[Gluster-devel] Progress on adding support for SEEK_DATA and SEEK_HOLE

[Niels de Vos]

On Tue, Jun 30, 2015 at 11:48:20PM +0530, Ravishankar N wrote:
> 
> 
> On 06/22/2015 03:22 PM, Ravishankar N wrote:
> >
> >
> >On 06/22/2015 01:41 PM, Miklos Szeredi wrote:
> >>On Sun, Jun 21, 2015 at 6:20 PM, Niels de Vos <ndevos at redhat.com> wrote:
> >>>Hi,
> >>>
> >>>it seems that there could be a reasonable benefit for virtual machine
> >>>images on a FUSE mountpoint when SEEK_DATA and SEEK_HOLE would be
> >>>available. At the moment, FUSE does not pass lseek() on to the
> >>>userspace
> >>>process that handles the I/O.
> >>>
> >>>Other filesystems that do not (need to) track the position in the
> >>>file-descriptor are starting to support SEEK_DATA/HOLE. One example is
> >>>NFS:
> >>>
> >>>https://tools.ietf.org/html/draft-ietf-nfsv4-minorversion2-38#section-15.11
> >>>
> >>>I would like to add this feature to Gluster, and am wondering if there
> >>>are any reasons why it should/could not be added to FUSE.
> >>I don't see any reason why it couldn't be added.  Please go ahead.
> >
> >Thanks for bouncing the mail to me Niels, I would be happy to work on
> >this. I'll submit a patch by Monday next.
> >
> 
> 
> Sent a patch @
> http://thread.gmane.org/gmane.comp.file-systems.fuse.devel/14752
> I've tested it with some skeleton code in gluster-fuse to handle lseek().

Ravi also sent his patch for glusterfs-fuse:

  http://review.gluster.org/11474

I have posted my COMPLETELY UNTESTED patches to their own Gerrit topic
so that we can easily track the progress:

  http://review.gluster.org/#/q/status:open+project:glusterfs+branch:master+topic:wip/SEEK_HOLE

My preference goes to share things early and make everyone able to
follow progress (know where to find the latest patches). Assistance in
testing, reviewing and improving is welcome! There are some outstanding
things like seek() for ec and sharding, and probably more.

This all was done as a suggestion from Christopher (kripper) Pereira,
for improving the handling of sparse files (like most VM images).

Thanks,
Niels