From nobody Tue Feb 10 20:07:23 2026 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 933FC3783DA; Tue, 3 Feb 2026 06:22:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770099768; cv=none; b=L7k5Sl5Aw3mqKo6mxcV7T+ikf+LHRiRYsYh7xZreFtQgN/u+OQWUJU6HCvRZICQhQOS1fvTVroLxdXPxeFxIcXWwjmRhlSggYwZ8edjO77ENJP8ebSjVAsH+ncoAeWuqid3lcjUm9U83/KtoGObRXwPurX+u4jsKO3QXEgk7oDw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770099768; c=relaxed/simple; bh=+srh8IiFzbZjZLF0lmTKeUvcZo51QNWddbClixoALwA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=CpopkaEIZc5qSL0uXZQUw6oy4uWsiRpHfqtQEPJTl6GDI/DfQ7LSzpPJ2DR1hBs7rYWOyV5Jrpq1RNjLLVKcHRI7un6WYqHgtmwwVkLWBmI+EPzYLBhMpI1ca0OBxeVuQYWskyAGYne5+VXNyqg05/iRTyT+N2AtqvZBprYyIpc= 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=45.249.212.51 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 [172.19.163.177]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4f4tg76SS1zYQtxN; Tue, 3 Feb 2026 14:21:55 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id D16F540593; Tue, 3 Feb 2026 14:22:42 +0800 (CST) Received: from huaweicloud.com (unknown [10.50.87.129]) by APP4 (Coremail) with SMTP id gCh0CgBHp_cilIFpIQhbGA--.27054S8; Tue, 03 Feb 2026 14:22:42 +0800 (CST) From: Zheng Qixing To: song@kernel.org, yukuai@fnnas.com, linan122@huawei.com Cc: xni@redhat.com, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, houtao1@huawei.com, zhengqixing@huawei.com Subject: [RFC v2 4/5] md: introduce MAX_RAID_DISKS macro to replace magic number Date: Tue, 3 Feb 2026 14:12:58 +0800 Message-Id: <20260203061259.609206-5-zhengqixing@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20260203061259.609206-1-zhengqixing@huaweicloud.com> References: <20260203061259.609206-1-zhengqixing@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: gCh0CgBHp_cilIFpIQhbGA--.27054S8 X-Coremail-Antispam: 1UD129KBjvJXoW7CFW5XFWrWF45Jw45WF47CFg_yoW8Zr13pa 9ruFy5Zw1rXr1UKwn7XrykCFy5Zw17GrWUKrWY939avas0yr1UArWDJa98Jr95WFn5AFnr Zrs8WrW5Was2qw7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPqb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW7JVWDJwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E 14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7 xfMcIj6xIIjxv20xvE14v26r126r1DMcIj6I8E87Iv67AKxVW8Jr0_Cr1UMcvjeVCFs4IE 7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262 kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s02 6c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw 0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvE c7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14 v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x 07UX189UUUUU= X-CM-SenderInfo: x2kh0wptl0x03j6k3tpzhluzxrxghudrp/ Content-Type: text/plain; charset="utf-8" From: Zheng Qixing Per-device state is stored as a __le16 dev_roles[] array (2 bytes per device) plus a fixed 256-byte header, still within a 4 KiB superblock. Therefore the theoretical maximum is (4096 - 256) / 2 =3D 1920 entries. Define MAX_RAID_DISKS macro for the maximum number of RAID disks. No functional change. Signed-off-by: Zheng Qixing --- drivers/md/md.c | 4 ++-- drivers/md/md.h | 5 +++++ 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index f319621c6832..aebbdbaa4e0a 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -1873,7 +1873,7 @@ static int super_1_load(struct md_rdev *rdev, struct = md_rdev *refdev, int minor_ =20 if (sb->magic !=3D cpu_to_le32(MD_SB_MAGIC) || sb->major_version !=3D cpu_to_le32(1) || - le32_to_cpu(sb->max_dev) > (4096-256)/2 || + le32_to_cpu(sb->max_dev) > MAX_RAID_DISKS || le64_to_cpu(sb->super_offset) !=3D rdev->sb_start || (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) !=3D 0) return -EINVAL; @@ -2050,7 +2050,7 @@ static int super_1_validate(struct mddev *mddev, stru= ct md_rdev *freshest, struc mddev->resync_offset =3D le64_to_cpu(sb->resync_offset); memcpy(mddev->uuid, sb->set_uuid, 16); =20 - mddev->max_disks =3D (4096-256)/2; + mddev->max_disks =3D MAX_RAID_DISKS; =20 if (!mddev->logical_block_size) mddev->logical_block_size =3D le32_to_cpu(sb->logical_block_size); diff --git a/drivers/md/md.h b/drivers/md/md.h index a083f37374d0..14f9db38b7c5 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -21,6 +21,11 @@ #include #include =20 +/* + * v1.x superblock occupies one 4 KiB block: 256B header + 2B per device + * in dev_roles[]. + */ +#define MAX_RAID_DISKS ((4096-256)/2) #define MaxSector (~(sector_t)0) =20 enum md_submodule_type { --=20 2.39.2