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

Revert r299454 and r299448.

Those changes were found confusing FreeBSD libc ACL code, that doesn't
differentiate ACL for directories and files, and report ACLs for all
directories created after those patches as non-trivial. On the other
side these changes were considered wrong from POSIX and NFSv4 points of
view. Until further investigation done upstream, revert those changes
locally in preparation for FreeBSD 11.0 release.

Approved by: re (hrs)

MFV r299442: 6762 POSIX write should imply DELETE_CHILD on directories - and
some additional considerations

Reviewed by: Gordon Ross <gwr@nexenta.com>
Reviewed by: Yuri Pankov <yuri.pankov@nexenta.com>
Author: Kevin Crowe <kevin.crowe@nexenta.com>

openzfs/openzfs@d316fffc9c361532a482208561bbb614dac7f916

Resurrect the ZFS "aclmode" property
Change default of "aclmode" to "discard".

Illumos-gate changeset: 13370:8c04143bd318

Obtained from: Illumos (Feature #742)
MFC after: 2 weeks

Finally... Import the latest open-source ZFS version - (SPA) 28.

Few new things available from now on:

- Data deduplication.
- Triple parity RAIDZ (RAIDZ3).
- zfs diff.
- zpool split.
- Snapshot holds.
- zpool import -F. Allows to rewind corrupted pool to earlier
transaction group.
- Possibility to import pool in read-only mode.

MFC after: 1 month

MFp4 changes neccessary for NFSv4 ACLs support in ZFS. This is mostly
about removing a few #ifdefs and providing compatibility wrappers and
VOP implementations to get and set an ACL; ZFS does ACL enforcement all
by itself.

Note that the VOPs are ifdefed out for now, so this change should be
a no-op.

Reviewed by: pjd

- rename atomic.S and crc32.c to avoid collisions when linking zfs in to the kernel
- update Makefile
- ifdef out acl_{alloc, free}, they aren't used by zfs and conflict with existing in-kernel routines

Update ZFS from version 6 to 13 and bring some FreeBSD-specific changes.

This bring huge amount of changes, I'll enumerate only user-visible changes:

- Delegated Administration

Allows regular users to perform ZFS operations, like file system
creation, snapshot creation, etc.

- L2ARC

Level 2 cache for ZFS - allows to use additional disks for cache.
Huge performance improvements mostly for random read of mostly
static content.

- slog

Allow to use additional disks for ZFS Intent Log to speed up
operations like fsync(2).

- vfs.zfs.super_owner

Allows regular users to perform privileged operations on files stored
on ZFS file systems owned by him. Very careful with this one.

- chflags(2)

Not all the flags are supported. This still needs work.

- ZFSBoot

Support to boot off of ZFS pool. Not finished, AFAIK.

Submitted by: dfr

- Snapshot properties

- New failure modes

Before if write requested failed, system paniced. Now one
can select from one of three failure modes:
- panic - panic on write error
- wait - wait for disk to reappear
- continue - serve read requests if possible, block write requests

- Refquota, refreservation properties

Just quota and reservation properties, but don't count space consumed
by children file systems, clones and snapshots.

- Sparse volumes

ZVOLs that don't reserve space in the pool.

- External attributes

Compatible with extattr(2).

- NFSv4-ACLs

Not sure about the status, might not be complete yet.

Submitted by: trasz

- Creation-time properties

- Regression tests for zpool(8) command.

Obtained from: OpenSolaris

Please welcome ZFS - The last word in file systems.

ZFS file system was ported from OpenSolaris operating system. The code in under
CDDL license.

I'd like to thank all SUN developers that created this great piece of software.

Supported by: Wheel LTD (http://www.wheel.pl/)
Supported by: The FreeBSD Foundation (http://www.freebsdfoundation.org/)
Supported by: Sentex (http://www.sentex.net/)