/*
 * 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");