From owner-dev-commits-src-main@freebsd.org Fri Aug 20 17:52:31 2021 Return-Path: Delivered-To: dev-commits-src-main@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 1DFAF664736; Fri, 20 Aug 2021 17:52:31 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Grq3M0Klyz4kGC; Fri, 20 Aug 2021 17:52:31 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id E65D01D54D; Fri, 20 Aug 2021 17:52:30 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 17KHqUaP084606; Fri, 20 Aug 2021 17:52:30 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 17KHqUVc084605; Fri, 20 Aug 2021 17:52:30 GMT (envelope-from git) Date: Fri, 20 Aug 2021 17:52:30 GMT Message-Id: <202108201752.17KHqUVc084605@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mateusz Guzik Subject: git: dbc689cdef0c - main - vfs: use vn_lock_pair to avoid establishing an ordering on mount MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: mjg X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: dbc689cdef0cc8ff11171642cdcf107dfbc3fb41 Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-main@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for the main branch of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 20 Aug 2021 17:52:31 -0000 The branch main has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=dbc689cdef0cc8ff11171642cdcf107dfbc3fb41 commit dbc689cdef0cc8ff11171642cdcf107dfbc3fb41 Author: Mateusz Guzik AuthorDate: 2021-08-18 21:14:16 +0000 Commit: Mateusz Guzik CommitDate: 2021-08-20 17:52:24 +0000 vfs: use vn_lock_pair to avoid establishing an ordering on mount This fixes some of the LORs seen on mount/unmount. Complete fix will require taking care of unmount as well. Reviewed by: kib Tested by: pho (previous version) Sponsored by: Rubicon Communications, LLC ("Netgate") Differential Revision: https://reviews.freebsd.org/D31611 --- sys/kern/vfs_mount.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c index 3c546392b213..92e70e45d46e 100644 --- a/sys/kern/vfs_mount.c +++ b/sys/kern/vfs_mount.c @@ -1191,19 +1191,28 @@ vfs_domount_first( mp->mnt_kern_flag &= ~MNTK_ASYNC; MNT_IUNLOCK(mp); - vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); - cache_purge(vp); VI_LOCK(vp); - vp->v_iflag &= ~VI_MOUNT; + cache_purge(vp); vn_irflag_set_locked(vp, VIRF_MOUNTPOINT); vp->v_mountedhere = mp; VI_UNLOCK(vp); + + /* + * We need to lock both vnodes. + * + * Use vn_lock_pair to avoid establishing an ordering between vnodes + * from different filesystems. + */ + vn_lock_pair(vp, false, newdp, false); + + VI_LOCK(vp); + vp->v_iflag &= ~VI_MOUNT; + VI_UNLOCK(vp); /* Place the new filesystem at the end of the mount list. */ mtx_lock(&mountlist_mtx); TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list); mtx_unlock(&mountlist_mtx); vfs_event_signal(NULL, VQ_MOUNT, 0); - vn_lock(newdp, LK_EXCLUSIVE | LK_RETRY); VOP_UNLOCK(vp); EVENTHANDLER_DIRECT_INVOKE(vfs_mounted, mp, newdp, td); VOP_UNLOCK(newdp);