Re: [patch 0/6][RFC] Cleanup FIBMAP

[Mike Waychison <mikew@google.com>]

Zach Brown wrote:
>>> And another of my pet peeves with ->bmap is that it uses 0 to mean  
>>> "sparse" which causes a conflict on NTFS at least as block zero is  
>>> part of the $Boot system file so it is a real, valid block...  NTFS  
>>> uses -1 to denote sparse blocks internally.
>> Reiserfs and Btrfs also use 0 to mean packed.  It would be nice if there
>> was a way to indicate your-data-is-here-but-isn't-alone.  But that's
>> more of a feature for the FIEMAP stuff.
> 
> And maybe we can step back and see what the callers of FIBMAP are doing
> with the results they're getting.
> 
> One use is to discover the order in which to read file data that will
> result in efficient IO.
> 
> If we had an interface specifically for this use case then perhaps a
> sparse block would be better reported as the position of the inode
> relative to other data blocks.  Maybe the inode block number in ext* land.
> 

Can you clarify what you mean above with an example?  I don't really follow.

Thanks,

Mike Waychison