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Commit 0a0fc960 authored by Thomas Maier's avatar Thomas Maier Committed by Linus Torvalds
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[PATCH] pktcdvd: bio write congestion using congestion_wait() 



This adds a bio write queue congestion control to the pktcdvd driver with
fixed on/off marks.  It prevents that the driver consumes a unlimited
amount of write requests.

[akpm@osdl.org: sync with congestion_wait() renaming]
Signed-off-by: default avatarThomas Maier <balagi@justmail.de>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2d4eeec5

drivers/block/pktcdvd.c

+32 −0
Original line number Diff line number Diff line
@@ -84,6 +84,8 @@ 
static struct pktcdvd_device *pkt_devs[MAX_WRITERS];

static struct proc_dir_entry *pkt_proc;

static int pktdev_major;

static int write_congestion_on  = PKT_WRITE_CONGESTION_ON;

static int write_congestion_off = PKT_WRITE_CONGESTION_OFF;

static struct mutex ctl_mutex;	/* Serialize open/close/setup/teardown */

static mempool_t *psd_pool;
@@ -894,6 +896,7 @@ static int pkt_handle_queue(struct pktcdvd_device *pd) 
	sector_t zone = 0; /* Suppress gcc warning */

	struct pkt_rb_node *node, *first_node;

	struct rb_node *n;

	int wakeup;



	VPRINTK("handle_queue\n");
@@ -966,7 +969,13 @@ try_next_bio: 
		pkt->write_size += bio->bi_size / CD_FRAMESIZE;

		spin_unlock(&pkt->lock);

	}

	/* check write congestion marks, and if bio_queue_size is

	   below, wake up any waiters */

	wakeup = (pd->write_congestion_on > 0

	 		&& pd->bio_queue_size <= pd->write_congestion_off);

	spin_unlock(&pd->lock);

	if (wakeup)

		blk_clear_queue_congested(pd->disk->queue, WRITE);



	pkt->sleep_time = max(PACKET_WAIT_TIME, 1);

	pkt_set_state(pkt, PACKET_WAITING_STATE);
@@ -2179,6 +2188,23 @@ static int pkt_make_request(request_queue_t *q, struct bio *bio) 
	}

	spin_unlock(&pd->cdrw.active_list_lock);



 	/*

	 * Test if there is enough room left in the bio work queue

	 * (queue size >= congestion on mark).

	 * If not, wait till the work queue size is below the congestion off mark.

	 */

	spin_lock(&pd->lock);

	if (pd->write_congestion_on > 0

	    && pd->bio_queue_size >= pd->write_congestion_on) {

		blk_set_queue_congested(q, WRITE);

		do {

			spin_unlock(&pd->lock);

			congestion_wait(WRITE, HZ);

			spin_lock(&pd->lock);

		} while(pd->bio_queue_size > pd->write_congestion_off);

	}

	spin_unlock(&pd->lock);



	/*

	 * No matching packet found. Store the bio in the work queue.

	 */
@@ -2298,6 +2324,9 @@ static int pkt_seq_show(struct seq_file *m, void *p) 
	seq_printf(m, "\tstate:\t\t\ti:%d ow:%d rw:%d ww:%d rec:%d fin:%d\n",

		   states[0], states[1], states[2], states[3], states[4], states[5]);



	seq_printf(m, "\twrite congestion marks:\toff=%d on=%d\n",

			pd->write_congestion_off,

			pd->write_congestion_on);

	return 0;

}
@@ -2474,6 +2503,9 @@ static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev) 
	init_waitqueue_head(&pd->wqueue);

	pd->bio_queue = RB_ROOT;



	pd->write_congestion_on  = write_congestion_on;

	pd->write_congestion_off = write_congestion_off;



	disk = alloc_disk(1);

	if (!disk)

		goto out_mem;

include/linux/pktcdvd.h

+9 −0
Original line number Diff line number Diff line
@@ -112,6 +112,12 @@ struct pkt_ctrl_command { 
#include <linux/completion.h>

#include <linux/cdrom.h>





/* default bio write queue congestion marks */

#define PKT_WRITE_CONGESTION_ON    10000

#define PKT_WRITE_CONGESTION_OFF   9000





struct packet_settings

{

	__u32			size;		/* packet size in (512 byte) sectors */
@@ -271,6 +277,9 @@ struct pktcdvd_device 


	struct packet_iosched   iosched;

	struct gendisk		*disk;



	int			write_congestion_off;

	int			write_congestion_on;

};



#endif /* __KERNEL__ */