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Commit 8a12c4a4 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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hd: dequeue and track in-flight request 



hd has at most single request in flight.  Till now, whenever it needs
to access the in-flight request it called elv_next_request().  This
patch makes hd track the in-flight request directly and dequeue it
when processing starts.  The added complexity is minimal and this will
help future block layer changes.

[ Impact: dequeue in-flight request, one elv_next_request() per request ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 5b36ad60

drivers/block/hd.c

+40 −23
Original line number Diff line number Diff line
@@ -98,10 +98,9 @@ 


static DEFINE_SPINLOCK(hd_lock);

static struct request_queue *hd_queue;

static struct request *hd_req;



#define MAJOR_NR HD_MAJOR

#define QUEUE (hd_queue)

#define CURRENT elv_next_request(hd_queue)



#define TIMEOUT_VALUE	(6*HZ)

#define	HD_DELAY	0
@@ -195,11 +194,24 @@ static void __init hd_setup(char *str, int *ints) 
	NR_HD = hdind+1;

}



static bool hd_end_request(int err, unsigned int bytes)

{

	if (__blk_end_request(hd_req, err, bytes))

		return true;

	hd_req = NULL;

	return false;

}



static bool hd_end_request_cur(int err)

{

	return hd_end_request(err, blk_rq_cur_bytes(hd_req));

}



static void dump_status(const char *msg, unsigned int stat)

{

	char *name = "hd?";

	if (CURRENT)

		name = CURRENT->rq_disk->disk_name;

	if (hd_req)

		name = hd_req->rq_disk->disk_name;



#ifdef VERBOSE_ERRORS

	printk("%s: %s: status=0x%02x { ", name, msg, stat & 0xff);
@@ -227,8 +239,8 @@ static void dump_status(const char *msg, unsigned int stat) 
		if (hd_error & (BBD_ERR|ECC_ERR|ID_ERR|MARK_ERR)) {

			printk(", CHS=%d/%d/%d", (inb(HD_HCYL)<<8) + inb(HD_LCYL),

				inb(HD_CURRENT) & 0xf, inb(HD_SECTOR));

			if (CURRENT)

				printk(", sector=%ld", blk_rq_pos(CURRENT));

			if (hd_req)

				printk(", sector=%ld", blk_rq_pos(hd_req));

		}

		printk("\n");

	}
@@ -406,11 +418,12 @@ static void unexpected_hd_interrupt(void) 
 */

static void bad_rw_intr(void)

{

	struct request *req = CURRENT;

	struct request *req = hd_req;



	if (req != NULL) {

		struct hd_i_struct *disk = req->rq_disk->private_data;

		if (++req->errors >= MAX_ERRORS || (hd_error & BBD_ERR)) {

			__blk_end_request_cur(req, -EIO);

			hd_end_request_cur(-EIO);

			disk->special_op = disk->recalibrate = 1;

		} else if (req->errors % RESET_FREQ == 0)

			reset = 1;
@@ -454,14 +467,14 @@ static void read_intr(void) 
	return;



ok_to_read:

	req = CURRENT;

	req = hd_req;

	insw(HD_DATA, req->buffer, 256);

#ifdef DEBUG

	printk("%s: read: sector %ld, remaining = %u, buffer=%p\n",

	       req->rq_disk->disk_name, blk_rq_pos(req) + 1,

	       blk_rq_sectors(req) - 1, req->buffer+512);

#endif

	if (__blk_end_request(req, 0, 512)) {

	if (hd_end_request(0, 512)) {

		SET_HANDLER(&read_intr);

		return;

	}
@@ -475,7 +488,7 @@ static void read_intr(void) 


static void write_intr(void)

{

	struct request *req = CURRENT;

	struct request *req = hd_req;

	int i;

	int retries = 100000;
@@ -494,7 +507,7 @@ static void write_intr(void) 
	return;



ok_to_write:

	if (__blk_end_request(req, 0, 512)) {

	if (hd_end_request(0, 512)) {

		SET_HANDLER(&write_intr);

		outsw(HD_DATA, req->buffer, 256);

		return;
@@ -525,18 +538,18 @@ static void hd_times_out(unsigned long dummy) 


	do_hd = NULL;



	if (!CURRENT)

	if (!hd_req)

		return;



	spin_lock_irq(hd_queue->queue_lock);

	reset = 1;

	name = CURRENT->rq_disk->disk_name;

	name = hd_req->rq_disk->disk_name;

	printk("%s: timeout\n", name);

	if (++CURRENT->errors >= MAX_ERRORS) {

	if (++hd_req->errors >= MAX_ERRORS) {

#ifdef DEBUG

		printk("%s: too many errors\n", name);

#endif

		__blk_end_request_cur(CURRENT, -EIO);

		hd_end_request_cur(-EIO);

	}

	hd_request();

	spin_unlock_irq(hd_queue->queue_lock);
@@ -551,7 +564,7 @@ static int do_special_op(struct hd_i_struct *disk, struct request *req) 
	}

	if (disk->head > 16) {

		printk("%s: cannot handle device with more than 16 heads - giving up\n", req->rq_disk->disk_name);

		__blk_end_request_cur(req, -EIO);

		hd_end_request_cur(-EIO);

	}

	disk->special_op = 0;

	return 1;
@@ -578,11 +591,15 @@ static void hd_request(void) 
repeat:

	del_timer(&device_timer);



	req = CURRENT;

	if (!req) {

	if (!hd_req) {

		hd_req = elv_next_request(hd_queue);

		if (!hd_req) {

			do_hd = NULL;

			return;

		}

		blkdev_dequeue_request(hd_req);

	}

	req = hd_req;



	if (reset) {

		reset_hd();
@@ -595,7 +612,7 @@ static void hd_request(void) 
	    ((block+nsect) > get_capacity(req->rq_disk))) {

		printk("%s: bad access: block=%d, count=%d\n",

			req->rq_disk->disk_name, block, nsect);

		__blk_end_request_cur(req, -EIO);

		hd_end_request_cur(-EIO);

		goto repeat;

	}
@@ -635,7 +652,7 @@ static void hd_request(void) 
			break;

		default:

			printk("unknown hd-command\n");

			__blk_end_request_cur(req, -EIO);

			hd_end_request_cur(-EIO);

			break;

		}

	}