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linux/drivers/md/linear.c
Jesper Juhl 990a8baf56 [PATCH] md: remove unneeded NULL checks before kfree
This patch removes some unneeded checks of pointers being NULL before
calling kfree() on them.  kfree() handles NULL pointers just fine, checking
first is pointless.

Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:48 -07:00

342 lines
8.4 KiB
C

/*
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 */