From owner-svn-src-head@FreeBSD.ORG Sat Sep 22 17:42:55 2012 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 047FA106567E; Sat, 22 Sep 2012 17:42:55 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id 7AB208FC0A; Sat, 22 Sep 2012 17:42:54 +0000 (UTC) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.4/8.14.4) with ESMTP id q8MHgs10011232; Sat, 22 Sep 2012 17:42:54 GMT (envelope-from avg@svn.freebsd.org) Received: (from avg@localhost) by svn.freebsd.org (8.14.4/8.14.4/Submit) id q8MHgsAQ011229; Sat, 22 Sep 2012 17:42:54 GMT (envelope-from avg@svn.freebsd.org) Message-Id: <201209221742.q8MHgsAQ011229@svn.freebsd.org> From: Andriy Gapon Date: Sat, 22 Sep 2012 17:42:54 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r240831 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 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: Sat, 22 Sep 2012 17:42:55 -0000 Author: avg Date: Sat Sep 22 17:42:53 2012 New Revision: 240831 URL: http://svn.freebsd.org/changeset/base/240831 Log: zfs: allow a zvol to be used as a pool vdev, again Do this by checking if spa_namespace_lock is already held and not taking it again in that case. Add a comment explaining why that is done and why it is safe. Reviewed by: pjd MFC after: 24 days Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c Sat Sep 22 17:41:56 2012 (r240830) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c Sat Sep 22 17:42:53 2012 (r240831) @@ -878,27 +878,36 @@ zvol_open(struct g_provider *pp, int fla { zvol_state_t *zv; int err = 0; + boolean_t locked = B_FALSE; - if (MUTEX_HELD(&spa_namespace_lock)) { - /* - * If the spa_namespace_lock is being held, it means that ZFS - * is trying to open ZVOL as its VDEV. This is not supported. - */ - return (EOPNOTSUPP); + /* + * Protect against recursively entering spa_namespace_lock + * when spa_open() is used for a pool on a (local) ZVOL(s). + * This is needed since we replaced upstream zfsdev_state_lock + * with spa_namespace_lock in the ZVOL code. + * We are using the same trick as spa_open(). + * Note that calls in zvol_first_open which need to resolve + * pool name to a spa object will enter spa_open() + * recursively, but that function already has all the + * necessary protection. + */ + if (!MUTEX_HELD(&spa_namespace_lock)) { + mutex_enter(&spa_namespace_lock); + locked = B_TRUE; } - mutex_enter(&spa_namespace_lock); - zv = pp->private; if (zv == NULL) { - mutex_exit(&spa_namespace_lock); + if (locked) + mutex_exit(&spa_namespace_lock); return (ENXIO); } if (zv->zv_total_opens == 0) err = zvol_first_open(zv); if (err) { - mutex_exit(&spa_namespace_lock); + if (locked) + mutex_exit(&spa_namespace_lock); return (err); } if ((flag & FWRITE) && (zv->zv_flags & ZVOL_RDONLY)) { @@ -920,13 +929,15 @@ zvol_open(struct g_provider *pp, int fla #endif zv->zv_total_opens += count; - mutex_exit(&spa_namespace_lock); + if (locked) + mutex_exit(&spa_namespace_lock); return (err); out: if (zv->zv_total_opens == 0) zvol_last_close(zv); - mutex_exit(&spa_namespace_lock); + if (locked) + mutex_exit(&spa_namespace_lock); return (err); } @@ -936,12 +947,18 @@ zvol_close(struct g_provider *pp, int fl { zvol_state_t *zv; int error = 0; + boolean_t locked = B_FALSE; - mutex_enter(&spa_namespace_lock); + /* See comment in zvol_open(). */ + if (!MUTEX_HELD(&spa_namespace_lock)) { + mutex_enter(&spa_namespace_lock); + locked = B_TRUE; + } zv = pp->private; if (zv == NULL) { - mutex_exit(&spa_namespace_lock); + if (locked) + mutex_exit(&spa_namespace_lock); return (ENXIO); } @@ -964,7 +981,8 @@ zvol_close(struct g_provider *pp, int fl if (zv->zv_total_opens == 0) zvol_last_close(zv); - mutex_exit(&spa_namespace_lock); + if (locked) + mutex_exit(&spa_namespace_lock); return (error); }