random number in driver

get_random_bytes():

ex:

unsigned char uuid[16];

get_random_bytes(uuid, sizeof (uuid));

type definition

struct block_device:

linux/fs.h

dev_t:

linux/types.h

struct page:

linux/mm_types.h

struct gendisk:

linux/genhd.h

struct request_queue:

linux/blkdev.h

wait_queue_head_t:

linux/wait.h

spinlock_t:

linux/spinlock_types.h

struct semaphore:

linux/semaphore.h

dmesg

/var/log/messages

dhclient

get new ip

dm

 //The request function that just remaps the bio built up by dm_merge_bvec

static int dm_request(struct request_queue *q, struct bio *bio)

       call  __split_bio

// Split the bio into several clones.

static int __split_bio(struct mapped_device *md, struct bio *bio)

       call  __clone_and_map with parameter ci

       ( ci.sector_count= bio_sectors(bio)  )

static int __clone_and_map(struct clone_info *ci)

call  split_bvec

sector_t

typedef unsigned long sector_t;

mkfs

create filesystem

ex:

mkfs -v  /dev/hda3