Re: [PATCH] backing dev unplugging

[Miquel van Smoorenburg]

In article <20040310210207.GL15087@xxxxxxx>,
Jens Axboe  <axboe@xxxxxxx> wrote:
>On Wed, Mar 10 2004, Andrew Morton wrote:
>> Jens Axboe <axboe@xxxxxxx> wrote:
>> >
>> > Here's a first cut at killing global plugging of block devices to reduce
>> > the nasty contention blk_plug_lock caused.
>> 
>> Shouldn't we take read_lock(&md->map_lock) in dm_table_unplug_all()?
>
>Ugh yes, we certainly should.

With the latest patches from Joe it would be more like

	map = dm_get_table(md);
	if (map) {
		dm_table_unplug_all(map);
		dm_table_put(map);
	}

No lock ranking issues, you just get a refcounted map (table, really).

Mike.

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