MFC r310705, r310706:
style(9) cleanups.

Just to reduce some of the issues found with indent(1).

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

ext2fs: Bring back the htree dir_index implementation.

The htree dir_index is perhaps one of the most characteristic
features of the linux ext3 implementation. It was removed
in r281670, due to repeated bug reports.

Damjan Jovanic detected and fixed three bugs and did some
stress testing by building Apache OpenOffice on top of it
so it is now in good shape to bring back.

Differential Revision: https://reviews.freebsd.org/D5007

Submitted by: Damjan Jovanovic
Reviewed by: pfg
Tested by: pho
Relnotes: Yes
MFC after: 2 months (only 10.x)

ext2: cosmetical issues

Minor sorting and note when the cases are expected to fall through.

MFC after: 1 week

ext2fs: make the hashing algorithm match the linux code.

There appears to be a hash function compatibility issue.
The code is currently disabled but fix it nevertheless.

PR: kern/183230
MFC after: 3 days

Small typo.

MFC after: 3 days

Add license for the half MD4 algorithm used in ext2_half_md4().

The htree implementation uses code derived from the
RSA Data Security, Inc. MD4 Message-Digest Algorithm.

Add a proper licensing statement for the code and clarify
the corresponding comments.

Approved by: core (hrs)

Initial implementation of the HTree directory index.

This is a port of NetBSD's GSoC 2012 Ext3 HTree directory indexing
by Vyacheslav Matyushin. It was cleaned up and enhanced for FreeBSD
by Zheng Liu (lz@).

This is an excellent example of work shared among different projects:
Vyacheslav was able to look at an early prototype from Zheng Liu who
was also able to check the code from Haiku (with permission).

As in linux, the feature is not available by default and must be
enabled explicitly with tune2fs. We still do not support the
workarounds required in readdir for NFS.

Submitted by: Zheng Liu
Tested by: Mike Ma
Sponsored by: Google Inc.
MFC after: 1 week