[PATCHES] vfs_gpfs: Update fallocate callback

[Christof Schmitt]

On Mon, Apr 22, 2019 at 04:00:26PM -0700, Jeremy Allison wrote:
> On Mon, Apr 22, 2019 at 10:15:30AM -0700, Christof Schmitt via samba-technical wrote:
> > All supported versions of the file system now support the fallocate()
> > call, so the gpfs_prealloc API call is no longer necessary. There is
> > also limited support for the punch hole call; allow that with the
> > limitation that ZERO_DATA can only be used on sparse files.
> 
> LGTM, although I'm going to have to trust
> you on the gpfs limitations :-).

Thank you.

The main limitation is that FALLOC_FL_KEEP_SIZE is not available. As
fsctl_zero_data() first punches the hole and then uses KEEP_SIZE to fill
the whole again for non-sparse files, this would create non-sparse files
with holes and log errors about the failed fallocate KEEP_SIZE call. So
only allowing PUNCH_HOLE for sparse files seems to be the easiest way
out.

Christof