Affects Version/s: Lustre 2.9.0, Lustre 2.10.0, Lustre 2.11.0
Fix Version/s: Upstream
This is prone to many errors, in particular: did not get reference count, so this mount struct might disappear, it does not take bind mounts into account not mount --move.
Might result in kernel panics in certain conditions.
Overall original patch is trying to "fix" something that's not broken in the kernel
If somebody does stat mountpoint in a tight loop, you will get -EBUSY there.
No matter what. What's more, you might very well get it after some check in
->umount_begin() has told you that at the moment the thing you were trying to
umount was not busy - just before the next stat hits.
The patch needs to be reworked and we just need to add some extra retrying logic in the test framework instead I guess.