From patchwork Wed May 25 15:47:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 12861392 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C618C433F5 for ; Wed, 25 May 2022 15:47:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245265AbiEYPrg (ORCPT ); Wed, 25 May 2022 11:47:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233702AbiEYPrf (ORCPT ); Wed, 25 May 2022 11:47:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0318834649 for ; Wed, 25 May 2022 08:47:35 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9895560FCF for ; Wed, 25 May 2022 15:47:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED610C385B8 for ; Wed, 25 May 2022 15:47:33 +0000 (UTC) Subject: [PATCH v3 1/4] NFSD: Fix possible sleep during nfsd4_release_lockowner() From: Chuck Lever To: linux-nfs@vger.kernel.org Date: Wed, 25 May 2022 11:47:33 -0400 Message-ID: <165349365296.4205.8927782660830418561.stgit@bazille.1015granger.net> In-Reply-To: <165349272692.4205.8499763565429173274.stgit@bazille.1015granger.net> References: <165349272692.4205.8499763565429173274.stgit@bazille.1015granger.net> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org nfsd4_release_lockowner() holds clp->cl_lock when it calls check_for_locks(). However, check_for_locks() calls nfsd_file_get() / nfsd_file_put() to access the backing inode's flc_posix list, and nfsd_file_put() can sleep if the inode was recently removed. Let's instead rely on the stateowner's reference count to gate whether the release is permitted. This should be a reliable indication of locks-in-use since file lock operations and ->lm_get_owner take appropriate references, which are released appropriately when file locks are removed. Reported-by: Dai Ngo Signed-off-by: Chuck Lever Cc: stable@vger.kernel.org --- fs/nfsd/nfs4state.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index a280256cbb03..4e0850a10550 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -7557,16 +7557,12 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp, if (sop->so_is_open_owner || !same_owner_str(sop, owner)) continue; - /* see if there are still any locks associated with it */ - lo = lockowner(sop); - list_for_each_entry(stp, &sop->so_stateids, st_perstateowner) { - if (check_for_locks(stp->st_stid.sc_file, lo)) { - status = nfserr_locks_held; - spin_unlock(&clp->cl_lock); - return status; - } + if (atomic_read(&sop->so_count) != 1) { + spin_unlock(&clp->cl_lock); + return nfserr_locks_held; } + lo = lockowner(sop); nfs4_get_stateowner(sop); break; }