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 4F40BC433EF for ; Wed, 20 Apr 2022 14:31:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379468AbiDTOeY (ORCPT ); Wed, 20 Apr 2022 10:34:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348369AbiDTOeX (ORCPT ); Wed, 20 Apr 2022 10:34:23 -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 ESMTP id B065733A00 for ; Wed, 20 Apr 2022 07:31:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650465095; 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=I7T6uNrxtdMv6Jk9B2TNgRBUsej61OwrtET1tcadZAw=; b=d17WWx1vnrXShPxIzd4PlfVK3K8tNJtM0XpFFc1Lj8C9hJwrcawWR8JKuNfI8B0cnMsV18 APPkbcLHh7qndvVnJtmrDYK8tcXEya6U/N3toEbnYVTnnHktjqcC1iM1Y+YKSIkz8DiZAb C0w+Rg4PLRpxaEafQy6Z0B0daYLYZm0= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-634-sopYKkH1O7a55SH0zeFU0Q-1; Wed, 20 Apr 2022 10:31:34 -0400 X-MC-Unique: sopYKkH1O7a55SH0zeFU0Q-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2DB0B8517E7; Wed, 20 Apr 2022 14:31:18 +0000 (UTC) Received: from localhost (ovpn-8-20.pek2.redhat.com [10.72.8.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id 464B854CE2F; Wed, 20 Apr 2022 14:31:16 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Ming Lei , linux-mm@kvack.org, linux-xfs@vger.kernel.org, Changhui Zhong Subject: [PATCH V2] block: ignore RWF_HIPRI hint for sync dio Date: Wed, 20 Apr 2022 22:31:10 +0800 Message-Id: <20220420143110.2679002-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org So far bio is marked as REQ_POLLED if RWF_HIPRI/IOCB_HIPRI is passed from userspace sync io interface, then block layer tries to poll until the bio is completed. But the current implementation calls blk_io_schedule() if bio_poll() returns 0, and this way causes io hang or timeout easily. But looks no one reports this kind of issue, which should have been triggered in normal io poll sanity test or blktests block/007 as observed by Changhui, that means it is very likely that no one uses it or no one cares it. Also after io_uring is invented, io poll for sync dio becomes legacy interface. So ignore RWF_HIPRI hint for sync dio. CC: linux-mm@kvack.org Cc: linux-xfs@vger.kernel.org Reported-by: Changhui Zhong Suggested-by: Christoph Hellwig Signed-off-by: Ming Lei --- V2: - avoid to break io_uring async polling as pointed by Chritoph block/fops.c | 22 +--------------------- fs/iomap/direct-io.c | 7 +++---- mm/page_io.c | 4 +--- 3 files changed, 5 insertions(+), 28 deletions(-) diff --git a/block/fops.c b/block/fops.c index e3643362c244..b9b83030e0df 100644 --- a/block/fops.c +++ b/block/fops.c @@ -44,14 +44,6 @@ static unsigned int dio_bio_write_op(struct kiocb *iocb) #define DIO_INLINE_BIO_VECS 4 -static void blkdev_bio_end_io_simple(struct bio *bio) -{ - struct task_struct *waiter = bio->bi_private; - - WRITE_ONCE(bio->bi_private, NULL); - blk_wake_io_task(waiter); -} - static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, unsigned int nr_pages) { @@ -83,8 +75,6 @@ static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb, bio_init(&bio, bdev, vecs, nr_pages, dio_bio_write_op(iocb)); } bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT; - bio.bi_private = current; - bio.bi_end_io = blkdev_bio_end_io_simple; bio.bi_ioprio = iocb->ki_ioprio; ret = bio_iov_iter_get_pages(&bio, iter); @@ -97,18 +87,8 @@ static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb, if (iocb->ki_flags & IOCB_NOWAIT) bio.bi_opf |= REQ_NOWAIT; - if (iocb->ki_flags & IOCB_HIPRI) - bio_set_polled(&bio, iocb); - submit_bio(&bio); - for (;;) { - set_current_state(TASK_UNINTERRUPTIBLE); - if (!READ_ONCE(bio.bi_private)) - break; - if (!(iocb->ki_flags & IOCB_HIPRI) || !bio_poll(&bio, NULL, 0)) - blk_io_schedule(); - } - __set_current_state(TASK_RUNNING); + submit_bio_wait(&bio); bio_release_pages(&bio, should_dirty); if (unlikely(bio.bi_status)) diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index 62da020d02a1..80f9b047aa1b 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -56,7 +56,8 @@ static void iomap_dio_submit_bio(const struct iomap_iter *iter, { atomic_inc(&dio->ref); - if (dio->iocb->ki_flags & IOCB_HIPRI) { + /* Sync dio can't be polled reliably */ + if ((dio->iocb->ki_flags & IOCB_HIPRI) && !is_sync_kiocb(dio->iocb)) { bio_set_polled(bio, dio->iocb); dio->submit.poll_bio = bio; } @@ -653,9 +654,7 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, if (!READ_ONCE(dio->submit.waiter)) break; - if (!dio->submit.poll_bio || - !bio_poll(dio->submit.poll_bio, NULL, 0)) - blk_io_schedule(); + blk_io_schedule(); } __set_current_state(TASK_RUNNING); } diff --git a/mm/page_io.c b/mm/page_io.c index 89fbf3cae30f..3fbdab6a940e 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -360,7 +360,6 @@ int swap_readpage(struct page *page, bool synchronous) * attempt to access it in the page fault retry time check. */ if (synchronous) { - bio->bi_opf |= REQ_POLLED; get_task_struct(current); bio->bi_private = current; } @@ -372,8 +371,7 @@ int swap_readpage(struct page *page, bool synchronous) if (!READ_ONCE(bio->bi_private)) break; - if (!bio_poll(bio, NULL, 0)) - blk_io_schedule(); + blk_io_schedule(); } __set_current_state(TASK_RUNNING); bio_put(bio); -- 2.31.1