From nobody Tue Oct 7 21:30:56 2025 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B2B020E328; Mon, 7 Jul 2025 01:32:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751851972; cv=none; b=edtc0IV/PUeR74jPUtB4C+pQr8iUwwqJMfhv6AojZ0kZ+DNPAMl3UfSmuxng67aWdrGYVbaAlcWHii4HXfl8HMT7Z8Vhzff0d5Z1iqBNO4UVnZzpJ4C0iuqNKjBgDKMQj1p2zsPOYa3ZW7HE3pmVWlh7TuadnxGDH+9tlQux55M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751851972; c=relaxed/simple; bh=MBu1mejQ++tU50EgLNX9tCdC8Z1xzYjVDlz1gKR4WM0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=jgTJKM4xzoFASCWtvXe1unBC35HN+Qsrf7a741244vmMSWdIxI4mqm6260c2LEzbhAzJbOYYHJZqh8KI7QF+rcTHkib2o33sQ4z/RjEe4tQGrFc6ZboHg1+yG6AOSaGmqS+vUtXRftT5/TXiR5iyeBjEpPpx4ZRPCrakwtcsBmQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4bb6Dr05QgzKHMbt; Mon, 7 Jul 2025 09:32:44 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id 74CCB1A0A83; Mon, 7 Jul 2025 09:32:42 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP3 (Coremail) with SMTP id _Ch0CgDnSCazI2to_nSRAw--.35890S13; Mon, 07 Jul 2025 09:32:42 +0800 (CST) From: Yu Kuai To: agk@redhat.com, snitzer@kernel.org, mpatocka@redhat.com, song@kernel.org, yukuai3@huawei.com Cc: dm-devel@lists.linux.dev, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [PATCH v5 09/15] md/raid1: check bitmap before behind write Date: Mon, 7 Jul 2025 09:27:05 +0800 Message-Id: <20250707012711.376844-10-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20250707012711.376844-1-yukuai1@huaweicloud.com> References: <20250707012711.376844-1-yukuai1@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _Ch0CgDnSCazI2to_nSRAw--.35890S13 X-Coremail-Antispam: 1UD129KBjvJXoWxAry8tr47Cr4xtF17Kw45Jrb_yoWrGryrpa 9FqFn0krW5trW3XrnrAFykuFyrXw4ktF9rtrWfW34FgF12yr90gF4FgFyrCrnxA3sxCF45 Zr4Yyr1UW3ySqFUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUmS14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkE bVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67 AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUCVW8JwCI 42IY6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF 4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBI daVFxhVjvjDU0xZFpf9x0JUQFxUUUUUU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Content-Type: text/plain; charset="utf-8" From: Yu Kuai behind write rely on bitmap, because the number of IO are recorded in bitmap->behind_writes, and callers rely on bitmap_wait_behind_writes() to wait for IO to be done. However, currently callers doesn't check if bitmap is enabeld before calling into behind methods. Hence if behind write start without bitmap, readers will not wait for slow write IO to be done and old data can be read in some corner cases. Signed-off-by: Yu Kuai --- drivers/md/md-bitmap.c | 6 ------ drivers/md/raid1.c | 45 ++++++++++++++++++++++++++---------------- 2 files changed, 28 insertions(+), 23 deletions(-) diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c index a079cbe2e6f1..5bd75fa6ee1d 100644 --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -2049,9 +2049,6 @@ static void bitmap_start_behind_write(struct mddev *m= ddev) struct bitmap *bitmap =3D mddev->bitmap; int bw; =20 - if (!bitmap) - return; - atomic_inc(&bitmap->behind_writes); bw =3D atomic_read(&bitmap->behind_writes); if (bw > bitmap->behind_writes_used) @@ -2065,9 +2062,6 @@ static void bitmap_end_behind_write(struct mddev *mdd= ev) { struct bitmap *bitmap =3D mddev->bitmap; =20 - if (!bitmap) - return; - if (atomic_dec_and_test(&bitmap->behind_writes)) wake_up(&bitmap->behind_wait); pr_debug("dec write-behind count %d/%lu\n", diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index a46ce996ea9c..015eabb502ec 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1366,7 +1366,8 @@ static void raid1_read_request(struct mddev *mddev, s= truct bio *bio, (unsigned long long)r1_bio->sector, mirror->rdev->bdev); =20 - if (test_bit(WriteMostly, &mirror->rdev->flags)) { + if (test_bit(WriteMostly, &mirror->rdev->flags) && + md_bitmap_enabled(mddev, false)) { /* * Reading from a write-mostly device must take care not to * over-take any writes that are 'behind' @@ -1452,6 +1453,30 @@ static bool wait_blocked_rdev(struct mddev *mddev, s= truct bio *bio) return true; } =20 +static void raid1_start_write_behind(struct mddev *mddev, struct r1bio *r1= _bio, + struct bio *bio) +{ + unsigned long max_write_behind =3D mddev->bitmap_info.max_write_behind; + struct md_bitmap_stats stats; + int err; + + /* behind write rely on bitmap, see bitmap_operations */ + if (!md_bitmap_enabled(mddev, false)) + return; + + err =3D mddev->bitmap_ops->get_stats(mddev->bitmap, &stats); + if (err) + return; + + /* Don't do behind IO if reader is waiting, or there are too many. */ + if (!stats.behind_wait && stats.behind_writes < max_write_behind) + alloc_behind_master_bio(r1_bio, bio); + + if (test_bit(R1BIO_BehindIO, &r1_bio->state)) + mddev->bitmap_ops->start_behind_write(mddev); + +} + static void raid1_write_request(struct mddev *mddev, struct bio *bio, int max_write_sectors) { @@ -1612,22 +1637,8 @@ static void raid1_write_request(struct mddev *mddev,= struct bio *bio, continue; =20 if (first_clone) { - unsigned long max_write_behind =3D - mddev->bitmap_info.max_write_behind; - struct md_bitmap_stats stats; - int err; - - /* do behind I/O ? - * Not if there are too many, or cannot - * allocate memory, or a reader on WriteMostly - * is waiting for behind writes to flush */ - err =3D mddev->bitmap_ops->get_stats(mddev->bitmap, &stats); - if (!err && write_behind && !stats.behind_wait && - stats.behind_writes < max_write_behind) - alloc_behind_master_bio(r1_bio, bio); - - if (test_bit(R1BIO_BehindIO, &r1_bio->state)) - mddev->bitmap_ops->start_behind_write(mddev); + if (write_behind) + raid1_start_write_behind(mddev, r1_bio, bio); first_clone =3D 0; } =20 --=20 2.39.2