From patchwork Mon Mar 13 15:14:06 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 9621315 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 40CD760522 for ; Mon, 13 Mar 2017 15:14:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 333E627F85 for ; Mon, 13 Mar 2017 15:14:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2852228480; Mon, 13 Mar 2017 15:14:26 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 52CB0284DC for ; Mon, 13 Mar 2017 15:14:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751401AbdCMPOW (ORCPT ); Mon, 13 Mar 2017 11:14:22 -0400 Received: from mx2.suse.de ([195.135.220.15]:45470 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751409AbdCMPOS (ORCPT ); Mon, 13 Mar 2017 11:14:18 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 3EEC0ADBE; Mon, 13 Mar 2017 15:14:15 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 417A01E1180; Mon, 13 Mar 2017 16:14:12 +0100 (CET) From: Jan Kara To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Dan Williams , Thiago Jung Bauermann , Tejun Heo , Tahsin Erdogan , Omar Sandoval , Jan Kara Subject: [PATCH 07/11] bdi: Do not wait for cgwbs release in bdi_unregister() Date: Mon, 13 Mar 2017 16:14:06 +0100 Message-Id: <20170313151410.5586-8-jack@suse.cz> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20170313151410.5586-1-jack@suse.cz> References: <20170313151410.5586-1-jack@suse.cz> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently we wait for all cgwbs to get released in cgwb_bdi_destroy() (called from bdi_unregister()). That is however unnecessary now when cgwb->bdi is a proper refcounted reference (thus bdi cannot get released before all cgwbs are released) and when cgwb_bdi_destroy() shuts down writeback directly. Acked-by: Tejun Heo Signed-off-by: Jan Kara --- include/linux/backing-dev-defs.h | 1 - mm/backing-dev.c | 22 +--------------------- 2 files changed, 1 insertion(+), 22 deletions(-) diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index 8af720f22a2d..e66d4722db8e 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -164,7 +164,6 @@ struct backing_dev_info { #ifdef CONFIG_CGROUP_WRITEBACK struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */ struct rb_root cgwb_congested_tree; /* their congested states */ - atomic_t usage_cnt; /* counts both cgwbs and cgwb_contested's */ #else struct bdi_writeback_congested *wb_congested; #endif diff --git a/mm/backing-dev.c b/mm/backing-dev.c index b67be4fc12c4..8c30b1a7aae5 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -406,11 +406,9 @@ static void wb_exit(struct bdi_writeback *wb) /* * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree, * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU - * protected. cgwb_release_wait is used to wait for the completion of cgwb - * releases from bdi destruction path. + * protected. */ static DEFINE_SPINLOCK(cgwb_lock); -static DECLARE_WAIT_QUEUE_HEAD(cgwb_release_wait); /** * wb_congested_get_create - get or create a wb_congested @@ -505,7 +503,6 @@ static void cgwb_release_workfn(struct work_struct *work) { struct bdi_writeback *wb = container_of(work, struct bdi_writeback, release_work); - struct backing_dev_info *bdi = wb->bdi; wb_shutdown(wb); @@ -516,9 +513,6 @@ static void cgwb_release_workfn(struct work_struct *work) percpu_ref_exit(&wb->refcnt); wb_exit(wb); kfree_rcu(wb, rcu); - - if (atomic_dec_and_test(&bdi->usage_cnt)) - wake_up_all(&cgwb_release_wait); } static void cgwb_release(struct percpu_ref *refcnt) @@ -608,7 +602,6 @@ static int cgwb_create(struct backing_dev_info *bdi, /* we might have raced another instance of this function */ ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb); if (!ret) { - atomic_inc(&bdi->usage_cnt); list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list); list_add(&wb->memcg_node, memcg_cgwb_list); list_add(&wb->blkcg_node, blkcg_cgwb_list); @@ -698,7 +691,6 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi) INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC); bdi->cgwb_congested_tree = RB_ROOT; - atomic_set(&bdi->usage_cnt, 1); ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL); if (!ret) { @@ -728,18 +720,6 @@ static void cgwb_bdi_destroy(struct backing_dev_info *bdi) spin_lock_irq(&cgwb_lock); } spin_unlock_irq(&cgwb_lock); - - /* - * All cgwb's must be shutdown and released before returning. Drain - * the usage counter to wait for all cgwb's ever created on @bdi. - */ - atomic_dec(&bdi->usage_cnt); - wait_event(cgwb_release_wait, !atomic_read(&bdi->usage_cnt)); - /* - * Grab back our reference so that we hold it when @bdi gets - * re-registered. - */ - atomic_inc(&bdi->usage_cnt); } /**