drivers/md/linear.c - linux/kernel/git/davem/net-next - Git at Google

 /*
    linear.c : Multiple Devices driver for Linux
 	      Copyright (C) 1994-96 Marc ZYNGIER
 	      <zyngier@ufr-info-p7.ibp.fr> or
 	      <maz@gloups.fdn.fr>

    Linear mode 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/md.h>
 #include <linux/slab.h>
 #include <linux/raid/linear.h>

 #define MAJOR_NR MD_MAJOR
 #define MD_DRIVER
 #define MD_PERSONALITY

 /*
  * find which device holds a particular offset
  */
 static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
 {
 	dev_info_t *hash;
 	linear_conf_t *conf = mddev_to_conf(mddev);
 	sector_t block = sector >> 1;

 	/*
 	 * sector_div(a,b) returns the remainer and sets a to a/b
 	 */
 	(void)sector_div(block, conf->smallest->size);
 	hash = conf->hash_table[block];

 	while ((sector>>1) >= (hash->size + hash->offset))
 		hash++;
 	return hash;
 }

 /**
  *	linear_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 take at this offset
  */
 static int linear_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
 {
 	mddev_t *mddev = q->queuedata;
 	dev_info_t *dev0;
 	unsigned long maxsectors, bio_sectors = bio->bi_size >> 9;
 	sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);

 	dev0 = which_dev(mddev, sector);
 	maxsectors = (dev0->size << 1) - (sector - (dev0->offset<<1));

 	if (maxsectors < bio_sectors)
 		maxsectors = 0;
 	else
 		maxsectors -= bio_sectors;

 	if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
 		return biovec->bv_len;
 	/* The bytes available at this offset could be really big,
 	 * so we cap at 2^31 to avoid overflow */
 	if (maxsectors > (1 << (31-9)))
 		return 1<<31;
 	return maxsectors << 9;
 }

 static void linear_unplug(request_queue_t *q)
 {
 	mddev_t *mddev = q->queuedata;
 	linear_conf_t *conf = mddev_to_conf(mddev);
 	int i;

 	for (i=0; i < mddev->raid_disks; i++) {
 		request_queue_t *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
 		if (r_queue->unplug_fn)
 			r_queue->unplug_fn(r_queue);
 	}
 }

 static int linear_issue_flush(request_queue_t *q, struct gendisk *disk,
 			      sector_t *error_sector)
 {
 	mddev_t *mddev = q->queuedata;
 	linear_conf_t *conf = mddev_to_conf(mddev);
 	int i, ret = 0;

 	for (i=0; i < mddev->raid_disks && ret == 0; i++) {
 		struct block_device *bdev = conf->disks[i].rdev->bdev;
 		request_queue_t *r_queue = bdev_get_queue(bdev);

 		if (!r_queue->issue_flush_fn)
 			ret = -EOPNOTSUPP;
 		else
 			ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector);
 	}
 	return ret;
 }

 static int linear_run (mddev_t *mddev)
 {
 	linear_conf_t *conf;
 	dev_info_t **table;
 	mdk_rdev_t *rdev;
 	int i, nb_zone, cnt;
 	sector_t start;
 	sector_t curr_offset;
 	struct list_head *tmp;

 	conf = kmalloc (sizeof (*conf) + mddev->raid_disks*sizeof(dev_info_t),
 			GFP_KERNEL);
 	if (!conf)
 		goto out;
 	memset(conf, 0, sizeof(*conf) + mddev->raid_disks*sizeof(dev_info_t));
 	mddev->private = conf;

 	/*
 	 * Find the smallest device.
 	 */

 	conf->smallest = NULL;
 	cnt = 0;
 	mddev->array_size = 0;

 	ITERATE_RDEV(mddev,rdev,tmp) {
 		int j = rdev->raid_disk;
 		dev_info_t *disk = conf->disks + j;

 		if (j < 0 || j > mddev->raid_disks || disk->rdev) {
 			printk("linear: disk numbering problem. Aborting!\n");
 			goto out;
 		}

 		disk->rdev = rdev;

 		blk_queue_stack_limits(mddev->queue,
 				       rdev->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 (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
 		    mddev->queue->max_sectors > (PAGE_SIZE>>9))
 			blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);

 		disk->size = rdev->size;
 		mddev->array_size += rdev->size;

 		if (!conf->smallest || (disk->size < conf->smallest->size))
 			conf->smallest = disk;
 		cnt++;
 	}
 	if (cnt != mddev->raid_disks) {
 		printk("linear: not enough drives present. Aborting!\n");
 		goto out;
 	}

 	/*
 	 * This code was restructured to work around a gcc-2.95.3 internal
 	 * compiler error.  Alter it with care.
 	 */
 	{
 		sector_t sz;
 		unsigned round;
 		unsigned long base;

 		sz = mddev->array_size;
 		base = conf->smallest->size;
 		round = sector_div(sz, base);
 		nb_zone = conf->nr_zones = sz + (round ? 1 : 0);
 	}

 	conf->hash_table = kmalloc (sizeof (dev_info_t*) * nb_zone,
 					GFP_KERNEL);
 	if (!conf->hash_table)
 		goto out;

 	/*
 	 * Here we generate the linear hash table
 	 */
 	table = conf->hash_table;
 	start = 0;
 	curr_offset = 0;
 	for (i = 0; i < cnt; i++) {
 		dev_info_t *disk = conf->disks + i;

 		disk->offset = curr_offset;
 		curr_offset += disk->size;

 		/* 'curr_offset' is the end of this disk
 		 * 'start' is the start of table
 		 */
 		while (start < curr_offset) {
 			*table++ = disk;
 			start += conf->smallest->size;
 		}
 	}
 	if (table-conf->hash_table != nb_zone)
 		BUG();

 	blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
 	mddev->queue->unplug_fn = linear_unplug;
 	mddev->queue->issue_flush_fn = linear_issue_flush;
 	return 0;

 out:
 	if (conf)
 		kfree(conf);
 	return 1;
 }

 static int linear_stop (mddev_t *mddev)
 {
 	linear_conf_t *conf = mddev_to_conf(mddev);

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

 	return 0;
 }

 static int linear_make_request (request_queue_t *q, struct bio *bio)
 {
 	mddev_t *mddev = q->queuedata;
 	dev_info_t *tmp_dev;
 	sector_t block;

 	if (bio_data_dir(bio)==WRITE) {
 		disk_stat_inc(mddev->gendisk, writes);
 		disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));
 	} else {
 		disk_stat_inc(mddev->gendisk, reads);
 		disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio));
 	}

 	tmp_dev = which_dev(mddev, bio->bi_sector);
 	block = bio->bi_sector >> 1;

 	if (unlikely(block >= (tmp_dev->size + tmp_dev->offset)
 		     || block < tmp_dev->offset)) {
 		char b[BDEVNAME_SIZE];

 		printk("linear_make_request: Block %llu out of bounds on "
 			"dev %s size %llu offset %llu\n",
 			(unsigned long long)block,
 			bdevname(tmp_dev->rdev->bdev, b),
 			(unsigned long long)tmp_dev->size,
 		        (unsigned long long)tmp_dev->offset);
 		bio_io_error(bio, bio->bi_size);
 		return 0;
 	}
 	if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
 		     (tmp_dev->offset + tmp_dev->size)<<1)) {
 		/* This bio crosses a device boundary, so we have to
 		 * split it.
 		 */
 		struct bio_pair *bp;
 		bp = bio_split(bio, bio_split_pool,
 			       (bio->bi_sector + (bio->bi_size >> 9) -
 				(tmp_dev->offset + tmp_dev->size))<<1);
 		if (linear_make_request(q, &bp->bio1))
 			generic_make_request(&bp->bio1);
 		if (linear_make_request(q, &bp->bio2))
 			generic_make_request(&bp->bio2);
 		bio_pair_release(bp);
 		return 0;
 	}

 	bio->bi_bdev = tmp_dev->rdev->bdev;
 	bio->bi_sector = bio->bi_sector - (tmp_dev->offset << 1) + tmp_dev->rdev->data_offset;

 	return 1;
 }

 static void linear_status (struct seq_file *seq, mddev_t *mddev)
 {

 #undef MD_DEBUG
 #ifdef MD_DEBUG
 	int j;
 	linear_conf_t *conf = mddev_to_conf(mddev);
 	sector_t s = 0;

 	seq_printf(seq, "      ");
 	for (j = 0; j < conf->nr_zones; j++)
 	{
 		char b[BDEVNAME_SIZE];
 		s += conf->smallest_size;
 		seq_printf(seq, "[%s",
 			   bdevname(conf->hash_table[j][0].rdev->bdev,b));

 		while (s > conf->hash_table[j][0].offset +
 		           conf->hash_table[j][0].size)
 			seq_printf(seq, "/%s] ",
 				   bdevname(conf->hash_table[j][1].rdev->bdev,b));
 		else
 			seq_printf(seq, "] ");
 	}
 	seq_printf(seq, "\n");
 #endif
 	seq_printf(seq, " %dk rounding", mddev->chunk_size/1024);
 }


 static mdk_personality_t linear_personality=
 {
 	.name		= "linear",
 	.owner		= THIS_MODULE,
 	.make_request	= linear_make_request,
 	.run		= linear_run,
 	.stop		= linear_stop,
 	.status		= linear_status,
 };

 static int __init linear_init (void)
 {
 	return register_md_personality (LINEAR, &linear_personality);
 }

 static void linear_exit (void)
 {
 	unregister_md_personality (LINEAR);
 }


 module_init(linear_init);
 module_exit(linear_exit);
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("md-personality-1"); /* LINEAR */
	/*
	linear.c : Multiple Devices driver for Linux
	Copyright (C) 1994-96 Marc ZYNGIER
	<zyngier@ufr-info-p7.ibp.fr> or
	<maz@gloups.fdn.fr>

	Linear mode 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/md.h>
	#include <linux/slab.h>
	#include <linux/raid/linear.h>

	#define MAJOR_NR MD_MAJOR
	#define MD_DRIVER
	#define MD_PERSONALITY

	/*
	* find which device holds a particular offset
	*/
	static inline dev_info_t which_dev(mddev_t mddev, sector_t sector)
	{
	dev_info_t *hash;
	linear_conf_t *conf = mddev_to_conf(mddev);
	sector_t block = sector >> 1;

	/*
	* sector_div(a,b) returns the remainer and sets a to a/b
	*/
	(void)sector_div(block, conf->smallest->size);
	hash = conf->hash_table[block];

	while ((sector>>1) >= (hash->size + hash->offset))
	hash++;
	return hash;
	}

	/**
	* linear_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 take at this offset
	*/
	static int linear_mergeable_bvec(request_queue_t q, struct bio bio, struct bio_vec *biovec)
	{
	mddev_t *mddev = q->queuedata;
	dev_info_t *dev0;
	unsigned long maxsectors, bio_sectors = bio->bi_size >> 9;
	sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);

	dev0 = which_dev(mddev, sector);
	maxsectors = (dev0->size << 1) - (sector - (dev0->offset<<1));

	if (maxsectors < bio_sectors)
	maxsectors = 0;
	else
	maxsectors -= bio_sectors;

	if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
	return biovec->bv_len;
	/* The bytes available at this offset could be really big,
	* so we cap at 2^31 to avoid overflow */
	if (maxsectors > (1 << (31-9)))
	return 1<<31;
	return maxsectors << 9;
	}

	static void linear_unplug(request_queue_t *q)
	{
	mddev_t *mddev = q->queuedata;
	linear_conf_t *conf = mddev_to_conf(mddev);
	int i;

	for (i=0; i < mddev->raid_disks; i++) {
	request_queue_t *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
	if (r_queue->unplug_fn)
	r_queue->unplug_fn(r_queue);
	}
	}

	static int linear_issue_flush(request_queue_t q, struct gendisk disk,
	sector_t *error_sector)
	{
	mddev_t *mddev = q->queuedata;
	linear_conf_t *conf = mddev_to_conf(mddev);
	int i, ret = 0;

	for (i=0; i < mddev->raid_disks && ret == 0; i++) {
	struct block_device *bdev = conf->disks[i].rdev->bdev;
	request_queue_t *r_queue = bdev_get_queue(bdev);

	if (!r_queue->issue_flush_fn)
	ret = -EOPNOTSUPP;
	else
	ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector);
	}
	return ret;
	}

	static int linear_run (mddev_t *mddev)
	{
	linear_conf_t *conf;
	dev_info_t **table;
	mdk_rdev_t *rdev;
	int i, nb_zone, cnt;
	sector_t start;
	sector_t curr_offset;
	struct list_head *tmp;

	conf = kmalloc (sizeof (conf) + mddev->raid_diskssizeof(dev_info_t),
	GFP_KERNEL);
	if (!conf)
	goto out;
	memset(conf, 0, sizeof(conf) + mddev->raid_diskssizeof(dev_info_t));
	mddev->private = conf;

	/*
	* Find the smallest device.
	*/

	conf->smallest = NULL;
	cnt = 0;
	mddev->array_size = 0;

	ITERATE_RDEV(mddev,rdev,tmp) {
	int j = rdev->raid_disk;
	dev_info_t *disk = conf->disks + j;

	if (j < 0 \|\| j > mddev->raid_disks \|\| disk->rdev) {
	printk("linear: disk numbering problem. Aborting!\n");
	goto out;
	}

	disk->rdev = rdev;

	blk_queue_stack_limits(mddev->queue,
	rdev->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 (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
	mddev->queue->max_sectors > (PAGE_SIZE>>9))
	blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);

	disk->size = rdev->size;
	mddev->array_size += rdev->size;

	if (!conf->smallest \|\| (disk->size < conf->smallest->size))
	conf->smallest = disk;
	cnt++;
	}
	if (cnt != mddev->raid_disks) {
	printk("linear: not enough drives present. Aborting!\n");
	goto out;
	}

	/*
	* This code was restructured to work around a gcc-2.95.3 internal
	* compiler error. Alter it with care.
	*/
	{
	sector_t sz;
	unsigned round;
	unsigned long base;

	sz = mddev->array_size;
	base = conf->smallest->size;
	round = sector_div(sz, base);
	nb_zone = conf->nr_zones = sz + (round ? 1 : 0);
	}

	conf->hash_table = kmalloc (sizeof (dev_info_t) nb_zone,
	GFP_KERNEL);
	if (!conf->hash_table)
	goto out;

	/*
	* Here we generate the linear hash table
	*/
	table = conf->hash_table;
	start = 0;
	curr_offset = 0;
	for (i = 0; i < cnt; i++) {
	dev_info_t *disk = conf->disks + i;

	disk->offset = curr_offset;
	curr_offset += disk->size;

	/* 'curr_offset' is the end of this disk
	* 'start' is the start of table
	*/
	while (start < curr_offset) {
	*table++ = disk;
	start += conf->smallest->size;
	}
	}
	if (table-conf->hash_table != nb_zone)
	BUG();

	blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
	mddev->queue->unplug_fn = linear_unplug;
	mddev->queue->issue_flush_fn = linear_issue_flush;
	return 0;

	out:
	if (conf)
	kfree(conf);
	return 1;
	}

	static int linear_stop (mddev_t *mddev)
	{
	linear_conf_t *conf = mddev_to_conf(mddev);

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

	return 0;
	}

	static int linear_make_request (request_queue_t q, struct bio bio)
	{
	mddev_t *mddev = q->queuedata;
	dev_info_t *tmp_dev;
	sector_t block;

	if (bio_data_dir(bio)==WRITE) {
	disk_stat_inc(mddev->gendisk, writes);
	disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));
	} else {
	disk_stat_inc(mddev->gendisk, reads);
	disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio));
	}

	tmp_dev = which_dev(mddev, bio->bi_sector);
	block = bio->bi_sector >> 1;

	if (unlikely(block >= (tmp_dev->size + tmp_dev->offset)
	\|\| block < tmp_dev->offset)) {
	char b[BDEVNAME_SIZE];

	printk("linear_make_request: Block %llu out of bounds on "
	"dev %s size %llu offset %llu\n",
	(unsigned long long)block,
	bdevname(tmp_dev->rdev->bdev, b),
	(unsigned long long)tmp_dev->size,
	(unsigned long long)tmp_dev->offset);
	bio_io_error(bio, bio->bi_size);
	return 0;
	}
	if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
	(tmp_dev->offset + tmp_dev->size)<<1)) {
	/* This bio crosses a device boundary, so we have to
	* split it.
	*/
	struct bio_pair *bp;
	bp = bio_split(bio, bio_split_pool,
	(bio->bi_sector + (bio->bi_size >> 9) -
	(tmp_dev->offset + tmp_dev->size))<<1);
	if (linear_make_request(q, &bp->bio1))
	generic_make_request(&bp->bio1);
	if (linear_make_request(q, &bp->bio2))
	generic_make_request(&bp->bio2);
	bio_pair_release(bp);
	return 0;
	}

	bio->bi_bdev = tmp_dev->rdev->bdev;
	bio->bi_sector = bio->bi_sector - (tmp_dev->offset << 1) + tmp_dev->rdev->data_offset;

	return 1;
	}

	static void linear_status (struct seq_file seq, mddev_t mddev)
	{

	#undef MD_DEBUG
	#ifdef MD_DEBUG
	int j;
	linear_conf_t *conf = mddev_to_conf(mddev);
	sector_t s = 0;

	seq_printf(seq, " ");
	for (j = 0; j < conf->nr_zones; j++)
	{
	char b[BDEVNAME_SIZE];
	s += conf->smallest_size;
	seq_printf(seq, "[%s",
	bdevname(conf->hash_table[j][0].rdev->bdev,b));

	while (s > conf->hash_table[j][0].offset +
	conf->hash_table[j][0].size)
	seq_printf(seq, "/%s] ",
	bdevname(conf->hash_table[j][1].rdev->bdev,b));
	else
	seq_printf(seq, "] ");
	}
	seq_printf(seq, "\n");
	#endif
	seq_printf(seq, " %dk rounding", mddev->chunk_size/1024);
	}


	static mdk_personality_t linear_personality=
	{
	.name = "linear",
	.owner = THIS_MODULE,
	.make_request = linear_make_request,
	.run = linear_run,
	.stop = linear_stop,
	.status = linear_status,
	};

	static int __init linear_init (void)
	{
	return register_md_personality (LINEAR, &linear_personality);
	}

	static void linear_exit (void)
	{
	unregister_md_personality (LINEAR);
	}


	module_init(linear_init);
	module_exit(linear_exit);
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("md-personality-1"); /* LINEAR */