On Wed, Feb 13, 2013 at 05:20:52PM -0500, Theodore Ts'o wrote: > Telldir() and seekdir() are basically implementation horrors for any > file system that is using anything other than a simple array of > directory entries ala the V7 Unix file system or the BSD FFS. For any > file system which is using a more advanced data structure, like > b-trees hash trees, etc, there **can't** possibly be a "offset" into a > readdir stream. I'll just point you to this: http://marc.info/?l=linux-ext4&m=136081996316453&w=2 so you can see that XFS implements what you say can't possibly be done. ;) FWIW, that post only talked about the data segment. I didn't mention that XFS has 2 other segments in the directory file (both beyond EOF) for the directory data indexes. One contains the name-hash btree index used for name based lookups and the other contains a freespace index for tracking free space in the data segment. IOWs persistent, deterministic, low cost telldir/seekdir behaviour was a problem solved in the 1990s. :) Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
