From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54D2DC4338F for ; Mon, 26 Jul 2021 11:58:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3553D60F38 for ; Mon, 26 Jul 2021 11:58:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233727AbhGZLSX (ORCPT ); Mon, 26 Jul 2021 07:18:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:37338 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233606AbhGZLSX (ORCPT ); Mon, 26 Jul 2021 07:18:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A5C2B60F22 for ; Mon, 26 Jul 2021 11:58:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627300731; bh=MMfyyZxqw5O4APMcwE3iA/CIXTgyGAHHU/8qhpzkU54=; h=From:To:Subject:Date:From; b=ZMUdc0VFMWXpCjZO6v/PnjWcreilpC8a+hONc/6ldUaM98crYoYBlzNL9sGda9CEN QuiuoIwys3wxPpT1yosZSc9pYsR+g5LaKWJ01cxNuQ+LTlAfH/ZwwbLqaGVMSM7oXr IjxZalqgsCsAZGz9mUv5WcQMCnzm8egh+WlW/AigiME9lvcBBkr8VNRSnBnWZCaHJn ySXG7/vC9Nst/ZFCZVfKkS0gTYL60y/sVPbfxfXpZffsWeRBAs1Qc/uyOfeedxusub ffLEtJrC/TD2mOPC6jHp0O+WY49Cd6cS4YkXeUZE3En2RS6zTOGhv2gQ8Kw/LKe6Z6 aRFTBIXaUDSTw== From: trondmy@kernel.org To: linux-nfs@vger.kernel.org Subject: [PATCH 1/2] NFSv4/pNFS: Fix a layoutget livelock loop Date: Mon, 26 Jul 2021 07:58:49 -0400 Message-Id: <20210726115850.8429-1-trondmy@kernel.org> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Trond Myklebust If NFS_LAYOUT_RETURN_REQUESTED is set, but there is no value set for the layout plh_return_seq, we can end up in a livelock loop in which every layout segment retrieved by a new call to layoutget is immediately invalidated by pnfs_layout_need_return(). To get around this, we should just set plh_return_seq to the current value of the layout stateid's seqid. Fixes: d474f96104bd ("NFS: Don't return layout segments that are in use") Signed-off-by: Trond Myklebust --- fs/nfs/pnfs.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index 4ed4586bc1a2..51049499e98f 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -347,11 +347,15 @@ pnfs_set_plh_return_info(struct pnfs_layout_hdr *lo, enum pnfs_iomode iomode, iomode = IOMODE_ANY; lo->plh_return_iomode = iomode; set_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags); - if (seq != 0) { - WARN_ON_ONCE(lo->plh_return_seq != 0 && lo->plh_return_seq != seq); + /* + * We must set lo->plh_return_seq to avoid livelocks with + * pnfs_layout_need_return() + */ + if (seq == 0) + seq = be32_to_cpu(lo->plh_stateid.seqid); + if (!lo->plh_return_seq || pnfs_seqid_is_newer(seq, lo->plh_return_seq)) lo->plh_return_seq = seq; - pnfs_barrier_update(lo, seq); - } + pnfs_barrier_update(lo, seq); } static void -- 2.31.1