Re: Problems with determining data presence by examining extents?

[David Howells]

Andreas Dilger <adilger@xxxxxxxxx> wrote:

> I think what is needed here is an fadvise/ioctl that tells the filesystem
> "don't allocate blocks unless actually written" for that file.

Yeah - and it would probably need to find its way onto disk so that its effect
is persistent and visible to out-of-kernel tools.

It would also have to say that blocks of zeros shouldn't be optimised away.

David