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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_GIT 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 59A28C4361A for ; Fri, 4 Dec 2020 09:45:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 036CE227BF for ; Fri, 4 Dec 2020 09:45:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387556AbgLDJpu (ORCPT ); Fri, 4 Dec 2020 04:45:50 -0500 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:32983 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387553AbgLDJpu (ORCPT ); Fri, 4 Dec 2020 04:45:50 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0UHV5WIO_1607075096; Received: from e18g09479.et15sqa.tbsite.net(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0UHV5WIO_1607075096) by smtp.aliyun-inc.com(127.0.0.1); Fri, 04 Dec 2020 17:45:06 +0800 From: Hao Xu To: Alexander Viro , Christoph Hellwig Cc: "Darrick J. Wong" , linux-fsdevel@vger.kernel.org, Jeffle Xu , Konstantin Khlebnikov , Jens Axboe , io-uring@vger.kernel.org, Joseph Qi Subject: [PATCH v3 RESEND] iomap: set REQ_NOWAIT according to IOCB_NOWAIT in Direct IO Date: Fri, 4 Dec 2020 17:44:56 +0800 Message-Id: <1607075096-94235-1-git-send-email-haoxu@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Currently, IOCB_NOWAIT is ignored in Direct IO, REQ_NOWAIT is only set when IOCB_HIPRI is set. But REQ_NOWAIT should be set as well when IOCB_NOWAIT is set. Suggested-by: Jeffle Xu Signed-off-by: Konstantin Khlebnikov Signed-off-by: Hao Xu --- Hi all, I tested fio io_uring direct read for a file on ext4 filesystem on a nvme ssd. I found that IOCB_NOWAIT is ignored in iomap layer, which means REQ_NOWAIT is not set in bio->bi_opf. This makes nowait IO a normal IO. Since I'm new to iomap and block layer, I sincerely ask yours opinions in case I misunderstand the code which is very likely to happen.:) The example I use: io_uring direct randread, the first try is with IOCB_NOWAIT but not IOCB_HIPRI, the IOCB_NOWAIT is ignored in block layer which I think is not the designed behaviour. I found that Konstantin found this issue before in May 2020 (https://www.spinics.net/lists/linux-block/msg53275.html), here add his signature, add Jeffle's as well since he gave me some help. v1->v2: * add same logic in __blkdev_direct_IO_simple() v2->v3: * add same logic in do_blockdev_direct_IO() fs/block_dev.c | 7 +++++++ fs/direct-io.c | 6 ++++-- fs/iomap/direct-io.c | 3 +++ 3 files changed, 14 insertions(+), 2 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 9e84b1928b94..ca6f365c2f14 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -263,6 +263,10 @@ static void blkdev_bio_end_io_simple(struct bio *bio) bio.bi_opf = dio_bio_write_op(iocb); task_io_account_write(ret); } + + if (iocb->ki_flags & IOCB_NOWAIT) + bio.bi_opf |= REQ_NOWAIT; + if (iocb->ki_flags & IOCB_HIPRI) bio_set_polled(&bio, iocb); @@ -417,6 +421,9 @@ static void blkdev_bio_end_io(struct bio *bio) task_io_account_write(bio->bi_iter.bi_size); } + if (iocb->ki_flags & IOCB_NOWAIT) + bio->bi_opf |= REQ_NOWAIT; + dio->size += bio->bi_iter.bi_size; pos += bio->bi_iter.bi_size; diff --git a/fs/direct-io.c b/fs/direct-io.c index d53fa92a1ab6..b221ed351c1c 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -1206,11 +1206,13 @@ static inline int drop_refcount(struct dio *dio) if (iov_iter_rw(iter) == WRITE) { dio->op = REQ_OP_WRITE; dio->op_flags = REQ_SYNC | REQ_IDLE; - if (iocb->ki_flags & IOCB_NOWAIT) - dio->op_flags |= REQ_NOWAIT; } else { dio->op = REQ_OP_READ; } + + if (iocb->ki_flags & IOCB_NOWAIT) + dio->op_flags |= REQ_NOWAIT; + if (iocb->ki_flags & IOCB_HIPRI) dio->op_flags |= REQ_HIPRI; diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index 933f234d5bec..2e897688ed6d 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -64,6 +64,9 @@ static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap, { atomic_inc(&dio->ref); + if (dio->iocb->ki_flags & IOCB_NOWAIT) + bio->bi_opf |= REQ_NOWAIT; + if (dio->iocb->ki_flags & IOCB_HIPRI) bio_set_polled(bio, dio->iocb); -- 1.8.3.1