From patchwork Tue Oct 19 13:42:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Gruenbacher X-Patchwork-Id: 12569953 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 2E21FC433F5 for ; Tue, 19 Oct 2021 13:45:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1164160F9F for ; Tue, 19 Oct 2021 13:45:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236039AbhJSNrO (ORCPT ); Tue, 19 Oct 2021 09:47:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:26719 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235739AbhJSNq5 (ORCPT ); Tue, 19 Oct 2021 09:46:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634651084; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GMMEkGGRgFD/FgwggFSt2zozeSaxloIxf+v0cQoYfqo=; b=D/TpC9CmfvsCHngFdpDFKRX6Cyuk/+Pys8q6EJFoB+gcXrgUTh9sNWE9BgE866GA5wiBRN uVByVPyV+cWij/SqU9RSt5QI8UGvxjBY/sS7mWR0nWBXtR4NPslR5dQ5NrJhihK0MkaG2R rxqX59t7XZCA9XyrhnXTXN1ztf5/PCU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-100-HKKK6yfmOYWiDVVxLiY4bQ-1; Tue, 19 Oct 2021 09:44:41 -0400 X-MC-Unique: HKKK6yfmOYWiDVVxLiY4bQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 97A061054F90; Tue, 19 Oct 2021 13:44:38 +0000 (UTC) Received: from max.com (unknown [10.40.193.143]) by smtp.corp.redhat.com (Postfix) with ESMTP id A41DD10016FC; Tue, 19 Oct 2021 13:44:04 +0000 (UTC) From: Andreas Gruenbacher To: Linus Torvalds , Catalin Marinas Cc: Alexander Viro , Christoph Hellwig , "Darrick J. Wong" , Paul Mackerras , Jan Kara , Matthew Wilcox , cluster-devel@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com, kvm-ppc@vger.kernel.org, linux-btrfs@vger.kernel.org, Andreas Gruenbacher Subject: [PATCH v8 13/17] iomap: Support partial direct I/O on user copy failures Date: Tue, 19 Oct 2021 15:42:00 +0200 Message-Id: <20211019134204.3382645-14-agruenba@redhat.com> In-Reply-To: <20211019134204.3382645-1-agruenba@redhat.com> References: <20211019134204.3382645-1-agruenba@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org 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 Reviewed-by: Darrick J. Wong --- 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 a2a368e824c0..a434fb7887b2 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -581,6 +581,12 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, if (iov_iter_rw(iter) == READ && iomi.pos >= dio->i_size) iov_iter_revert(iter, iomi.pos - dio->i_size); + if (ret == -EFAULT && dio->size && (dio_flags & IOMAP_DIO_PARTIAL)) { + if (!(iocb->ki_flags & IOCB_NOWAIT)) + 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 24f8489583ca..2a213b0d1e1f 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -330,6 +330,13 @@ 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);