When replacing the bd_super check with a bd_openers I followed a logical
conclusion, which turns out to be utterly wrong.  When a block device has
bd_super sets it has a mount file system on it (although not every
mounted file system sets bd_super), but that also implies it doesn't even
have partitions to start with.
So instead of trying to come up with a logical check for all openers,
just remove the check entirely.
Fixes: d3ef5536274f ("block: fix busy device checking in blk_drop_partitions")
Fixes: cb6b771b05c3 ("block: fix busy device checking in blk_drop_partitions again")
Reported-by: Michal Koutný <mkoutny@suse.com>
Reported-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
 
        if (!disk_part_scan_enabled(disk))
                return 0;
-       if (bdev->bd_part_count || bdev->bd_openers > 1)
+       if (bdev->bd_part_count)
                return -EBUSY;
        res = invalidate_partition(disk, 0);
        if (res)