Re: 2.5.69-mjb1: undefined reference to `blk_queue_empty'

[Bharata B Rao]

On Wed, May 14, 2003 at 10:32:24AM +0200, Jens Axboe wrote:
> 
> That really has to be locked down as well. For your purpose, I think the
> use of elv_queue_empty() is much better even though it really is an
> internal function. The problem mainly comes from AS, that can have non
> empty queue but still return NULL in elv_next_request().
> 
> But yes, it needs to be locked. If you have pinned the other CPUs, then
> I suppose it should work. But it's still a violation of the locking
> rules, and one would get in trouble dropping the queue lock from the io
> scheduler elevator_queue_empty_fn. No one does that currently, but... So
> please take the lock.
> 

Ok, Now we try to acquire the lock and refuse to dump if we don't get 
the lock.

--- 2569+mjb1/drivers/dump/dump_blockdev.c.orig	Wed May 14 13:23:36 2003
+++ 2569+mjb1/drivers/dump/dump_blockdev.c	Thu May 15 09:26:12 2003
@@ -258,10 +258,19 @@
 dump_block_silence(struct dump_dev *dev)
 {
 	struct dump_blockdev *dump_bdev = DUMP_BDEV(dev);
+	struct request_queue *q = bdev_get_queue(dump_bdev->bdev);
+	int ret;
+
+	/* If we can't get request queue lock, refuse to take the dump */
+	if (!spin_trylock(q->queue_lock))
+		return -EBUSY;
+
+	ret = elv_queue_empty(q);
+	spin_unlock(q->queue_lock);
 
 	/* For now we assume we have the device to ourselves */
 	/* Just a quick sanity check */
-	if (!blk_queue_empty(bdev_get_queue(dump_bdev->bdev))) {
+	if (!ret) {
 		/* i/o in flight - safer to quit */
 		return -EBUSY;
 	}

Regards,
Bharata.