Re: Efficient handling of sparse files

[Zach Brown <zab@zabbo.net>]

> Please keep one thing in mind and that is that there are file systems 
> where ->bmap actually makes no sense whatsoever

Of course, so return -ESORRY.

> This is one of the reasons why noone should be using ->bmap.  It is a 
> stupid interface that only fits very particular sets of file systems and 
> cannot be applied generically.

No, it's a reason to only ask about the details of block mapping in
cases where it actually makes sense (like, wanting to find out of
concurrent file extension is getting good batched contiguous allocation,
etc).  Just because file systems x, y, and z can't answer the question
meaningfully doesn't mean it isn't a reasonble thing to ask of file
systems m, n, and o.

Now, I'm not at all opposed to an explicit sparse-testing interface that
doesn't confuse that functionality with querying specific block mappings.

- z