Re: [PATCH v4 1/5] fuse: Fix leak in fuse_dentry_automount() error path

[Miklos Szeredi]

On Thu, 20 May 2021 at 21:45, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> On Thu, May 20, 2021 at 05:46:50PM +0200, Greg Kurz wrote:
> > Some rollback was forgotten during the addition of crossmounts.
>
> Have you actually tested that?  Because I strongly suspect that
> by that point the ownership of fc and fm is with sb and those
> should be taken care of by deactivate_locked_super().

Not quite.  Patch looks correct because destruction of fm is done in
fuse_put_super(), which only gets called if the sb initialization gets
as far as setting up sb->s_root, which only happens after the
successful fuse_fill_super_submount() call in this case.

Doing the destruction from the various ->kill_sb() instances instead
of from ->put_super() would also fix this, but I'm not quite sure that
that would be any cleaner.

Thanks,
Miklos