Commit d92c370a authored Jun 27, 2020 by Christoph Hellwig Committed by Jens Axboe Jun 29, 2020

block: really clone the block cgroup in bio_clone_blkg_association



bio_clone_blkg_association is supposed to clone the associatation, but
actually ends up doing a search with a tryget.  As we know we have a
reference on the source cgroup just get an unconditional additional
reference to it and call it a day.  That also removes the need for
a RCU critical section.

Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent db9819c7

block/bio.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -1737,12 +1737,12 @@ EXPORT_SYMBOL_GPL(bio_associate_blkg);
		*/
		void bio_clone_blkg_association(struct bio dst, struct bio src)
		{
		rcu_read_lock();

		if (src->bi_blkg)
		__bio_associate_blkg(dst, src->bi_blkg);

		rcu_read_unlock();
		if (src->bi_blkg) {
		if (dst->bi_blkg)
		blkg_put(dst->bi_blkg);
		blkg_get(src->bi_blkg);
		dst->bi_blkg = src->bi_blkg;
		}
		}
		EXPORT_SYMBOL_GPL(bio_clone_blkg_association);
		#endif /* CONFIG_BLK_CGROUP */