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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 DB085C19425 for ; Wed, 9 Dec 2020 09:07:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A050423B79 for ; Wed, 9 Dec 2020 09:07:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728509AbgLIJH3 (ORCPT ); Wed, 9 Dec 2020 04:07:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727339AbgLIJH3 (ORCPT ); Wed, 9 Dec 2020 04:07:29 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5465C0613D6; Wed, 9 Dec 2020 01:06:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=MNMpVWDVu1xKs8I0T0Bns+VkPimcOASCojWukxDS8ng=; b=IpPbZN2f78dxphMHqQpYHqe58S vw4NwnQ+Xz59+sElzQ/B5L3eRJkdnRh6BnNVuFZ5y34CD+z1GqrWUYj06V+i7uo3q/XpaDl+cG884 drRT2Fl5JdUamqqF/e3c5FVm4cZdv6ufagIWq3l2FmDBRTe88w+7D76jqPZ+a/1/2aZbc/Kq3RR8b AW1FVBy6gWIDlGSu1r/dQhnWUKxtmBmSBD63N8Y1uTWHiW0k+fHm0hzv4digf/kQigNWvUXpNwcCN p7YE1vjhW3f9nlvBiwMKeZthCUjMehbPAaFYLfvK5cVKrRzzP+XOPQDrNS+A5UhEbrU/2s3/fcJsv mt+CWOYQ==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kmvQs-00089J-7s; Wed, 09 Dec 2020 09:06:46 +0000 Date: Wed, 9 Dec 2020 09:06:46 +0000 From: Christoph Hellwig To: Pavel Begunkov Cc: Jens Axboe , Alexander Viro , linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] iov: introduce ITER_BVEC_FLAG_FIXED Message-ID: <20201209090646.GA28832@infradead.org> References: <20201209083645.GB21968@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201209083645.GB21968@infradead.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Dec 09, 2020 at 08:36:45AM +0000, Christoph Hellwig wrote: > This is making the iter type even more of a mess than it already is. > I think we at least need placeholders for 0/1 here and an explicit > flags namespace, preferably after the types. > > Then again I'd much prefer if we didn't even add the flag or at best > just add it for a short-term transition and move everyone over to the > new scheme. Otherwise the amount of different interfaces and supporting > code keeps exploding. Note that the only other callers that use iov_iter_bvec and asynchronous read/write are loop, target and nvme-target, so this should actually be pretty simple. Out of these only target needs something like this trivial change to keep the bvec available over the duration of the I/O, the other two should be fine already: --- >From 581a8eabbb1759e3dcfee4b1d2e419f814a8cb80 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 9 Dec 2020 10:05:04 +0100 Subject: target/file: allocate the bvec array as part of struct target_core_file_cmd This saves one memory allocation, and ensures the bvecs aren't freed before the AIO completion. This will allow the lower level code to be optimized so that it can avoid allocating another bvec array. Signed-off-by: Christoph Hellwig --- drivers/target/target_core_file.c | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c index 7143d03f0e027e..ed0c39a1f7c649 100644 --- a/drivers/target/target_core_file.c +++ b/drivers/target/target_core_file.c @@ -241,6 +241,7 @@ struct target_core_file_cmd { unsigned long len; struct se_cmd *cmd; struct kiocb iocb; + struct bio_vec bvecs[]; }; static void cmd_rw_aio_complete(struct kiocb *iocb, long ret, long ret2) @@ -268,29 +269,22 @@ fd_execute_rw_aio(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, struct target_core_file_cmd *aio_cmd; struct iov_iter iter = {}; struct scatterlist *sg; - struct bio_vec *bvec; ssize_t len = 0; int ret = 0, i; - aio_cmd = kmalloc(sizeof(struct target_core_file_cmd), GFP_KERNEL); + aio_cmd = kmalloc(struct_size(aio_cmd, bvecs, sgl_nents), GFP_KERNEL); if (!aio_cmd) return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; - bvec = kcalloc(sgl_nents, sizeof(struct bio_vec), GFP_KERNEL); - if (!bvec) { - kfree(aio_cmd); - return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; - } - for_each_sg(sgl, sg, sgl_nents, i) { - bvec[i].bv_page = sg_page(sg); - bvec[i].bv_len = sg->length; - bvec[i].bv_offset = sg->offset; + aio_cmd->bvecs[i].bv_page = sg_page(sg); + aio_cmd->bvecs[i].bv_len = sg->length; + aio_cmd->bvecs[i].bv_offset = sg->offset; len += sg->length; } - iov_iter_bvec(&iter, is_write, bvec, sgl_nents, len); + iov_iter_bvec(&iter, is_write, aio_cmd->bvecs, sgl_nents, len); aio_cmd->cmd = cmd; aio_cmd->len = len; @@ -307,8 +301,6 @@ fd_execute_rw_aio(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, else ret = call_read_iter(file, &aio_cmd->iocb, &iter); - kfree(bvec); - if (ret != -EIOCBQUEUED) cmd_rw_aio_complete(&aio_cmd->iocb, ret, 0); -- 2.29.2