Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

- Add support for 'memsync' mode. This is the fastest replication mode that's
why it will now be the default.
- Bump protocol version to 2 and add backward compatibility for version 1.
- Allow to specify hosts by kern.hostid as well (in addition to hostname and
kern.hostuuid) in configuration file.

Sponsored by: Panzura
Tested by: trociny

For functions that return -1 on failure check exactly for -1 and not for
any negative number.

MFC after: 3 days

Use PJDLOG_ASSERT() and PJDLOG_ABORT() everywhere instead of assert().

MFC after: 3 days

Add missing ifdef. This fixes build with NO_OPENSSL.

Reported by: Pawel Tyll <ptyll@nitronet.pl>
Approved by: pjd (mentor)
MFC after: 1 week

Remove hast_proto_recv(). It was used only in one place, where
hast_proto_recv_hdr() may be used. This also fixes the issue
(introduced by r220523) with hastctl, which crashed on assert in
hast_proto_recv_data().

Suggested and approved by: pjd (mentor)

In hast_proto_recv() remove unnecessary check. The size is checked
later in hast_proto_recv_data().

Approved by: pjd (mentor)
MFC after: 1 week

In hast_proto_recv_data() check that the size of the data to be
received does not exceed the buffer size.

Approved by: pjd (mentor)
MFC after: 1 week

Allow to compress on-the-wire data using two algorithms:
- HOLE - it simply turns all-zero blocks into few bytes header;
it is extremely fast, so it is turned on by default;
it is mostly intended to speed up initial synchronization
where we expect many zeros;
- LZF - very fast algorithm by Marc Alexander Lehmann, which shows
very decent compression ratio and has BSD license.

MFC after: 2 weeks

Allow to checksum on-the-wire data using either CRC32 or SHA256.

MFC after: 2 weeks

Constify arguments we can constify.

MFC after: 2 weeks
Obtained from: Wheel Systems Sp. z o.o. http://www.wheelsystems.com

Eliminate dead code.

Found by: Coverity Prevent
CID: 5158
MFC after: 3 days

Fix compilation with WITHOUT_CRYPT or WITHOUT_OPENSSL options.

Reported by: Andrei V. Lavreniyuk <andy.lavr@reactor-xg.kiev.ua>
MFC after: 3 days

Please welcome HAST - Highly Avalable Storage.

HAST allows to transparently store data on two physically separated machines
connected over the TCP/IP network. HAST works in Primary-Secondary
(Master-Backup, Master-Slave) configuration, which means that only one of the
cluster nodes can be active at any given time. Only Primary node is able to
handle I/O requests to HAST-managed devices. Currently HAST is limited to two
cluster nodes in total.

HAST operates on block level - it provides disk-like devices in /dev/hast/
directory for use by file systems and/or applications. Working on block level
makes it transparent for file systems and applications. There in no difference
between using HAST-provided device and raw disk, partition, etc. All of them
are just regular GEOM providers in FreeBSD.

For more information please consult hastd(8), hastctl(8) and hast.conf(5)
manual pages, as well as http://wiki.FreeBSD.org/HAST.

Sponsored by: FreeBSD Foundation
Sponsored by: OMCnet Internet Service GmbH
Sponsored by: TransIP BV