From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:59640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932838AbdKPBO2 (ORCPT ); Wed, 15 Nov 2017 20:14:28 -0500 Date: Wed, 15 Nov 2017 17:14:27 -0800 From: "Darrick J. Wong" Subject: [PATCH for 4.14] xfs_copy: don't hang if /all/ the targets hit write errors Message-ID: <20171116011232.GG5119@magnolia> Reply-To: darrick.wong@oracle.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Eric Sandeen Cc: xfs , djwong@kernel.org From: Darrick J. Wong If xfs_copy is told to copy a filesystem and /all/ the writer threads hit an write error, there won't be any threads to unlock mainwait, which means that write_wbuf will deadlock with itself trying to lock mainwait. Therefore, if we discover that all the writer threads are dead, just bail out. Discovered by running xfs/073 with a tiny test device. Signed-off-by: Darrick J. Wong --- copy/xfs_copy.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/copy/xfs_copy.c b/copy/xfs_copy.c index 33e05df..fb37375 100644 --- a/copy/xfs_copy.c +++ b/copy/xfs_copy.c @@ -476,6 +476,7 @@ void write_wbuf(void) { int i; + int badness = 0; /* verify target threads */ for (i = 0; i < num_targets; i++) @@ -486,6 +487,17 @@ write_wbuf(void) for (i = 0; i < num_targets; i++) if (target[i].state != INACTIVE) pthread_mutex_unlock(&targ[i].wait); /* wake up */ + else + badness++; + + /* + * If all the targets are inactive then there won't be any io + * threads left to release mainwait. We're screwed, so bail out. + */ + if (badness == num_targets) { + check_errors(); + exit(1); + } signal_maskfunc(SIGCHLD, SIG_UNBLOCK); pthread_mutex_lock(&mainwait);