Re: git: 10037d0978f8 - main - fusefs: Implement support for the auto_unmount option kernel-side

On Sun, Jan 25, 2026 at 10:39 PM Konstantin Belousov
<kostikbel@gmail.com> wrote:
>
>
> > +             vfs_ref(fdata->mp);
> Don't you need to take the reference when the fdata is created and mp member
> is initialized, and not here?
>
> What guarantees that the mp is still ours?
> In fact, I think that you should use vfs_busy() and not vfs_ref(),
> since what prevents mp from being unmounted under us?

Using vfs_busy() before dounmount() results in a soft hang:
- vfs_busy increments mp->mnt_lockref in
https://github.com/freebsd/freebsd-src/blob/98bdf63f6e94be42a1787de73608de15bcb3419a/sys/kern/vfs_subr.c#L929
- dounmount spins until mp->mnt_lockref becomes 0 in
https://github.com/freebsd/freebsd-src/blob/98bdf63f6e94be42a1787de73608de15bcb3419a/sys/kern/vfs_mount.c#L2318-L2322

This results in a FUSE process to hang in the "mount drain" state.