From patchwork Thu Mar 2 04:32:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Imran Khan X-Patchwork-Id: 13156679 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 0B0BDC7EE32 for ; Thu, 2 Mar 2023 04:33:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229708AbjCBEdA (ORCPT ); Wed, 1 Mar 2023 23:33:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229761AbjCBEc0 (ORCPT ); Wed, 1 Mar 2023 23:32:26 -0500 Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CAC484989B; Wed, 1 Mar 2023 20:32:22 -0800 (PST) Received: from pps.filterd (m0246617.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 321MuxpQ010778; Thu, 2 Mar 2023 04:32:18 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=corp-2022-7-12; bh=TnmHeNRcAoyXl5CEEGM2b0RdtGuW/vrovhZ7nMWGPa0=; b=2gOGmw3Wh0CLC7D2pE1j5DHV7xeIlF0qqJR/e8+rBMWqHBO4lL2cFG9eriTgocpPDkaO rDHEzJCB5blI11WLf/+3E4diSRpDf8DsnRMttn47zhqEnW+7fb4ASMjcvwd8LjO2e+Tl snt5n1xfm4/ZyWmiDR8J26VURmdYlmG9iLGWOf8XT/OsjaEq5ffNVmmz1SY3tT1nxdAq As80PfpE7lj0amVB3E/0r4sk+Kr5Iaesd+EaR56HCy8LbTvj9RDA/LPfGYnkWf+nz4bR ePgjIixaF/LS7R/CPkjEJIoecQabd6pOiZ/fvT0m9bjH4BAQp2XHlI4NLxbHT+ORZLPO 5A== Received: from iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta02.appoci.oracle.com [147.154.18.20]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3nybb2jnht-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 02 Mar 2023 04:32:18 +0000 Received: from pps.filterd (iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com (8.17.1.5/8.17.1.5) with ESMTP id 3223Grw5031559; Thu, 2 Mar 2023 04:32:15 GMT Received: from pps.reinject (localhost [127.0.0.1]) by iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 3ny8sga7g1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 02 Mar 2023 04:32:15 +0000 Received: from iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 3224W8eW012677; Thu, 2 Mar 2023 04:32:15 GMT Received: from localhost.localdomain (dhcp-10-191-129-161.vpn.oracle.com [10.191.129.161]) by iadpaimrmta02.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTP id 3ny8sga7bn-3; Thu, 02 Mar 2023 04:32:14 +0000 From: Imran Khan To: tj@kernel.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, joe.jin@oracle.com Subject: [PATCH 2/3] kernfs: Use a per-fs rwsem to protect per-fs list of kernfs_super_info. Date: Thu, 2 Mar 2023 15:32:02 +1100 Message-Id: <20230302043203.1695051-3-imran.f.khan@oracle.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230302043203.1695051-1-imran.f.khan@oracle.com> References: <20230302043203.1695051-1-imran.f.khan@oracle.com> MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-02_01,2023-03-01_03,2023-02-09_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxlogscore=999 mlxscore=0 adultscore=0 bulkscore=0 malwarescore=0 phishscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2303020035 X-Proofpoint-GUID: dxhkk4ncYBTkcogIzjvu99Hbi9OzkoaW X-Proofpoint-ORIG-GUID: dxhkk4ncYBTkcogIzjvu99Hbi9OzkoaW Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Right now per-fs kernfs_rwsem protects list of kernfs_super_info instances for a kernfs_root. Since kernfs_rwsem is used to synchronize several other operations across kernfs and since most of these operations don't impact kernfs_super_info, we can use a separate per-fs rwsem to synchronize access to list of kernfs_super_info. This helps in reducing contention around kernfs_rwsem and also allows operations that change/access list of kernfs_super_info to proceed without contending for kernfs_rwsem. Signed-off-by: Imran Khan --- fs/kernfs/dir.c | 1 + fs/kernfs/file.c | 2 ++ fs/kernfs/kernfs-internal.h | 1 + fs/kernfs/mount.c | 8 ++++---- 4 files changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 953b2717c60e6..2cdb8516e5287 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -944,6 +944,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, idr_init(&root->ino_idr); init_rwsem(&root->kernfs_rwsem); init_rwsem(&root->kernfs_iattr_rwsem); + init_rwsem(&root->kernfs_supers_rwsem); INIT_LIST_HEAD(&root->supers); /* diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index e4a50e4ff0d23..b84cf0cd4bd44 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -924,6 +924,7 @@ static void kernfs_notify_workfn(struct work_struct *work) /* kick fsnotify */ down_write(&root->kernfs_rwsem); + down_write(&root->kernfs_supers_rwsem); list_for_each_entry(info, &kernfs_root(kn)->supers, node) { struct kernfs_node *parent; struct inode *p_inode = NULL; @@ -960,6 +961,7 @@ static void kernfs_notify_workfn(struct work_struct *work) iput(inode); } + up_write(&root->kernfs_supers_rwsem); up_write(&root->kernfs_rwsem); kernfs_put(kn); goto repeat; diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h index 3297093c920de..a9b854cdfdb5f 100644 --- a/fs/kernfs/kernfs-internal.h +++ b/fs/kernfs/kernfs-internal.h @@ -48,6 +48,7 @@ struct kernfs_root { wait_queue_head_t deactivate_waitq; struct rw_semaphore kernfs_rwsem; struct rw_semaphore kernfs_iattr_rwsem; + struct rw_semaphore kernfs_supers_rwsem; }; /* +1 to avoid triggering overflow warning when negating it */ diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index e08e8d9998070..d49606accb07b 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -351,9 +351,9 @@ int kernfs_get_tree(struct fs_context *fc) } sb->s_flags |= SB_ACTIVE; - down_write(&root->kernfs_rwsem); + down_write(&root->kernfs_supers_rwsem); list_add(&info->node, &info->root->supers); - up_write(&root->kernfs_rwsem); + up_write(&root->kernfs_supers_rwsem); } fc->root = dget(sb->s_root); @@ -380,9 +380,9 @@ void kernfs_kill_sb(struct super_block *sb) struct kernfs_super_info *info = kernfs_info(sb); struct kernfs_root *root = info->root; - down_write(&root->kernfs_rwsem); + down_write(&root->kernfs_supers_rwsem); list_del(&info->node); - up_write(&root->kernfs_rwsem); + up_write(&root->kernfs_supers_rwsem); /* * Remove the superblock from fs_supers/s_instances