block: bypass blkg_tryget_closest for the root_blkg
authorChristoph Hellwig <hch@lst.de>
Sat, 27 Jun 2020 07:31:53 +0000 (09:31 +0200)
committerJens Axboe <axboe@kernel.dk>
Mon, 29 Jun 2020 15:09:08 +0000 (09:09 -0600)
commita5b97526bf2860fe8306959f19ee428d1f5cc732
tree8f3c46c26cb255774957970073be840bdc23af9f
parent8c5462875224a6d81683e733087f501f58fccd4c
block: bypass blkg_tryget_closest for the root_blkg

The root_blkg is only torn down at the very end of removing a queue.
So in the I/O submission path is always has a life reference and we
can just grab another one using blkg_get instead of doing a tryget
and parent walk that won't lead anywhere.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block/blk-cgroup.c