Re: dir_index filesystem feature? (was: Re: installation error

[Roland McGrath]

> He has a spurious dir_index filesystem optio, which seems to be new in
> e2fsprogs 1.30.  Anybody knows what that is, if we should implement this,
> or if we better write a bug report ASAP to disable this for -o hurd?

It is listed in the feature_compat flags word, which is supposed to
indicate that it's compatible with a filesystem that doesn't know about it.

As far as I can tell, the Linux ext2fs patches that use this flag have not
been integrated into Linux.  So many Linux users are living happily without
the functionality.  With a little searching I've found an old version of
the patch.  It stores a hash table in directories alongside the normal
linear records, so lookups can be done by a hash table lookup instead of
the normal linear search.  At least the reading of this format should be
quite easy to implement in the Hurd's ext2fs format.  The issues with
writing the new flavor of directory blocks robustly could be more complex,
which might have something to do with why this code has never made it into
the Linux kernel mainline.