block: add comment on why we save and disable interrupts in flush_plug_list()



It's done at the top to avoid doing it for every queue we unplug.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

parent 94b5eb28

block/blk-core.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -2696,6 +2696,11 @@ static void flush_plug_list(struct blk_plug *plug)

		q = NULL;
		depth = 0;

		/*
		* Save and disable interrupts here, to avoid doing it for every
		* queue lock we have to take.
		*/
		local_irq_save(flags);
		while (!list_empty(&list)) {
		rq = list_entry_rq(list.next);