block: add callback function for unplug notification
MD would like to know when a queue is unplugged, so it can flush
it's bitmap writes. Add such a callback.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index 0c0ea10..76850fc 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2672,6 +2672,9 @@
{
trace_block_unplug_io(q, depth);
__blk_run_queue(q, false);
+
+ if (q->unplugged_fn)
+ q->unplugged_fn(q);
}
static void flush_plug_list(struct blk_plug *plug)