Re: [PATCH] fs: Add additional checks for block devices during mount

[Zizhi Wo <wozizhi@huawei.com>]

在 2025/7/19 12:17, Al Viro 写道:
> 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...
> 

Since this problem can only occur in the superblock reuse scenario, and
the .test function used in sget_fc() for bdev filesystems is
super_s_dev_test(), I considered adding an additional condition check
within that function.

I'm wondering if there's a better way to handle this...

Thanks,
Zizhi Wo