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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF2C4C3A59F for ; Mon, 26 Aug 2019 16:07:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC6FA20828 for ; Mon, 26 Aug 2019 16:07:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566835646; bh=75sevnElSVQkSWHj0jk5tjITBnjjmYiMrbnKf2uzbbU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=mgVGlwX+cO/cbPWfJ9mWdwEkDQhHNMnOD3fdVMW0sS5yqXh+f2nIm6HHRcsZTArwt BujyZoRC19zc6IsE3YPhI8X3bMhGdw6x1mqmk4FZzEZz0UsaAYZTiCi58xYsK5wEx1 NwXa9C7Plx4klBZvR22v9PvqF+B+ZA8m+QdDeglU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732708AbfHZQHR (ORCPT ); Mon, 26 Aug 2019 12:07:17 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:38970 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732612AbfHZQHL (ORCPT ); Mon, 26 Aug 2019 12:07:11 -0400 Received: by mail-qt1-f193.google.com with SMTP id l9so18371244qtu.6; Mon, 26 Aug 2019 09:07:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=sbi9AtPpKs90xX0XCzYWXMGLwoRRPZP34bqUM0NUXLs=; b=gX5n0n0Iya2r+6HfxSBgduwjqnM9PRtJlmoEm5ghngBsve/UtQYFYtPDwNviTIYOMH yLHoMeNJ+DWQ0bdNx4cvSVgcN681dV36+OkH/g1jKJgRguOi7VsP0NlyTZAz7cNUZOE6 zqnuyTGB/QvBuFExLTGnei+AosOZ6sQ0y8LkGtkVWGqoLaIqdMokGxmf43BnVYTMWOsm TfgrfDI+kUfbZopDzIk1PUoIxNGEh7GWOOExZRBb6f7AdZPpR69VNoZkY4jlUDeGLJQo pcOBl6W9Exf/K3YN+IZmyKLnwa/O+zqQugMqiuDEyPBkAwPlHoZuAITEWOR87u2+0DCW ok0w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references; bh=sbi9AtPpKs90xX0XCzYWXMGLwoRRPZP34bqUM0NUXLs=; b=lAu9S9iex0vX+b+i6BGbhCh4rCDjb43qIoeBVZA0tbOjfj9vr7MNd+YwOwUVM+3D41 a+zUZF1tLNpg9fHAP4GFK5BhpDv9XOQlzIBq7p48d3Wpf+PFOjU6/3+w8r3Kv2vMq+JG blol3er/fN5nVDAtoCLtcSbQDrbPcv4LuOHHpZ5cfDL299hxyOZpg9s+BeBNyEM0Zl60 aj0SN8Ve3bnRDLy0VipTz1b0OgcIHH7yTQEmMGt9iQDX0J4t0FXNWTvF1cee4rUEdud7 Yd1Pp99OZnjfU7JBoSoxf0iSkeniqtgwPI82tFPH0mieM3PKz5WX8ZsLSYXpCXzwLqP9 WtHQ== X-Gm-Message-State: APjAAAWoMp9YiSRWdG7FmtrDlswnL6gZa+W1wRtHZUDG+2Ms+Nf8WIxN 9O1K00hRYQ1w8Wq97WVAuQ0= X-Google-Smtp-Source: APXvYqwfRmoFj279L2wsJx3QYrn8JRDZ4xVVrNIXLn3zjcDpszmBL7Yzn1lB3z9lIiUyrSDzWNyx1Q== X-Received: by 2002:ac8:4789:: with SMTP id k9mr18184801qtq.41.1566835630468; Mon, 26 Aug 2019 09:07:10 -0700 (PDT) Received: from localhost ([2620:10d:c091:500::d081]) by smtp.gmail.com with ESMTPSA id 131sm6410446qkn.7.2019.08.26.09.07.09 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 26 Aug 2019 09:07:09 -0700 (PDT) From: Tejun Heo To: axboe@kernel.dk, jack@suse.cz, hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com Cc: cgroups@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, guro@fb.com, akpm@linux-foundation.org, Tejun Heo Subject: [PATCH 3/5] writeback: Separate out wb_get_lookup() from wb_get_create() Date: Mon, 26 Aug 2019 09:06:54 -0700 Message-Id: <20190826160656.870307-4-tj@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190826160656.870307-1-tj@kernel.org> References: <20190826160656.870307-1-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Separate out wb_get_lookup() which doesn't try to create one if there isn't already one from wb_get_create(). This will be used by later patches. Signed-off-by: Tejun Heo Reviewed-by: Jan Kara --- include/linux/backing-dev.h | 2 ++ mm/backing-dev.c | 55 +++++++++++++++++++++++++------------ 2 files changed, 39 insertions(+), 18 deletions(-) diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 84cdcfbc763f..97967ce06de3 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -230,6 +230,8 @@ static inline int bdi_sched_wait(void *word) struct bdi_writeback_congested * wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp); void wb_congested_put(struct bdi_writeback_congested *congested); +struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi, + struct cgroup_subsys_state *memcg_css); struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, struct cgroup_subsys_state *memcg_css, gfp_t gfp); diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 612aa7c5ddbd..d9daa3e422d0 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -618,13 +618,12 @@ static int cgwb_create(struct backing_dev_info *bdi, } /** - * wb_get_create - get wb for a given memcg, create if necessary + * wb_get_lookup - get wb for a given memcg * @bdi: target bdi * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) - * @gfp: allocation mask to use * - * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to - * create one. The returned wb has its refcount incremented. + * Try to get the wb for @memcg_css on @bdi. The returned wb has its + * refcount incremented. * * This function uses css_get() on @memcg_css and thus expects its refcnt * to be positive on invocation. IOW, rcu_read_lock() protection on @@ -641,6 +640,39 @@ static int cgwb_create(struct backing_dev_info *bdi, * each lookup. On mismatch, the existing wb is discarded and a new one is * created. */ +struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi, + struct cgroup_subsys_state *memcg_css) +{ + struct bdi_writeback *wb; + + if (!memcg_css->parent) + return &bdi->wb; + + rcu_read_lock(); + wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); + if (wb) { + struct cgroup_subsys_state *blkcg_css; + + /* see whether the blkcg association has changed */ + blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); + if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb))) + wb = NULL; + css_put(blkcg_css); + } + rcu_read_unlock(); + + return wb; +} + +/** + * wb_get_create - get wb for a given memcg, create if necessary + * @bdi: target bdi + * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) + * @gfp: allocation mask to use + * + * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to + * create one. See wb_get_lookup() for more details. + */ struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, struct cgroup_subsys_state *memcg_css, gfp_t gfp) @@ -653,20 +685,7 @@ struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, return &bdi->wb; do { - rcu_read_lock(); - wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); - if (wb) { - struct cgroup_subsys_state *blkcg_css; - - /* see whether the blkcg association has changed */ - blkcg_css = cgroup_get_e_css(memcg_css->cgroup, - &io_cgrp_subsys); - if (unlikely(wb->blkcg_css != blkcg_css || - !wb_tryget(wb))) - wb = NULL; - css_put(blkcg_css); - } - rcu_read_unlock(); + wb = wb_get_lookup(bdi, memcg_css); } while (!wb && !cgwb_create(bdi, memcg_css, gfp)); return wb; -- 2.17.1