Re: [RFC 0/3] bpf: Add d_path helper

Al Viro
2020-04-06T03:16:14Z

On Fri, Apr 03, 2020 at 11:08:28AM +0200, Jiri Olsa wrote:

> if we limit it just to task context I think it would still be
> helpful for us:
>
> if (in_task())
> d_path..
>
> perhaps even create a d_path version without d_dname callback
> if that'd be still a problem, because it seems to be there mainly
> for special filesystems..?

IDGI...
1) d_path(), by definition, is dependent upon the
process' root - the same <mount,dentry> pair will yield
different strings if caller is chrooted. You *can't* just
use a random process' root
2) we are *NOT* making rename_lock and mount_lock
disable interrupts. Not happening.

So it has to be process-synchronous anyway. Could you describe
where that thing is going to be callable?