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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/partitions/devfs.c | |
download | op-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip op-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'fs/partitions/devfs.c')
-rw-r--r-- | fs/partitions/devfs.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/fs/partitions/devfs.c b/fs/partitions/devfs.c new file mode 100644 index 0000000..87f5044 --- /dev/null +++ b/fs/partitions/devfs.c @@ -0,0 +1,130 @@ +/* + * 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 <asm/semaphore.h> + + +struct unique_numspace { + u32 num_free; /* Num free in bits */ + u32 length; /* Array length in bytes */ + unsigned long *bits; + struct semaphore mutex; +}; + +static DECLARE_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; + + down(&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); + } + up(&numspace_mutex); + + return rval; +} + +static void dealloc_unique_number(struct unique_numspace *s, int number) +{ + int old_val; + + if (number >= 0) { + down(&numspace_mutex); + old_val = __test_and_clear_bit(number, s->bits); + if (old_val) + ++s->num_free; + up(&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); +} + + |