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=-16.4 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 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 C0215C433EF for ; Fri, 3 Sep 2021 18:54:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9363460EC0 for ; Fri, 3 Sep 2021 18:54:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351307AbhICSzb (ORCPT ); Fri, 3 Sep 2021 14:55:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:44954 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350591AbhICSzb (ORCPT ); Fri, 3 Sep 2021 14:55:31 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C6EEA61051; Fri, 3 Sep 2021 18:54:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1630695270; bh=k0qqhjIBTc+gyB6NzqxwhhFn9y/tnKZkCVBCXngFTi8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HRnrrB2Jph7uelGBkGR4cg8QVuct3/B8w1s6Z0i9VbiI/DtTVFnp+DrP1Xub+jM70 lmogrtDA/ZqdzzOc+e2aXU9GM0i/HCLA6VN2gnpIlzRLP1JMg9aDZ+aHd15ySB2lHH fyPyxnLYOm+h1GW7euhDaleRRE9GTNOF1Nov7nbC60eUJHOn0bFAwH0OFQKNiJHiJX mBM+xvs8AA8K3HtMs5yrVF5MNu/LlNNa+VD9UOWY+eGQPhDTsi5MEDW08a8uVTrD7V tgQOmK41k0WgmvOpPT8nPUZaHHULhWTOKci1vhBpn9R7LZGpM0l4jgxNqd6kr3UWsL WYOYmAKFZW7hw== Date: Fri, 3 Sep 2021 11:54:30 -0700 From: "Darrick J. Wong" To: Andreas Gruenbacher Cc: Linus Torvalds , Alexander Viro , Christoph Hellwig , Jan Kara , Matthew Wilcox , cluster-devel@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com Subject: Re: [PATCH v7 15/19] iomap: Support partial direct I/O on user copy failures Message-ID: <20210903185430.GE9892@magnolia> References: <20210827164926.1726765-1-agruenba@redhat.com> <20210827164926.1726765-16-agruenba@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210827164926.1726765-16-agruenba@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Aug 27, 2021 at 06:49:22PM +0200, Andreas Gruenbacher wrote: > In iomap_dio_rw, when iomap_apply returns an -EFAULT error and the > IOMAP_DIO_PARTIAL flag is set, complete the request synchronously and > return a partial result. This allows the caller to deal with the page > fault and retry the remainder of the request. > > Signed-off-by: Andreas Gruenbacher Pretty straightforward. Reviewed-by: Darrick J. Wong --D > --- > fs/iomap/direct-io.c | 6 ++++++ > include/linux/iomap.h | 7 +++++++ > 2 files changed, 13 insertions(+) > > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c > index 8054f5d6c273..ba88fe51b77a 100644 > --- a/fs/iomap/direct-io.c > +++ b/fs/iomap/direct-io.c > @@ -561,6 +561,12 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > ret = iomap_apply(inode, pos, count, iomap_flags, ops, dio, > iomap_dio_actor); > if (ret <= 0) { > + if (ret == -EFAULT && dio->size && > + (dio_flags & IOMAP_DIO_PARTIAL)) { > + wait_for_completion = true; > + ret = 0; > + } > + > /* magic error code to fall back to buffered I/O */ > if (ret == -ENOTBLK) { > wait_for_completion = true; > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 479c1da3e221..bcae4814b8e3 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -267,6 +267,13 @@ struct iomap_dio_ops { > */ > #define IOMAP_DIO_OVERWRITE_ONLY (1 << 1) > > +/* > + * When a page fault occurs, return a partial synchronous result and allow > + * the caller to retry the rest of the operation after dealing with the page > + * fault. > + */ > +#define IOMAP_DIO_PARTIAL (1 << 2) > + > ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > const struct iomap_ops *ops, const struct iomap_dio_ops *dops, > unsigned int dio_flags); > -- > 2.26.3 >