From nobody Tue Dec 2 01:30:15 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 862812F39A7; Fri, 21 Nov 2025 05:14:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763702053; cv=none; b=rEYP0i5wQsMIsLm7KuwRQVqsNYUeIzRwxr5iwNae06EP2IxvYuSMCmy47x5pTKFywK9jPVXFO/ZCMqSJk/ajWTOzmX2zcH3C6CGxGN9vLDMHKzzvQqMq9lPY2ADjVAcD+YkLJ5u+bgwdHlZTGdRksLnNqyVsNmZMEMe0Nf6EcvM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763702053; c=relaxed/simple; bh=4KDj2pNSq+lxsIMg4XH14s5KHKgds2odyGUls6jJW2Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KMwjd0SptPb6YvGX2ue5NgGTlmHS4FK8b17PyWD0PiEvIu+ShtBXJoTqbIvCWJTCXxwjALQ4nNyZybjwDYAmdzJdGOlMbiCg3hpKOpbUInp6myNRjr8CnFy/+Cpgb47dqmj71qBAtKFaAUQ37V02Lhqevo4sRX2BSTTqt6NAoGg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id C38DDC16AAE; Fri, 21 Nov 2025 05:14:11 +0000 (UTC) From: Yu Kuai To: song@kernel.org, yukuai@fnnas.com Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, linan122@huawei.com, xni@redhat.com Subject: [PATCH] md: support to align bio to limits Date: Fri, 21 Nov 2025 13:14:00 +0800 Message-ID: <20251121051406.1316884-3-yukuai@fnnas.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251121051406.1316884-1-yukuai@fnnas.com> References: <20251121051406.1316884-1-yukuai@fnnas.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 Content-Type: text/plain; charset="utf-8" For personalities that report optimal IO size, it's indicate that users can get the best IO bandwidth if they issue IO with this size. However there is also an implicit condition that IO should also be aligned to the optimal IO size. Currently, bio will only be split by limits, if bio offset is not aligned to limits, then all split bio will not be aligned. This patch add a new feature to align bio to limits first, and following patches will support this for each personality if necessary. Signed-off-by: Yu Kuai --- drivers/md/md.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ drivers/md/md.h | 1 + 2 files changed, 47 insertions(+) diff --git a/drivers/md/md.c b/drivers/md/md.c index 7b5c5967568f..b09f87b27807 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -427,6 +427,48 @@ bool md_handle_request(struct mddev *mddev, struct bio= *bio) } EXPORT_SYMBOL(md_handle_request); =20 +static struct bio *__md_bio_align_to_limits(struct mddev *mddev, + struct bio *bio) +{ + unsigned int max_sectors =3D mddev->gendisk->queue->limits.max_sectors; + sector_t start =3D bio->bi_iter.bi_sector; + sector_t align_start =3D roundup(start, max_sectors); + sector_t end; + sector_t align_end; + + /* already aligned */ + if (align_start =3D=3D start) + return bio; + + end =3D start + bio_sectors(bio); + align_end =3D rounddown(end, max_sectors); + + /* bio is too small to split */ + if (align_end <=3D align_start) + return bio; + + return bio_submit_split_bioset(bio, align_start - start, + &mddev->gendisk->bio_split); +} + +static struct bio *md_bio_align_to_limits(struct mddev *mddev, struct bio = *bio) +{ + if (!mddev->bio_align_to_limits) + return bio; + + /* atomic write can't split */ + if (bio->bi_opf & REQ_ATOMIC) + return bio; + + switch (bio_op(bio)) { + case REQ_OP_READ: + case REQ_OP_WRITE: + return __md_bio_align_to_limits(mddev, bio); + default: + return bio; + } +} + static void md_submit_bio(struct bio *bio) { const int rw =3D bio_data_dir(bio); @@ -442,6 +484,10 @@ static void md_submit_bio(struct bio *bio) return; } =20 + bio =3D md_bio_align_to_limits(mddev, bio); + if (!bio) + return; + bio =3D bio_split_to_limits(bio); if (!bio) return; diff --git a/drivers/md/md.h b/drivers/md/md.h index 75fd8c873b6f..1ed90fd85ac4 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -630,6 +630,7 @@ struct mddev { bool has_superblocks:1; bool fail_last_dev:1; bool serialize_policy:1; + bool bio_align_to_limits:1; }; =20 enum recovery_flags { --=20 2.51.0