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