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

Include sys/sbuf.h directly.

Reviewed by: pjd

- Improve error message consistency and wording.

- Fix a case where a RAID5 volume would think that it is supposed to grow a new
subdisk after a parity rebuild.

Import the gvinum work that have been done during and after Summer of Code 2007.
The work have been under testing and fixing since then, and it is mature enough
to be put into HEAD for further testing.

A lot have changed in this time, and here are the most important:
- Gvinum now uses one single workerthread instead of one thread for each
volume and each plex. The reason for this is that the previous scheme was
very complex, and was the cause of many of the bugs discovered in gvinum.
Instead, gvinum now uses one worker thread with an event queue, quite
similar to what used in gmirror.
- The rebuild/grow/initialize/parity check routines no longer runs in
separate threads, but are run as regular I/O requests with special flags.
This made it easier to support mounted growing and parity rebuild.
- Support for growing striped and raid5-plexes, meaning that one can extend the
volumes for these plex types in addition to the concat type. Also works while
the volume is mounted.
- Implementation of many of the missing commands from the old vinum:
attach/detach, start (was partially implemented), stop (was partially
implemented), concat, mirror, stripe, raid5 (shortcuts for creating volumes
with one plex of these organizations).
- The parity check and rebuild no longer goes between userland/kernel, meaning
that the gvinum command will not stay and wait forever for the rebuild to
finish. You can instead watch the status with the list command.
- Many problems with gvinum have been reported since 5.x, and some has been hard
to fix due to the complicated architecture. Hopefully, it should be more
stable and better handle edge cases that previously made gvinum crash.
- Failed drives no longer disappears entirely, but now leave behind a dummy
drive that makes sure the original state is not forgotten in case the system
is rebooted between drive failures/swaps.
- Update manpage to reflect new commands and extend it with some examples.

Sponsored by: Google Summer of Code 2007
Mentored by: le
Tested by: Rick C. Petty <rick-freebsd2008 -at- kiwi-computer.com>

- Import macros used in gmirror for printing gvinum debug messages and making
the output more standardized.
- Add a sysctl to set the verbosity of the debug messages.
- While there, fixup typos and wording in the messages.

- Fix a logic error when updating plex configuration.

Approved by: pjd (mentor)

-) Correct sdcount for a plex when removing or adding subdisks.
-) Set correct sizes for plexes and volumes a subdisk has been removed.

Submitted by: Ulf Lilleengen <lulf_AT_freebsd.org>

Protect from creating striped and RAID5 plexes with unequally sized
subdisks.

Get rid of the gv_bioq hack in most parts of the I/O path and
use the standard bioq structures.

Reset object flags after killing off an object's worker thread.

Share gv_roughlength() between kernel and userland, as we will need it
there later.

Correctly skip the '/dev/' part when creating new drives and prefix
a drive's provider with '/dev/' when printing the config.

Reported by: will@

Re-vamp how I/O is handled in volumes and plexes.

Analogous to the drive level, give each volume and plex a worker thread
that picks up and processes incoming and completed BIOs.

This should fix the data corruption issues that have come up a few
weeks ago and improve performance, especially of RAID5 plexes.

The volume level needs a little work, though.

Give the DRIVE geom a worker thread that picks up incoming bios,
sends them down, and takes care of the finished bios. This makes it
easier to handle I/O errors at drive level.

Rename gv_kill_thread() to gv_kill_plex_thread(), since there are more
threads to come.

Add forgotten format specifier in a KASSERT and shut up the compiler.

Submitted by: Gavin Atkinson <gavin.atkinson@ury.york.ac.uk>

If we kill the worklist thread of a RAID5 plex we can destroy
the worklist mutex at the same time, so move the mtx_destroy() call
to gv_kill_thread().

Propagate size changes upwards.

Mark a plex as 'newborn' when it is created. This is used to indicate
that new RAID5 plexes need to be initialized first.

Handle dead disks in a somewhat sane way.

Fix several bugs related to subdisk drive_offset calculation.

Add a first version of a GEOMified vinum.