Can not resume "import disk" after reboot

I was importing from NTFS to zpool.. I shutdown and restarted the system when "import disk" was in progress. I thought the importing task will resume either automatically or manually. But no matter what I did, it just won't resume. The error message told me device busy but actually there is no any device busy. It seems that partition was marked as busy permenately somewhere and restarting the "import disk" task became impossible.

The error message is following:

Error: Traceback (most recent call last):
File "/usr/local/lib/python3.8/site-packages/middlewared/job.py", line 361, in run
await self.future
File "/usr/local/lib/python3.8/site-packages/middlewared/job.py", line 397, in __run_body
rv = await self.method(*([self] + args))
File "/usr/local/lib/python3.8/site-packages/middlewared/schema.py", line 973, in nf
return await f(*args, **kwargs)
File "/usr/local/lib/python3.8/site-packages/middlewared/plugins/pool_/import_disk.py", line 47, in import_disk
os.rmdir(src)
OSError: [Errno 16] Device busy: '/var/run/importcopy/tmpdir/dev/ada3s2'