MFC r326276:

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

MFC r328108:

gnop(8): add the ability to set a nop provider's physical path

While I'm here, expand the existing tests a bit.

Differential Revision: https://reviews.freebsd.org/D13579

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 a way to specify stripesize and stripeoffset to gnop(8). This makes
it possible to "simulate" 4K media, to eg test alignment handling.

Reviewed by: mav@
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D3664

- Remove gc_argname field. It was introduced for gpart(8), but if I
understand everything correctly, we don't really need it.
- Provide default numeric value as strings. This allows to simplify
a lot of code.
- Bump version number.

Add gpart(8).

In order to support gpart(8), geom(8) needs to support a named
argument. Also, optional string parameters are a requirement.
Both have been added to the infrastructure. The former required
all existing classes to be adjusted.

MFp4: G_TYPE_BOOL sounds much better than G_TYPE_NONE.

Changes: 98722

- Split failure probability configuration into read failure probability and
write failure probability.
- Allow to specify an error number to return of failure.

MFC after: 3 days

Remove trailing spaces.

Teach NOP GEOM class how to gather the following statistics:
- number of read I/O requests,
- number of write I/O requests,
- number of read bytes,
- number of written bytes.
Add 'reset' subcommand for resetting statistics.

Define subcommands' usage inside g_command structure.

MFC after: 1 week

Fix arguments syntax.

Manual pages fixes by: ru
MFC after: 3 days

- Add '-S' option, which allow to specify sector size for transparent
provider.
- Bump version number.

This allows for a quite interesting trick. One can setup a stripe with
stripe size of 512 bytes and create transparent provider on top of it
with sector size equal to <ndisks> * 512. The result will be something
like RAID3 without parity disk (every access will touch all disks).

MFp4: Add two options for gnop(8)'s 'create' command:
-o offset - specifies where to start on the original provider
-s size - specifies size of the transparent provider

- Change command name from 'config' to 'configure'.
- Bump version number.

Introduce geom(8)-specific shared libraries for CONCAT, STRIPE and NOP
GEOM classes. CONCAT should be 100% compatible with existing gconcat(8)
utility, which is going to be removed.

Supported by: Wheel - Open Technologies - http://www.wheel.pl