// SPDX-License-Identifier: GPL-2.0-or-later
/*
   raid0.c : Multiple Devices driver for Linux
             Copyright (C) 1994-96 Marc ZYNGIER
             <zyngier@ufr-info-p7.ibp.fr> or
             <maz@gloups.fdn.fr>
             Copyright (C) 1999, 2000 Ingo Molnar, Red Hat

   RAID-0 management functions.

*/

#include <linux/blkdev.h>
#include <linux/seq_file.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <trace/events/block.h>
#include "md.h"
#include "raid0.h"
#include "raid5.h"

static int default_layout = 0;
module_param(default_layout, int, 0644);

#define UNSUPPORTED_MDDEV_FLAGS         \
        ((1L << MD_HAS_JOURNAL) |       \
         (1L << MD_JOURNAL_CLEAN) |     \
         (1L << MD_FAILFAST_SUPPORTED) |\
         (1L << MD_HAS_PPL) |           \
         (1L << MD_HAS_MULTIPLE_PPLS) | \
         (1L << MD_FAILLAST_DEV) |      \
         (1L << MD_SERIALIZE_POLICY))

/*
 * inform the user of the raid configuration
*/
static void dump_zones(struct mddev *mddev)
{
        int j, k;
        sector_t zone_size = 0;
        sector_t zone_start = 0;
        struct r0conf *conf = mddev->private;
        int raid_disks = conf->strip_zone[0].nb_dev;
        pr_debug("md: RAID0 configuration for %s - %d zone%s\n",
                 mdname(mddev),
                 conf->nr_strip_zones, conf->nr_strip_zones==1?"":"s");
        for (j = 0; j < conf->nr_strip_zones; j++) {
                char line[200];
                int len = 0;

                for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
                        len += scnprintf(line+len, 200-len, "%s%pg", k?"/":"",
                                conf->devlist[j * raid_disks + k]->bdev);
                pr_debug("md: zone%d=[%s]\n", j, line);

                zone_size  = conf->strip_zone[j].zone_end - zone_start;
                pr_debug("      zone-offset=%10lluKB, device-offset=%10lluKB, size=%10lluKB\n",
                        (unsigned long long)zone_start>>1,
                        (unsigned long long)conf->strip_zone[j].dev_start>>1,
                        (unsigned long long)zone_size>>1);
                zone_start = conf->strip_zone[j].zone_end;
        }
}

static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
{
        int i, c, err;
        sector_t curr_zone_end, sectors;
        struct md_rdev *smallest, *rdev1, *rdev2, *rdev, **dev;
        struct strip_zone *zone;
        int cnt;
        struct r0conf *conf = kzalloc_obj(*conf);
        unsigned int blksize = 512;

        if (!mddev_is_dm(mddev))
                blksize = queue_logical_block_size(mddev->gendisk->queue);

        *private_conf = ERR_PTR(-ENOMEM);
        if (!conf)
                return -ENOMEM;
        rdev_for_each(rdev1, mddev) {
                pr_debug("md/raid0:%s: looking at %pg\n",
                         mdname(mddev),
                         rdev1->bdev);
                c = 0;

                /* round size to chunk_size */
                sectors = rdev1->sectors;
                sector_div(sectors, mddev->chunk_sectors);
                rdev1->sectors = sectors * mddev->chunk_sectors;

                if (mddev_is_dm(mddev))
                        blksize = max(blksize, queue_logical_block_size(
                                      rdev1->bdev->bd_disk->queue));

                rdev_for_each(rdev2, mddev) {
                        pr_debug("md/raid0:%s:   comparing %pg(%llu)"
                                 " with %pg(%llu)\n",
                                 mdname(mddev),
                                 rdev1->bdev,
                                 (unsigned long long)rdev1->sectors,
                                 rdev2->bdev,
                                 (unsigned long long)rdev2->sectors);
                        if (rdev2 == rdev1) {
                                pr_debug("md/raid0:%s:   END\n",
                                         mdname(mddev));
                                break;
                        }
                        if (rdev2->sectors == rdev1->sectors) {
                                /*
                                 * Not unique, don't count it as a new
                                 * group
                                 */
                                pr_debug("md/raid0:%s:   EQUAL\n",
                                         mdname(mddev));
                                c = 1;
                                break;
                        }
                        pr_debug("md/raid0:%s:   NOT EQUAL\n",
                                 mdname(mddev));
                }
                if (!c) {
                        pr_debug("md/raid0:%s:   ==> UNIQUE\n",
                                 mdname(mddev));
                        conf->nr_strip_zones++;
                        pr_debug("md/raid0:%s: %d zones\n",
                                 mdname(mddev), conf->nr_strip_zones);
                }
        }
        pr_debug("md/raid0:%s: FINAL %d zones\n",
                 mdname(mddev), conf->nr_strip_zones);

        /*
         * now since we have the hard sector sizes, we can make sure
         * chunk size is a multiple of that sector size
         */
        if ((mddev->chunk_sectors << 9) % blksize) {
                pr_warn("md/raid0:%s: chunk_size of %d not multiple of block size %d\n",
                        mdname(mddev),
                        mddev->chunk_sectors << 9, blksize);
                err = -EINVAL;
                goto abort;
        }

        err = -ENOMEM;
        conf->strip_zone = kzalloc_objs(struct strip_zone, conf->nr_strip_zones);
        if (!conf->strip_zone)
                goto abort;
        conf->devlist = kzalloc(array3_size(sizeof(struct md_rdev *),
                                            conf->nr_strip_zones,
                                            mddev->raid_disks),
                                GFP_KERNEL);
        if (!conf->devlist)
                goto abort;

        /* The first zone must contain all devices, so here we check that
         * there is a proper alignment of slots to devices and find them all
         */
        zone = &conf->strip_zone[0];
        cnt = 0;
        smallest = NULL;
        dev = conf->devlist;
        err = -EINVAL;
        rdev_for_each(rdev1, mddev) {
                int j = rdev1->raid_disk;

                if (mddev->level == 10) {
                        /* taking over a raid10-n2 array */
                        j /= 2;
                        rdev1->new_raid_disk = j;
                }

                if (mddev->level == 1) {
                        /* taiking over a raid1 array-
                         * we have only one active disk
                         */
                        j = 0;
                        rdev1->new_raid_disk = j;
                }

                if (j < 0) {
                        pr_warn("md/raid0:%s: remove inactive devices before converting to RAID0\n",
                                mdname(mddev));
                        goto abort;
                }
                if (j >= mddev->raid_disks) {
                        pr_warn("md/raid0:%s: bad disk number %d - aborting!\n",
                                mdname(mddev), j);
                        goto abort;
                }
                if (dev[j]) {
                        pr_warn("md/raid0:%s: multiple devices for %d - aborting!\n",
                                mdname(mddev), j);
                        goto abort;
                }
                dev[j] = rdev1;

                if (!smallest || (rdev1->sectors < smallest->sectors))
                        smallest = rdev1;
                cnt++;
        }
        if (cnt != mddev->raid_disks) {
                pr_warn("md/raid0:%s: too few disks (%d of %d) - aborting!\n",
                        mdname(mddev), cnt, mddev->raid_disks);
                goto abort;
        }
        zone->nb_dev = cnt;
        zone->zone_end = smallest->sectors * cnt;

        curr_zone_end = zone->zone_end;

        /* now do the other zones */
        for (i = 1; i < conf->nr_strip_zones; i++)
        {
                int j;

                zone = conf->strip_zone + i;
                dev = conf->devlist + i * mddev->raid_disks;

                pr_debug("md/raid0:%s: zone %d\n", mdname(mddev), i);
                zone->dev_start = smallest->sectors;
                smallest = NULL;
                c = 0;

                for (j=0; j<cnt; j++) {
                        rdev = conf->devlist[j];
                        if (rdev->sectors <= zone->dev_start) {
                                pr_debug("md/raid0:%s: checking %pg ... nope\n",
                                         mdname(mddev),
                                         rdev->bdev);
                                continue;
                        }
                        pr_debug("md/raid0:%s: checking %pg ..."
                                 " contained as device %d\n",
                                 mdname(mddev),
                                 rdev->bdev, c);
                        dev[c] = rdev;
                        c++;
                        if (!smallest || rdev->sectors < smallest->sectors) {
                                smallest = rdev;
                                pr_debug("md/raid0:%s:  (%llu) is smallest!.\n",
                                         mdname(mddev),
                                         (unsigned long long)rdev->sectors);
                        }
                }

                zone->nb_dev = c;
                sectors = (smallest->sectors - zone->dev_start) * c;
                pr_debug("md/raid0:%s: zone->nb_dev: %d, sectors: %llu\n",
                         mdname(mddev),
                         zone->nb_dev, (unsigned long long)sectors);

                curr_zone_end += sectors;
                zone->zone_end = curr_zone_end;

                pr_debug("md/raid0:%s: current zone start: %llu\n",
                         mdname(mddev),
                         (unsigned long long)smallest->sectors);
        }

        if (conf->nr_strip_zones == 1 || conf->strip_zone[1].nb_dev == 1) {
                conf->layout = RAID0_ORIG_LAYOUT;
        } else if (mddev->layout == RAID0_ORIG_LAYOUT ||
                   mddev->layout == RAID0_ALT_MULTIZONE_LAYOUT) {
                conf->layout = mddev->layout;
        } else if (default_layout == RAID0_ORIG_LAYOUT ||
                   default_layout == RAID0_ALT_MULTIZONE_LAYOUT) {
                conf->layout = default_layout;
        } else {
                pr_err("md/raid0:%s: cannot assemble multi-zone RAID0 with default_layout setting\n",
                       mdname(mddev));
                pr_err("md/raid0: please set raid0.default_layout to 1 or 2\n");
                err = -EOPNOTSUPP;
                goto abort;
        }

        if (conf->layout == RAID0_ORIG_LAYOUT) {
                for (i = 1; i < conf->nr_strip_zones; i++) {
                        sector_t first_sector = conf->strip_zone[i-1].zone_end;

                        sector_div(first_sector, mddev->chunk_sectors);
                        zone = conf->strip_zone + i;
                        /* disk_shift is first disk index used in the zone */
                        zone->disk_shift = sector_div(first_sector,
                                                      zone->nb_dev);
                }
        }

        pr_debug("md/raid0:%s: done.\n", mdname(mddev));
        *private_conf = conf;

        return 0;
abort:
        kfree(conf->strip_zone);
        kfree(conf->devlist);
        kfree(conf);
        *private_conf = ERR_PTR(err);
        return err;
}

/* Find the zone which holds a particular offset
 * Update *sectorp to be an offset in that zone
 */
static struct strip_zone *find_zone(struct r0conf *conf,
                                    sector_t *sectorp)
{
        int i;
        struct strip_zone *z = conf->strip_zone;
        sector_t sector = *sectorp;

        for (i = 0; i < conf->nr_strip_zones; i++)
                if (sector < z[i].zone_end) {
                        if (i)
                                *sectorp = sector - z[i-1].zone_end;
                        return z + i;
                }
        BUG();
}

/*
 * remaps the bio to the target device. we separate two flows.
 * power 2 flow and a general flow for the sake of performance
*/
static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
                                sector_t sector, sector_t *sector_offset)
{
        unsigned int sect_in_chunk;
        sector_t chunk;
        struct r0conf *conf = mddev->private;
        int raid_disks = conf->strip_zone[0].nb_dev;
        unsigned int chunk_sects = mddev->chunk_sectors;

        if (is_power_of_2(chunk_sects)) {
                int chunksect_bits = ffz(~chunk_sects);
                /* find the sector offset inside the chunk */
                sect_in_chunk  = sector & (chunk_sects - 1);
                sector >>= chunksect_bits;
                /* chunk in zone */
                chunk = *sector_offset;
                /* quotient is the chunk in real device*/
                sector_div(chunk, zone->nb_dev << chunksect_bits);
        } else{
                sect_in_chunk = sector_div(sector, chunk_sects);
                chunk = *sector_offset;
                sector_div(chunk, chunk_sects * zone->nb_dev);
        }
        /*
        *  position the bio over the real device
        *  real sector = chunk in device + starting of zone
        *       + the position in the chunk
        */
        *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
        return conf->devlist[(zone - conf->strip_zone)*raid_disks
                             + sector_div(sector, zone->nb_dev)];
}

static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
{
        sector_t array_sectors = 0;
        struct md_rdev *rdev;

        WARN_ONCE(sectors || raid_disks,
                  "%s does not support generic reshape\n", __func__);

        rdev_for_each(rdev, mddev)
                array_sectors += (rdev->sectors &
                                  ~(sector_t)(mddev->chunk_sectors-1));

        return array_sectors;
}

static void raid0_free(struct mddev *mddev, void *priv)
{
        struct r0conf *conf = priv;

        kfree(conf->strip_zone);
        kfree(conf->devlist);
        kfree(conf);
}

static int raid0_set_limits(struct mddev *mddev)
{
        struct queue_limits lim;
        int err;

        md_init_stacking_limits(&lim);
        lim.max_hw_sectors = mddev->chunk_sectors;
        lim.max_write_zeroes_sectors = mddev->chunk_sectors;
        lim.max_hw_wzeroes_unmap_sectors = mddev->chunk_sectors;
        lim.logical_block_size = mddev->logical_block_size;
        lim.io_min = mddev->chunk_sectors << 9;
        lim.io_opt = lim.io_min * mddev->raid_disks;
        lim.chunk_sectors = mddev->chunk_sectors;
        lim.features |= BLK_FEAT_ATOMIC_WRITES;
        err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
        if (err)
                return err;
        return queue_limits_set(mddev->gendisk->queue, &lim);
}

static int raid0_run(struct mddev *mddev)
{
        struct r0conf *conf;
        int ret;

        if (mddev->chunk_sectors == 0) {
                pr_warn("md/raid0:%s: chunk size must be set.\n", mdname(mddev));
                return -EINVAL;
        }
        if (md_check_no_bitmap(mddev))
                return -EINVAL;

        if (!mddev_is_dm(mddev)) {
                ret = raid0_set_limits(mddev);
                if (ret)
                        return ret;
        }

        /* if private is not null, we are here after takeover */
        if (mddev->private == NULL) {
                ret = create_strip_zones(mddev, &conf);
                if (ret < 0)
                        return ret;
                mddev->private = conf;
        }
        conf = mddev->private;

        /* calculate array device size */
        md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));

        pr_debug("md/raid0:%s: md_size is %llu sectors.\n",
                 mdname(mddev),
                 (unsigned long long)mddev->array_sectors);

        dump_zones(mddev);

        return md_integrity_register(mddev);
}

/*
 * Convert disk_index to the disk order in which it is read/written.
 *  For example, if we have 4 disks, they are numbered 0,1,2,3. If we
 *  write the disks starting at disk 3, then the read/write order would
 *  be disk 3, then 0, then 1, and then disk 2 and we want map_disk_shift()
 *  to map the disks as follows 0,1,2,3 => 1,2,3,0. So disk 0 would map
 *  to 1, 1 to 2, 2 to 3, and 3 to 0. That way we can compare disks in
 *  that 'output' space to understand the read/write disk ordering.
 */
static int map_disk_shift(int disk_index, int num_disks, int disk_shift)
{
        return ((disk_index + num_disks - disk_shift) % num_disks);
}

static void raid0_handle_discard(struct mddev *mddev, struct bio *bio)
{
        struct r0conf *conf = mddev->private;
        struct strip_zone *zone;
        sector_t start = bio->bi_iter.bi_sector;
        sector_t end;
        unsigned int stripe_size;
        sector_t first_stripe_index, last_stripe_index;
        sector_t start_disk_offset;
        unsigned int start_disk_index;
        sector_t end_disk_offset;
        unsigned int end_disk_index;
        unsigned int disk;
        sector_t orig_start, orig_end;

        orig_start = start;
        zone = find_zone(conf, &start);

        if (bio_end_sector(bio) > zone->zone_end) {
                bio = bio_submit_split_bioset(bio,
                                zone->zone_end - bio->bi_iter.bi_sector,
                                &mddev->bio_set);
                if (!bio)
                        return;

                end = zone->zone_end;
        } else {
                end = bio_end_sector(bio);
        }

        orig_end = end;
        if (zone != conf->strip_zone)
                end = end - zone[-1].zone_end;

        /* Now start and end is the offset in zone */
        stripe_size = zone->nb_dev * mddev->chunk_sectors;

        first_stripe_index = start;
        sector_div(first_stripe_index, stripe_size);
        last_stripe_index = end;
        sector_div(last_stripe_index, stripe_size);

        /* In the first zone the original and alternate layouts are the same */
        if ((conf->layout == RAID0_ORIG_LAYOUT) && (zone != conf->strip_zone)) {
                sector_div(orig_start, mddev->chunk_sectors);
                start_disk_index = sector_div(orig_start, zone->nb_dev);
                start_disk_index = map_disk_shift(start_disk_index,
                                                  zone->nb_dev,
                                                  zone->disk_shift);
                sector_div(orig_end, mddev->chunk_sectors);
                end_disk_index = sector_div(orig_end, zone->nb_dev);
                end_disk_index = map_disk_shift(end_disk_index,
                                                zone->nb_dev, zone->disk_shift);
        } else {
                start_disk_index = (int)(start - first_stripe_index * stripe_size) /
                        mddev->chunk_sectors;
                end_disk_index = (int)(end - last_stripe_index * stripe_size) /
                        mddev->chunk_sectors;
        }
        start_disk_offset = ((int)(start - first_stripe_index * stripe_size) %
                mddev->chunk_sectors) +
                first_stripe_index * mddev->chunk_sectors;
        end_disk_offset = ((int)(end - last_stripe_index * stripe_size) %
                mddev->chunk_sectors) +
                last_stripe_index * mddev->chunk_sectors;

        for (disk = 0; disk < zone->nb_dev; disk++) {
                sector_t dev_start, dev_end;
                struct md_rdev *rdev;
                int compare_disk;

                compare_disk = map_disk_shift(disk, zone->nb_dev,
                                              zone->disk_shift);

                if (compare_disk < start_disk_index)
                        dev_start = (first_stripe_index + 1) *
                                mddev->chunk_sectors;
                else if (compare_disk > start_disk_index)
                        dev_start = first_stripe_index * mddev->chunk_sectors;
                else
                        dev_start = start_disk_offset;

                if (compare_disk < end_disk_index)
                        dev_end = (last_stripe_index + 1) * mddev->chunk_sectors;
                else if (compare_disk > end_disk_index)
                        dev_end = last_stripe_index * mddev->chunk_sectors;
                else
                        dev_end = end_disk_offset;

                if (dev_end <= dev_start)
                        continue;

                rdev = conf->devlist[(zone - conf->strip_zone) *
                        conf->strip_zone[0].nb_dev + disk];
                md_submit_discard_bio(mddev, rdev, bio,
                        dev_start + zone->dev_start + rdev->data_offset,
                        dev_end - dev_start);
        }
        bio_endio(bio);
}

static void raid0_map_submit_bio(struct mddev *mddev, struct bio *bio)
{
        struct r0conf *conf = mddev->private;
        struct strip_zone *zone;
        struct md_rdev *tmp_dev;
        sector_t bio_sector = bio->bi_iter.bi_sector;
        sector_t sector = bio_sector;

        md_account_bio(mddev, &bio);

        zone = find_zone(mddev->private, &sector);
        switch (conf->layout) {
        case RAID0_ORIG_LAYOUT:
                tmp_dev = map_sector(mddev, zone, bio_sector, &sector);
                break;
        case RAID0_ALT_MULTIZONE_LAYOUT:
                tmp_dev = map_sector(mddev, zone, sector, &sector);
                break;
        default:
                WARN(1, "md/raid0:%s: Invalid layout\n", mdname(mddev));
                bio_io_error(bio);
                return;
        }

        if (unlikely(is_rdev_broken(tmp_dev))) {
                bio_io_error(bio);
                md_error(mddev, tmp_dev);
                return;
        }

        bio_set_dev(bio, tmp_dev->bdev);
        bio->bi_iter.bi_sector = sector + zone->dev_start +
                tmp_dev->data_offset;
        mddev_trace_remap(mddev, bio, bio_sector);
        mddev_check_write_zeroes(mddev, bio);
        submit_bio_noacct(bio);
}

static bool raid0_make_request(struct mddev *mddev, struct bio *bio)
{
        sector_t sector;
        unsigned chunk_sects;
        unsigned sectors;

        if (unlikely(bio->bi_opf & REQ_PREFLUSH)
            && md_flush_request(mddev, bio))
                return true;

        if (unlikely((bio_op(bio) == REQ_OP_DISCARD))) {
                raid0_handle_discard(mddev, bio);
                return true;
        }

        sector = bio->bi_iter.bi_sector;
        chunk_sects = mddev->chunk_sectors;

        sectors = chunk_sects -
                (likely(is_power_of_2(chunk_sects))
                 ? (sector & (chunk_sects-1))
                 : sector_div(sector, chunk_sects));

        if (sectors < bio_sectors(bio)) {
                bio = bio_submit_split_bioset(bio, sectors,
                                              &mddev->bio_set);
                if (!bio)
                        return true;
        }

        raid0_map_submit_bio(mddev, bio);
        return true;
}

static void raid0_status(struct seq_file *seq, struct mddev *mddev)
{
        seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
        return;
}

static void raid0_error(struct mddev *mddev, struct md_rdev *rdev)
{
        if (!test_and_set_bit(MD_BROKEN, &mddev->flags)) {
                char *md_name = mdname(mddev);

                pr_crit("md/raid0%s: Disk failure on %pg detected, failing array.\n",
                        md_name, rdev->bdev);
        }
}

static void *raid0_takeover_raid45(struct mddev *mddev)
{
        struct md_rdev *rdev;
        struct r0conf *priv_conf;

        if (mddev->degraded != 1) {
                pr_warn("md/raid0:%s: raid5 must be degraded! Degraded disks: %d\n",
                        mdname(mddev),
                        mddev->degraded);
                return ERR_PTR(-EINVAL);
        }

        rdev_for_each(rdev, mddev) {
                /* check slot number for a disk */
                if (rdev->raid_disk == mddev->raid_disks-1) {
                        pr_warn("md/raid0:%s: raid5 must have missing parity disk!\n",
                                mdname(mddev));
                        return ERR_PTR(-EINVAL);
                }
                rdev->sectors = mddev->dev_sectors;
        }

        /* Set new parameters */
        mddev->new_level = 0;
        mddev->new_layout = 0;
        mddev->new_chunk_sectors = mddev->chunk_sectors;
        mddev->raid_disks--;
        mddev->delta_disks = -1;
        /* make sure it will be not marked as dirty */
        mddev->resync_offset = MaxSector;
        mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);

        create_strip_zones(mddev, &priv_conf);

        return priv_conf;
}

static void *raid0_takeover_raid10(struct mddev *mddev)
{
        struct r0conf *priv_conf;

        /* Check layout:
         *  - far_copies must be 1
         *  - near_copies must be 2
         *  - disks number must be even
         *  - all mirrors must be already degraded
         */
        if (mddev->layout != ((1 << 8) + 2)) {
                pr_warn("md/raid0:%s:: Raid0 cannot takeover layout: 0x%x\n",
                        mdname(mddev),
                        mddev->layout);
                return ERR_PTR(-EINVAL);
        }
        if (mddev->raid_disks & 1) {
                pr_warn("md/raid0:%s: Raid0 cannot takeover Raid10 with odd disk number.\n",
                        mdname(mddev));
                return ERR_PTR(-EINVAL);
        }
        if (mddev->degraded != (mddev->raid_disks>>1)) {
                pr_warn("md/raid0:%s: All mirrors must be already degraded!\n",
                        mdname(mddev));
                return ERR_PTR(-EINVAL);
        }

        /* Set new parameters */
        mddev->new_level = 0;
        mddev->new_layout = 0;
        mddev->new_chunk_sectors = mddev->chunk_sectors;
        mddev->delta_disks = - mddev->raid_disks / 2;
        mddev->raid_disks += mddev->delta_disks;
        mddev->degraded = 0;
        /* make sure it will be not marked as dirty */
        mddev->resync_offset = MaxSector;
        mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);

        create_strip_zones(mddev, &priv_conf);
        return priv_conf;
}

static void *raid0_takeover_raid1(struct mddev *mddev)
{
        struct r0conf *priv_conf;
        int chunksect;

        /* Check layout:
         *  - (N - 1) mirror drives must be already faulty
         */
        if ((mddev->raid_disks - 1) != mddev->degraded) {
                pr_err("md/raid0:%s: (N - 1) mirrors drives must be already faulty!\n",
                       mdname(mddev));
                return ERR_PTR(-EINVAL);
        }

        /*
         * a raid1 doesn't have the notion of chunk size, so
         * figure out the largest suitable size we can use.
         */
        chunksect = 64 * 2; /* 64K by default */

        /* The array must be an exact multiple of chunksize */
        while (chunksect && (mddev->array_sectors & (chunksect - 1)))
                chunksect >>= 1;

        if ((chunksect << 9) < PAGE_SIZE)
                /* array size does not allow a suitable chunk size */
                return ERR_PTR(-EINVAL);

        /* Set new parameters */
        mddev->new_level = 0;
        mddev->new_layout = 0;
        mddev->new_chunk_sectors = chunksect;
        mddev->chunk_sectors = chunksect;
        mddev->delta_disks = 1 - mddev->raid_disks;
        mddev->raid_disks = 1;
        /* make sure it will be not marked as dirty */
        mddev->resync_offset = MaxSector;
        mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);

        create_strip_zones(mddev, &priv_conf);
        return priv_conf;
}

static void *raid0_takeover(struct mddev *mddev)
{
        /* raid0 can take over:
         *  raid4 - if all data disks are active.
         *  raid5 - providing it is Raid4 layout and one disk is faulty
         *  raid10 - assuming we have all necessary active disks
         *  raid1 - with (N -1) mirror drives faulty
         */

        if (mddev->bitmap) {
                pr_warn("md/raid0: %s: cannot takeover array with bitmap\n",
                        mdname(mddev));
                return ERR_PTR(-EBUSY);
        }
        if (mddev->level == 4)
                return raid0_takeover_raid45(mddev);

        if (mddev->level == 5) {
                if (mddev->layout == ALGORITHM_PARITY_N)
                        return raid0_takeover_raid45(mddev);

                pr_warn("md/raid0:%s: Raid can only takeover Raid5 with layout: %d\n",
                        mdname(mddev), ALGORITHM_PARITY_N);
        }

        if (mddev->level == 10)
                return raid0_takeover_raid10(mddev);

        if (mddev->level == 1)
                return raid0_takeover_raid1(mddev);

        pr_warn("Takeover from raid%i to raid0 not supported\n",
                mddev->level);

        return ERR_PTR(-EINVAL);
}

static void raid0_quiesce(struct mddev *mddev, int quiesce)
{
}

static struct md_personality raid0_personality=
{
        .head = {
                .type   = MD_PERSONALITY,
                .id     = ID_RAID0,
                .name   = "raid0",
                .owner  = THIS_MODULE,
        },

        .make_request   = raid0_make_request,
        .run            = raid0_run,
        .free           = raid0_free,
        .status         = raid0_status,
        .size           = raid0_size,
        .takeover       = raid0_takeover,
        .quiesce        = raid0_quiesce,
        .error_handler  = raid0_error,
};

static int __init raid0_init(void)
{
        return register_md_submodule(&raid0_personality.head);
}

static void __exit raid0_exit(void)
{
        unregister_md_submodule(&raid0_personality.head);
}

module_init(raid0_init);
module_exit(raid0_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("RAID0 (striping) personality for MD");
MODULE_ALIAS("md-personality-2"); /* RAID0 */
MODULE_ALIAS("md-raid0");
MODULE_ALIAS("md-level-0");