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

From: Bharata B Rao (bharata@in.ibm.com)
Date: Wed May 14 2003 - 23:07:31 EST


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.
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