Re: Problems with determining data presence by examining extents?

[David Howells]

Andreas Dilger <adilger@xxxxxxxxx> wrote:

> > It would also have to say that blocks of zeros shouldn't be optimised away.
> 
> I don't necessarily see that as a requirement, so long as the filesystem
> stores a "block" at that offset, but it could dedupe all zero-filled blocks
> to the same "zero block".  That still allows saving storage space, while
> keeping the semantics of "this block was written into the file" rather than
> "there is a hole at this offset".

Yeah, that's more what I was thinking of.  Provided I can find out that
something is present, it should be fine.

David