR("Mirror read failed from %s. Trying alternative device.",
+                      m->dev->name);
+
+                m = read_record->m;
+                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_postsuspend(struct dm_target *ti)
+static void mirror_presuspend(struct dm_target *ti)
 {
         struct mirror_set *ms = (struct mirror_set *) ti->private;
         struct dirty_log *log = ms->rh.log;
 
+        atomic_set(&ms->suspend, 1);
+
+        /*
+         * We must finish up all the work that we've
+         * generated (i.e. recovery work).
+         */
         rh_stop_recovery(&ms->rh);
 
-        /* Wait for all I/O we generated to complete */
         wait_event(_kmirrord_recovery_stopped,
                    !atomic_read(&ms->rh.recovery_in_flight));
 
+        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 dirty_log *log = ms->rh.log;
+
         if (log->type->postsuspend && log->type->postsuspend(log))
                 /* FIXME: need better error handling */
-                DMWARN("log suspend failed");
+                DMWARN("log postsuspend failed");
 }
 
 static void mirror_resume(struct dm_target *ti)
 {
-        struct mirror_set *ms = (struct mirror_set *) ti->private;
+        struct mirror_set *ms = ti->private;
         struct dirty_log *log = ms->rh.log;
+
+        atomic_set(&ms->suspend, 0);
         if (log->type->resume && log->type->resume(log))
                 /* FIXME: need better error handling */
                 DMWARN("log resume failed");
         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 dirty_log *log = ms->rh.log;
+        char buffer[ms->nr_mirrors + 1];
 
         switch (type) {
         case STATUSTYPE_INFO:
                 DMEMIT("%d ", ms->nr_mirrors);
-                for (m = 0; m < ms->nr_mirrors; m++)
+                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 0 ",
-                        (unsigned long long)ms->rh.log->type->
-                                get_sync_count(ms->rh.log),
-                        (unsigned long long)ms->nr_regions);
+                DMEMIT("%llu/%llu 1 %s ",
+                      (unsigned long long)log->type->get_sync_count(ms->rh.log),
+                      (unsigned long long)ms->nr_regions, buffer);
 
-                sz += ms->rh.log->type->status(ms->rh.log, type, result+sz, maxlen-sz);
+                sz += log->type->status(ms->rh.log, type, result+sz, maxlen-sz);
 
                 break;
 
         case STATUSTYPE_TABLE:
-                sz = ms->rh.log->type->status(ms->rh.log, type, result, maxlen);
+                sz = log->type->status(ms->rh.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);
+                               (unsigned long long)ms->mirror[m].offset);
 
                 if (ms->features & DM_RAID1_HANDLE_ERRORS)
                         DMEMIT(" 1 handle_errors");
@@ -1360,12 +1847,13 @@ static int mirror_status(struct dm_target *ti, status_type_t type,
 
 static struct target_type mirror_target = {
         .name    = "mirror",
-        .version = {1, 0, 3},
+        .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,