Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

[CHECKER] Need help on mmap on FUSE (linux user-land file system)

10 views
Skip to first unread message

Junfeng Yang

unread,
Mar 13, 2005, 2:30:13 AM3/13/05
to

Does anyone know how to set up mmap on FUSE (linux user-land file system)?
Or is it even possible to have mmap on FUSE?

Our file system checker can potentially check a lot more things if we can
have mmap working on a FUSE file system. Your help on this are well
appreciated!

-Junfeng

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majo...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Junfeng Yang

unread,
Mar 13, 2005, 2:40:08 AM3/13/05
to

Forget to mention, we are checking linux 2.6. It appears to us that mmap
doesnt' work for FUSE in linux 2.6.

-Junfeng

On Sat, 12 Mar 2005, Junfeng Yang wrote:

>
> Does anyone know how to set up mmap on FUSE (linux user-land file system)?
> Or is it even possible to have mmap on FUSE?
>
> Our file system checker can potentially check a lot more things if we can
> have mmap working on a FUSE file system. Your help on this are well
> appreciated!
>
> -Junfeng
>
>

> _______________________________________________
> MC mailing list
> M...@keeda.stanford.edu
> http://keeda.stanford.edu/cgi-bin/mailman/listinfo/mc

Kyle Moffett

unread,
Mar 13, 2005, 9:00:12 AM3/13/05
to
On Mar 13, 2005, at 02:28, Junfeng Yang wrote:
> Forget to mention, we are checking linux 2.6. It appears to us that
> mmap
> doesnt' work for FUSE in linux 2.6.

IIRC, the reason mmap doesn't work on FUSE is because when it dirties
pages they
cannot be flushed reliably, because writing them out involves calling a
userspace
process which may allocate RAM, etc.

Cheers,
Kyle Moffett

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GCM/CS/IT/U d- s++: a18 C++++>$ UB/L/X/*++++(+)>$ P+++(++++)>$
L++++(+++) E W++(+) N+++(++) o? K? w--- O? M++ V? PS+() PE+(-) Y+
PGP+++ t+(+++) 5 X R? tv-(--) b++++(++) DI+ D+ G e->++++$ h!*()>++$ r
!y?(-)
------END GEEK CODE BLOCK------

Miklos Szeredi

unread,
Mar 14, 2005, 5:30:18 AM3/14/05
to
> > Forget to mention, we are checking linux 2.6. It appears to us
> > that mmap doesnt' work for FUSE in linux 2.6.
>
> IIRC, the reason mmap doesn't work on FUSE is because when it
> dirties pages they cannot be flushed reliably, because writing them
> out involves calling a userspace process which may allocate RAM,
> etc.

Yes. To be precise this only affects writable shared mmap(), which is
not used by the great majority of applications. Any other kind of
memory mapping should work OK.

Thanks,
Miklos

0 new messages