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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB751C43219 for ; Mon, 15 Nov 2021 18:17:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A21D5633F7 for ; Mon, 15 Nov 2021 18:17:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241428AbhKOSUB (ORCPT ); Mon, 15 Nov 2021 13:20:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:45792 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238065AbhKORcf (ORCPT ); Mon, 15 Nov 2021 12:32:35 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9525563251; Mon, 15 Nov 2021 17:20:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636996851; bh=gA1nP/SKTZLsmWMhFjIdHKMajsBoEMT3gOgPbtgnPRo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D1MhhM6iqmysVVVQyef8BOnaFEfDUR/6BVaERngVSF2yH4Ud4f+5WDEeftinl93ku vXAn9U9VgQQ9aNThgMDtZhEHBLd3en1bdkngbnvtjM4GgX7gFN+qZFSaasV8yRBfWV 53bySRvtCbD+zCbBhdJ2G9cLs0jM3MyVkL0frjN0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Baptiste Lepers , Trond Myklebust , Sasha Levin Subject: [PATCH 5.4 291/355] pnfs/flexfiles: Fix misplaced barrier in nfs4_ff_layout_prepare_ds Date: Mon, 15 Nov 2021 18:03:35 +0100 Message-Id: <20211115165323.136170301@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165313.549179499@linuxfoundation.org> References: <20211115165313.549179499@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Baptiste Lepers [ Upstream commit a2915fa06227b056a8f9b0d79b61dca08ad5cfc6 ] _nfs4_pnfs_v3/v4_ds_connect do some work smp_wmb ds->ds_clp = clp; And nfs4_ff_layout_prepare_ds currently does smp_rmb if(ds->ds_clp) ... This patch places the smp_rmb after the if. This ensures that following reads only happen once nfs4_ff_layout_prepare_ds has checked that data has been properly initialized. Fixes: d67ae825a59d6 ("pnfs/flexfiles: Add the FlexFile Layout Driver") Signed-off-by: Baptiste Lepers Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin --- fs/nfs/flexfilelayout/flexfilelayoutdev.c | 4 ++-- fs/nfs/pnfs_nfs.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c index 3eda40a320a53..1f12297109b41 100644 --- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c +++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c @@ -378,10 +378,10 @@ nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, goto noconnect; ds = mirror->mirror_ds->ds; + if (READ_ONCE(ds->ds_clp)) + goto out; /* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */ smp_rmb(); - if (ds->ds_clp) - goto out; /* FIXME: For now we assume the server sent only one version of NFS * to use for the DS. diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c index 249cf9037dbd7..aff44a7b98f86 100644 --- a/fs/nfs/pnfs_nfs.c +++ b/fs/nfs/pnfs_nfs.c @@ -641,7 +641,7 @@ static int _nfs4_pnfs_v3_ds_connect(struct nfs_server *mds_srv, } smp_wmb(); - ds->ds_clp = clp; + WRITE_ONCE(ds->ds_clp, clp); dprintk("%s [new] addr: %s\n", __func__, ds->ds_remotestr); out: return status; @@ -714,7 +714,7 @@ static int _nfs4_pnfs_v4_ds_connect(struct nfs_server *mds_srv, } smp_wmb(); - ds->ds_clp = clp; + WRITE_ONCE(ds->ds_clp, clp); dprintk("%s [new] addr: %s\n", __func__, ds->ds_remotestr); out: return status; -- 2.33.0