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SubjectRe: [NFS] blocks of zeros (NULLs) in NFS files in kernels >= 2.6.20
Hi,

On Sep 22 10:45 AM, Aaron Straus wrote:
> > diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> > index 3229e21..eb6b211 100644
> > --- a/fs/nfs/write.c
> > +++ b/fs/nfs/write.c
> > @@ -1428,7 +1428,8 @@ static int nfs_write_mapping(struct address_space *mapping, int how)
> > .sync_mode = WB_SYNC_NONE,
> > .nr_to_write = LONG_MAX,
> > .for_writepages = 1,
> > - .range_cyclic = 1,
> > + .range_start = 0,
> > + .range_end = LLONG_MAX,
> > };
> > int ret;
> >
>
> Also, I should test this, but I thought the VM was calling
> nfs_writepages directly i.e. not going through nfs_write_mapping. Let
> me test with this patch.

Yes. This patch doesn't seem to help. The VM is calling nfs_writepages
directly. I have debug statements in the nfs_write_mapping() call and it
hasn't been called when the hole appears.

It's the VM dirty page writeout that is happening out of order, *not*
nfs_wb_* stuff. That's why we can see it so easily. The dirty pages
are only scanned periodically. In-between scans is when we see the
hole.

I think :). I'm obviously not an expert here.

Thanks,
=a=


--
===================
Aaron Straus
aaron@merfinllc.com


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