/*
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:
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,
((tmp_dev->offset + tmp_dev->size)<<1) - bio->bi_sector);
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 */
