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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 D3036C433F5 for ; Mon, 20 Sep 2021 18:44:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B8D7A61354 for ; Mon, 20 Sep 2021 18:44:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1383312AbhITSoX (ORCPT ); Mon, 20 Sep 2021 14:44:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:52158 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353092AbhITShD (ORCPT ); Mon, 20 Sep 2021 14:37:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D065563322; Mon, 20 Sep 2021 17:29:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632158983; bh=MwLgoaxQ710nxayWGUIn6POkndliC9rSgcVdZwxI3l4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UZGmshzVJUS7XZVUieHV1pj8vq87Bg5bxJENJ8uPBjbI8T7k6gGgXs+LwsFeNJ7tx T8NfoiHN/gB0VzuqxEneqJL+koPdKYANWNFKsySVeXUSZiWZSuNlHWEr4tgapQgY+g zouwx2GM2k4Q/Kly3ITZOTdixaMvX9Y2kQqwsdj0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jens Axboe , Dan Melnic Subject: [PATCH 5.14 022/168] io_uring: allow retry for O_NONBLOCK if async is supported Date: Mon, 20 Sep 2021 18:42:40 +0200 Message-Id: <20210920163922.377541288@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210920163921.633181900@linuxfoundation.org> References: <20210920163921.633181900@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: Jens Axboe commit 5d329e1286b0a040264e239b80257c937f6e685f upstream. A common complaint is that using O_NONBLOCK files with io_uring can be a bit of a pain. Be a bit nicer and allow normal retry IFF the file does support async behavior. This makes it possible to use io_uring more reliably with O_NONBLOCK files, for use cases where it either isn't possible or feasible to modify the file flags. Cc: stable@vger.kernel.org Reported-and-tested-by: Dan Melnic Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/io_uring.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2683,7 +2683,8 @@ static bool io_file_supports_async(struc return __io_file_supports_async(req->file, rw); } -static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe) +static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe, + int rw) { struct io_ring_ctx *ctx = req->ctx; struct kiocb *kiocb = &req->rw.kiocb; @@ -2705,8 +2706,13 @@ static int io_prep_rw(struct io_kiocb *r if (unlikely(ret)) return ret; - /* don't allow async punt for O_NONBLOCK or RWF_NOWAIT */ - if ((kiocb->ki_flags & IOCB_NOWAIT) || (file->f_flags & O_NONBLOCK)) + /* + * If the file is marked O_NONBLOCK, still allow retry for it if it + * supports async. Otherwise it's impossible to use O_NONBLOCK files + * reliably. If not, or it IOCB_NOWAIT is set, don't retry. + */ + if ((kiocb->ki_flags & IOCB_NOWAIT) || + ((file->f_flags & O_NONBLOCK) && !io_file_supports_async(req, rw))) req->flags |= REQ_F_NOWAIT; ioprio = READ_ONCE(sqe->ioprio); @@ -3193,7 +3199,7 @@ static int io_read_prep(struct io_kiocb { if (unlikely(!(req->file->f_mode & FMODE_READ))) return -EBADF; - return io_prep_rw(req, sqe); + return io_prep_rw(req, sqe, READ); } /* @@ -3382,7 +3388,7 @@ static int io_write_prep(struct io_kiocb { if (unlikely(!(req->file->f_mode & FMODE_WRITE))) return -EBADF; - return io_prep_rw(req, sqe); + return io_prep_rw(req, sqe, WRITE); } static int io_write(struct io_kiocb *req, unsigned int issue_flags)