3 files changed, 722 insertions, 0 deletions

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index bf1a95e3155..98d9ec85e0e 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -240,6 +240,30 @@ config DM_MIRROR
          Allow volume managers to mirror logical volumes, also
          needed for live data migration tools such as 'pvmove'.
 
+config DM_RAID
+       tristate "RAID 4/5/6 target (EXPERIMENTAL)"
+       depends on BLK_DEV_DM && EXPERIMENTAL
+       select MD_RAID456
+       select BLK_DEV_MD
+       ---help---
+         A dm target that supports RAID4, RAID5 and RAID6 mappings
+
+         A RAID-5 set of N drives with a capacity of C MB per drive provides
+         the capacity of C * (N - 1) MB, and protects against a failure
+         of a single drive. For a given sector (row) number, (N - 1) drives
+         contain data sectors, and one drive contains the parity protection.
+         For a RAID-4 set, the parity blocks are present on a single drive,
+         while a RAID-5 set distributes the parity across the drives in one
+         of the available parity distribution methods.
+
+         A RAID-6 set of N drives with a capacity of C MB per drive
+         provides the capacity of C * (N - 2) MB, and protects
+         against a failure of any two drives. For a given sector
+         (row) number, (N - 2) drives contain data sectors, and two
+         drives contains two independent redundancy syndromes.  Like
+         RAID-5, RAID-6 distributes the syndromes across the drives
+         in one of the available parity distribution methods.
+
 config DM_LOG_USERSPACE
         tristate "Mirror userspace logging (EXPERIMENTAL)"
         depends on DM_MIRROR && EXPERIMENTAL && NET
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 5e3aac41919..d0138606c2e 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_DM_SNAPSHOT)	+= dm-snapshot.o
 obj-$(CONFIG_DM_MIRROR)         += dm-mirror.o dm-log.o dm-region-hash.o
 obj-$(CONFIG_DM_LOG_USERSPACE)  += dm-log-userspace.o
 obj-$(CONFIG_DM_ZERO)           += dm-zero.o
+obj-$(CONFIG_DM_RAID)   += dm-raid.o
 
 ifeq ($(CONFIG_DM_UEVENT),y)
 dm-mod-objs                     += dm-uevent.o
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
new file mode 100644
index 00000000000..b9e1e15ef11
--- /dev/null
+++ b/drivers/md/dm-raid.c
@@ -0,0 +1,697 @@
+/*
+ * Copyright (C) 2010-2011 Neil Brown
+ * Copyright (C) 2010-2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/slab.h>
+
+#include "md.h"
+#include "raid5.h"
+#include "dm.h"
+#include "bitmap.h"
+
+#define DM_MSG_PREFIX "raid"
+
+/*
+ * If the MD doesn't support MD_SYNC_STATE_FORCED yet, then
+ * make it so the flag doesn't set anything.
+ */
+#ifndef MD_SYNC_STATE_FORCED
+#define MD_SYNC_STATE_FORCED 0
+#endif
+
+struct raid_dev {
+        /*
+         * Two DM devices, one to hold metadata and one to hold the
+         * actual data/parity.  The reason for this is to not confuse
+         * ti->len and give more flexibility in altering size and
+         * characteristics.
+         *
+         * While it is possible for this device to be associated
+         * with a different physical device than the data_dev, it
+         * is intended for it to be the same.
+         *    |--------- Physical Device ---------|
+         *    |- meta_dev -|------ data_dev ------|
+         */
+        struct dm_dev *meta_dev;
+        struct dm_dev *data_dev;
+        struct mdk_rdev_s rdev;
+};
+
+/*
+ * Flags for rs->print_flags field.
+ */
+#define DMPF_DAEMON_SLEEP      0x1
+#define DMPF_MAX_WRITE_BEHIND  0x2
+#define DMPF_SYNC              0x4
+#define DMPF_NOSYNC            0x8
+#define DMPF_STRIPE_CACHE      0x10
+#define DMPF_MIN_RECOVERY_RATE 0x20
+#define DMPF_MAX_RECOVERY_RATE 0x40
+
+struct raid_set {
+        struct dm_target *ti;
+
+        uint64_t print_flags;
+
+        struct mddev_s md;
+        struct raid_type *raid_type;
+        struct dm_target_callbacks callbacks;
+
+        struct raid_dev dev[0];
+};
+
+/* Supported raid types and properties. */
+static struct raid_type {
+        const char *name;               /* RAID algorithm. */
+        const char *descr;              /* Descriptor text for logging. */
+        const unsigned parity_devs;     /* # of parity devices. */
+        const unsigned minimal_devs;    /* minimal # of devices in set. */
+        const unsigned level;           /* RAID level. */
+        const unsigned algorithm;       /* RAID algorithm. */
+} raid_types[] = {
+        {"raid4",    "RAID4 (dedicated parity disk)",   1, 2, 5, ALGORITHM_PARITY_0},
+        {"raid5_la", "RAID5 (left asymmetric)",         1, 2, 5, ALGORITHM_LEFT_ASYMMETRIC},
+        {"raid5_ra", "RAID5 (right asymmetric)",        1, 2, 5, ALGORITHM_RIGHT_ASYMMETRIC},
+        {"raid5_ls", "RAID5 (left symmetric)",          1, 2, 5, ALGORITHM_LEFT_SYMMETRIC},
+        {"raid5_rs", "RAID5 (right symmetric)",         1, 2, 5, ALGORITHM_RIGHT_SYMMETRIC},
+        {"raid6_zr", "RAID6 (zero restart)",            2, 4, 6, ALGORITHM_ROTATING_ZERO_RESTART},
+        {"raid6_nr", "RAID6 (N restart)",               2, 4, 6, ALGORITHM_ROTATING_N_RESTART},
+        {"raid6_nc", "RAID6 (N continue)",              2, 4, 6, ALGORITHM_ROTATING_N_CONTINUE}
+};
+
+static struct raid_type *get_raid_type(char *name)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(raid_types); i++)
+                if (!strcmp(raid_types[i].name, name))
+                        return &raid_types[i];
+
+        return NULL;
+}
+
+static struct raid_set *context_alloc(struct dm_target *ti, struct raid_type *raid_type, unsigned raid_devs)
+{
+        unsigned i;
+        struct raid_set *rs;
+        sector_t sectors_per_dev;
+
+        if (raid_devs <= raid_type->parity_devs) {
+                ti->error = "Insufficient number of devices";
+                return ERR_PTR(-EINVAL);
+        }
+
+        sectors_per_dev = ti->len;
+        if (sector_div(sectors_per_dev, (raid_devs - raid_type->parity_devs))) {
+                ti->error = "Target length not divisible by number of data devices";
+                return ERR_PTR(-EINVAL);
+        }
+
+        rs = kzalloc(sizeof(*rs) + raid_devs * sizeof(rs->dev[0]), GFP_KERNEL);
+        if (!rs) {
+                ti->error = "Cannot allocate raid context";
+                return ERR_PTR(-ENOMEM);
+        }
+
+        mddev_init(&rs->md);
+
+        rs->ti = ti;
+        rs->raid_type = raid_type;
+        rs->md.raid_disks = raid_devs;
+        rs->md.level = raid_type->level;
+        rs->md.new_level = rs->md.level;
+        rs->md.dev_sectors = sectors_per_dev;
+        rs->md.layout = raid_type->algorithm;
+        rs->md.new_layout = rs->md.layout;
+        rs->md.delta_disks = 0;
+        rs->md.recovery_cp = 0;
+
+        for (i = 0; i < raid_devs; i++)
+                md_rdev_init(&rs->dev[i].rdev);
+
+        /*
+         * Remaining items to be initialized by further RAID params:
+         *  rs->md.persistent
+         *  rs->md.external
+         *  rs->md.chunk_sectors
+         *  rs->md.new_chunk_sectors
+         */
+
+        return rs;
+}
+
+static void context_free(struct raid_set *rs)
+{
+        int i;
+
+        for (i = 0; i < rs->md.raid_disks; i++)
+                if (rs->dev[i].data_dev)
+                        dm_put_device(rs->ti, rs->dev[i].data_dev);
+
+        kfree(rs);
+}
+
+/*
+ * For every device we have two words
+ *  <meta_dev>: meta device name or '-' if missing
+ *  <data_dev>: data device name or '-' if missing
+ *
+ * This code parses those words.
+ */
+static int dev_parms(struct raid_set *rs, char **argv)
+{
+        int i;
+        int rebuild = 0;
+        int metadata_available = 0;
+        int ret = 0;
+
+        for (i = 0; i < rs->md.raid_disks; i++, argv += 2) {
+                rs->dev[i].rdev.raid_disk = i;
+
+                rs->dev[i].meta_dev = NULL;
+                rs->dev[i].data_dev = NULL;
+
+                /*
+                 * There are no offsets, since there is a separate device
+                 * for data and metadata.
+                 */
+                rs->dev[i].rdev.data_offset = 0;
+                rs->dev[i].rdev.mddev = &rs->md;
+
+                if (strcmp(argv[0], "-")) {
+                        rs->ti->error = "Metadata devices not supported";
+                        return -EINVAL;
+                }
+
+                if (!strcmp(argv[1], "-")) {
+                        if (!test_bit(In_sync, &rs->dev[i].rdev.flags) &&
+                            (!rs->dev[i].rdev.recovery_offset)) {
+                                rs->ti->error = "Drive designated for rebuild not specified";
+                                return -EINVAL;
+                        }
+
+                        continue;
+                }
+
+                ret = dm_get_device(rs->ti, argv[1],
+                                    dm_table_get_mode(rs->ti->table),
+                                    &rs->dev[i].data_dev);
+                if (ret) {
+                        rs->ti->error = "RAID device lookup failure";
+                        return ret;
+                }
+
+                rs->dev[i].rdev.bdev = rs->dev[i].data_dev->bdev;
+                list_add(&rs->dev[i].rdev.same_set, &rs->md.disks);
+                if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
+                        rebuild++;
+        }
+
+        if (metadata_available) {
+                rs->md.external = 0;
+                rs->md.persistent = 1;
+                rs->md.major_version = 2;
+        } else if (rebuild && !rs->md.recovery_cp) {
+                /*
+                 * Without metadata, we will not be able to tell if the array
+                 * is in-sync or not - we must assume it is not.  Therefore,
+                 * it is impossible to rebuild a drive.
+                 *
+                 * Even if there is metadata, the on-disk information may
+                 * indicate that the array is not in-sync and it will then
+                 * fail at that time.
+                 *
+                 * User could specify 'nosync' option if desperate.
+                 */
+                DMERR("Unable to rebuild drive while array is not in-sync");
+                rs->ti->error = "RAID device lookup failure";
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+/*
+ * Possible arguments are...
+ * RAID456:
+ *      <chunk_size> [optional_args]
+ *
+ * Optional args:
+ *    [[no]sync]                        Force or prevent recovery of the entire array
+ *    [rebuild <idx>]                   Rebuild the drive indicated by the index
+ *    [daemon_sleep <ms>]               Time between bitmap daemon work to clear bits
+ *    [min_recovery_rate <kB/sec/disk>] Throttle RAID initialization
+ *    [max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
+ *    [max_write_behind <sectors>]      See '-write-behind=' (man mdadm)
+ *    [stripe_cache <sectors>]          Stripe cache size for higher RAIDs
+ */
+static int parse_raid_params(struct raid_set *rs, char **argv,
+                             unsigned num_raid_params)
+{
+        unsigned i, rebuild_cnt = 0;
+        unsigned long value;
+        char *key;
+
+        /*
+         * First, parse the in-order required arguments
+         */
+        if ((strict_strtoul(argv[0], 10, &value) < 0) ||
+            !is_power_of_2(value) || (value < 8)) {
+                rs->ti->error = "Bad chunk size";
+                return -EINVAL;
+        }
+
+        rs->md.new_chunk_sectors = rs->md.chunk_sectors = value;
+        argv++;
+        num_raid_params--;
+
+        /*
+         * Second, parse the unordered optional arguments
+         */
+        for (i = 0; i < rs->md.raid_disks; i++)
+                set_bit(In_sync, &rs->dev[i].rdev.flags);
+
+        for (i = 0; i < num_raid_params; i++) {
+                if (!strcmp(argv[i], "nosync")) {
+                        rs->md.recovery_cp = MaxSector;
+                        rs->print_flags |= DMPF_NOSYNC;
+                        rs->md.flags |= MD_SYNC_STATE_FORCED;
+                        continue;
+                }
+                if (!strcmp(argv[i], "sync")) {
+                        rs->md.recovery_cp = 0;
+                        rs->print_flags |= DMPF_SYNC;
+                        rs->md.flags |= MD_SYNC_STATE_FORCED;
+                        continue;
+                }
+
+                /* The rest of the optional arguments come in key/value pairs */
+                if ((i + 1) >= num_raid_params) {
+                        rs->ti->error = "Wrong number of raid parameters given";
+                        return -EINVAL;
+                }
+
+                key = argv[i++];
+                if (strict_strtoul(argv[i], 10, &value) < 0) {
+                        rs->ti->error = "Bad numerical argument given in raid params";
+                        return -EINVAL;
+                }
+
+                if (!strcmp(key, "rebuild")) {
+                        if (++rebuild_cnt > rs->raid_type->parity_devs) {
+                                rs->ti->error = "Too many rebuild drives given";
+                                return -EINVAL;
+                        }
+                        if (value > rs->md.raid_disks) {
+                                rs->ti->error = "Invalid rebuild index given";
+                                return -EINVAL;
+                        }
+                        clear_bit(In_sync, &rs->dev[value].rdev.flags);
+                        rs->dev[value].rdev.recovery_offset = 0;
+                } else if (!strcmp(key, "max_write_behind")) {
+                        rs->print_flags |= DMPF_MAX_WRITE_BEHIND;
+
+                        /*
+                         * In device-mapper, we specify things in sectors, but
+                         * MD records this value in kB
+                         */
+                        value /= 2;
+                        if (value > COUNTER_MAX) {
+                                rs->ti->error = "Max write-behind limit out of range";
+                                return -EINVAL;
+                        }
+                        rs->md.bitmap_info.max_write_behind = value;
+                } else if (!strcmp(key, "daemon_sleep")) {
+                        rs->print_flags |= DMPF_DAEMON_SLEEP;
+                        if (!value || (value > MAX_SCHEDULE_TIMEOUT)) {
+                                rs->ti->error = "daemon sleep period out of range";
+                                return -EINVAL;
+                        }
+                        rs->md.bitmap_info.daemon_sleep = value;
+                } else if (!strcmp(key, "stripe_cache")) {
+                        rs->print_flags |= DMPF_STRIPE_CACHE;
+
+                        /*
+                         * In device-mapper, we specify things in sectors, but
+                         * MD records this value in kB
+                         */
+                        value /= 2;
+
+                        if (rs->raid_type->level < 5) {
+                                rs->ti->error = "Inappropriate argument: stripe_cache";
+                                return -EINVAL;
+                        }
+                        if (raid5_set_cache_size(&rs->md, (int)value)) {
+                                rs->ti->error = "Bad stripe_cache size";
+                                return -EINVAL;
+                        }
+                } else if (!strcmp(key, "min_recovery_rate")) {
+                        rs->print_flags |= DMPF_MIN_RECOVERY_RATE;
+                        if (value > INT_MAX) {
+                                rs->ti->error = "min_recovery_rate out of range";
+                                return -EINVAL;
+                        }
+                        rs->md.sync_speed_min = (int)value;
+                } else if (!strcmp(key, "max_recovery_rate")) {
+                        rs->print_flags |= DMPF_MAX_RECOVERY_RATE;
+                        if (value > INT_MAX) {
+                                rs->ti->error = "max_recovery_rate out of range";
+                                return -EINVAL;
+                        }
+                        rs->md.sync_speed_max = (int)value;
+                } else {
+                        DMERR("Unable to parse RAID parameter: %s", key);
+                        rs->ti->error = "Unable to parse RAID parameters";
+                        return -EINVAL;
+                }
+        }
+
+        /* Assume there are no metadata devices until the drives are parsed */
+        rs->md.persistent = 0;
+        rs->md.external = 1;
+
+        return 0;
+}
+
+static void do_table_event(struct work_struct *ws)
+{
+        struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);
+
+        dm_table_event(rs->ti->table);
+}
+
+static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
+{
+        struct raid_set *rs = container_of(cb, struct raid_set, callbacks);
+
+        return md_raid5_congested(&rs->md, bits);
+}
+
+static void raid_unplug(struct dm_target_callbacks *cb)
+{
+        struct raid_set *rs = container_of(cb, struct raid_set, callbacks);
+
+        md_raid5_unplug_device(rs->md.private);
+}
+
+/*
+ * Construct a RAID4/5/6 mapping:
+ * Args:
+ *      <raid_type> <#raid_params> <raid_params>                \
+ *      <#raid_devs> { <meta_dev1> <dev1> .. <meta_devN> <devN> }
+ *
+ * ** metadata devices are not supported yet, use '-' instead **
+ *
+ * <raid_params> varies by <raid_type>.  See 'parse_raid_params' for
+ * details on possible <raid_params>.
+ */
+static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
+{
+        int ret;
+        struct raid_type *rt;
+        unsigned long num_raid_params, num_raid_devs;
+        struct raid_set *rs = NULL;
+
+        /* Must have at least <raid_type> <#raid_params> */
+        if (argc < 2) {
+                ti->error = "Too few arguments";
+                return -EINVAL;
+        }
+
+        /* raid type */
+        rt = get_raid_type(argv[0]);
+        if (!rt) {
+                ti->error = "Unrecognised raid_type";
+                return -EINVAL;
+        }
+        argc--;
+        argv++;
+
+        /* number of RAID parameters */
+        if (strict_strtoul(argv[0], 10, &num_raid_params) < 0) {
+                ti->error = "Cannot understand number of RAID parameters";
+                return -EINVAL;
+        }
+        argc--;
+        argv++;
+
+        /* Skip over RAID params for now and find out # of devices */
+        if (num_raid_params + 1 > argc) {
+                ti->error = "Arguments do not agree with counts given";
+                return -EINVAL;
+        }
+
+        if ((strict_strtoul(argv[num_raid_params], 10, &num_raid_devs) < 0) ||
+            (num_raid_devs >= INT_MAX)) {
+                ti->error = "Cannot understand number of raid devices";
+                return -EINVAL;
+        }
+
+        rs = context_alloc(ti, rt, (unsigned)num_raid_devs);
+        if (IS_ERR(rs))
+                return PTR_ERR(rs);
+
+        ret = parse_raid_params(rs, argv, (unsigned)num_raid_params);
+        if (ret)
+                goto bad;
+
+        ret = -EINVAL;
+
+        argc -= num_raid_params + 1; /* +1: we already have num_raid_devs */
+        argv += num_raid_params + 1;
+
+        if (argc != (num_raid_devs * 2)) {
+                ti->error = "Supplied RAID devices does not match the count given";
+                goto bad;
+        }
+
+        ret = dev_parms(rs, argv);
+        if (ret)
+                goto bad;
+
+        INIT_WORK(&rs->md.event_work, do_table_event);
+        ti->split_io = rs->md.chunk_sectors;
+        ti->private = rs;
+
+        mutex_lock(&rs->md.reconfig_mutex);
+        ret = md_run(&rs->md);
+        rs->md.in_sync = 0; /* Assume already marked dirty */
+        mutex_unlock(&rs->md.reconfig_mutex);
+
+        if (ret) {
+                ti->error = "Fail to run raid array";
+                goto bad;
+        }
+
+        rs->callbacks.congested_fn = raid_is_congested;
+        rs->callbacks.unplug_fn = raid_unplug;
+        dm_table_add_target_callbacks(ti->table, &rs->callbacks);
+
+        return 0;
+
+bad:
+        context_free(rs);
+
+        return ret;
+}
+
+static void raid_dtr(struct dm_target *ti)
+{
+        struct raid_set *rs = ti->private;
+
+        list_del_init(&rs->callbacks.list);
+        md_stop(&rs->md);
+        context_free(rs);
+}
+
+static int raid_map(struct dm_target *ti, struct bio *bio, union map_info *map_context)
+{
+        struct raid_set *rs = ti->private;
+        mddev_t *mddev = &rs->md;
+
+        mddev->pers->make_request(mddev, bio);
+
+        return DM_MAPIO_SUBMITTED;
+}
+
+static int raid_status(struct dm_target *ti, status_type_t type,
+                       char *result, unsigned maxlen)
+{
+        struct raid_set *rs = ti->private;
+        unsigned raid_param_cnt = 1; /* at least 1 for chunksize */
+        unsigned sz = 0;
+        int i;
+        sector_t sync;
+
+        switch (type) {
+        case STATUSTYPE_INFO:
+                DMEMIT("%s %d ", rs->raid_type->name, rs->md.raid_disks);
+
+                for (i = 0; i < rs->md.raid_disks; i++) {
+                        if (test_bit(Faulty, &rs->dev[i].rdev.flags))
+                                DMEMIT("D");
+                        else if (test_bit(In_sync, &rs->dev[i].rdev.flags))
+                                DMEMIT("A");
+                        else
+                                DMEMIT("a");
+                }
+
+                if (test_bit(MD_RECOVERY_RUNNING, &rs->md.recovery))
+                        sync = rs->md.curr_resync_completed;
+                else
+                        sync = rs->md.recovery_cp;
+
+                if (sync > rs->md.resync_max_sectors)
+                        sync = rs->md.resync_max_sectors;
+
+                DMEMIT(" %llu/%llu",
+                       (unsigned long long) sync,
+                       (unsigned long long) rs->md.resync_max_sectors);
+
+                break;
+        case STATUSTYPE_TABLE:
+                /* The string you would use to construct this array */
+                for (i = 0; i < rs->md.raid_disks; i++)
+                        if (rs->dev[i].data_dev &&
+                            !test_bit(In_sync, &rs->dev[i].rdev.flags))
+                                raid_param_cnt++; /* for rebuilds */
+
+                raid_param_cnt += (hweight64(rs->print_flags) * 2);
+                if (rs->print_flags & (DMPF_SYNC | DMPF_NOSYNC))
+                        raid_param_cnt--;
+
+                DMEMIT("%s %u %u", rs->raid_type->name,
+                       raid_param_cnt, rs->md.chunk_sectors);
+
+                if ((rs->print_flags & DMPF_SYNC) &&
+                    (rs->md.recovery_cp == MaxSector))
+                        DMEMIT(" sync");
+                if (rs->print_flags & DMPF_NOSYNC)
+                        DMEMIT(" nosync");
+
+                for (i = 0; i < rs->md.raid_disks; i++)
+                        if (rs->dev[i].data_dev &&
+                            !test_bit(In_sync, &rs->dev[i].rdev.flags))
+                                DMEMIT(" rebuild %u", i);
+
+                if (rs->print_flags & DMPF_DAEMON_SLEEP)
+                        DMEMIT(" daemon_sleep %lu",
+                               rs->md.bitmap_info.daemon_sleep);
+
+                if (rs->print_flags & DMPF_MIN_RECOVERY_RATE)
+                        DMEMIT(" min_recovery_rate %d", rs->md.sync_speed_min);
+
+                if (rs->print_flags & DMPF_MAX_RECOVERY_RATE)
+                        DMEMIT(" max_recovery_rate %d", rs->md.sync_speed_max);
+
+                if (rs->print_flags & DMPF_MAX_WRITE_BEHIND)
+                        DMEMIT(" max_write_behind %lu",
+                               rs->md.bitmap_info.max_write_behind);
+
+                if (rs->print_flags & DMPF_STRIPE_CACHE) {
+                        raid5_conf_t *conf = rs->md.private;
+
+                        /* convert from kiB to sectors */
+                        DMEMIT(" stripe_cache %d",
+                               conf ? conf->max_nr_stripes * 2 : 0);
+                }
+
+                DMEMIT(" %d", rs->md.raid_disks);
+                for (i = 0; i < rs->md.raid_disks; i++) {
+                        DMEMIT(" -"); /* metadata device */
+
+                        if (rs->dev[i].data_dev)
+                                DMEMIT(" %s", rs->dev[i].data_dev->name);
+                        else
+                                DMEMIT(" -");
+                }
+        }
+
+        return 0;
+}
+
+static int raid_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
+{
+        struct raid_set *rs = ti->private;
+        unsigned i;
+        int ret = 0;
+
+        for (i = 0; !ret && i < rs->md.raid_disks; i++)
+                if (rs->dev[i].data_dev)
+                        ret = fn(ti,
+                                 rs->dev[i].data_dev,
+                                 0, /* No offset on data devs */
+                                 rs->md.dev_sectors,
+                                 data);
+
+        return ret;
+}
+
+static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+        struct raid_set *rs = ti->private;
+        unsigned chunk_size = rs->md.chunk_sectors << 9;
+        raid5_conf_t *conf = rs->md.private;
+
+        blk_limits_io_min(limits, chunk_size);
+        blk_limits_io_opt(limits, chunk_size * (conf->raid_disks - conf->max_degraded));
+}
+
+static void raid_presuspend(struct dm_target *ti)
+{
+        struct raid_set *rs = ti->private;
+
+        md_stop_writes(&rs->md);
+}
+
+static void raid_postsuspend(struct dm_target *ti)
+{
+        struct raid_set *rs = ti->private;
+
+        mddev_suspend(&rs->md);
+}
+
+static void raid_resume(struct dm_target *ti)
+{
+        struct raid_set *rs = ti->private;
+
+        mddev_resume(&rs->md);
+}
+
+static struct target_type raid_target = {
+        .name = "raid",
+        .version = {1, 0, 0},
+        .module = THIS_MODULE,
+        .ctr = raid_ctr,
+        .dtr = raid_dtr,
+        .map = raid_map,
+        .status = raid_status,
+        .iterate_devices = raid_iterate_devices,
+        .io_hints = raid_io_hints,
+        .presuspend = raid_presuspend,
+        .postsuspend = raid_postsuspend,
+        .resume = raid_resume,
+};
+
+static int __init dm_raid_init(void)
+{
+        return dm_register_target(&raid_target);
+}
+
+static void __exit dm_raid_exit(void)
+{
+        dm_unregister_target(&raid_target);
+}
+
+module_init(dm_raid_init);
+module_exit(dm_raid_exit);
+
+MODULE_DESCRIPTION(DM_NAME " raid4/5/6 target");
+MODULE_ALIAS("dm-raid4");
+MODULE_ALIAS("dm-raid5");
+MODULE_ALIAS("dm-raid6");
+MODULE_AUTHOR("Neil Brown <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");