From nobody Tue Feb 10 19:50:26 2026 Received: from dggsgout12.his.huawei.com (unknown [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 6728917BA1; Thu, 22 Feb 2024 08:03:53 +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=1708589037; cv=none; b=CTCLUn+40NF+6c3TD7Pbjasy3xSQtJrjKVd/1ULuJAhWXDX1i291VzbslCtVW+OO0CkaUbbb0/yF51cdGKxThjXJw7uUghl2emf45pG3pb20brrJLigmqrmFWMuiFyUP1dR6nZRWTZYnPhN29k5PjmzL5p3sgiqhcTn1VLm1YEI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708589037; c=relaxed/simple; bh=VED7vyza1XPnVVt1G1gqgD1vJ+Gh9DgRXBESSaC/Xtc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=hz2CfAny/RUzIKAE8BmWGJXfCMmOVRnxWR0wwbiSALR6N638pwZD350S+y6ktXrIsPJLmAo3KNZcveOrjBPpEu8i6K74ft7ORxTvERGMBmCJt5tCaeJLcsPINMG5iqIxHHmW0s8kL/VE+L5mmeiNZiVL8AQWomu6o7tOBbSdAjY= 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 [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4TgQd96lyZz4f3l6y; Thu, 22 Feb 2024 16:03:41 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id EFAB11A1051; Thu, 22 Feb 2024 16:03:46 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP1 (Coremail) with SMTP id cCh0CgBXKBHc_9ZlnaUhEw--.37287S7; Thu, 22 Feb 2024 16:03:46 +0800 (CST) From: Yu Kuai To: paul.e.luse@linux.intel.com, song@kernel.org, neilb@suse.com, shli@fb.com Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com Subject: [PATCH md-6.9 03/10] md/raid1: fix choose next idle in read_balance() Date: Thu, 22 Feb 2024 15:57:59 +0800 Message-Id: <20240222075806.1816400-4-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240222075806.1816400-1-yukuai1@huaweicloud.com> References: <20240222075806.1816400-1-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: cCh0CgBXKBHc_9ZlnaUhEw--.37287S7 X-Coremail-Antispam: 1UD129KBjvJXoWxXryrKr1kKr4fAFyUWrW3ZFb_yoW5CFW5pa 1jvwsavr4UX343C3s8tw48ZrySq345JFW8CFZ7A34Fgry3XFWYqa18K34a9ry8CFn3t34a qr1UGrZF93WkGaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBE14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JrWl82xGYIkIc2 x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v2 6r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2 Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_ Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUd8n5UUUUU = X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Content-Type: text/plain; charset="utf-8" From: Yu Kuai Commit 12cee5a8a29e ("md/raid1: prevent merging too large request") add the case choose next idle in read_balance(): read_balance: for_each_rdev if(next_seq_sect =3D=3D this_sector || disk =3D=3D 0) -> sequential reads best_disk =3D disk; if (...) choose_next_idle =3D 1 continue; for_each_rdev -> iterate next rdev if (pending =3D=3D 0) best_disk =3D disk; -> choose the next idle disk break; if (choose_next_idle) -> keep using this rdev if there are no other idle disk contine However, commit 2e52d449bcec ("md/raid1: add failfast handling for reads.") remove the code: - /* If device is idle, use it */ - if (pending =3D=3D 0) { - best_disk =3D disk; - break; - } Hence choose next idle will never work now, fix this problem by following: 1) don't set best_disk in this case, read_balance() will choose the best disk after iterating all the disks; 2) add 'pending' so that other idle disk will be chosen; 3) set 'dist' to 0 so that if there is no other idle disk, and all disks are rotational, this disk will still be chosen; Fixes: 2e52d449bcec ("md/raid1: add failfast handling for reads.") Co-developed-by: Paul Luse Signed-off-by: Paul Luse Signed-off-by: Yu Kuai --- drivers/md/raid1.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index c60ea58ae8c5..d0bc67e6d068 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -604,7 +604,6 @@ static int read_balance(struct r1conf *conf, struct r1b= io *r1_bio, int *max_sect unsigned int min_pending; struct md_rdev *rdev; int choose_first; - int choose_next_idle; =20 /* * Check if we can balance. We can balance on the whole @@ -619,7 +618,6 @@ static int read_balance(struct r1conf *conf, struct r1b= io *r1_bio, int *max_sect best_pending_disk =3D -1; min_pending =3D UINT_MAX; best_good_sectors =3D 0; - choose_next_idle =3D 0; clear_bit(R1BIO_FailFast, &r1_bio->state); =20 if ((conf->mddev->recovery_cp < this_sector + sectors) || @@ -712,7 +710,6 @@ static int read_balance(struct r1conf *conf, struct r1b= io *r1_bio, int *max_sect int opt_iosize =3D bdev_io_opt(rdev->bdev) >> 9; struct raid1_info *mirror =3D &conf->mirrors[disk]; =20 - best_disk =3D disk; /* * If buffered sequential IO size exceeds optimal * iosize, check if there is idle disk. If yes, choose @@ -731,15 +728,21 @@ static int read_balance(struct r1conf *conf, struct r= 1bio *r1_bio, int *max_sect mirror->next_seq_sect > opt_iosize && mirror->next_seq_sect - opt_iosize >=3D mirror->seq_start) { - choose_next_idle =3D 1; - continue; + /* + * Add 'pending' to avoid choosing this disk if + * there is other idle disk. + * Set 'dist' to 0, so that if there is no other + * idle disk and all disks are rotational, this + * disk will still be chosen. + */ + pending++; + dist =3D 0; + } else { + best_disk =3D disk; + break; } - break; } =20 - if (choose_next_idle) - continue; - if (min_pending > pending) { min_pending =3D pending; best_pending_disk =3D disk; --=20 2.39.2