On Fri, Dec 13, 2013 at 10:24:43AM +1100, Dave Chinner wrote: > I'd prefer to just see the new physical length field always filled > out, regardless of whether it is a compressed extent or not. In > terms of backwards compatibility to userspace, it makes no > difference because the value of reserved/unused fields is undefined > by the API. Yes, the implementation zeros them, but there's nothing > in the documentation that says "reserved fields must be zero". > Hence I think we should just set it for every extent. > > >From the point of view of the kernel API (fiemap_fill_next_extent), > passing the physical extent size in the "len" parameter for normal > extents, then passing 0 for the "physical length" makes absolutely > no sense. I tend to agree, but the additional complication here is that this is a change to an existing API. We'd need another HAVE_PHYS_LEN flag for non-compressed extents so that userspace can rely on it. Given that it's only useful for that case I think the userspace API introduced is the best we can get. I think however that we should always pass the phys_len argument in the kernel API just to make it less confusing. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
