Re: stat64 for over 2TB file returned invalid st_blocks

["Takashi Sato" <sho@bsd.tnes.nec.co.jp>]

Hi,

> On Dec 03, 2005  22:00 +0900, Takashi Sato wrote:
> > Andreas Dilger wrote:
> > >Actually, it should probably be "sector_t", because it isn't really
> > >possible to have a file with more blocks than the size of the block
> > >device.  This avoids memory overhead for small systems that have no
> > >need for it in a very highly-used struct.  It may be for some network
> > >filesystems that support gigantic non-sparse files they would need to
> > >enable CONFIG_LBD in order to get support for this.
> >
> > I think sector_t is ok for local filesystem as you said.  However,
> > on NFS, there may be over 2TB file on server side, and inode.i_blocks
> > for over 2TB file will become invalid on client side in case CONFIG_LBD
> > is disabled.
>
> I don't know the exact specs of NFS v2 and v3, but I doubt they can have
> single files larger than 2TB.  Even if they could then this is not a

I believe NFS v3 can handle over 2TB file. :-)

> very common situation and if someone is running in such an environment
> then they can easily enable CONFIG_LBD (or make e.g. CONFIG_NFS_V4 have
> a dependency to enable this if it is important enough).  What I'd rather
> avoid is needless growth of heavily-used structures for rather uncommon
> cases (at the current time at least, this can be re-examined later).

I agree above.

> It might also be possible to have a separate CONFIG_LSF (or whatever)
> that enables support for large single files, maybe enabled by default
> with CONFIG_LBD and also configurable separately for clients of network
> filesystems with large single files.  Someone who cares more about the
> proliferation of configuration options than I can decide whether it
> makes sense to keep these as separate options.

I don't think CONFIG_LBD should determine whether large single
files is enabled.  So, I agree your suggestion basically.
It would be nice if there was a suitable configuration option for it.
I will examine the implementation in detail.

-- Takashi Sato
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