From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: [PATCH 04/14] block: merge __bio_associate_blkg into bio_associate_blkg_from_css Date: Sat, 27 Jun 2020 09:31:49 +0200 Message-ID: <20200627073159.2447325-5-hch@lst.de> References: <20200627073159.2447325-1-hch@lst.de> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200627073159.2447325-1-hch@lst.de> Sender: linux-kernel-owner@vger.kernel.org To: Jens Axboe , Tejun Heo Cc: Dennis Zhou , Li Zefan , Johannes Weiner , dm-devel@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org List-Id: dm-devel.ids Merge __bio_associate_blkg into the only caller, which allows to slightly reduce the RCU crticial section and better explain the code flow. Signed-off-by: Christoph Hellwig --- block/bio.c | 45 +++++++++++++-------------------------------- 1 file changed, 13 insertions(+), 32 deletions(-) diff --git a/block/bio.c b/block/bio.c index e1d01acce8070c..bc8de2432e3645 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1628,52 +1628,33 @@ int bioset_init_from_src(struct bio_set *bs, struct bio_set *src) EXPORT_SYMBOL(bioset_init_from_src); #ifdef CONFIG_BLK_CGROUP - -/** - * __bio_associate_blkg - associate a bio with the a blkg - * @bio: target bio - * @blkg: the blkg to associate - * - * This tries to associate @bio with the specified @blkg. Association failure - * is handled by walking up the blkg tree. Therefore, the blkg associated can - * be anything between @blkg and the root_blkg. This situation only happens - * when a cgroup is dying and then the remaining bios will spill to the closest - * alive blkg. - * - * A reference will be taken on the @blkg and will be released when @bio is - * freed. - */ -static void __bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg) -{ - if (bio->bi_blkg) - blkg_put(bio->bi_blkg); - bio->bi_blkg = blkg_tryget_closest(blkg); -} - /** * bio_associate_blkg_from_css - associate a bio with a specified css * @bio: target bio * @css: target css * * Associate @bio with the blkg found by combining the css's blkg and the - * request_queue of the @bio. This falls back to the queue's root_blkg if - * the association fails with the css. + * request_queue of the @bio. An association failure is handled by walking up + * the blkg tree. Therefore, the blkg associated can be anything between @blkg + * and q->root_blkg. This situation only happens when a cgroup is dying and + * then the remaining bios will spill to the closest alive blkg. + * + * A reference will be taken on the blkg and will be released when @bio is + * freed. */ void bio_associate_blkg_from_css(struct bio *bio, struct cgroup_subsys_state *css) { struct request_queue *q = bio->bi_disk->queue; - struct blkcg_gq *blkg; + struct blkcg_gq *blkg = q->root_blkg; - rcu_read_lock(); + if (bio->bi_blkg) + blkg_put(bio->bi_blkg); - if (!css || !css->parent) - blkg = q->root_blkg; - else + rcu_read_lock(); + if (css && css->parent) blkg = blkg_lookup_create(css_to_blkcg(css), q); - - __bio_associate_blkg(bio, blkg); - + bio->bi_blkg = blkg_tryget_closest(blkg); rcu_read_unlock(); } EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css); -- 2.26.2