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 91D18C433EF for ; Wed, 24 Nov 2021 12:23:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244575AbhKXM0e (ORCPT ); Wed, 24 Nov 2021 07:26:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:42284 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244907AbhKXMYV (ORCPT ); Wed, 24 Nov 2021 07:24:21 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 49769611EF; Wed, 24 Nov 2021 12:14:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637756080; bh=DANHyUhkyh2QkW2UxzgTi2ylXMNXuZR/2kO69c4BXnY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SmjzhbJqgkF8C1UwGxb0yte2H2t/NO8CK/38yOOoAUBZKYCISm55macK++rXs1LNh gD3GTknM1AFmRi3yQRo1VB1cdwtGIFhBSHodwxfO4oocB1eewso5qWhjLmXkYhZ+vl AdoprTkbJzTSQHWMCzvKpJcJr5l/0ZsS0g3SOi4I= 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 4.9 131/207] pnfs/flexfiles: Fix misplaced barrier in nfs4_ff_layout_prepare_ds Date: Wed, 24 Nov 2021 12:56:42 +0100 Message-Id: <20211124115708.281965301@linuxfoundation.org> X-Mailer: git-send-email 2.34.0 In-Reply-To: <20211124115703.941380739@linuxfoundation.org> References: <20211124115703.941380739@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 c8863563c6350..287ed99a7e513 100644 --- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c +++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c @@ -383,10 +383,10 @@ nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx, goto out_fail; 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 53b4705abcc76..1f2da20946640 100644 --- a/fs/nfs/pnfs_nfs.c +++ b/fs/nfs/pnfs_nfs.c @@ -666,7 +666,7 @@ 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; @@ -742,7 +742,7 @@ 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