From owner-svn-src-head@freebsd.org Mon Apr 10 01:28:02 2017 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id B878CD35671; Mon, 10 Apr 2017 01:28:02 +0000 (UTC) (envelope-from rmacklem@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 8A55A14A; Mon, 10 Apr 2017 01:28:02 +0000 (UTC) (envelope-from rmacklem@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id v3A1S1wI045658; Mon, 10 Apr 2017 01:28:01 GMT (envelope-from rmacklem@FreeBSD.org) Received: (from rmacklem@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id v3A1S1b2045657; Mon, 10 Apr 2017 01:28:01 GMT (envelope-from rmacklem@FreeBSD.org) Message-Id: <201704100128.v3A1S1b2045657@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: rmacklem set sender to rmacklem@FreeBSD.org using -f From: Rick Macklem Date: Mon, 10 Apr 2017 01:28:01 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r316669 - head/sys/fs/nfsclient X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Apr 2017 01:28:02 -0000 Author: rmacklem Date: Mon Apr 10 01:28:01 2017 New Revision: 316669 URL: https://svnweb.freebsd.org/changeset/base/316669 Log: Avoid starvation of the server crash recovery thread for the NFSv4 client. This patch gives a requestor of the exclusive lock on the client state in the NFSv4 client priority over shared lock requestors. This avoids the server crash recovery thread being starved out by other threads doing RPCs. Tested by: cperciva PR: 216087 MFC after: 2 weeks Modified: head/sys/fs/nfsclient/nfs_clstate.c Modified: head/sys/fs/nfsclient/nfs_clstate.c ============================================================================== --- head/sys/fs/nfsclient/nfs_clstate.c Mon Apr 10 01:26:12 2017 (r316668) +++ head/sys/fs/nfsclient/nfs_clstate.c Mon Apr 10 01:28:01 2017 (r316669) @@ -797,8 +797,18 @@ nfscl_getcl(struct mount *mp, struct ucr (mp->mnt_kern_flag & MNTK_UNMOUNTF) == 0) igotlock = nfsv4_lock(&clp->nfsc_lock, 1, NULL, NFSCLSTATEMUTEXPTR, mp); - if (!igotlock) + if (igotlock == 0) { + /* + * Call nfsv4_lock() with "iwantlock == 0" so that it will + * wait for a pending exclusive lock request. This gives the + * exclusive lock request priority over this shared lock + * request. + * An exclusive lock on nfsc_lock is used mainly for server + * crash recoveries. + */ + nfsv4_lock(&clp->nfsc_lock, 0, NULL, NFSCLSTATEMUTEXPTR, mp); nfsv4_getref(&clp->nfsc_lock, NULL, NFSCLSTATEMUTEXPTR, mp); + } if (igotlock == 0 && (mp->mnt_kern_flag & MNTK_UNMOUNTF) != 0) { /* * Both nfsv4_lock() and nfsv4_getref() know to check