From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id LPzkHcYtHlssWQAAmS7hNA ; Mon, 11 Jun 2018 08:08:37 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 125D5607E4; Mon, 11 Jun 2018 08:08:37 +0000 (UTC) Authentication-Results: smtp.codeaurora.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=szeredi.hu header.i=@szeredi.hu header.b="SE/3zlEa" X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI,T_DKIM_INVALID autolearn=unavailable autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 9D5CB605A5; Mon, 11 Jun 2018 08:08:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 9D5CB605A5 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=szeredi.hu Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932365AbeFKIIe (ORCPT + 19 others); Mon, 11 Jun 2018 04:08:34 -0400 Received: from mail-ot0-f196.google.com ([74.125.82.196]:43533 "EHLO mail-ot0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754053AbeFKIIb (ORCPT ); Mon, 11 Jun 2018 04:08:31 -0400 Received: by mail-ot0-f196.google.com with SMTP id i19-v6so22736280otk.10 for ; Mon, 11 Jun 2018 01:08:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=FpTTIKkOane+I4capCYDktNntDMiKJ+XoY5kZucG7L0=; b=SE/3zlEaoLos5ao2n0h0Xhne34moNI4AvZRLSvi8VTMbEK9XHlPjp/IZBJNoqjIgEA ZkoCW92ol5fo6WOMng8X0xikfTSxpOMHu1ckpMsZL+wmlSsnp2i6YrWu4TW/7xaQI9OX PeR6gH0WmWI0dD44j5rE1udttiuWDx8cYJdCc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=FpTTIKkOane+I4capCYDktNntDMiKJ+XoY5kZucG7L0=; b=JltoarhBr7oWUA4aMBXIVHRVxnNj75Wku1t6q3JRsu14SObS1374BBf7V2UlWa0uo2 KaM5v7YKaTUI+uPpyIWi+dAXnHvhP4b/Yjs3ssRVOaBFNNhprh0oSdGABC9zFDOK6xj3 48gM/ZarVz54JjEzXVa5tqO5i/EIVG8zcch4dyc8PnO/R9qoSBlyi7O3QcWuxe0ng8iq YpouqRUa6LUdwD7AmH3FBoZPhmOfb/a+z5Y49FadEMVkJ4zN4JwztnqAzBfhwvLtu3mb ulpELDizLKH/7ZUrM8Jl1Xfn3v69NhILE4aSwRWnHRv2ytX1ctVCZbpyNUFce/Wfxypj NxMQ== X-Gm-Message-State: APt69E0Z7OXkns22zF4dYISQliOkbKshXhWOfMDXp624va5YFkxL19Ty gflHr+FOHcfBCChlf3BoVyJaPH0KCrTSU14ty0xLBg== X-Google-Smtp-Source: ADUXVKLUmMumNDgQpp4bfjKl2JNRXRkzLdX7EvqhAf0JK7r1YuQYWVeZzapB/B4lGKTQNBgCrPshxJfnjWukD8Tw8vg= X-Received: by 2002:a9d:19e8:: with SMTP id k95-v6mr8719786otk.368.1528704511062; Mon, 11 Jun 2018 01:08:31 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a9d:1123:0:0:0:0:0 with HTTP; Mon, 11 Jun 2018 01:08:30 -0700 (PDT) X-Originating-IP: [194.176.227.33] In-Reply-To: <20180610053128.GO30522@ZenIV.linux.org.uk> References: <20180529144339.16538-1-mszeredi@redhat.com> <20180529144339.16538-24-mszeredi@redhat.com> <20180610053128.GO30522@ZenIV.linux.org.uk> From: Miklos Szeredi Date: Mon, 11 Jun 2018 10:08:30 +0200 Message-ID: Subject: Re: [PATCH 23/39] ovl: add O_DIRECT support To: Al Viro Cc: Miklos Szeredi , overlayfs , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jun 10, 2018 at 7:31 AM, Al Viro wrote: > On Tue, May 29, 2018 at 04:43:23PM +0200, Miklos Szeredi wrote: >> Signed-off-by: Miklos Szeredi >> --- >> fs/overlayfs/file.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c >> index 3f610a5b38e4..e5e7ccaaf9ec 100644 >> --- a/fs/overlayfs/file.c >> +++ b/fs/overlayfs/file.c >> @@ -110,6 +110,9 @@ static int ovl_open(struct inode *inode, struct file *file) >> if (IS_ERR(realfile)) >> return PTR_ERR(realfile); >> >> + /* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */ >> + file->f_mapping = realfile->f_mapping; > > Umm... What happens if upper layer doesn't allow O_DIRECT, while the lower one does? Will get EINVAL on read(2) after copy up. Not sure if it can be called a regression, since it's a corner case of a corner case. I think proper solution is to support O_DIRECT unconditionally on upper (and for the likes of shmfs, just fall back to "cached" I/O). Thanks, Miklos