MFC r331701: MFV r331695, 331700: 9166 zfs storage pool checkpoint

illumos/illumos-gate@8671400134a11c848244896ca51a7db4d0f69da4

The idea of Storage Pool Checkpoint (aka zpool checkpoint) deals with
exactly that. It can be thought of as a “pool-wide snapshot” (or a
variation of extreme rewind that doesn’t corrupt your data). It remembers
the entire state of the pool at the point that it was taken and the user
can revert back to it later or discard it. Its generic use case is an
administrator that is about to perform a set of destructive actions to ZFS
as part of a critical procedure. She takes a checkpoint of the pool before
performing the actions, then rewinds back to it if one of them fails or puts
the pool into an unexpected state. Otherwise, she discards it. With the
assumption that no one else is making modifications to ZFS, she basically
wraps all these actions into a “high-level transaction”.

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
Author: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>

MFC r324350: zdb.8: replace with the slighly modified upstream version

MFC r324221:

MFV r316861: 6866 zdb -l should return non-zero if it fails to find any label

illumos/illumos-gate@64723e361134b2a2c45341334174f9d34002f8d0
https://github.com/illumos/illumos-gate/commit/64723e361134b2a2c45341334174f9d34002f8d0

https://www.illumos.org/issues/6866
Need this for #6865.
To be generally more scripting-friendly, overload this issue with adding '-q'
option which should skip printing any label information.

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Yuri Pankov <yuri.pankov@nexenta.com>

MFC r324220:

MFV r316858 7280 Allow changing global libzpool variables in zdb

7280 Allow changing global libzpool variables in zdb and ztest through command line

illumos/illumos-gate@0e60744c982adecd0a1f146f5637475d07ab1069
https://github.com/illumos/illumos-gate/commit/0e60744c982adecd0a1f146f5637475d07ab1069

https://www.illumos.org/issues/7280
zdb is very handy for diagnosing problems with a pool in a safe and
quick way. When a pool is in a bad shape, we often want to disable some
fail-safes, or adjust some tunables in order to open them. In the
kernel, this is done by changing public variables in mdb. The goal of
this feature is to add the same capability to zdb and ztest, so that
they can change libzpool tuneables from the command line.

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Pavel Zakharov <pavel.zakharov@delphix.com>

MFC r303086: 7164 zdb should be able to open the root dataset