[deliverable/linux.git] / drivers / md / raid0.c

/*
   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/module.h>
#include <linux/raid/raid0.h>

#define MAJOR_NR MD_MAJOR
#define MD_DRIVER
#define MD_PERSONALITY

static void raid0_unplug(struct request_queue *q)
{
	mddev_t *mddev = q->queuedata;
	raid0_conf_t *conf = mddev_to_conf(mddev);
	mdk_rdev_t **devlist = conf->strip_zone[0].dev;
	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_to_conf(mddev);
	mdk_rdev_t **devlist = conf->strip_zone[0].dev;
	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;
}


static int create_strip_zones (mddev_t *mddev)
{
	int i, c, j;
	sector_t current_offset, curr_zone_offset;
	sector_t min_spacing;
	raid0_conf_t *conf = mddev_to_conf(mddev);
	mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
	struct list_head *tmp1, *tmp2;
	struct strip_zone *zone;
	int cnt;
	char b[BDEVNAME_SIZE];
 
	/*
	 * The number of 'same size groups'
	 */
	conf->nr_strip_zones = 0;
 
	ITERATE_RDEV(mddev,rdev1,tmp1) {
		printk("raid0: looking at %s\n",
			bdevname(rdev1->bdev,b));
		c = 0;
		ITERATE_RDEV(mddev,rdev2,tmp2) {
			printk("raid0:   comparing %s(%llu)",
			       bdevname(rdev1->bdev,b),
			       (unsigned long long)rdev1->size);
			printk(" with %s(%llu)\n",
			       bdevname(rdev2->bdev,b),
			       (unsigned long long)rdev2->size);
			if (rdev2 == rdev1) {
				printk("raid0:   END\n");
				break;
			}
			if (rdev2->size == rdev1->size)
			{
				/*
				 * Not unique, don't count it as a new
				 * group
				 */
				printk("raid0:   EQUAL\n");
				c = 1;
				break;
			}
			printk("raid0:   NOT EQUAL\n");
		}
		if (!c) {
			printk("raid0:   ==> UNIQUE\n");
			conf->nr_strip_zones++;
			printk("raid0: %d zones\n", conf->nr_strip_zones);
		}
	}
	printk("raid0: FINAL %d zones\n", conf->nr_strip_zones);

	conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
				conf->nr_strip_zones, GFP_KERNEL);
	if (!conf->strip_zone)
		return 1;
	conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
				conf->nr_strip_zones*mddev->raid_disks,
				GFP_KERNEL);
	if (!conf->devlist)
		return 1;

	/* 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;
	zone->dev = conf->devlist;
	ITERATE_RDEV(mddev, rdev1, tmp1) {
		int j = rdev1->raid_disk;

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

		blk_queue_stack_limits(mddev->queue,
				       rdev1->bdev->bd_disk->queue);
		/* 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 &&
		    mddev->queue->max_sectors > (PAGE_SIZE>>9))
			blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);

		if (!smallest || (rdev1->size <smallest->size))
			smallest = rdev1;
		cnt++;
	}
	if (cnt != mddev->raid_disks) {
		printk("raid0: too few disks (%d of %d) - aborting!\n",
			cnt, mddev->raid_disks);
		goto abort;
	}
	zone->nb_dev = cnt;
	zone->size = smallest->size * cnt;
	zone->zone_offset = 0;

	current_offset = smallest->size;
	curr_zone_offset = zone->size;

	/* now do the other zones */
	for (i = 1; i < conf->nr_strip_zones; i++)
	{
		zone = conf->strip_zone + i;
		zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;

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

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

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

		zone->zone_offset = curr_zone_offset;
		curr_zone_offset += zone->size;

		current_offset = smallest->size;
		printk("raid0: current zone offset: %llu\n",
			(unsigned long long)current_offset);
	}

	/* Now find appropriate hash spacing.
	 * We want a number which causes most hash entries to cover
	 * at most two strips, but the hash table must be at most
	 * 1 PAGE.  We choose the smallest strip, or contiguous collection
	 * of strips, that has big enough size.  We never consider the last
	 * strip though as it's size has no bearing on the efficacy of the hash
	 * table.
	 */
	conf->hash_spacing = curr_zone_offset;
	min_spacing = curr_zone_offset;
	sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
	for (i=0; i < conf->nr_strip_zones-1; i++) {
		sector_t sz = 0;
		for (j=i; j<conf->nr_strip_zones-1 &&
			     sz < min_spacing ; j++)
			sz += conf->strip_zone[j].size;
		if (sz >= min_spacing && sz < conf->hash_spacing)
			conf->hash_spacing = sz;
	}

	mddev->queue->unplug_fn = raid0_unplug;

	mddev->queue->backing_dev_info.congested_fn = raid0_congested;
	mddev->queue->backing_dev_info.congested_data = mddev;

	printk("raid0: done.\n");
	return 0;
 abort:
	return 1;
}

/**
 *	raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
 *	@q: request queue
 *	@bio: the buffer head that's been built up so far
 *	@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 bio *bio, struct bio_vec *biovec)
{
	mddev_t *mddev = q->queuedata;
	sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
	int max;
	unsigned int chunk_sectors = mddev->chunk_size >> 9;
	unsigned int bio_sectors = bio->bi_size >> 9;

	max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + 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 int raid0_run (mddev_t *mddev)
{
	unsigned  cur=0, i=0, nb_zone;
	s64 size;
	raid0_conf_t *conf;
	mdk_rdev_t *rdev;
	struct list_head *tmp;

	if (mddev->chunk_size == 0) {
		printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
		return -EINVAL;
	}
	printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
	       mdname(mddev),
	       mddev->chunk_size >> 9,
	       (mddev->chunk_size>>1)-1);
	blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
	blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);

	conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
	if (!conf)
		goto out;
	mddev->private = (void *)conf;
 
	conf->strip_zone = NULL;
	conf->devlist = NULL;
	if (create_strip_zones (mddev)) 
		goto out_free_conf;

	/* calculate array device size */
	mddev->array_size = 0;
	ITERATE_RDEV(mddev,rdev,tmp)
		mddev->array_size += rdev->size;

	printk("raid0 : md_size is %llu blocks.\n", 
		(unsigned long long)mddev->array_size);
	printk("raid0 : conf->hash_spacing is %llu blocks.\n",
		(unsigned long long)conf->hash_spacing);
	{
		sector_t s = mddev->array_size;
		sector_t space = conf->hash_spacing;
		int round;
		conf->preshift = 0;
		if (sizeof(sector_t) > sizeof(u32)) {
			/*shift down space and s so that sector_div will work */
			while (space > (sector_t) (~(u32)0)) {
				s >>= 1;
				space >>= 1;
				s += 1; /* force round-up */
				conf->preshift++;
			}
		}
		round = sector_div(s, (u32)space) ? 1 : 0;
		nb_zone = s + round;
	}
	printk("raid0 : nb_zone is %d.\n", nb_zone);

	printk("raid0 : Allocating %Zd bytes for hash.\n",
				nb_zone*sizeof(struct strip_zone*));
	conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
	if (!conf->hash_table)
		goto out_free_conf;
	size = conf->strip_zone[cur].size;

	conf->hash_table[0] = conf->strip_zone + cur;
	for (i=1; i< nb_zone; i++) {
		while (size <= conf->hash_spacing) {
			cur++;
			size += conf->strip_zone[cur].size;
		}
		size -= conf->hash_spacing;
		conf->hash_table[i] = conf->strip_zone + cur;
	}
	if (conf->preshift) {
		conf->hash_spacing >>= conf->preshift;
		/* round hash_spacing up so when we divide by it, we
		 * err on the side of too-low, which is safest
		 */
		conf->hash_spacing++;
	}

	/* 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_size / 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);
	return 0;

out_free_conf:
	kfree(conf->strip_zone);
	kfree(conf->devlist);
	kfree(conf);
	mddev->private = NULL;
out:
	return -ENOMEM;
}

static int raid0_stop (mddev_t *mddev)
{
	raid0_conf_t *conf = mddev_to_conf(mddev);

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

	return 0;
}

static int raid0_make_request (struct request_queue *q, struct bio *bio)
{
	mddev_t *mddev = q->queuedata;
	unsigned int sect_in_chunk, chunksize_bits,  chunk_size, chunk_sects;
	raid0_conf_t *conf = mddev_to_conf(mddev);
	struct strip_zone *zone;
	mdk_rdev_t *tmp_dev;
	sector_t chunk;
	sector_t block, rsect;
	const int rw = bio_data_dir(bio);

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

	disk_stat_inc(mddev->gendisk, ios[rw]);
	disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));

	chunk_size = mddev->chunk_size >> 10;
	chunk_sects = mddev->chunk_size >> 9;
	chunksize_bits = ffz(~chunk_size);
	block = bio->bi_sector >> 1;
	

	if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
		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.
		 */
		bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
		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_t x = block >> conf->preshift;
		sector_div(x, (u32)conf->hash_spacing);
		zone = conf->hash_table[x];
	}
 
	while (block >= (zone->zone_offset + zone->size)) 
		zone++;
    
	sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1);


	{
		sector_t x =  (block - zone->zone_offset) >> chunksize_bits;

		sector_div(x, zone->nb_dev);
		chunk = x;

		x = block >> chunksize_bits;
		tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
	}
	rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
		+ sect_in_chunk;
 
	bio->bi_bdev = tmp_dev->bdev;
	bio->bi_sector = rsect + 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_size, 
		(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_to_conf(mddev);

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

		seq_printf(seq, "] zo=%d do=%d s=%d\n",
				conf->strip_zone[j].zone_offset,
				conf->strip_zone[j].dev_offset,
				conf->strip_zone[j].size);
	}
#endif
	seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
	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,
};

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");
Commit	Line	Data
1da177e4 LT	1	/*
	2	raid0.c : Multiple Devices driver for Linux
	3	Copyright (C) 1994-96 Marc ZYNGIER
	4	<zyngier@ufr-info-p7.ibp.fr> or
	5	<maz@gloups.fdn.fr>
	6	Copyright (C) 1999, 2000 Ingo Molnar, Red Hat
	7
	8
	9	RAID-0 management functions.
	10
	11	This program is free software; you can redistribute it and/or modify
	12	it under the terms of the GNU General Public License as published by
	13	the Free Software Foundation; either version 2, or (at your option)
	14	any later version.
	15
	16	You should have received a copy of the GNU General Public License
	17	(for example /usr/src/linux/COPYING); if not, write to the Free
	18	Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	19	*/
	20
	21	#include <linux/module.h>
	22	#include <linux/raid/raid0.h>
	23
	24	#define MAJOR_NR MD_MAJOR
	25	#define MD_DRIVER
	26	#define MD_PERSONALITY
	27
165125e1	28	static void raid0_unplug(struct request_queue *q)
1da177e4 LT	29	{
	30	mddev_t *mddev = q->queuedata;
	31	raid0_conf_t *conf = mddev_to_conf(mddev);
	32	mdk_rdev_t **devlist = conf->strip_zone[0].dev;
	33	int i;
	34
	35	for (i=0; i<mddev->raid_disks; i++) {
165125e1	36	struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);
1da177e4	37
2ad8b1ef	38	blk_unplug(r_queue);
1da177e4 LT	39	}
	40	}
	41
26be34dc N	42	static int raid0_congested(void *data, int bits)
	43	{
	44	mddev_t *mddev = data;
	45	raid0_conf_t *conf = mddev_to_conf(mddev);
	46	mdk_rdev_t **devlist = conf->strip_zone[0].dev;
	47	int i, ret = 0;
	48
	49	for (i = 0; i < mddev->raid_disks && !ret ; i++) {
165125e1	50	struct request_queue *q = bdev_get_queue(devlist[i]->bdev);
26be34dc N	51
	52	ret \|= bdi_congested(&q->backing_dev_info, bits);
	53	}
	54	return ret;
	55	}
	56
1da177e4 LT	57
	58	static int create_strip_zones (mddev_t *mddev)
	59	{
	60	int i, c, j;
	61	sector_t current_offset, curr_zone_offset;
	62	sector_t min_spacing;
	63	raid0_conf_t *conf = mddev_to_conf(mddev);
	64	mdk_rdev_t smallest, rdev1, rdev2, rdev;
	65	struct list_head tmp1, tmp2;
	66	struct strip_zone *zone;
	67	int cnt;
	68	char b[BDEVNAME_SIZE];
	69
	70	/*
	71	* The number of 'same size groups'
	72	*/
	73	conf->nr_strip_zones = 0;
	74
	75	ITERATE_RDEV(mddev,rdev1,tmp1) {
	76	printk("raid0: looking at %s\n",
	77	bdevname(rdev1->bdev,b));
	78	c = 0;
	79	ITERATE_RDEV(mddev,rdev2,tmp2) {
	80	printk("raid0: comparing %s(%llu)",
	81	bdevname(rdev1->bdev,b),
	82	(unsigned long long)rdev1->size);
	83	printk(" with %s(%llu)\n",
	84	bdevname(rdev2->bdev,b),
	85	(unsigned long long)rdev2->size);
	86	if (rdev2 == rdev1) {
	87	printk("raid0: END\n");
	88	break;
	89	}
	90	if (rdev2->size == rdev1->size)
	91	{
	92	/*
	93	* Not unique, don't count it as a new
	94	* group
	95	*/
	96	printk("raid0: EQUAL\n");
	97	c = 1;
	98	break;
	99	}
	100	printk("raid0: NOT EQUAL\n");
	101	}
	102	if (!c) {
	103	printk("raid0: ==> UNIQUE\n");
	104	conf->nr_strip_zones++;
	105	printk("raid0: %d zones\n", conf->nr_strip_zones);
	106	}
	107	}
	108	printk("raid0: FINAL %d zones\n", conf->nr_strip_zones);
	109
9ffae0cf	110	conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
1da177e4 LT	111	conf->nr_strip_zones, GFP_KERNEL);
	112	if (!conf->strip_zone)
	113	return 1;
9ffae0cf	114	conf->devlist = kzalloc(sizeof(mdk_rdev_t)
1da177e4 LT	115	conf->nr_strip_zones*mddev->raid_disks,
	116	GFP_KERNEL);
	117	if (!conf->devlist)
	118	return 1;
	119
1da177e4 LT	120	/* The first zone must contain all devices, so here we check that
	121	* there is a proper alignment of slots to devices and find them all
	122	*/
	123	zone = &conf->strip_zone[0];
	124	cnt = 0;
	125	smallest = NULL;
	126	zone->dev = conf->devlist;
	127	ITERATE_RDEV(mddev, rdev1, tmp1) {
	128	int j = rdev1->raid_disk;
	129
	130	if (j < 0 \|\| j >= mddev->raid_disks) {
	131	printk("raid0: bad disk number %d - aborting!\n", j);
	132	goto abort;
	133	}
	134	if (zone->dev[j]) {
	135	printk("raid0: multiple devices for %d - aborting!\n",
	136	j);
	137	goto abort;
	138	}
	139	zone->dev[j] = rdev1;
	140
	141	blk_queue_stack_limits(mddev->queue,
	142	rdev1->bdev->bd_disk->queue);
	143	/* as we don't honour merge_bvec_fn, we must never risk
	144	* violating it, so limit ->max_sector to one PAGE, as
	145	* a one page request is never in violation.
	146	*/
	147
	148	if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
	149	mddev->queue->max_sectors > (PAGE_SIZE>>9))
	150	blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
	151
	152	if (!smallest \|\| (rdev1->size <smallest->size))
	153	smallest = rdev1;
	154	cnt++;
	155	}
	156	if (cnt != mddev->raid_disks) {
	157	printk("raid0: too few disks (%d of %d) - aborting!\n",
	158	cnt, mddev->raid_disks);
	159	goto abort;
	160	}
	161	zone->nb_dev = cnt;
	162	zone->size = smallest->size * cnt;
	163	zone->zone_offset = 0;
	164
	165	current_offset = smallest->size;
	166	curr_zone_offset = zone->size;
	167
	168	/* now do the other zones */
	169	for (i = 1; i < conf->nr_strip_zones; i++)
	170	{
	171	zone = conf->strip_zone + i;
	172	zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
	173
	174	printk("raid0: zone %d\n", i);
	175	zone->dev_offset = current_offset;
	176	smallest = NULL;
	177	c = 0;
	178
	179	for (j=0; j<cnt; j++) {
	180	char b[BDEVNAME_SIZE];
	181	rdev = conf->strip_zone[0].dev[j];
	182	printk("raid0: checking %s ...", bdevname(rdev->bdev,b));
	183	if (rdev->size > current_offset)
184	{
185	printk(" contained as device %d\n", c);
186	zone->dev[c] = rdev;
187	c++;
188	if (!smallest \|\| (rdev->size <smallest->size)) {
189	smallest = rdev;
190	printk(" (%llu) is smallest!.\n",
191	(unsigned long long)rdev->size);
192	}
193	} else
194	printk(" nope.\n");
195	}
196
197	zone->nb_dev = c;
198	zone->size = (smallest->size - current_offset) * c;
199	printk("raid0: zone->nb_dev: %d, size: %llu\n",
200	zone->nb_dev, (unsigned long long)zone->size);
201
202	zone->zone_offset = curr_zone_offset;
203	curr_zone_offset += zone->size;
204
205	current_offset = smallest->size;
206	printk("raid0: current zone offset: %llu\n",
207	(unsigned long long)current_offset);
208	}
209
210	/* Now find appropriate hash spacing.
211	* We want a number which causes most hash entries to cover
212	* at most two strips, but the hash table must be at most
213	* 1 PAGE. We choose the smallest strip, or contiguous collection
214	* of strips, that has big enough size. We never consider the last
215	* strip though as it's size has no bearing on the efficacy of the hash
216	* table.
217	*/
218	conf->hash_spacing = curr_zone_offset;
219	min_spacing = curr_zone_offset;
220	sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
221	for (i=0; i < conf->nr_strip_zones-1; i++) {
222	sector_t sz = 0;
223	for (j=i; j<conf->nr_strip_zones-1 &&
224	sz < min_spacing ; j++)
225	sz += conf->strip_zone[j].size;
226	if (sz >= min_spacing && sz < conf->hash_spacing)
227	conf->hash_spacing = sz;
228	}
229
230	mddev->queue->unplug_fn = raid0_unplug;
231
26be34dc N	232	mddev->queue->backing_dev_info.congested_fn = raid0_congested;
26be34dc N	233	mddev->queue->backing_dev_info.congested_data = mddev;
1da177e4 LT	234
	235	printk("raid0: done.\n");
	236	return 0;
	237	abort:
	238	return 1;
	239	}
	240
	241	/**
	242	* raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
	243	* @q: request queue
	244	* @bio: the buffer head that's been built up so far
	245	* @biovec: the request that could be merged to it.
	246	*
	247	* Return amount of bytes we can accept at this offset
	248	*/
165125e1	249	static int raid0_mergeable_bvec(struct request_queue q, struct bio bio, struct bio_vec *biovec)
1da177e4 LT	250	{
	251	mddev_t *mddev = q->queuedata;
	252	sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
	253	int max;
	254	unsigned int chunk_sectors = mddev->chunk_size >> 9;
	255	unsigned int bio_sectors = bio->bi_size >> 9;
	256
	257	max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
	258	if (max < 0) max = 0; /* bio_add cannot handle a negative return */
	259	if (max <= biovec->bv_len && bio_sectors == 0)
	260	return biovec->bv_len;
	261	else
	262	return max;
	263	}
	264
	265	static int raid0_run (mddev_t *mddev)
	266	{
	267	unsigned cur=0, i=0, nb_zone;
	268	s64 size;
	269	raid0_conf_t *conf;
	270	mdk_rdev_t *rdev;
	271	struct list_head *tmp;
	272
2604b703 N	273	if (mddev->chunk_size == 0) {
	274	printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
	275	return -EINVAL;
	276	}
	277	printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
1da177e4 LT	278	mdname(mddev),
	279	mddev->chunk_size >> 9,
	280	(mddev->chunk_size>>1)-1);
	281	blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
	282	blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);
	283
	284	conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
	285	if (!conf)
	286	goto out;
	287	mddev->private = (void *)conf;
	288
	289	conf->strip_zone = NULL;
	290	conf->devlist = NULL;
	291	if (create_strip_zones (mddev))
	292	goto out_free_conf;
	293
	294	/* calculate array device size */
	295	mddev->array_size = 0;
	296	ITERATE_RDEV(mddev,rdev,tmp)
	297	mddev->array_size += rdev->size;
	298
	299	printk("raid0 : md_size is %llu blocks.\n",
	300	(unsigned long long)mddev->array_size);
	301	printk("raid0 : conf->hash_spacing is %llu blocks.\n",
	302	(unsigned long long)conf->hash_spacing);
	303	{
1da177e4 LT	304	sector_t s = mddev->array_size;
	305	sector_t space = conf->hash_spacing;
	306	int round;
	307	conf->preshift = 0;
1eb29128	308	if (sizeof(sector_t) > sizeof(u32)) {
1da177e4	309	/shift down space and s so that sector_div will work /
1eb29128	310	while (space > (sector_t) (~(u32)0)) {
1da177e4 LT	311	s >>= 1;
	312	space >>= 1;
	313	s += 1; /* force round-up */
	314	conf->preshift++;
	315	}
	316	}
1eb29128	317	round = sector_div(s, (u32)space) ? 1 : 0;
1da177e4 LT	318	nb_zone = s + round;
	319	}
	320	printk("raid0 : nb_zone is %d.\n", nb_zone);
	321
	322	printk("raid0 : Allocating %Zd bytes for hash.\n",
	323	nb_zonesizeof(struct strip_zone));
	324	conf->hash_table = kmalloc (sizeof (struct strip_zone )nb_zone, GFP_KERNEL);
	325	if (!conf->hash_table)
	326	goto out_free_conf;
	327	size = conf->strip_zone[cur].size;
	328
5c4c3331 N	329	conf->hash_table[0] = conf->strip_zone + cur;
5c4c3331 N	330	for (i=1; i< nb_zone; i++) {
1da177e4 LT	331	while (size <= conf->hash_spacing) {
	332	cur++;
	333	size += conf->strip_zone[cur].size;
	334	}
	335	size -= conf->hash_spacing;
5c4c3331	336	conf->hash_table[i] = conf->strip_zone + cur;
1da177e4 LT	337	}
	338	if (conf->preshift) {
	339	conf->hash_spacing >>= conf->preshift;
	340	/* round hash_spacing up so when we divide by it, we
	341	* err on the side of too-low, which is safest
	342	*/
	343	conf->hash_spacing++;
	344	}
	345
	346	/* calculate the max read-ahead size.
	347	* For read-ahead of large files to be effective, we need to
	348	* readahead at least twice a whole stripe. i.e. number of devices
	349	* multiplied by chunk size times 2.
	350	* If an individual device has an ra_pages greater than the
	351	* chunk size, then we will not drive that device as hard as it
	352	* wants. We consider this a configuration error: a larger
	353	* chunksize should be used in that case.
	354	*/
	355	{
2d1f3b5d	356	int stripe = mddev->raid_disks * mddev->chunk_size / PAGE_SIZE;
1da177e4 LT	357	if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
	358	mddev->queue->backing_dev_info.ra_pages = 2* stripe;
	359	}
	360
	361
	362	blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
	363	return 0;
	364
	365	out_free_conf:
990a8baf JJ	366	kfree(conf->strip_zone);
990a8baf JJ	367	kfree(conf->devlist);
1da177e4 LT	368	kfree(conf);
	369	mddev->private = NULL;
	370	out:
29fc7e3e	371	return -ENOMEM;
1da177e4 LT	372	}
	373
	374	static int raid0_stop (mddev_t *mddev)
	375	{
	376	raid0_conf_t *conf = mddev_to_conf(mddev);
	377
	378	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
990a8baf	379	kfree(conf->hash_table);
1da177e4	380	conf->hash_table = NULL;
990a8baf	381	kfree(conf->strip_zone);
1da177e4	382	conf->strip_zone = NULL;
990a8baf	383	kfree(conf);
1da177e4 LT	384	mddev->private = NULL;
	385
	386	return 0;
	387	}
	388
165125e1	389	static int raid0_make_request (struct request_queue q, struct bio bio)
1da177e4 LT	390	{
	391	mddev_t *mddev = q->queuedata;
	392	unsigned int sect_in_chunk, chunksize_bits, chunk_size, chunk_sects;
	393	raid0_conf_t *conf = mddev_to_conf(mddev);
	394	struct strip_zone *zone;
	395	mdk_rdev_t *tmp_dev;
787f17fe	396	sector_t chunk;
1da177e4	397	sector_t block, rsect;
a362357b	398	const int rw = bio_data_dir(bio);
1da177e4	399
e5dcdd80	400	if (unlikely(bio_barrier(bio))) {
6712ecf8	401	bio_endio(bio, -EOPNOTSUPP);
e5dcdd80 N	402	return 0;
	403	}
	404
a362357b JA	405	disk_stat_inc(mddev->gendisk, ios[rw]);
a362357b JA	406	disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
1da177e4 LT	407
	408	chunk_size = mddev->chunk_size >> 10;
	409	chunk_sects = mddev->chunk_size >> 9;
	410	chunksize_bits = ffz(~chunk_size);
	411	block = bio->bi_sector >> 1;
	412
	413
	414	if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
	415	struct bio_pair *bp;
	416	/* Sanity check -- queue functions should prevent this happening */
	417	if (bio->bi_vcnt != 1 \|\|
	418	bio->bi_idx != 0)
	419	goto bad_map;
	420	/* This is a one page bio that upper layers
	421	* refuse to split for us, so we need to split it.
	422	*/
	423	bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
	424	if (raid0_make_request(q, &bp->bio1))
	425	generic_make_request(&bp->bio1);
	426	if (raid0_make_request(q, &bp->bio2))
	427	generic_make_request(&bp->bio2);
	428
	429	bio_pair_release(bp);
	430	return 0;
	431	}
	432
	433
	434	{
1da177e4	435	sector_t x = block >> conf->preshift;
1eb29128	436	sector_div(x, (u32)conf->hash_spacing);
1da177e4 LT	437	zone = conf->hash_table[x];
	438	}
	439
	440	while (block >= (zone->zone_offset + zone->size))
	441	zone++;
	442
	443	sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1);
	444
	445
	446	{
	447	sector_t x = (block - zone->zone_offset) >> chunksize_bits;
	448
	449	sector_div(x, zone->nb_dev);
	450	chunk = x;
1da177e4 LT	451
	452	x = block >> chunksize_bits;
	453	tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
	454	}
	455	rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
	456	+ sect_in_chunk;
	457
	458	bio->bi_bdev = tmp_dev->bdev;
	459	bio->bi_sector = rsect + tmp_dev->data_offset;
	460
	461	/*
	462	* Let the main block layer submit the IO and resolve recursion:
	463	*/
	464	return 1;
	465
	466	bad_map:
	467	printk("raid0_make_request bug: can't convert block across chunks"
	468	" or bigger than %dk %llu %d\n", chunk_size,
	469	(unsigned long long)bio->bi_sector, bio->bi_size >> 10);
	470
6712ecf8	471	bio_io_error(bio);
1da177e4 LT	472	return 0;
1da177e4 LT	473	}
8299d7f7	474
1da177e4 LT	475	static void raid0_status (struct seq_file seq, mddev_t mddev)
	476	{
	477	#undef MD_DEBUG
	478	#ifdef MD_DEBUG
	479	int j, k, h;
	480	char b[BDEVNAME_SIZE];
	481	raid0_conf_t *conf = mddev_to_conf(mddev);
8299d7f7	482
1da177e4 LT	483	h = 0;
	484	for (j = 0; j < conf->nr_strip_zones; j++) {
	485	seq_printf(seq, " z%d", j);
	486	if (conf->hash_table[h] == conf->strip_zone+j)
8299d7f7	487	seq_printf(seq, "(h%d)", h++);
1da177e4 LT	488	seq_printf(seq, "=[");
1da177e4 LT	489	for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
8299d7f7	490	seq_printf(seq, "%s/", bdevname(
1da177e4 LT	491	conf->strip_zone[j].dev[k]->bdev,b));
1da177e4 LT	492
8299d7f7	493	seq_printf(seq, "] zo=%d do=%d s=%d\n",
1da177e4 LT	494	conf->strip_zone[j].zone_offset,
	495	conf->strip_zone[j].dev_offset,
	496	conf->strip_zone[j].size);
	497	}
	498	#endif
	499	seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
	500	return;
	501	}
	502
2604b703	503	static struct mdk_personality raid0_personality=
1da177e4 LT	504	{
1da177e4 LT	505	.name = "raid0",
2604b703	506	.level = 0,
1da177e4 LT	507	.owner = THIS_MODULE,
	508	.make_request = raid0_make_request,
	509	.run = raid0_run,
	510	.stop = raid0_stop,
	511	.status = raid0_status,
	512	};
	513
	514	static int __init raid0_init (void)
	515	{
2604b703	516	return register_md_personality (&raid0_personality);
1da177e4 LT	517	}
	518
	519	static void raid0_exit (void)
	520	{
2604b703	521	unregister_md_personality (&raid0_personality);
1da177e4 LT	522	}
	523
	524	module_init(raid0_init);
	525	module_exit(raid0_exit);
	526	MODULE_LICENSE("GPL");
	527	MODULE_ALIAS("md-personality-2"); /* RAID0 */
d9d166c2	528	MODULE_ALIAS("md-raid0");
2604b703	529	MODULE_ALIAS("md-level-0");