Re: btrfs filesystem df not working

[Chris Mason <chris.mason@oracle.com>]

On Thu, Oct 14, 2010 at 12:45:59PM +0100, Leonidas Spyropoulos wrote:
> On Wed, Oct 13, 2010 at 4:08 PM, Chris Mason <chris.mason@oracle.com>=
 wrote:
> > On Wed, Oct 13, 2010 at 10:52:57AM +0100, Leonidas Spyropoulos wrot=
e:
> >> On Wed, Oct 13, 2010 at 1:43 AM, Chris Mason <chris.mason@oracle.c=
om> wrote:
> >> > On Tue, Oct 12, 2010 at 02:45:19PM +0100, Leonidas Spyropoulos w=
rote:
> >> >> On Tue, Oct 12, 2010 at 2:43 PM, cwillu <cwillu@cwillu.com> wro=
te:
> >> >> > On Tue, Oct 12, 2010 at 4:12 AM, Leonidas Spyropoulos
> >> >> > <artafinde@gmail.com> wrote:
> >> >> >> The above command is not working on my system.
> >> >> >> Information:
> >> >> >> btrfs f df /media/data
> >> >> >
> >> >> > btrfs f isn't unique; =A0fi is the minimum to specify "filesy=
stem"
> >> >> >
> >> >> I tried even with btrfs filesystem df /media/data
> >> >> and same results.
> >> >
> >> > Does strace give us any clues?
> >> >
> >> According to strace there is inappropriate ioctl for the device.
> >> Here is the log
> >
> > I missed this before:
> >
> > 2.6.32-5-amd64
> >
> > The df ioctl was added after 2.6.32 (2.6.33 I think).
>=20
> So in debian squeeze/unstable which is currently on 2.6.32 (and won't
> change any sooner) I cannot use btrfs. All I can do is try
> experimental kernels?

Or backport the changes, yes.

> My question though is, if I use experimental kernels can I then load
> an "old" kernel and still use the btrfs filesystem?
> Or the newer kernels write anything specials on ionodes which the old
> ones cannot read?

We haven't made any of those changes, you'll be fine going back and
forth.

-chris
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