MFC r327700:
Sort and remove unneeded includes.

MFC r309321:
Add `gmirror create` subcommand, alike to gstripe, gconcat, etc.

It is quite specific mode of operation without storing on-disk metadata.
It can be useful in some cases in combination with some external control
tools handling mirror creation and disks hot-plug.

Sponsored by: iXsystems, Inc.

MFC r306762: Fix possible geom destruction before final provider close.

Introduce internal counter to track opens. Using provider's counters is
not very successfull after calling g_wither_provider().

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

Add an ability to stop gmirror and clear its metadata in one command.
This fixes the problem, when gmirror starts again just after stop.

The problem occurs when gmirror's component has geom label with equal size.
E.g. gpt and gptid have the same size as partition, diskid has the same
size as entire disk. When gmirror's geom has been destroyed, glabel
creates its providers and this initiate retaste.

Now "gmirror destroy" command is available. It destroys geom and also
erases gmirror's metadata.

MFC after: 2 weeks

Prevent users from deactivating the last component of a mirror.

PR: 184985
MFC after: 1 week

Add "resize" verb to gmirror(8) and such functionality to geom_mirror(4).
Now it is easy to expand the size of the mirror when all its components
are replaced. Also add g_resize method to geom_mirror class. It will write
updated metadata to new last sector, when parent provider is resized.

Silence from: geom@
MFC after: 1 month

Prevent removing of the last active component from a mirror.

PR: kern/154860
Reviewed by: pjd
MFC after: 1 week

- Allow to specify value as const pointers.
- Make optional string values always an empty string.

Add support for changing providers priority.

Submitted by: Mel Flynn

Now, that we have gjournal in the tree add possibility to configure
gmirror and graid3 in a way that it is not resynchronized after a
power failure or system crash.
It is safe when gjournal is running on top of gmirror/graid3.

Always allow to specify components with /dev/ prefix.

MFC after: 3 days

Introduce and use delayed-destruction functionality from a pre-sync hook,
which means that devices will be destroyed on last close.

This fixes destruction order problems when, eg. RAID3 array is build on
top of RAID1 arrays.

Requested, reviewed and tested by: ru
MFC after: 2 weeks

Update copyright for 2006.

- Speed up synchronization process by using configurable number of I/O
requests in parallel.
+ Add kern.geom.mirror.sync_requests tunable which defines how many parallel
I/O requests should be used.
+ Retire kern.geom.mirror.reqs_per_sync and kern.geom.mirror.syncs_per_sec
sysctls.
- Fix race between regular and synchronization requests.
- Reimplement mirror's data synchronization - do not use the topology lock
for this purpose, as it may case deadlocks.
- Stop synchronization from pre-sync hook.
- Fix some other minor issues.

MFC after: 3 days

When inserting a new component md_provsize metadata field wasn't set, which
means that old problem was triggered (when two providers end at the same
offset, eg. ad0 and ad0s1 and the wrong was is picked up by gmirror/graid3).

Reported by: Michal Suszko <dry@dry.pl>
MFC after: 3 days

Remove trailing spaces.

Fix provider's size check for 'insert' command.
Before this fix one was able to insert one sector too small provider.

MFC after: 3 days

Check for return values.

Submitted by: sam
Found by: Coverity Prevent analysis tool

Update copyright in files changed this year.

Spoiling is now not possible, because we keep consumers open for writing
all the time. Remove unused code then.

MFC after: 4 days

Fix 'rebuild' command (we ignore retaste event now, so don't relay on it).

- Add genid field to the metadata which will allow to improve reliability a bit.
After this change, when component is disconnected because of an I/O error,
it will not be connected and synchronized automatically, it will be logged
as broken and skipped. Autosynchronization can occur, when component is
disconnected (on orphan event) and connected again - there were no I/O
error, so there is no need to not connected the component, but when there were
writes while it wasn't connected, it will be synchronized.
This fix cases, when component is disconnected because of I/O error and can be
connected again and again.
- Bump version number.
- Add version change history.
- Implement backward compatibility mechanism. After this change when metadata in
old version is detected, it is automatically upgraded to the new (current)
version.

Don't quit on first failure, just skip failures.

Forgot to commit those: introduce hardcoded provider functionality,
which allow to store provider's name in the metadata and avoid
problems when few providers share the same last sector.

Add '-p' option for 'insert' command which allows to specify priority
of the new component.
Version number wasn't bumped (it should be), because I think there are
no geom_mirror users yet.

- Check if 'slice' argument was given.
- Check if disk isn't already the mirror component.

Add GEOM_MIRROR class which provide RAID1 functionality and has many useful
features. The gmirror(8) utility should be used for control of this class.
There is no manual page yet, but I'm working on it with keramida@.

Many useful tests provided by: simon (thank you!)
Some ideas from: scottl, simon, phk