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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 [172.19.163.216]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Tlmxv3x36z4f3k5n; Thu, 29 Feb 2024 18:03:15 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id E80871A132B; Thu, 29 Feb 2024 18:03:18 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP1 (Coremail) with SMTP id cCh0CgAX5g5hVuBlFsMHFg--.11578S8; Thu, 29 Feb 2024 18:03:18 +0800 (CST) From: Yu Kuai To: xni@redhat.com, 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 v4 04/11] md/raid1: fix choose next idle in read_balance() Date: Thu, 29 Feb 2024 17:57:07 +0800 Message-Id: <20240229095714.926789-5-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240229095714.926789-1-yukuai1@huaweicloud.com> References: <20240229095714.926789-1-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: cCh0CgAX5g5hVuBlFsMHFg--.11578S8 X-Coremail-Antispam: 1UD129KBjvJXoWxXryrKr1kKr4fAFyUJry3twb_yoWrXw1xpw 4jvwsaqrWUXF43u3sxJw4UurySg345JayrGrZ7C34Fgry3XrWqqa47K342vry8CFs3J347 Xw18GrZru3WkKa7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPF14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E 14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIx kGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAF wI0_Cr0_Gr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJV W8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUOBTY UUUUU 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 de6ea87d4d24..fa86d9fdb16f 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