ext4: Question about directory entry minor hash usage (documentation error?)

[Zeno Endemann <zeno.endemann@mailbox.org>]

Hello,

The documentation of hash tree directories claims that interior nodes are
"indexed by a minor hash".

However from my current understanding of the code, it seems to me the node
splitting works somewhat like regular B-trees, and there is no re-sorting
with a minor hash going on. The minor hash doesn't influence at all the
on-disk data structure, and is only used for sorting in a kernel internal
rb-tree. Is this correct? If so, I could offer to write up a patch for the
documentation.

As a side question, I was wondering a bit why the kernel differentiates
between htree-indexed dirs and others when simply iterating over it (as in
e.g. ext4_readdir), and what the point of that rb-tree there is, i.e. why one
would want to iterate over the entries in hash tree order.


Thanks and cheers,
Zeno Endemann