/*
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
*/
block >>= conf->preshift;
(void)sector_div(block, conf->hash_spacing);
hash = conf->hash_table[block];
while ((sector>>1) >= (hash->size + hash->offset))
hash++;
return hash;
}
/**
* linear_mergeable_bvec -- tell bio layer if 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(struct request_queue *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(struct request_queue *q)
{
mddev_t *mddev = q->queuedata;
linear_conf_t *conf = mddev_to_conf(mddev);
int i;
for (i=0; i < mddev->raid_disks; i++) {
struct request_queue *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
blk_unplug(r_queue);
}
}
static int linear_congested(void *data, int bits)
{
mddev_t *mddev = data;
linear_conf_t *conf = mddev_to_conf(mddev);
int i, ret = 0;
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);
}
return ret;
}
static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
{
linear_conf_t *conf;
dev_info_t **table;
mdk_rdev_t *rdev;
int i, nb_zone, cnt;
sector_t min_spacing;
sector_t curr_offset;
struct list_head *tmp;
conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
GFP_KERNEL);
if (!conf)
return NULL;
cnt = 0;
conf->array_size = 0;
rdev_for_each(rdev, tmp, mddev) {
int j = rdev->raid_disk;
dev_info_t *disk = conf->disks + j;
if (j < 0 || j > 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;
conf->array_size += rdev->size;
cnt++;
}
if (cnt != raid_disks) {
printk("linear: not enough drives present. Aborting!\n");
goto out;
}
min_spacing = conf->array_size;
sector_div(min_spacing, PAGE_SIZE/sizeof(struct dev_info *));
/* min_spacing is the minimum spacing that will fit the hash
* table in one PAGE. This may be much smaller than needed.
* We find the smallest non-terminal set of consecutive devices
* that is larger than min_spacing as use the size of that as
* the actual spacing
*/
conf->hash_spacing = conf->array_size;
for (i=0; i < cnt-1 ; i++) {
sector_t sz = 0;
int j;
for (j = i; j < cnt - 1 && sz < min_spacing; j++)
sz += conf->disks[j].size;
if (sz >= min_spacing && sz < conf->hash_spacing)
conf->hash_spacing = sz;
}
/* hash_spacing may be too large for sector_div to work with,
* so we might need to pre-shift
*/
conf->preshift = 0;
if (sizeof(sector_t) > sizeof(u32)) {
sector_t space = conf->hash_spacing;
while (space > (sector_t)(~(u32)0)) {
space >>= 1;
conf->preshift++;
}
}
/*
* 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 = conf->array_size >> conf->preshift;
sz += 1; /* force round-up */
base = conf->hash_spacing >> conf->preshift;
round = sector_div(sz, base);
nb_zone = sz + (round ? 1 : 0);
}
BUG_ON(nb_zone > PAGE_SIZE / sizeof(struct dev_info *));
conf->hash_table = kmalloc (sizeof (struct dev_info *) * nb_zone,
GFP_KERNEL);
if (!conf->hash_table)
goto out;
/*
* Here we generate the linear hash table
* First calculate the device offsets.
*/
conf->disks[0].offset = 0;
for (i = 1; i < raid_disks; i++)
conf->disks[i].offset =
conf->disks[i-1].offset +
conf->disks[i-1].size;
table = conf->hash_table;
curr_offset = 0;
i = 0;
for (curr_offset = 0;
curr_offset < conf->array_size;
curr_offset += conf->hash_spacing) {
while (i < raid_disks-1 &&
curr_offset >= conf->disks[i+1].offset)
i++;
*table ++ = conf->disks + i;
}
if (conf->preshift) {
conf->hash_spacing >>= conf->preshift;
/* round hash_spacing up so that when we divide by it,
* we err on the side of "too-low", which is safest.
*/
conf->hash_spacing++;
}
BUG_ON(table - conf->hash_table > nb_zone);
return conf;
out:
kfree(conf);
return NULL;
}
static int linear_run (mddev_t *mddev)
{
linear_conf_t *conf;
mddev->queue->queue_lock = &mddev->queue->__queue_lock;
conf = linear_conf(mddev, mddev->raid_disks);
if (!conf)
return 1;
mddev->private = conf;
mddev->array_size = conf->array_size;
blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
mddev->queue->unplug_fn = linear_unplug;
mddev->queue->backing_dev_info.congested_fn = linear_congested;
mddev->queue->backing_dev_info.congested_data = mddev;
return 0;
}
static int linear_add(mddev_t *mddev, mdk_rdev_t *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.
*/
linear_conf_t *newconf;
if (rdev->saved_raid_disk != mddev->raid_disks)
return -EINVAL;
rdev->raid_disk = rdev->saved_raid_disk;
newconf = linear_conf(mddev,mddev->raid_disks+1);
if (!newconf)
return -ENOMEM;
newconf->prev = mddev_to_conf(mddev);
mddev->private = newconf;
mddev->raid_disks++;
mddev->array_size = newconf->array_size;
set_capacity(mddev->gendisk, mddev->array_size << 1);
return 0;
}
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'*/
do {
linear_conf_t *t = conf->prev;
kfree(conf->hash_table);
kfree(conf);
conf = t;
} while (conf);
return 0;
}
static int linear_make_request (struct request_queue *q, struct bio *bio)
{
const int rw = bio_data_dir(bio);
mddev_t *mddev = q->queuedata;
dev_info_t *tmp_dev;
sector_t block;
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));
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);
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 < mddev->raid_disks; 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 struct mdk_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,
};
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_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
MODULE_ALIAS("md-linear");
MODULE_ALIAS("md-level--1");
