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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC113C4332F for ; Thu, 3 Nov 2022 08:51:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229459AbiKCIv0 (ORCPT ); Thu, 3 Nov 2022 04:51:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229379AbiKCIvZ (ORCPT ); Thu, 3 Nov 2022 04:51:25 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93034D2DC for ; Thu, 3 Nov 2022 01:50:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667465428; 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; bh=FeqABZBo26005zjL1Br5RZrJuJL5HVgW06cRmiuIaZg=; b=hAe7c+oox8n9rrYyuKYT6zujshRu2HaAQlSmtwZSGzQUsGDMMiUDuhhZXZgkh5FJlRKXfN xBuN9F9SYqA4e316fF5t0WvEu69/Ps2MEmcLd79BNKDGZKNohuhinahiGn52894B2iIB/o LOmqwCSyClFn4LYzpSZGld/qxkagcas= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-100-LeVvhBuJPlGnBUxBUZBlrw-1; Thu, 03 Nov 2022 04:50:25 -0400 X-MC-Unique: LeVvhBuJPlGnBUxBUZBlrw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 165491C0513A; Thu, 3 Nov 2022 08:50:25 +0000 (UTC) Received: from localhost (ovpn-8-20.pek2.redhat.com [10.72.8.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id B7B9839D6A; Thu, 3 Nov 2022 08:50:23 +0000 (UTC) From: Ming Lei To: Jens Axboe , io-uring@vger.kernel.org Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Miklos Szeredi , Stefan Hajnoczi , ZiyangZhang , Ming Lei Subject: [RFC PATCH 0/4] io_uring/splice: extend splice for supporting ublk zero copy Date: Thu, 3 Nov 2022 16:50:00 +0800 Message-Id: <20221103085004.1029763-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Hello Guys, This patch extends io_uring/splice by adding two flags(SPLICE_F_DIRECT & SPLICE_F_READ_TO_READ) for supporting ublk zero copy, and fuse could benefit from the change too. - SPLICE_F_DIRECT is for using do_splice_direct() to support zero copy - SPLICE_F_READ_TO_READ is for supporting ublk READ zero copy, the plain splice can support WRITE zero copy by: splice(ublkc_fd, ublkc_pos, pipe_wr_fd, NULL, len, flags) splice(pipe_rd_fd, NULL, backing_fd, backing_off, len, flags) but can't support READ zc. Extend splice to allow to splice from the 1st ->splice_read()(producer) to the 2nd ->splice_read()(consumer), then READ request pages reference can be transferred to backing IO code path. The initial idea is suggested by Miklos Szeredi & Stefan Hajnoczi. The patchset has been verified basically by ublk builtin tests(loop/008, loop/009, generic/003), and basic mount, git clone, kernel building, umount tests on ublk-loop[1] which is created by 'ublk add -t loop -f $backing -z'. The next step is to allow io_uring to run do_splice_direct*() in async style like normal async RW instead of offloading to iowq context, so that top performance can be reached, and that depends on current work. Any comments are welcome. [1] https://github.com/ming1/ubdsrv/commits/splice-zc Ming Lei (4): io_uring/splice: support do_splice_direct fs/splice: add helper of splice_dismiss_pipe() io_uring/splice: support splice from ->splice_read to ->splice_read ublk_drv: support splice based read/write zero copy drivers/block/ublk_drv.c | 151 +++++++++++++++++++++++++- fs/read_write.c | 5 +- fs/splice.c | 193 +++++++++++++++++++++++++++++----- include/linux/fs.h | 2 + include/linux/pipe_fs_i.h | 9 ++ include/linux/splice.h | 14 +++ include/uapi/linux/ublk_cmd.h | 34 +++++- io_uring/splice.c | 16 ++- 8 files changed, 392 insertions(+), 32 deletions(-) -- 2.31.1