Re: [PATCH] fs: make i_generation a u64

[Josef Bacik <josef@redhat.com>]

On Thu, Apr 12, 2012 at 08:46:14AM +0200, Marco Stornelli wrote:
> 2012/4/11 Josef Bacik <josef@redhat.com>:
> > Btrfs stores generation numbers as 64bit numbers, which means we ha=
ve to
> > carry around a u64 in our incore inode in addition to setting i_gen=
eration.
> > So convert to a u64 so btrfs can kill it's incore generation. =A0Th=
anks,
> >
> > Signed-off-by: Josef Bacik <josef@redhat.com>
> > ---
> > =A0include/linux/fs.h | =A0 =A02 +-
> > =A01 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index 9be896d..40564e0 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -831,7 +831,7 @@ struct inode {
> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0struct cdev =A0 =A0 =A0 =A0 =A0 =A0 =
*i_cdev;
> > =A0 =A0 =A0 =A0};
> >
> > - =A0 =A0 =A0 __u32 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 i_generatio=
n;
> > + =A0 =A0 =A0 u64 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 i_generat=
ion;
> >
> > =A0#ifdef CONFIG_FSNOTIFY
> > =A0 =A0 =A0 =A0__u32 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 i_fsnotify=
_mask; /* all events this inode cares about */
> > --
> > 1.7.7.6
>=20
> This patch can have several impact on other fs. Only to do an example
> you can see the code in ioctl of ext4. I haven't got study the code
> but the ioctl returns a long, but on 32bit system, long means 4 bytes=
,
> so how we can return i_generation with ioctl?

So looking through everybody I'd have to convert a bunch of cpu_to_le32=
 to
(u32)cpu_to_le64 and some other such crap which I'm not terribly intere=
sted in
doing, I don't care _that_ much about saving 8 bytes, so I'll just drop=
 this for
now.  Thanks,

Josef
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