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/*
* This tries to keep block devices away from devfs as much as possible.
*/
#include <linux/fs.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/vmalloc.h>
#include <linux/genhd.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
struct unique_numspace {
u32 num_free; /* Num free in bits */
u32 length; /* Array length in bytes */
unsigned long *bits;
struct semaphore mutex;
};
static DEFINE_MUTEX(numspace_mutex);
static int expand_numspace(struct unique_numspace *s)
{
u32 length;
void *bits;
if (s->length < 16)
length = 16;
else
length = s->length << 1;
bits = vmalloc(length);
if (!bits)
return -ENOMEM;
if (s->bits) {
memcpy(bits, s->bits, s->length);
vfree(s->bits);
}
s->num_free = (length - s->length) << 3;
s->bits = bits;
memset(bits + s->length, 0, length - s->length);
s->length = length;
return 0;
}
static int alloc_unique_number(struct unique_numspace *s)
{
int rval = 0;
mutex_lock(&numspace_mutex);
if (s->num_free < 1)
rval = expand_numspace(s);
if (!rval) {
rval = find_first_zero_bit(s->bits, s->length << 3);
--s->num_free;
__set_bit(rval, s->bits);
}
mutex_unlock(&numspace_mutex);
return rval;
}
static void dealloc_unique_number(struct unique_numspace *s, int number)
{
int old_val;
if (number >= 0) {
mutex_lock(&numspace_mutex);
old_val = __test_and_clear_bit(number, s->bits);
if (old_val)
++s->num_free;
mutex_unlock(&numspace_mutex);
}
}
static struct unique_numspace disc_numspace;
static struct unique_numspace cdrom_numspace;
void devfs_add_partitioned(struct gendisk *disk)
{
char dirname[64], symlink[16];
devfs_mk_dir(disk->devfs_name);
devfs_mk_bdev(MKDEV(disk->major, disk->first_minor),
S_IFBLK|S_IRUSR|S_IWUSR,
"%s/disc", disk->devfs_name);
disk->number = alloc_unique_number(&disc_numspace);
sprintf(symlink, "discs/disc%d", disk->number);
sprintf(dirname, "../%s", disk->devfs_name);
devfs_mk_symlink(symlink, dirname);
}
void devfs_add_disk(struct gendisk *disk)
{
devfs_mk_bdev(MKDEV(disk->major, disk->first_minor),
(disk->flags & GENHD_FL_CD) ?
S_IFBLK|S_IRUGO|S_IWUGO :
S_IFBLK|S_IRUSR|S_IWUSR,
"%s", disk->devfs_name);
if (disk->flags & GENHD_FL_CD) {
char dirname[64], symlink[16];
disk->number = alloc_unique_number(&cdrom_numspace);
sprintf(symlink, "cdroms/cdrom%d", disk->number);
sprintf(dirname, "../%s", disk->devfs_name);
devfs_mk_symlink(symlink, dirname);
}
}
void devfs_remove_disk(struct gendisk *disk)
{
if (disk->minors != 1) {
devfs_remove("discs/disc%d", disk->number);
dealloc_unique_number(&disc_numspace, disk->number);
devfs_remove("%s/disc", disk->devfs_name);
}
if (disk->flags & GENHD_FL_CD) {
devfs_remove("cdroms/cdrom%d", disk->number);
dealloc_unique_number(&cdrom_numspace, disk->number);
}
devfs_remove(disk->devfs_name);
}
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