#ifndef _BLK_H#define _BLK_H#include <linux/major.h>#include <linux/sched.h>#include <linux/locks.h>#include <linux/genhd.h>/* * NR_REQUEST is the number of entries in the request-queue. * NOTE that writes may use only the low 2/3 of these: reads * take precedence. * * 32 seems to be a reasonable number: enough to get some benefit * from the elevator-mechanism, but not so much as to lock a lot of * buffers when they are in the queue. 64 seems to be too many (easily * long pauses in reading when heavy writing/syncing is going on) */#define NR_REQUEST	64/* * Ok, this is an expanded form so that we can use the same * request for paging requests when that is implemented. In * paging, 'bh' is NULL, and 'waiting' is used to wait for * read/write completion. */struct request {	int dev;		/* -1 if no request */	int cmd;		/* READ or WRITE */	int errors;	unsigned long sector;	unsigned long nr_sectors;	unsigned long current_nr_sectors;	char * buffer;	struct task_struct * waiting;	struct buffer_head * bh;	struct buffer_head * bhtail;	struct request * next;};/* * This is used in the elevator algorithm: Note that * reads always go before writes. This is natural: reads * are much more time-critical than writes. */#define IN_ORDER(s1,s2) \((s1)->cmd < (s2)->cmd || ((s1)->cmd == (s2)->cmd && \((s1)->dev < (s2)->dev || (((s1)->dev == (s2)->dev && \(s1)->sector < (s2)->sector)))))struct blk_dev_struct {	void (*request_fn)(void);	struct request * current_request;};struct sec_size {	unsigned block_size;	unsigned block_size_bits;};/* * These will have to be changed to be aware of different buffer * sizes etc.. It actually needs a major cleanup. */#define SECTOR_MASK (blksize_size[MAJOR_NR] &&     \	blksize_size[MAJOR_NR][MINOR(CURRENT->dev)] ? \	((blksize_size[MAJOR_NR][MINOR(CURRENT->dev)] >> 9) - 1) :  \	((BLOCK_SIZE >> 9)  -  1))#define SUBSECTOR(block) (CURRENT->current_nr_sectors > 0)extern struct sec_size * blk_sec[MAX_BLKDEV];extern struct blk_dev_struct blk_dev[MAX_BLKDEV];extern struct wait_queue * wait_for_request;extern void resetup_one_dev(struct gendisk *dev, int drive);extern int * blk_size[MAX_BLKDEV];extern int * blksize_size[MAX_BLKDEV];extern unsigned long hd_init(unsigned long mem_start, unsigned long mem_end);extern unsigned long cdu31a_init(unsigned long mem_start, unsigned long mem_end);extern unsigned long mcd_init(unsigned long mem_start, unsigned long mem_end);extern int is_read_only(int dev);extern void set_device_ro(int dev,int flag);extern void rd_load(void);extern long rd_init(long mem_start, int length);extern int ramdisk_size;extern unsigned long xd_init(unsigned long mem_start, unsigned long mem_end);#define RO_IOCTLS(dev,where) \  case BLKROSET: if (!suser()) return -EPERM; \		 set_device_ro((dev),get_fs_long((long *) (where))); return 0; \  case BLKROGET: { int __err = verify_area(VERIFY_WRITE, (void *) (where), sizeof(long)); \		   if (!__err) put_fs_long(is_read_only(dev),(long *) (where)); return __err; }		 #ifdef MAJOR_NR/* * Add entries as needed. Currently the only block devices * supported are hard-disks and floppies. */#if (MAJOR_NR == MEM_MAJOR)/* ram disk */#define DEVICE_NAME "ramdisk"#define DEVICE_REQUEST do_rd_request#define DEVICE_NR(device) ((device) & 7)#define DEVICE_ON(device) #define DEVICE_OFF(device)#elif (MAJOR_NR == FLOPPY_MAJOR)static void floppy_on(unsigned int nr);static void floppy_off(unsigned int nr);#define DEVICE_NAME "floppy"#define DEVICE_INTR do_floppy#define DEVICE_REQUEST do_fd_request#define DEVICE_NR(device) ((device) & 3)#define DEVICE_ON(device) floppy_on(DEVICE_NR(device))#define DEVICE_OFF(device) floppy_off(DEVICE_NR(device))#elif (MAJOR_NR == HD_MAJOR)/* harddisk: timeout is 6 seconds.. */#define DEVICE_NAME "harddisk"#define DEVICE_INTR do_hd#define DEVICE_TIMEOUT HD_TIMER#define TIMEOUT_VALUE 600#define DEVICE_REQUEST do_hd_request#define DEVICE_NR(device) (MINOR(device)>>6)#define DEVICE_ON(device)#define DEVICE_OFF(device)#elif (MAJOR_NR == SCSI_DISK_MAJOR)#define DEVICE_NAME "scsidisk"#define DEVICE_INTR do_sd  #define TIMEOUT_VALUE 200#define DEVICE_REQUEST do_sd_request#define DEVICE_NR(device) (MINOR(device) >> 4)#define DEVICE_ON(device)#define DEVICE_OFF(device)#elif (MAJOR_NR == SCSI_TAPE_MAJOR)#define DEVICE_NAME "scsitape"#define DEVICE_INTR do_st  #define DEVICE_NR(device) (MINOR(device))#define DEVICE_ON(device)#define DEVICE_OFF(device)#elif (MAJOR_NR == SCSI_CDROM_MAJOR)#define DEVICE_NAME "CD-ROM"#define DEVICE_INTR do_sr#define DEVICE_REQUEST do_sr_request#define DEVICE_NR(device) (MINOR(device))#define DEVICE_ON(device)#define DEVICE_OFF(device)#elif (MAJOR_NR == XT_DISK_MAJOR)#define DEVICE_NAME "xt disk"#define DEVICE_REQUEST do_xd_request#define DEVICE_NR(device) (MINOR(device) >> 6)#define DEVICE_ON(device)#define DEVICE_OFF(device)#elif (MAJOR_NR == CDU31A_CDROM_MAJOR)#define DEVICE_NAME "CDU31A"#define DEVICE_REQUEST do_cdu31a_request#define DEVICE_NR(device) (MINOR(device))#define DEVICE_ON(device)#define DEVICE_OFF(device)#elif (MAJOR_NR == MITSUMI_CDROM_MAJOR)#define DEVICE_NAME "Mitsumi CD-ROM"/* #define DEVICE_INTR do_mcd */#define DEVICE_REQUEST do_mcd_request#define DEVICE_NR(device) (MINOR(device))#define DEVICE_ON(device)#define DEVICE_OFF(device)#elif (MAJOR_NR == MATSUSHITA_CDROM_MAJOR)#define DEVICE_NAME "Matsushita CD-ROM"#define DEVICE_REQUEST do_sbpcd_request#define DEVICE_NR(device) (MINOR(device))#define DEVICE_ON(device)#define DEVICE_OFF(device)#else#error "unknown blk device"#endif#if (MAJOR_NR != SCSI_TAPE_MAJOR)#ifndef CURRENT#define CURRENT (blk_dev[MAJOR_NR].current_request)#endif#define CURRENT_DEV DEVICE_NR(CURRENT->dev)#ifdef DEVICE_INTRvoid (*DEVICE_INTR)(void) = NULL;#endif#ifdef DEVICE_TIMEOUT#define SET_TIMER \((timer_table[DEVICE_TIMEOUT].expires = jiffies + TIMEOUT_VALUE), \(timer_active |= 1<<DEVICE_TIMEOUT))#define CLEAR_TIMER \timer_active &= ~(1<<DEVICE_TIMEOUT)#define SET_INTR(x) \if ((DEVICE_INTR = (x)) != NULL) \	SET_TIMER; \else \	CLEAR_TIMER;#else#define SET_INTR(x) (DEVICE_INTR = (x))#endifstatic void (DEVICE_REQUEST)(void);/* end_request() - SCSI devices have their own version */#if ! SCSI_MAJOR(MAJOR_NR)static void end_request(int uptodate){	struct request * req;	struct buffer_head * bh;	struct task_struct * p;	req = CURRENT;	req->errors = 0;	if (!uptodate) {		printk(DEVICE_NAME " I/O error\n");		printk("dev %04lX, sector %lu\n",		       (unsigned long)req->dev, req->sector);		req->nr_sectors--;		req->nr_sectors &= ~SECTOR_MASK;		req->sector += (BLOCK_SIZE / 512);		req->sector &= ~SECTOR_MASK;			}	if ((bh = req->bh) != NULL) {		req->bh = bh->b_reqnext;		bh->b_reqnext = NULL;		bh->b_uptodate = uptodate;		unlock_buffer(bh);		if ((bh = req->bh) != NULL) {			req->current_nr_sectors = bh->b_size >> 9;			if (req->nr_sectors < req->current_nr_sectors) {				req->nr_sectors = req->current_nr_sectors;				printk("end_request: buffer-list destroyed\n");			}			req->buffer = bh->b_data;			return;		}	}	DEVICE_OFF(req->dev);	CURRENT = req->next;	if ((p = req->waiting) != NULL) {		req->waiting = NULL;		p->state = TASK_RUNNING;		if (p->counter > current->counter)			need_resched = 1;	}	req->dev = -1;	wake_up(&wait_for_request);}#endif#ifdef DEVICE_INTR#define CLEAR_INTR SET_INTR(NULL)#else#define CLEAR_INTR#endif#define INIT_REQUEST \	if (!CURRENT) {\		CLEAR_INTR; \		return; \	} \	if (MAJOR(CURRENT->dev) != MAJOR_NR) \		panic(DEVICE_NAME ": request list destroyed"); \	if (CURRENT->bh) { \		if (!CURRENT->bh->b_lock) \			panic(DEVICE_NAME ": block not locked"); \	}#endif#endif#endif