/*   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){	struct linear_hash *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;	if ((sector>>1) >= (hash->dev0->size + hash->dev0->offset))		return hash->dev1;	else		return hash->dev0;}/** *	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; 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;			break;		}		ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector);		if (ret)			break;	}	return ret;}static int linear_run (mddev_t *mddev){	linear_conf_t *conf;	struct linear_hash *table;	mdk_rdev_t *rdev;	int size, i, nb_zone, cnt;	unsigned int 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 (struct linear_hash) * nb_zone,					GFP_KERNEL);	if (!conf->hash_table)		goto out;	/*	 * Here we generate the linear hash table	 */	table = conf->hash_table;	size = 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;		if (size < 0) {			table[-1].dev1 = disk;		}		size += disk->size;		while (size>0) {			table->dev0 = disk;			table->dev1 = NULL;			size -= conf->smallest->size;			table++;		}	}	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);  	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(!tmp_dev)) {		printk("linear_make_request: hash->dev1==NULL for block %llu\n",			(unsigned long long)block);		bio_io_error(bio, bio->bi_size);		return 0;	}    	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 %ld offset %ld\n",			(unsigned long long)block,			bdevname(tmp_dev->rdev->bdev, b),			tmp_dev->size, 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);  	seq_printf(seq, "      ");	for (j = 0; j < conf->nr_zones; j++)	{		char b[BDEVNAME_SIZE];		seq_printf(seq, "[%s",			   bdevname(conf->hash_table[j].dev0->rdev->bdev,b));		if (conf->hash_table[j].dev1)			seq_printf(seq, "/%s] ",				   bdevname(conf->hash_table[j].dev1->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 */