text: // 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))
  
  /*
   * 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;
  	char b[BDEVNAME_SIZE];
  	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 += snprintf(line+len, 200-len, "%s%s", k?"/":"",
  					bdevname(conf->devlist[j*raid_disks
  							       + k]->bdev, b));
  		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;
  	char b[BDEVNAME_SIZE];
  	char b2[BDEVNAME_SIZE];
  	struct r0conf *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
  	unsigned blksize = 512;
  
  	*private_conf = ERR_PTR(-ENOMEM);
  	if (!conf)
  		return -ENOMEM;
  	rdev_for_each(rdev1, mddev) {
  		pr_debug("md/raid0:%s: looking at %s\n",
  			 mdname(mddev),
  			 bdevname(rdev1->bdev, b));
  		c = 0;
  
  		/* round size to chunk_size */
  		sectors = rdev1->sectors;
  		sector_div(sectors, mddev->chunk_sectors);
  		rdev1->sectors = sectors * mddev->chunk_sectors;
  
  		blksize = max(blksize, queue_logical_block_size(
  				      rdev1->bdev->bd_disk->queue));
  
  		rdev_for_each(rdev2, mddev) {
  			pr_debug("md/raid0:%s:   comparing %s(%llu)"
  				 " with %s(%llu)\n",
  				 mdname(mddev),
  				 bdevname(rdev1->bdev,b),
  				 (unsigned long long)rdev1->sectors,
  				 bdevname(rdev2->bdev,b2),
  				 (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);
  
  	if (conf->nr_strip_zones == 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 = -ENOTSUPP;
  		goto abort;
  	}
  	/*
  	 * 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 = kcalloc(conf->nr_strip_zones,
  				   sizeof(struct strip_zone),
  				   GFP_KERNEL);
  	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 %s ... nope\n",
  					 mdname(mddev),
  					 bdevname(rdev->bdev, b));
  				continue;
  			}
  			pr_debug("md/raid0:%s: checking %s ..."
  				 " contained as device %d\n",
  				 mdname(mddev),
  				 bdevname(rdev->bdev, b), 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);
  	}
  
  	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);
  
  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 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;
  	if (mddev->queue) {
  		struct md_rdev *rdev;
  		bool discard_supported = false;
  
  		blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
  		blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
  		blk_queue_max_write_zeroes_sectors(mddev->queue, mddev->chunk_sectors);
  		blk_queue_max_discard_sectors(mddev->queue, UINT_MAX);
  
  		blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
  		blk_queue_io_opt(mddev->queue,
  				 (mddev->chunk_sectors << 9) * mddev->raid_disks);
  
  		rdev_for_each(rdev, mddev) {
  			disk_stack_limits(mddev->gendisk, rdev->bdev,
  					  rdev->data_offset << 9);
  			if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
  				discard_supported = true;
  		}
  		if (!discard_supported)
  			blk_queue_flag_clear(QUEUE_FLAG_DISCARD, mddev->queue);
  		else
  			blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);
  	}
  
  	/* 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);
  
  	ret = md_integrity_register(mddev);
  
  	return ret;
  }
  
  static void raid0_free(struct mddev *mddev, void *priv)
  {
  	struct r0conf *conf = priv;
  
  	kfree(conf->strip_zone);
  	kfree(conf->devlist);
  	kfree(conf);
  }
  
  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;
  
  	zone = find_zone(conf, &start);
  
  	if (bio_end_sector(bio) > zone->zone_end) {
  		struct bio *split = bio_split(bio,
  			zone->zone_end - bio->bi_iter.bi_sector, GFP_NOIO,
  			&mddev->bio_set);
  		bio_chain(split, bio);
  		submit_bio_noacct(bio);
  		bio = split;
  		end = zone->zone_end;
  	} else
  		end = bio_end_sector(bio);
  
  	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);
  
  	start_disk_index = (int)(start - first_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_index = (int)(end - last_stripe_index * stripe_size) /
  		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 bio *discard_bio = NULL;
  		struct md_rdev *rdev;
  
  		if (disk < start_disk_index)
  			dev_start = (first_stripe_index + 1) *
  				mddev->chunk_sectors;
  		else if (disk > start_disk_index)
  			dev_start = first_stripe_index * mddev->chunk_sectors;
  		else
  			dev_start = start_disk_offset;
  
  		if (disk < end_disk_index)
  			dev_end = (last_stripe_index + 1) * mddev->chunk_sectors;
  		else if (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];
  		if (__blkdev_issue_discard(rdev->bdev,
  			dev_start + zone->dev_start + rdev->data_offset,
  			dev_end - dev_start, GFP_NOIO, 0, &discard_bio) ||
  		    !discard_bio)
  			continue;
  		bio_chain(discard_bio, bio);
  		bio_clone_blkg_association(discard_bio, bio);
  		if (mddev->gendisk)
  			trace_block_bio_remap(bdev_get_queue(rdev->bdev),
  				discard_bio, disk_devt(mddev->gendisk),
  				bio->bi_iter.bi_sector);
  		submit_bio_noacct(discard_bio);
  	}
  	bio_endio(bio);
  }
  
  static bool raid0_make_request(struct mddev *mddev, struct bio *bio)
  {
  	struct r0conf *conf = mddev->private;
  	struct strip_zone *zone;
  	struct md_rdev *tmp_dev;
  	sector_t bio_sector;
  	sector_t sector;
  	sector_t orig_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;
  	}
  
  	bio_sector = bio->bi_iter.bi_sector;
  	sector = bio_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));
  
  	/* Restore due to sector_div */
  	sector = bio_sector;
  
  	if (sectors < bio_sectors(bio)) {
  		struct bio *split = bio_split(bio, sectors, GFP_NOIO,
  					      &mddev->bio_set);
  		bio_chain(split, bio);
  		submit_bio_noacct(bio);
  		bio = split;
  	}
  
  	orig_sector = sector;
  	zone = find_zone(mddev->private, &sector);
  	switch (conf->layout) {
  	case RAID0_ORIG_LAYOUT:
  		tmp_dev = map_sector(mddev, zone, orig_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 true;
  	}
  
  	if (unlikely(is_mddev_broken(tmp_dev, "raid0"))) {
  		bio_io_error(bio);
  		return true;
  	}
  
  	bio_set_dev(bio, tmp_dev->bdev);
  	bio->bi_iter.bi_sector = sector + zone->dev_start +
  		tmp_dev->data_offset;
  
  	if (mddev->gendisk)
  		trace_block_bio_remap(bio->bi_disk->queue, bio,
  				disk_devt(mddev->gendisk), bio_sector);
  	mddev_check_writesame(mddev, bio);
  	mddev_check_write_zeroes(mddev, bio);
  	submit_bio_noacct(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_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->recovery_cp = 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->recovery_cp = 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->recovery_cp = 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=
  {
  	.name		= "raid0",
  	.level		= 0,
  	.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,
  };
  
  static int __init raid0_init (void)
  {
  	return register_md_personality (&raid0_personality);
  }
  
  static void raid0_exit (void)
  {
  	unregister_md_personality (&raid0_personality);
  }
  
  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");
  