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	Sat, 19 Jul 2025 04:17:09 +0000
Date: Sat, 19 Jul 2025 05:17:09 +0100
From: Al Viro <viro@zeniv.linux.org.uk>
To: Zizhi Wo <wozizhi@huawei.com>
Cc: jack@suse.com, brauner@kernel.org, axboe@kernel.dk, hch@lst.de,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	yukuai3@huawei.com, yangerkun@huawei.com
Subject: Re: [PATCH] fs: Add additional checks for block devices during mount
Message-ID: <20250719041709.GI2580412@ZenIV>
References: <20250719024403.3452285-1-wozizhi@huawei.com>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Sat, Jul 19, 2025 at 10:44:03AM +0800, Zizhi Wo wrote:

> mkfs.ext4 -F /dev/sdb
> mount /dev/sdb /mnt
> mknod /dev/test b 8 16    # [sdb 8:16]
> echo 1 > /sys/block/sdb/device/delete
> mount /dev/test /mnt1    # -> mount success
> 
> Therefore, it is necessary to add an extra check. Solve this problem by
> checking disk_live() in super_s_dev_test().

That smells like a wrong approach...  You are counting upon the failure
of setup_bdev_super() after the thing is forced on the "no reuse" path,
and that's too convoluted and brittle...