Ocfs2 devel - Feb 2023 - report BUG: io_uring triggers umount error

Hello List,

I found a weird bug on ocfs2. I am busying with other jobs, if anyone have time
he/she could fix it. This bug is blocking fstest generic/013 test case, and also
blocking fstest to do later test cases.

How to trigger:
```
git clone git://git.kernel.dk/liburing.git
cd liburing
make
cd examples
mount -t ocfs2 /dev/sda /mnt
cp /etc/hosts /mnt/a
./link-cp /mnt/a /mnt/b
umount /mnt
```

umount trigger error message:
```
# umount /mnt 
umount: /mnt: target is busy.
```

The umount error can only be triggered by liburing write operation.

Thanks,
Heming

I can reproduce this in my local VM.
I've traced ocfs2_dismount_volume and found that it hasn't been called.
So EBUSY is returned in VFS layer. I guess something wrong when doing
a copy with linked SQEs (normal copy seems no problem).

Thanks,
Joseph

On 2/24/23 8:32 AM, Heming Zhao wrote:
> Hello List,
> 
> I found a weird bug on ocfs2. I am busying with other jobs, if anyone have
time
> he/she could fix it. This bug is blocking fstest generic/013 test case, and
also
> blocking fstest to do later test cases.
> 
> How to trigger:
> ```
> git clone git://git.kernel.dk/liburing.git
> cd liburing
> make
> cd examples
> mount -t ocfs2 /dev/sda /mnt
> cp /etc/hosts /mnt/a
> ./link-cp /mnt/a /mnt/b
> umount /mnt
> ```
> 
> umount trigger error message:
> ```
> # umount /mnt 
> umount: /mnt: target is busy.
> ```
> 
> The umount error can only be triggered by liburing write operation.
> 
> Thanks,
> Heming