On Sunday November 7, akpm@xxxxxxxx wrote:
> > I couldn't find blk_sync_queue in 2.6.10-rc1-mm2 ....
>
> I added it in -mm3 to replace all the open-coded del_timer_sync()s.
Yeh... right... of course ... I saw that mail...
I think I missed the trust of Jens' mail.
I now see the point was that:
.... you have to prevent new requests from setting it (the timer)
off again.
That isn't a problem in my case. By the time I to want to remove
the timer, I know that no-one has the device open, and so no requests
are going to arrive.
The blk_wait_queue_drained has no relevance for md as we don't use the
same sort of queue.
So I think blk_sync_queue is all that is needed.
>
> We should be able to stick all the above inside block_sync_queue()
Maybe:
###Comments for ChangeSet
Document blk_sync_queue and complete it's functionality.
blk_sync_queue needs to call kblock_flush as the unplug function
is not actually called by the timer, but rather by a work_queue that
the timer triggers.
Also, use blk_sync_queue to abstract identical functionality from
blk_cleanup_queue.
Signed-off-by: Neil Brown <neilb@xxxxxxxxxxxxxxx>
### Diffstat output
./drivers/block/ll_rw_blk.c | 14 +++++++++++---
1 files changed, 11 insertions(+), 3 deletions(-)
diff ./drivers/block/ll_rw_blk.c~current~ ./drivers/block/ll_rw_blk.c
--- ./drivers/block/ll_rw_blk.c~current~ 2004-11-08 11:57:40.000000000 +1100
+++ ./drivers/block/ll_rw_blk.c 2004-11-08 12:17:53.000000000 +1100
@@ -1361,12 +1361,21 @@ void blk_stop_queue(request_queue_t *q)
EXPORT_SYMBOL(blk_stop_queue);
/**
- * blk_sync_queue - prepare to destroy a queue
+ * blk_sync_queue - cancel any pending callbacks a queue
* @q: the queue
+ *
+ * Description:
+ * The block layer may perform asynchronous callback activity
+ * on a queue, such as calling the unplug function after a timeout.
+ * A block device may call blk_sync_queue to ensure that any
+ * such activity is cancelled, thus allowing it to release resources
+ * the the callbacks might use.
+ *
*/
void blk_sync_queue(struct request_queue *q)
{
del_timer_sync(&q->unplug_timer);
+ kblockd_flush();
}
EXPORT_SYMBOL(blk_sync_queue);
@@ -1410,8 +1419,7 @@ void blk_cleanup_queue(request_queue_t *
if (q->elevator)
elevator_exit(q->elevator);
- del_timer_sync(&q->unplug_timer);
- kblockd_flush();
+ blk_sync_queue(q);
if (rl->rq_pool)
mempool_destroy(rl->rq_pool);
-
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