MFC r305205: MFV r302657:
4521 zfstest is trying to execute evil "zfs unmount -a"

illumos/illumos-gate@8808ac5dae118369991f158b6ab736cb2691ecde
https://github.com/illumos/illumos-gate/commit/8808ac5dae118369991f158b6ab736cb2
691ecde

https://www.illumos.org/issues/4521
zfstest is trying to execute evil "zfs unmount -a", which fails (fortunately,
as it would otherwise leave me with my ~ missing):
03:44:11.86 cannot unmount '/export/home/yuri': Device busy cannot unmount '/
export/home': Device busy
03:44:11.86 ERROR: /usr/sbin/zfs unmount -a exited 1
This affects, at least, zfs_mount_009_neg and zfs_mount_all_001_pos, both
failing on that step. The pool containing the /export/home hierarchy is
included in KEEP variable, but it doesn't seem to affect anything here.

Reviewed by: Andriy Gapon <avg@FreeBSD.org>
Reviewed by: Dan McDonald <danmcd@omniti.com>
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 r296528: MFV r296527: 6659 nvlist_free(NULL) is a no-op

Reviewed by: Toomas Soome <tsoome@me.com>
Reviewed by: Marcel Telka <marcel@telka.sk>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>

illumos/illumos-gate@aab83bb83be7342f6cfccaed8d5fe0b2f404855d

MFC r295047: MFV 295046:
6358 A faulted pool with only unavailable vdevs triggers assertion
failure in libzfs

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Andrew Stormont <andyjstormont@gmail.com>
Reviewed by: Serban Maduta <serban.maduta@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Dan Vatca <dan.vatca@gmail.com>

illumos/illumos-gate@b289d045e084af53efcc025255af8242e41f28fa

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Merge illumos commit 13749:df4cd82e2b60

1796 "ZFS HOLD" should not be used when doing "ZFS SEND" froma read-only pool
2871 support for __ZFS_POOL_RESTRICT used by ZFS test suite
2903 zfs destroy -d does not work
2957 zfs destroy -R/r sometimes fails when removing defer-destroyed snapshot

References:
https://www.illumos.org/issues/1796
https://www.illumos.org/issues/2871
https://www.illumos.org/issues/2903
https://www.illumos.org/issues/2957

MFC after: 1 week

Introduce "feature flags" for ZFS pools (bump SPA version to 5000).
Add first feature "com.delphix:async_destroy" (asynchronous destroy
of ZFS datasets).
Implement features support in ZFS boot code.

Illumos revisions merged:
13700:2889e2596bd6
13701:1949b688d5fb
2619 asynchronous destruction of ZFS file systems
2747 SPA versioning with zfs feature flags

References:
https://www.illumos.org/issues/2619
https://www.illumos.org/issues/2747

Obtained from: illumos (issue #2619, #2747)
MFC after: 1 month

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

Forced commit to note that these files were repo copied.

MFp4:

@118370 Correct typo.

@118371 Integrate changes from vendor.

@118491 Show backtrace on unexpected code paths.

@118494 Integrate changes from vendor.

@118504 Fix sendfile(2). I had two ways of fixing it:
1. Fixing sendfile(2) itself to use VOP_GETPAGES() instead of
hacking around with vn_rdwr(UIO_NOCOPY), which was suggested
by ups.
2. Modify ZFS behaviour to handle this special case.

Although 1 is more correct, I've choosen 2, because hack from 1
have a side-effect of beeing faster - it reads ahead MAXBSIZE
bytes instead of reading page by page. This is not easy to implement
with VOP_GETPAGES(), at least not for me in this very moment.

Reported by: Andrey V. Elsukov <bu7cher@yandex.ru>

@118525 Reorganize the code to reduce diff.

@118526 This code path is expected. It is simply when file is opened with
O_FSYNC flag.

Reported by: kris
Reported by: Michal Suszko <dry@dry.pl>

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/)