[RFC, PATCH 0/2] xfs: Fast zeroing of allocated space

[Alex Elder]

On Tue, 2010-07-27 at 15:55 +1000, Dave Chinner wrote:
> These two patches allow conversion of a written range of a file into
> back into unwritten state. The first patch converts page cache
> helper functions to use the correct range primitives as we need to
> be able to toss (invalidate) pages only within the range specified,
> not to to the end of the file as it currently uses.
> 
> The actual conversion also preallocates any holes in the range, so
> it turns the entire range requested into allocated, unwritten
> extents.
> 
> I also have a patch that adds this functionality to fallocate(). I
> haven't tested that at all, but if this is something we want to
> support, I'd suggest that we want fallocate to be able to do it...

Nice feature.  Kind of surprising to me how small the set
of changes it requires is.

I agree with Christoph's comments.  These two patches otherwise
look good to me as well.

Reviewed-by: Alex Elder <aelder at sgi.com>