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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=45.249.212.51 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 dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4TkbrF5cpzz4f3mHQ; Tue, 27 Feb 2024 20:09:17 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 198EB1A0283; Tue, 27 Feb 2024 20:09:25 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP1 (Coremail) with SMTP id cCh0CgAn+RHv0N1lpKNAFQ--.28259S7; Tue, 27 Feb 2024 20:09:24 +0800 (CST) From: Yu Kuai To: xni@redhat.com, paul.e.luse@linux.intel.com, song@kernel.org, shli@fb.com, neilb@suse.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 v2 03/10] md/raid1: fix choose next idle in read_balance() Date: Tue, 27 Feb 2024 20:03:20 +0800 Message-Id: <20240227120327.1432511-4-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240227120327.1432511-1-yukuai1@huaweicloud.com> References: <20240227120327.1432511-1-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: cCh0CgAn+RHv0N1lpKNAFQ--.28259S7 X-Coremail-Antispam: 1UD129KBjvJXoWxXryrKr1kKr4fAFyUJry3twb_yoWrXF48pw 4jvwsaqr4UXF43u3sxJw4UurySg345JayrGrZ7C34Ygry3XrWqq3W7K342vry8CFs3J342 qw18GrZrW3WkKa7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBK14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JrWl82xGYIkIc2 x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Cr0_Gr1UM2 8EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2AI xVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20x vE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xv r2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7M4IIrI8v6xkF7I0E8cxan2IY04 v7MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_ Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x 0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8 JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIx AIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUbJ73DUUUUU= = 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 || dist =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) add a new local variable 'sequential_disk' to record the disk, and if there is no other idle disk, 'sequential_disk' will 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 Reviewed-by: Xiao Ni --- drivers/md/raid1.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 0fed01b06de9..fc5899fb08c1 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -598,13 +598,12 @@ static int read_balance(struct r1conf *conf, struct r= 1bio *r1_bio, int *max_sect const sector_t this_sector =3D r1_bio->sector; int sectors; int best_good_sectors; - int best_disk, best_dist_disk, best_pending_disk; + int best_disk, best_dist_disk, best_pending_disk, sequential_disk; int disk; sector_t best_dist; 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 @@ -615,11 +614,11 @@ static int read_balance(struct r1conf *conf, struct r= 1bio *r1_bio, int *max_sect sectors =3D r1_bio->sectors; best_disk =3D -1; best_dist_disk =3D -1; + sequential_disk =3D -1; best_dist =3D MaxSector; 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 +711,6 @@ 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 +729,22 @@ 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. + */ + pending++; + /* + * If there is no other idle disk, this disk + * will be chosen. + */ + sequential_disk =3D disk; + } 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; @@ -751,6 +756,13 @@ static int read_balance(struct r1conf *conf, struct r1= bio *r1_bio, int *max_sect } } =20 + /* + * sequential IO size exceeds optimal iosize, however, there is no other + * idle disk, so choose the sequential disk. + */ + if (best_disk =3D=3D -1 && min_pending !=3D 0) + best_disk =3D sequential_disk; + /* * If all disks are rotational, choose the closest disk. If any disk is * non-rotational, choose the disk with less pending request even the --=20 2.39.2