From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3936AC001DE for ; Wed, 26 Jul 2023 07:35:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232754AbjGZHf0 (ORCPT ); Wed, 26 Jul 2023 03:35:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231460AbjGZHe4 (ORCPT ); Wed, 26 Jul 2023 03:34:56 -0400 Received: from out-57.mta1.migadu.com (out-57.mta1.migadu.com [IPv6:2001:41d0:203:375::39]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FD0A26B8 for ; Wed, 26 Jul 2023 00:32:28 -0700 (PDT) Message-ID: <4ee26da4-314e-0517-5d9a-31fb107368ef@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1690356746; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OYGRVTqgscFQdcJoAIv1RQJgZK2J3Xems6RanwsA4o0=; b=GCsKw+CqeG0NLvU5JG9vhNLkiCqBIozjq4+mghrN4n54qEc8Ada19ZBzziy+rqbgGP2UKc TRnfIbI6wQqD1XzBynZ64zgbT937OIDi9314tjiKBhNwZptVDCqjhQglYT3NeOO47ZzKdD /L1dy0OB1iSvzxJ2Vh5k44+kOPJOpuA= Date: Wed, 26 Jul 2023 15:32:10 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v2 28/47] bcache: dynamically allocate the md-bcache shrinker To: Qi Zheng , akpm@linux-foundation.org, david@fromorbit.com, tkhai@ya.ru, vbabka@suse.cz, roman.gushchin@linux.dev, djwong@kernel.org, brauner@kernel.org, paulmck@kernel.org, tytso@mit.edu, steven.price@arm.com, cel@kernel.org, senozhatsky@chromium.org, yujie.liu@intel.com, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, linux-erofs@lists.ozlabs.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, linux-mtd@lists.infradead.org, rcu@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-bcache@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org References: <20230724094354.90817-1-zhengqi.arch@bytedance.com> <20230724094354.90817-29-zhengqi.arch@bytedance.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Muchun Song In-Reply-To: <20230724094354.90817-29-zhengqi.arch@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 2023/7/24 17:43, Qi Zheng wrote: > In preparation for implementing lockless slab shrink, use new APIs to > dynamically allocate the md-bcache shrinker, so that it can be freed > asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU > read-side critical section when releasing the struct cache_set. > > Signed-off-by: Qi Zheng > --- > drivers/md/bcache/bcache.h | 2 +- > drivers/md/bcache/btree.c | 27 ++++++++++++++++----------- > drivers/md/bcache/sysfs.c | 3 ++- > 3 files changed, 19 insertions(+), 13 deletions(-) > > diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h > index 5a79bb3c272f..c622bc50f81b 100644 > --- a/drivers/md/bcache/bcache.h > +++ b/drivers/md/bcache/bcache.h > @@ -541,7 +541,7 @@ struct cache_set { > struct bio_set bio_split; > > /* For the btree cache */ > - struct shrinker shrink; > + struct shrinker *shrink; > > /* For the btree cache and anything allocation related */ > struct mutex bucket_lock; > diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c > index fd121a61f17c..c176c7fc77d9 100644 > --- a/drivers/md/bcache/btree.c > +++ b/drivers/md/bcache/btree.c > @@ -667,7 +667,7 @@ static int mca_reap(struct btree *b, unsigned int min_order, bool flush) > static unsigned long bch_mca_scan(struct shrinker *shrink, > struct shrink_control *sc) > { > - struct cache_set *c = container_of(shrink, struct cache_set, shrink); > + struct cache_set *c = shrink->private_data; > struct btree *b, *t; > unsigned long i, nr = sc->nr_to_scan; > unsigned long freed = 0; > @@ -734,7 +734,7 @@ static unsigned long bch_mca_scan(struct shrinker *shrink, > static unsigned long bch_mca_count(struct shrinker *shrink, > struct shrink_control *sc) > { > - struct cache_set *c = container_of(shrink, struct cache_set, shrink); > + struct cache_set *c = shrink->private_data; > > if (c->shrinker_disabled) > return 0; > @@ -752,8 +752,8 @@ void bch_btree_cache_free(struct cache_set *c) > > closure_init_stack(&cl); > > - if (c->shrink.list.next) > - unregister_shrinker(&c->shrink); > + if (c->shrink) > + shrinker_unregister(c->shrink); > > mutex_lock(&c->bucket_lock); > > @@ -828,14 +828,19 @@ int bch_btree_cache_alloc(struct cache_set *c) > c->verify_data = NULL; > #endif > > - c->shrink.count_objects = bch_mca_count; > - c->shrink.scan_objects = bch_mca_scan; > - c->shrink.seeks = 4; > - c->shrink.batch = c->btree_pages * 2; > + c->shrink = shrinker_alloc(0, "md-bcache:%pU", c->set_uuid); > + if (!c->shrink) { > + pr_warn("bcache: %s: could not allocate shrinker\n", __func__); > + return -ENOMEM; Seems you have cheanged the semantic of this. In the past, it is better to have a shrinker, but now it becomes a mandatory. Right? I don't know if it is acceptable. From my point of view, just do the cleanup, don't change any behaviour. > + } > + > + c->shrink->count_objects = bch_mca_count; > + c->shrink->scan_objects = bch_mca_scan; > + c->shrink->seeks = 4; > + c->shrink->batch = c->btree_pages * 2; > + c->shrink->private_data = c; > > - if (register_shrinker(&c->shrink, "md-bcache:%pU", c->set_uuid)) > - pr_warn("bcache: %s: could not register shrinker\n", > - __func__); > + shrinker_register(c->shrink); > > return 0; > } > diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c > index 0e2c1880f60b..45d8af755de6 100644 > --- a/drivers/md/bcache/sysfs.c > +++ b/drivers/md/bcache/sysfs.c > @@ -866,7 +866,8 @@ STORE(__bch_cache_set) > > sc.gfp_mask = GFP_KERNEL; > sc.nr_to_scan = strtoul_or_return(buf); > - c->shrink.scan_objects(&c->shrink, &sc); > + if (c->shrink) > + c->shrink->scan_objects(c->shrink, &sc); > } > > sysfs_strtoul_clamp(congested_read_threshold_us,