drivers/md/raid0.c - kernel/msm-4.9 - Gitiles

 /*
    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.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2, or (at your option)
    any later version.

    You should have received a copy of the GNU General Public License
    (for example /usr/src/linux/COPYING); if not, write to the Free
    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

 #include <linux/blkdev.h>
 #include <linux/seq_file.h>
 #include "md.h"
 #include "raid0.h"

 static void raid0_unplug(struct request_queue *q)
 {
 	mddev_t *mddev = q->queuedata;
 	raid0_conf_t *conf = mddev->private;
 	mdk_rdev_t **devlist = conf->devlist;
 	int i;

 	for (i=0; i<mddev->raid_disks; i++) {
 		struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);

 		blk_unplug(r_queue);
 	}
 }

 static int raid0_congested(void *data, int bits)
 {
 	mddev_t *mddev = data;
 	raid0_conf_t *conf = mddev->private;
 	mdk_rdev_t **devlist = conf->devlist;
 	int i, ret = 0;

 	for (i = 0; i < mddev->raid_disks && !ret ; i++) {
 		struct request_queue *q = bdev_get_queue(devlist[i]->bdev);

 		ret |= bdi_congested(&q->backing_dev_info, bits);
 	}
 	return ret;
 }

 /*
  * inform the user of the raid configuration
 */
 static void dump_zones(mddev_t *mddev)
 {
 	int j, k, h;
 	sector_t zone_size = 0;
 	sector_t zone_start = 0;
 	char b[BDEVNAME_SIZE];
 	raid0_conf_t *conf = mddev->private;
 	printk(KERN_INFO "******* %s configuration *********\n",
 		mdname(mddev));
 	h = 0;
 	for (j = 0; j < conf->nr_strip_zones; j++) {
 		printk(KERN_INFO "zone%d=[", j);
 		for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
 			printk("%s/",
 			bdevname(conf->devlist[j*mddev->raid_disks
 						+ k]->bdev, b));
 		printk("]\n");

 		zone_size  = conf->strip_zone[j].zone_end - zone_start;
 		printk(KERN_INFO "        zone offset=%llukb "
 				"device offset=%llukb size=%llukb\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;
 	}
 	printk(KERN_INFO "**********************************\n\n");
 }

 static int create_strip_zones(mddev_t *mddev)
 {
 	int i, c, err;
 	sector_t curr_zone_end, sectors;
 	mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev, **dev;
 	struct strip_zone *zone;
 	int cnt;
 	char b[BDEVNAME_SIZE];
 	raid0_conf_t *conf = kzalloc(sizeof(*conf), GFP_KERNEL);

 	if (!conf)
 		return -ENOMEM;
 	list_for_each_entry(rdev1, &mddev->disks, same_set) {
 		printk(KERN_INFO "raid0: looking at %s\n",
 			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;

 		list_for_each_entry(rdev2, &mddev->disks, same_set) {
 			printk(KERN_INFO "raid0:   comparing %s(%llu)",
 			       bdevname(rdev1->bdev,b),
 			       (unsigned long long)rdev1->sectors);
 			printk(KERN_INFO " with %s(%llu)\n",
 			       bdevname(rdev2->bdev,b),
 			       (unsigned long long)rdev2->sectors);
 			if (rdev2 == rdev1) {
 				printk(KERN_INFO "raid0:   END\n");
 				break;
 			}
 			if (rdev2->sectors == rdev1->sectors) {
 				/*
 				 * Not unique, don't count it as a new
 				 * group
 				 */
 				printk(KERN_INFO "raid0:   EQUAL\n");
 				c = 1;
 				break;
 			}
 			printk(KERN_INFO "raid0:   NOT EQUAL\n");
 		}
 		if (!c) {
 			printk(KERN_INFO "raid0:   ==> UNIQUE\n");
 			conf->nr_strip_zones++;
 			printk(KERN_INFO "raid0: %d zones\n",
 				conf->nr_strip_zones);
 		}
 	}
 	printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones);
 	err = -ENOMEM;
 	conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
 				conf->nr_strip_zones, GFP_KERNEL);
 	if (!conf->strip_zone)
 		goto abort;
 	conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
 				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;
 	list_for_each_entry(rdev1, &mddev->disks, same_set) {
 		int j = rdev1->raid_disk;

 		if (j < 0 || j >= mddev->raid_disks) {
 			printk(KERN_ERR "raid0: bad disk number %d - "
 				"aborting!\n", j);
 			goto abort;
 		}
 		if (dev[j]) {
 			printk(KERN_ERR "raid0: multiple devices for %d - "
 				"aborting!\n", j);
 			goto abort;
 		}
 		dev[j] = rdev1;

 		disk_stack_limits(mddev->gendisk, rdev1->bdev,
 				  rdev1->data_offset << 9);
 		/* as we don't honour merge_bvec_fn, we must never risk
 		 * violating it, so limit ->max_sector to one PAGE, as
 		 * a one page request is never in violation.
 		 */

 		if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
 		    queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
 			blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);

 		if (!smallest || (rdev1->sectors < smallest->sectors))
 			smallest = rdev1;
 		cnt++;
 	}
 	if (cnt != mddev->raid_disks) {
 		printk(KERN_ERR "raid0: too few disks (%d of %d) - "
 			"aborting!\n", 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;

 		printk(KERN_INFO "raid0: zone %d\n", i);
 		zone->dev_start = smallest->sectors;
 		smallest = NULL;
 		c = 0;

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

 		zone->nb_dev = c;
 		sectors = (smallest->sectors - zone->dev_start) * c;
 		printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
 			zone->nb_dev, (unsigned long long)sectors);

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

 		printk(KERN_INFO "raid0: current zone start: %llu\n",
 			(unsigned long long)smallest->sectors);
 	}
 	mddev->queue->unplug_fn = raid0_unplug;
 	mddev->queue->backing_dev_info.congested_fn = raid0_congested;
 	mddev->queue->backing_dev_info.congested_data = mddev;

 	/*
 	 * 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) % queue_logical_block_size(mddev->queue)) {
 		printk(KERN_ERR "%s chunk_size of %d not valid\n",
 		       mdname(mddev),
 		       mddev->chunk_sectors << 9);
 		goto abort;
 	}

 	blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
 	blk_queue_io_opt(mddev->queue,
 			 (mddev->chunk_sectors << 9) * mddev->raid_disks);

 	printk(KERN_INFO "raid0: done.\n");
 	mddev->private = conf;
 	return 0;
 abort:
 	kfree(conf->strip_zone);
 	kfree(conf->devlist);
 	kfree(conf);
 	mddev->private = NULL;
 	return err;
 }

 /**
  *	raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
  *	@q: request queue
  *	@bvm: properties of new bio
  *	@biovec: the request that could be merged to it.
  *
  *	Return amount of bytes we can accept at this offset
  */
 static int raid0_mergeable_bvec(struct request_queue *q,
 				struct bvec_merge_data *bvm,
 				struct bio_vec *biovec)
 {
 	mddev_t *mddev = q->queuedata;
 	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 	int max;
 	unsigned int chunk_sectors = mddev->chunk_sectors;
 	unsigned int bio_sectors = bvm->bi_size >> 9;

 	if (is_power_of_2(chunk_sectors))
 		max =  (chunk_sectors - ((sector & (chunk_sectors-1))
 						+ bio_sectors)) << 9;
 	else
 		max =  (chunk_sectors - (sector_div(sector, chunk_sectors)
 						+ bio_sectors)) << 9;
 	if (max < 0) max = 0; /* bio_add cannot handle a negative return */
 	if (max <= biovec->bv_len && bio_sectors == 0)
 		return biovec->bv_len;
 	else
 		return max;
 }

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

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

 	list_for_each_entry(rdev, &mddev->disks, same_set)
 		array_sectors += rdev->sectors;

 	return array_sectors;
 }

 static int raid0_run(mddev_t *mddev)
 {
 	int ret;

 	if (mddev->chunk_sectors == 0) {
 		printk(KERN_ERR "md/raid0: chunk size must be set.\n");
 		return -EINVAL;
 	}
 	if (md_check_no_bitmap(mddev))
 		return -EINVAL;
 	blk_queue_max_sectors(mddev->queue, mddev->chunk_sectors);
 	mddev->queue->queue_lock = &mddev->queue->__queue_lock;

 	ret = create_strip_zones(mddev);
 	if (ret < 0)
 		return ret;

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

 	printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
 		(unsigned long long)mddev->array_sectors);
 	/* calculate the max read-ahead size.
 	 * For read-ahead of large files to be effective, we need to
 	 * readahead at least twice a whole stripe. i.e. number of devices
 	 * multiplied by chunk size times 2.
 	 * If an individual device has an ra_pages greater than the
 	 * chunk size, then we will not drive that device as hard as it
 	 * wants.  We consider this a configuration error: a larger
 	 * chunksize should be used in that case.
 	 */
 	{
 		int stripe = mddev->raid_disks *
 			(mddev->chunk_sectors << 9) / PAGE_SIZE;
 		if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
 			mddev->queue->backing_dev_info.ra_pages = 2* stripe;
 	}

 	blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
 	dump_zones(mddev);
 	md_integrity_register(mddev);
 	return 0;
 }

 static int raid0_stop(mddev_t *mddev)
 {
 	raid0_conf_t *conf = mddev->private;

 	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 	kfree(conf->strip_zone);
 	kfree(conf->devlist);
 	kfree(conf);
 	mddev->private = NULL;
 	return 0;
 }

 /* Find the zone which holds a particular offset
  * Update *sectorp to be an offset in that zone
  */
 static struct strip_zone *find_zone(struct raid0_private_data *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 perfromance
 */
 static mdk_rdev_t *map_sector(mddev_t *mddev, struct strip_zone *zone,
 				sector_t sector, sector_t *sector_offset)
 {
 	unsigned int sect_in_chunk;
 	sector_t chunk;
 	raid0_conf_t *conf = mddev->private;
 	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)*mddev->raid_disks
 			     + sector_div(sector, zone->nb_dev)];
 }

 /*
  * Is io distribute over 1 or more chunks ?
 */
 static inline int is_io_in_chunk_boundary(mddev_t *mddev,
 			unsigned int chunk_sects, struct bio *bio)
 {
 	if (likely(is_power_of_2(chunk_sects))) {
 		return chunk_sects >= ((bio->bi_sector & (chunk_sects-1))
 					+ (bio->bi_size >> 9));
 	} else{
 		sector_t sector = bio->bi_sector;
 		return chunk_sects >= (sector_div(sector, chunk_sects)
 						+ (bio->bi_size >> 9));
 	}
 }

 static int raid0_make_request(struct request_queue *q, struct bio *bio)
 {
 	mddev_t *mddev = q->queuedata;
 	unsigned int chunk_sects;
 	sector_t sector_offset;
 	struct strip_zone *zone;
 	mdk_rdev_t *tmp_dev;
 	const int rw = bio_data_dir(bio);
 	int cpu;

 	if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) {
 		bio_endio(bio, -EOPNOTSUPP);
 		return 0;
 	}

 	cpu = part_stat_lock();
 	part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
 	part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
 		      bio_sectors(bio));
 	part_stat_unlock();

 	chunk_sects = mddev->chunk_sectors;
 	if (unlikely(!is_io_in_chunk_boundary(mddev, chunk_sects, bio))) {
 		sector_t sector = bio->bi_sector;
 		struct bio_pair *bp;
 		/* Sanity check -- queue functions should prevent this happening */
 		if (bio->bi_vcnt != 1 ||
 		    bio->bi_idx != 0)
 			goto bad_map;
 		/* This is a one page bio that upper layers
 		 * refuse to split for us, so we need to split it.
 		 */
 		if (likely(is_power_of_2(chunk_sects)))
 			bp = bio_split(bio, chunk_sects - (sector &
 							   (chunk_sects-1)));
 		else
 			bp = bio_split(bio, chunk_sects -
 				       sector_div(sector, chunk_sects));
 		if (raid0_make_request(q, &bp->bio1))
 			generic_make_request(&bp->bio1);
 		if (raid0_make_request(q, &bp->bio2))
 			generic_make_request(&bp->bio2);

 		bio_pair_release(bp);
 		return 0;
 	}

 	sector_offset = bio->bi_sector;
 	zone =  find_zone(mddev->private, &sector_offset);
 	tmp_dev = map_sector(mddev, zone, bio->bi_sector,
 			     &sector_offset);
 	bio->bi_bdev = tmp_dev->bdev;
 	bio->bi_sector = sector_offset + zone->dev_start +
 		tmp_dev->data_offset;
 	/*
 	 * Let the main block layer submit the IO and resolve recursion:
 	 */
 	return 1;

 bad_map:
 	printk("raid0_make_request bug: can't convert block across chunks"
 		" or bigger than %dk %llu %d\n", chunk_sects / 2,
 		(unsigned long long)bio->bi_sector, bio->bi_size >> 10);

 	bio_io_error(bio);
 	return 0;
 }

 static void raid0_status(struct seq_file *seq, mddev_t *mddev)
 {
 #undef MD_DEBUG
 #ifdef MD_DEBUG
 	int j, k, h;
 	char b[BDEVNAME_SIZE];
 	raid0_conf_t *conf = mddev->private;

 	sector_t zone_size;
 	sector_t zone_start = 0;
 	h = 0;

 	for (j = 0; j < conf->nr_strip_zones; j++) {
 		seq_printf(seq, "      z%d", j);
 		seq_printf(seq, "=[");
 		for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
 			seq_printf(seq, "%s/", bdevname(
 				conf->devlist[j*mddev->raid_disks + k]
 						->bdev, b));

 		zone_size  = conf->strip_zone[j].zone_end - zone_start;
 		seq_printf(seq, "] ze=%lld ds=%lld s=%lld\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;
 	}
 #endif
 	seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
 	return;
 }

 static struct mdk_personality raid0_personality=
 {
 	.name		= "raid0",
 	.level		= 0,
 	.owner		= THIS_MODULE,
 	.make_request	= raid0_make_request,
 	.run		= raid0_run,
 	.stop		= raid0_stop,
 	.status		= raid0_status,
 	.size		= raid0_size,
 };

 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_ALIAS("md-personality-2"); /* RAID0 */
 MODULE_ALIAS("md-raid0");
 MODULE_ALIAS("md-level-0");
	/*
	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.

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2, or (at your option)
	any later version.

	You should have received a copy of the GNU General Public License
	(for example /usr/src/linux/COPYING); if not, write to the Free
	Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*/

	#include <linux/blkdev.h>
	#include <linux/seq_file.h>
	#include "md.h"
	#include "raid0.h"

	static void raid0_unplug(struct request_queue *q)
	{
	mddev_t *mddev = q->queuedata;
	raid0_conf_t *conf = mddev->private;
	mdk_rdev_t **devlist = conf->devlist;
	int i;

	for (i=0; i<mddev->raid_disks; i++) {
	struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);

	blk_unplug(r_queue);
	}
	}

	static int raid0_congested(void *data, int bits)
	{
	mddev_t *mddev = data;
	raid0_conf_t *conf = mddev->private;
	mdk_rdev_t **devlist = conf->devlist;
	int i, ret = 0;

	for (i = 0; i < mddev->raid_disks && !ret ; i++) {
	struct request_queue *q = bdev_get_queue(devlist[i]->bdev);

	ret \|= bdi_congested(&q->backing_dev_info, bits);
	}
	return ret;
	}

	/*
	* inform the user of the raid configuration
	*/
	static void dump_zones(mddev_t *mddev)
	{
	int j, k, h;
	sector_t zone_size = 0;
	sector_t zone_start = 0;
	char b[BDEVNAME_SIZE];
	raid0_conf_t *conf = mddev->private;
	printk(KERN_INFO "***** %s configuration *******\n",
	mdname(mddev));
	h = 0;
	for (j = 0; j < conf->nr_strip_zones; j++) {
	printk(KERN_INFO "zone%d=[", j);
	for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
	printk("%s/",
	bdevname(conf->devlist[j*mddev->raid_disks
	+ k]->bdev, b));
	printk("]\n");

	zone_size = conf->strip_zone[j].zone_end - zone_start;
	printk(KERN_INFO " zone offset=%llukb "
	"device offset=%llukb size=%llukb\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;
	}
	printk(KERN_INFO "**********************************\n\n");
	}

	static int create_strip_zones(mddev_t *mddev)
	{
	int i, c, err;
	sector_t curr_zone_end, sectors;
	mdk_rdev_t smallest, rdev1, rdev2, rdev, **dev;
	struct strip_zone *zone;
	int cnt;
	char b[BDEVNAME_SIZE];
	raid0_conf_t conf = kzalloc(sizeof(conf), GFP_KERNEL);

	if (!conf)
	return -ENOMEM;
	list_for_each_entry(rdev1, &mddev->disks, same_set) {
	printk(KERN_INFO "raid0: looking at %s\n",
	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;

	list_for_each_entry(rdev2, &mddev->disks, same_set) {
	printk(KERN_INFO "raid0: comparing %s(%llu)",
	bdevname(rdev1->bdev,b),
	(unsigned long long)rdev1->sectors);
	printk(KERN_INFO " with %s(%llu)\n",
	bdevname(rdev2->bdev,b),
	(unsigned long long)rdev2->sectors);
	if (rdev2 == rdev1) {
	printk(KERN_INFO "raid0: END\n");
	break;
	}
	if (rdev2->sectors == rdev1->sectors) {
	/*
	* Not unique, don't count it as a new
	* group
	*/
	printk(KERN_INFO "raid0: EQUAL\n");
	c = 1;
	break;
	}
	printk(KERN_INFO "raid0: NOT EQUAL\n");
	}
	if (!c) {
	printk(KERN_INFO "raid0: ==> UNIQUE\n");
	conf->nr_strip_zones++;
	printk(KERN_INFO "raid0: %d zones\n",
	conf->nr_strip_zones);
	}
	}
	printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones);
	err = -ENOMEM;
	conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
	conf->nr_strip_zones, GFP_KERNEL);
	if (!conf->strip_zone)
	goto abort;
	conf->devlist = kzalloc(sizeof(mdk_rdev_t)
	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;
	list_for_each_entry(rdev1, &mddev->disks, same_set) {
	int j = rdev1->raid_disk;

	if (j < 0 \|\| j >= mddev->raid_disks) {
	printk(KERN_ERR "raid0: bad disk number %d - "
	"aborting!\n", j);
	goto abort;
	}
	if (dev[j]) {
	printk(KERN_ERR "raid0: multiple devices for %d - "
	"aborting!\n", j);
	goto abort;
	}
	dev[j] = rdev1;

	disk_stack_limits(mddev->gendisk, rdev1->bdev,
	rdev1->data_offset << 9);
	/* as we don't honour merge_bvec_fn, we must never risk
	* violating it, so limit ->max_sector to one PAGE, as
	* a one page request is never in violation.
	*/

	if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
	queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
	blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);

	if (!smallest \|\| (rdev1->sectors < smallest->sectors))
	smallest = rdev1;
	cnt++;
	}
	if (cnt != mddev->raid_disks) {
	printk(KERN_ERR "raid0: too few disks (%d of %d) - "
	"aborting!\n", 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;

	printk(KERN_INFO "raid0: zone %d\n", i);
	zone->dev_start = smallest->sectors;
	smallest = NULL;
	c = 0;

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

	zone->nb_dev = c;
	sectors = (smallest->sectors - zone->dev_start) * c;
	printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
	zone->nb_dev, (unsigned long long)sectors);

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

	printk(KERN_INFO "raid0: current zone start: %llu\n",
	(unsigned long long)smallest->sectors);
	}
	mddev->queue->unplug_fn = raid0_unplug;
	mddev->queue->backing_dev_info.congested_fn = raid0_congested;
	mddev->queue->backing_dev_info.congested_data = mddev;

	/*
	* 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) % queue_logical_block_size(mddev->queue)) {
	printk(KERN_ERR "%s chunk_size of %d not valid\n",
	mdname(mddev),
	mddev->chunk_sectors << 9);
	goto abort;
	}

	blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
	blk_queue_io_opt(mddev->queue,
	(mddev->chunk_sectors << 9) * mddev->raid_disks);

	printk(KERN_INFO "raid0: done.\n");
	mddev->private = conf;
	return 0;
	abort:
	kfree(conf->strip_zone);
	kfree(conf->devlist);
	kfree(conf);
	mddev->private = NULL;
	return err;
	}

	/**
	* raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
	* @q: request queue
	* @bvm: properties of new bio
	* @biovec: the request that could be merged to it.
	*
	* Return amount of bytes we can accept at this offset
	*/
	static int raid0_mergeable_bvec(struct request_queue *q,
	struct bvec_merge_data *bvm,
	struct bio_vec *biovec)
	{
	mddev_t *mddev = q->queuedata;
	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
	int max;
	unsigned int chunk_sectors = mddev->chunk_sectors;
	unsigned int bio_sectors = bvm->bi_size >> 9;

	if (is_power_of_2(chunk_sectors))
	max = (chunk_sectors - ((sector & (chunk_sectors-1))
	+ bio_sectors)) << 9;
	else
	max = (chunk_sectors - (sector_div(sector, chunk_sectors)
	+ bio_sectors)) << 9;
	if (max < 0) max = 0; /* bio_add cannot handle a negative return */
	if (max <= biovec->bv_len && bio_sectors == 0)
	return biovec->bv_len;
	else
	return max;
	}

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

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

	list_for_each_entry(rdev, &mddev->disks, same_set)
	array_sectors += rdev->sectors;

	return array_sectors;
	}

	static int raid0_run(mddev_t *mddev)
	{
	int ret;

	if (mddev->chunk_sectors == 0) {
	printk(KERN_ERR "md/raid0: chunk size must be set.\n");
	return -EINVAL;
	}
	if (md_check_no_bitmap(mddev))
	return -EINVAL;
	blk_queue_max_sectors(mddev->queue, mddev->chunk_sectors);
	mddev->queue->queue_lock = &mddev->queue->__queue_lock;

	ret = create_strip_zones(mddev);
	if (ret < 0)
	return ret;

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

	printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
	(unsigned long long)mddev->array_sectors);
	/* calculate the max read-ahead size.
	* For read-ahead of large files to be effective, we need to
	* readahead at least twice a whole stripe. i.e. number of devices
	* multiplied by chunk size times 2.
	* If an individual device has an ra_pages greater than the
	* chunk size, then we will not drive that device as hard as it
	* wants. We consider this a configuration error: a larger
	* chunksize should be used in that case.
	*/
	{
	int stripe = mddev->raid_disks *
	(mddev->chunk_sectors << 9) / PAGE_SIZE;
	if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
	mddev->queue->backing_dev_info.ra_pages = 2* stripe;
	}

	blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
	dump_zones(mddev);
	md_integrity_register(mddev);
	return 0;
	}

	static int raid0_stop(mddev_t *mddev)
	{
	raid0_conf_t *conf = mddev->private;

	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
	kfree(conf->strip_zone);
	kfree(conf->devlist);
	kfree(conf);
	mddev->private = NULL;
	return 0;
	}

	/* Find the zone which holds a particular offset
	* Update *sectorp to be an offset in that zone
	*/
	static struct strip_zone find_zone(struct raid0_private_data 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 perfromance
	*/
	static mdk_rdev_t map_sector(mddev_t mddev, struct strip_zone *zone,
	sector_t sector, sector_t *sector_offset)
	{
	unsigned int sect_in_chunk;
	sector_t chunk;
	raid0_conf_t *conf = mddev->private;
	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)*mddev->raid_disks
	+ sector_div(sector, zone->nb_dev)];
	}

	/*
	* Is io distribute over 1 or more chunks ?
	*/
	static inline int is_io_in_chunk_boundary(mddev_t *mddev,
	unsigned int chunk_sects, struct bio *bio)
	{
	if (likely(is_power_of_2(chunk_sects))) {
	return chunk_sects >= ((bio->bi_sector & (chunk_sects-1))
	+ (bio->bi_size >> 9));
	} else{
	sector_t sector = bio->bi_sector;
	return chunk_sects >= (sector_div(sector, chunk_sects)
	+ (bio->bi_size >> 9));
	}
	}

	static int raid0_make_request(struct request_queue q, struct bio bio)
	{
	mddev_t *mddev = q->queuedata;
	unsigned int chunk_sects;
	sector_t sector_offset;
	struct strip_zone *zone;
	mdk_rdev_t *tmp_dev;
	const int rw = bio_data_dir(bio);
	int cpu;

	if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) {
	bio_endio(bio, -EOPNOTSUPP);
	return 0;
	}

	cpu = part_stat_lock();
	part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
	part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
	bio_sectors(bio));
	part_stat_unlock();

	chunk_sects = mddev->chunk_sectors;
	if (unlikely(!is_io_in_chunk_boundary(mddev, chunk_sects, bio))) {
	sector_t sector = bio->bi_sector;
	struct bio_pair *bp;
	/* Sanity check -- queue functions should prevent this happening */
	if (bio->bi_vcnt != 1 \|\|
	bio->bi_idx != 0)
	goto bad_map;
	/* This is a one page bio that upper layers
	* refuse to split for us, so we need to split it.
	*/
	if (likely(is_power_of_2(chunk_sects)))
	bp = bio_split(bio, chunk_sects - (sector &
	(chunk_sects-1)));
	else
	bp = bio_split(bio, chunk_sects -
	sector_div(sector, chunk_sects));
	if (raid0_make_request(q, &bp->bio1))
	generic_make_request(&bp->bio1);
	if (raid0_make_request(q, &bp->bio2))
	generic_make_request(&bp->bio2);

	bio_pair_release(bp);
	return 0;
	}

	sector_offset = bio->bi_sector;
	zone = find_zone(mddev->private, &sector_offset);
	tmp_dev = map_sector(mddev, zone, bio->bi_sector,
	&sector_offset);
	bio->bi_bdev = tmp_dev->bdev;
	bio->bi_sector = sector_offset + zone->dev_start +
	tmp_dev->data_offset;
	/*
	* Let the main block layer submit the IO and resolve recursion:
	*/
	return 1;

	bad_map:
	printk("raid0_make_request bug: can't convert block across chunks"
	" or bigger than %dk %llu %d\n", chunk_sects / 2,
	(unsigned long long)bio->bi_sector, bio->bi_size >> 10);

	bio_io_error(bio);
	return 0;
	}

	static void raid0_status(struct seq_file seq, mddev_t mddev)
	{
	#undef MD_DEBUG
	#ifdef MD_DEBUG
	int j, k, h;
	char b[BDEVNAME_SIZE];
	raid0_conf_t *conf = mddev->private;

	sector_t zone_size;
	sector_t zone_start = 0;
	h = 0;

	for (j = 0; j < conf->nr_strip_zones; j++) {
	seq_printf(seq, " z%d", j);
	seq_printf(seq, "=[");
	for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
	seq_printf(seq, "%s/", bdevname(
	conf->devlist[j*mddev->raid_disks + k]
	->bdev, b));

	zone_size = conf->strip_zone[j].zone_end - zone_start;
	seq_printf(seq, "] ze=%lld ds=%lld s=%lld\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;
	}
	#endif
	seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
	return;
	}

	static struct mdk_personality raid0_personality=
	{
	.name = "raid0",
	.level = 0,
	.owner = THIS_MODULE,
	.make_request = raid0_make_request,
	.run = raid0_run,
	.stop = raid0_stop,
	.status = raid0_status,
	.size = raid0_size,
	};

	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_ALIAS("md-personality-2"); /* RAID0 */
	MODULE_ALIAS("md-raid0");
	MODULE_ALIAS("md-level-0");