Re: [Dazuko-devel] dazukofs and /dev/dazukofs.ign

[John Ogness]

On 2009-02-19, Frantisek Hrbata <address@hidden> wrote:
> it there any particular reason to store task_struct pointer for
> processes which should be ignored? This requires for multi-threaded
> application to register each thread to dazukofs.

Correct.

> I cannot figure out what is this good for. Isn't tgid enough?

You have to define "enough". The ignore feature can be implemented
however we want. Like the old trusted feature, it is there for
applications to allow themselves to be ignored (as well as have some
control over _how_ they are ignored).

It is possible that a multi-threaded application only wants one of its
threads to be ignored because the other threads are doing tasks (such
as downloading files) that should _not_ be ignored.

> AFAIK old dazuko supports whole process(including its threads) to be
> trusted and all you need to do is to call dazukoRegisterTrusted just
> once for each process.  Or am I missing something?

Actually that is only partially correct. Dazuko 2.x also uses the task
struct (individual threads) to implement the trusted feature. However,
dazukoRegisterTrusted() also had a flag DAZUKO_TRUST_CHILDREN that
would allow all the threads of the process and all children-processes
to be trusted.

The DazukoFS ignore feature does not have such an option because I
could not find a safe method for traversing process trees. But we
could expand the feature to allow configuring it to trust all threads
of a process. This is technically not necessary. It would only be
there as a convenience for developers.

John Ogness

-- 
Dazuko Maintainer