/*   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/blkdev.h>#include <linux/raid/md_u.h>#include <linux/seq_file.h>#include <linux/module.h>#include <linux/slab.h>#include "md.h"#include "linear.h" /* * find which device holds a particular offset  */static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector){	int lo, mid, hi;	struct linear_conf *conf; 	lo = 0;	hi = mddev->raid_disks - 1;	conf = rcu_dereference(mddev->private); 	/*	 * Binary Search	 */ 	while (hi > lo) { 		mid = (hi + lo) / 2;		if (sector < conf->disks[mid].end_sector)			hi = mid;		else			lo = mid + 1;	} 	return conf->disks + lo;} /** *	linear_mergeable_bvec -- tell bio layer if 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 take at this offset */static int linear_mergeable_bvec(struct request_queue *q,				 struct bvec_merge_data *bvm,				 struct bio_vec *biovec){	struct mddev *mddev = q->queuedata;	struct dev_info *dev0;	unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev); 	rcu_read_lock();	dev0 = which_dev(mddev, sector);	maxsectors = dev0->end_sector - sector;	rcu_read_unlock(); 	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 int linear_congested(void *data, int bits){	struct mddev *mddev = data;	struct linear_conf *conf;	int i, ret = 0; 	if (mddev_congested(mddev, bits))		return 1; 	rcu_read_lock();	conf = rcu_dereference(mddev->private); 	for (i = 0; i < mddev->raid_disks && !ret ; i++) {		struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);		ret |= bdi_congested(&q->backing_dev_info, bits);	} 	rcu_read_unlock();	return ret;} static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks){	struct linear_conf *conf;	sector_t array_sectors; 	rcu_read_lock();	conf = rcu_dereference(mddev->private);	WARN_ONCE(sectors || raid_disks,		  "%s does not support generic reshape\n", __func__);	array_sectors = conf->array_sectors;	rcu_read_unlock(); 	return array_sectors;} static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks){	struct linear_conf *conf;	struct md_rdev *rdev;	int i, cnt; 	conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),			GFP_KERNEL);	if (!conf)		return NULL; 	cnt = 0;	conf->array_sectors = 0; 	list_for_each_entry(rdev, &mddev->disks, same_set) {		int j = rdev->raid_disk;		struct dev_info *disk = conf->disks + j;		sector_t sectors; 		if (j < 0 || j >= raid_disks || disk->rdev) {			printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",			       mdname(mddev));			goto out;		} 		disk->rdev = rdev;		if (mddev->chunk_sectors) {			sectors = rdev->sectors;			sector_div(sectors, mddev->chunk_sectors);			rdev->sectors = sectors * mddev->chunk_sectors;		} 		disk_stack_limits(mddev->gendisk, rdev->bdev,				  rdev->data_offset << 9);		/* as we don't honour merge_bvec_fn, we must never risk		 * violating it, so limit max_segments to 1 lying within		 * a single page.		 */		if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {			blk_queue_max_segments(mddev->queue, 1);			blk_queue_segment_boundary(mddev->queue,						   PAGE_CACHE_SIZE - 1);		} 		conf->array_sectors += rdev->sectors;		cnt++; 	}	if (cnt != raid_disks) {		printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",		       mdname(mddev));		goto out;	} 	/*	 * Here we calculate the device offsets.	 */	conf->disks[0].end_sector = conf->disks[0].rdev->sectors; 	for (i = 1; i < raid_disks; i++)		conf->disks[i].end_sector =			conf->disks[i-1].end_sector +			conf->disks[i].rdev->sectors; 	return conf; out:	kfree(conf);	return NULL;} static int linear_run (struct mddev *mddev){	struct linear_conf *conf; 	if (md_check_no_bitmap(mddev))		return -EINVAL;	conf = linear_conf(mddev, mddev->raid_disks); 	if (!conf)		return 1;	mddev->private = conf;	md_set_array_sectors(mddev, linear_size(mddev, 0, 0)); 	blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);	mddev->queue->backing_dev_info.congested_fn = linear_congested;	mddev->queue->backing_dev_info.congested_data = mddev;	return md_integrity_register(mddev);} static int linear_add(struct mddev *mddev, struct md_rdev *rdev){	/* Adding a drive to a linear array allows the array to grow.	 * It is permitted if the new drive has a matching superblock	 * already on it, with raid_disk equal to raid_disks.	 * It is achieved by creating a new linear_private_data structure	 * and swapping it in in-place of the current one.	 * The current one is never freed until the array is stopped.	 * This avoids races.	 */	struct linear_conf *newconf, *oldconf; 	if (rdev->saved_raid_disk != mddev->raid_disks)		return -EINVAL; 	rdev->raid_disk = rdev->saved_raid_disk;	rdev->saved_raid_disk = -1; 	newconf = linear_conf(mddev,mddev->raid_disks+1); 	if (!newconf)		return -ENOMEM; 	oldconf = rcu_dereference(mddev->private);	mddev->raid_disks++;	rcu_assign_pointer(mddev->private, newconf);	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));	set_capacity(mddev->gendisk, mddev->array_sectors);	revalidate_disk(mddev->gendisk);	kfree_rcu(oldconf, rcu);	return 0;} static int linear_stop (struct mddev *mddev){	struct linear_conf *conf = mddev->private; 	/*	 * We do not require rcu protection here since	 * we hold reconfig_mutex for both linear_add and	 * linear_stop, so they cannot race.	 * We should make sure any old 'conf's are properly	 * freed though.	 */	rcu_barrier();	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/	kfree(conf);	mddev->private = NULL; 	return 0;} static void linear_make_request(struct mddev *mddev, struct bio *bio){	struct dev_info *tmp_dev;	sector_t start_sector; 	if (unlikely(bio->bi_rw & REQ_FLUSH)) {		md_flush_request(mddev, bio);		return;	} 	rcu_read_lock();	tmp_dev = which_dev(mddev, bio->bi_sector);	start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;  	if (unlikely(bio->bi_sector >= (tmp_dev->end_sector)		     || (bio->bi_sector < start_sector))) {		char b[BDEVNAME_SIZE]; 		printk(KERN_ERR		       "md/linear:%s: make_request: Sector %llu out of bounds on "		       "dev %s: %llu sectors, offset %llu\n",		       mdname(mddev),		       (unsigned long long)bio->bi_sector,		       bdevname(tmp_dev->rdev->bdev, b),		       (unsigned long long)tmp_dev->rdev->sectors,		       (unsigned long long)start_sector);		rcu_read_unlock();		bio_io_error(bio);		return;	}	if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >		     tmp_dev->end_sector)) {		/* This bio crosses a device boundary, so we have to		 * split it.		 */		struct bio_pair *bp;		sector_t end_sector = tmp_dev->end_sector; 		rcu_read_unlock(); 		bp = bio_split(bio, end_sector - bio->bi_sector); 		linear_make_request(mddev, &bp->bio1);		linear_make_request(mddev, &bp->bio2);		bio_pair_release(bp);		return;	}		    	bio->bi_bdev = tmp_dev->rdev->bdev;	bio->bi_sector = bio->bi_sector - start_sector		+ tmp_dev->rdev->data_offset;	rcu_read_unlock();	generic_make_request(bio);} static void linear_status (struct seq_file *seq, struct mddev *mddev){ 	seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);}  static struct md_personality linear_personality ={	.name		= "linear",	.level		= LEVEL_LINEAR,	.owner		= THIS_MODULE,	.make_request	= linear_make_request,	.run		= linear_run,	.stop		= linear_stop,	.status		= linear_status,	.hot_add_disk	= linear_add,	.size		= linear_size,}; static int __init linear_init (void){	return register_md_personality (&linear_personality);} static void linear_exit (void){	unregister_md_personality (&linear_personality);}  module_init(linear_init);module_exit(linear_exit);MODULE_LICENSE("GPL");MODULE_DESCRIPTION("Linear device concatenation personality for MD");MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/MODULE_ALIAS("md-linear");MODULE_ALIAS("md-level--1");