You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
141 lines
3.4 KiB
141 lines
3.4 KiB
2 years ago
|
#ifndef _BLK_H
|
||
|
|
#define _BLK_H
|
||
|
|
|
||
|
|
#define NR_BLK_DEV 7
|
||
|
|
/*
|
||
|
|
* 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 32
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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;
|
||
|
|
char * buffer;
|
||
|
|
struct task_struct * waiting;
|
||
|
|
struct buffer_head * bh;
|
||
|
|
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;
|
||
|
|
};
|
||
|
|
|
||
|
|
extern struct blk_dev_struct blk_dev[NR_BLK_DEV];
|
||
|
|
extern struct request request[NR_REQUEST];
|
||
|
|
extern struct task_struct * wait_for_request;
|
||
|
|
|
||
|
|
#ifdef MAJOR_NR
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Add entries as needed. Currently the only block devices
|
||
|
|
* supported are hard-disks and floppies.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#if (MAJOR_NR == 1)
|
||
|
|
/* 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 == 2)
|
||
|
|
/* floppy */
|
||
|
|
#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 == 3)
|
||
|
|
/* harddisk */
|
||
|
|
#define DEVICE_NAME "harddisk"
|
||
|
|
#define DEVICE_INTR do_hd
|
||
|
|
#define DEVICE_REQUEST do_hd_request
|
||
|
|
#define DEVICE_NR(device) (MINOR(device)/5)
|
||
|
|
#define DEVICE_ON(device)
|
||
|
|
#define DEVICE_OFF(device)
|
||
|
|
|
||
|
|
#elif (MAJOR_NR > 3)
|
||
|
|
/* unknown blk device */
|
||
|
|
#error "unknown blk device"
|
||
|
|
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#define CURRENT (blk_dev[MAJOR_NR].current_request)
|
||
|
|
#define CURRENT_DEV DEVICE_NR(CURRENT->dev)
|
||
|
|
|
||
|
|
#ifdef DEVICE_INTR
|
||
|
|
void (*DEVICE_INTR)(void) = NULL;
|
||
|
|
#endif
|
||
|
|
static void (DEVICE_REQUEST)(void);
|
||
|
|
|
||
|
|
static inline void unlock_buffer(struct buffer_head * bh)
|
||
|
|
{
|
||
|
|
if (!bh->b_lock)
|
||
|
|
printk(DEVICE_NAME ": free buffer being unlocked\n");
|
||
|
|
bh->b_lock=0;
|
||
|
|
wake_up(&bh->b_wait);
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline void end_request(int uptodate)
|
||
|
|
{
|
||
|
|
DEVICE_OFF(CURRENT->dev);
|
||
|
|
if (CURRENT->bh) {
|
||
|
|
CURRENT->bh->b_uptodate = uptodate;
|
||
|
|
unlock_buffer(CURRENT->bh);
|
||
|
|
}
|
||
|
|
if (!uptodate) {
|
||
|
|
printk(DEVICE_NAME " I/O error\n\r");
|
||
|
|
printk("dev %04x, block %d\n\r",CURRENT->dev,
|
||
|
|
CURRENT->bh->b_blocknr);
|
||
|
|
}
|
||
|
|
wake_up(&CURRENT->waiting);
|
||
|
|
wake_up(&wait_for_request);
|
||
|
|
CURRENT->dev = -1;
|
||
|
|
CURRENT = CURRENT->next;
|
||
|
|
}
|
||
|
|
|
||
|
|
#define INIT_REQUEST \
|
||
|
|
repeat: \
|
||
|
|
if (!CURRENT) \
|
||
|
|
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
|