From owner-svn-src-all@freebsd.org Mon Sep 16 21:32:21 2019 Return-Path: Delivered-To: svn-src-all@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 D758AED210; Mon, 16 Sep 2019 21:32:21 +0000 (UTC) (envelope-from mjg@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) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46XKFx5JRcz4BBf; Mon, 16 Sep 2019 21:32:21 +0000 (UTC) (envelope-from mjg@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 mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 993FE2653F; Mon, 16 Sep 2019 21:32:21 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x8GLWLuD003394; Mon, 16 Sep 2019 21:32:21 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x8GLWLRu003393; Mon, 16 Sep 2019 21:32:21 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <201909162132.x8GLWLRu003393@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik Date: Mon, 16 Sep 2019 21:32:21 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r352425 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 352425 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Sep 2019 21:32:21 -0000 Author: mjg Date: Mon Sep 16 21:32:21 2019 New Revision: 352425 URL: https://svnweb.freebsd.org/changeset/base/352425 Log: vfs: manage mnt_lockref with atomics See r352424. Reviewed by: kib, jeff Tested by: pho Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21574 Modified: head/sys/kern/vfs_subr.c Modified: head/sys/kern/vfs_subr.c ============================================================================== --- head/sys/kern/vfs_subr.c Mon Sep 16 21:31:02 2019 (r352424) +++ head/sys/kern/vfs_subr.c Mon Sep 16 21:32:21 2019 (r352425) @@ -641,6 +641,18 @@ vfs_busy(struct mount *mp, int flags) MPASS((flags & ~MBF_MASK) == 0); CTR3(KTR_VFS, "%s: mp %p with flags %d", __func__, mp, flags); + if (vfs_op_thread_enter(mp)) { + MPASS((mp->mnt_kern_flag & MNTK_DRAINING) == 0); + MPASS((mp->mnt_kern_flag & MNTK_UNMOUNT) == 0); + MPASS((mp->mnt_kern_flag & MNTK_REFEXPIRE) == 0); + MNT_REF_UNLOCKED(mp); + atomic_add_int(&mp->mnt_lockref, 1); + vfs_op_thread_exit(mp); + if (flags & MBF_MNTLSTLOCK) + mtx_unlock(&mountlist_mtx); + return (0); + } + MNT_ILOCK(mp); MNT_REF(mp); /* @@ -673,7 +685,7 @@ vfs_busy(struct mount *mp, int flags) } if (flags & MBF_MNTLSTLOCK) mtx_unlock(&mountlist_mtx); - mp->mnt_lockref++; + atomic_add_int(&mp->mnt_lockref, 1); MNT_IUNLOCK(mp); return (0); } @@ -684,13 +696,24 @@ vfs_busy(struct mount *mp, int flags) void vfs_unbusy(struct mount *mp) { + int c; CTR2(KTR_VFS, "%s: mp %p", __func__, mp); + + if (vfs_op_thread_enter(mp)) { + MPASS((mp->mnt_kern_flag & MNTK_DRAINING) == 0); + c = atomic_fetchadd_int(&mp->mnt_lockref, -1) - 1; + KASSERT(c >= 0, ("%s: negative mnt_lockref %d\n", __func__, c)); + MNT_REL_UNLOCKED(mp); + vfs_op_thread_exit(mp); + return; + } + MNT_ILOCK(mp); MNT_REL(mp); - KASSERT(mp->mnt_lockref > 0, ("negative mnt_lockref")); - mp->mnt_lockref--; - if (mp->mnt_lockref == 0 && (mp->mnt_kern_flag & MNTK_DRAINING) != 0) { + c = atomic_fetchadd_int(&mp->mnt_lockref, -1) - 1; + KASSERT(c >= 0, ("%s: negative mnt_lockref %d\n", __func__, c)); + if (c == 0 && (mp->mnt_kern_flag & MNTK_DRAINING) != 0) { MPASS(mp->mnt_kern_flag & MNTK_UNMOUNT); CTR1(KTR_VFS, "%s: waking up waiters", __func__); mp->mnt_kern_flag &= ~MNTK_DRAINING;