6939941 problem with moving files in zfs

References:
  illumos/illumos-gate@d39ee142a97a7c58f60f7b52c62409f2ff64b234

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775

Porting notes:

1. This commit was so old that only two lines applied to the modern
   code base.
6977619 NULL pointer deference in sa_handle_get_from_db()

References:
  illumos/illumos-gate@44bffe012cad6481c82ad67bacd6b40bd29def2b

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Illumos #3582, #3584

3582 zfs_delay() should support a variable resolution
3584 DTrace sdt probes for ZFS txg states

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Dan McDonald <danmcd@nexenta.com>
Reviewed by: Richard Elling <richard.elling@dey-sys.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
    https://www.illumos.org/issues/3582
    illumos/illumos-gate@0689f76

Ported by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Illumos #3699, #3739

3699 zfs hold or release of a non-existent snapshot does not output error
3739 cannot set zfs quota or reservation on pool version < 22
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Eric Shrock <eric.schrock@delphix.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

References:
  https://www.illumos.org/issues/3699
  https://www.illumos.org/issues/3739
  illumos/illumos-gate@013023d4ed2f6d0cf75380ec686a4aac392b4e43

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Illumos #3741

3741 zfs needs better comments
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://www.illumos.org/issues/3741
  illumos/illumos-gate@3e30c24aeefdee1631958ecf17f18da671781956

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Illumos #3742

3742 zfs comments need cleaner, more consistent style
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://www.illumos.org/issues/3742
  illumos/illumos-gate@f7170741490edba9d1d9c697c177c887172bc741

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775

Porting notes:

1. The change to zfs_vfsops.c was dropped because it involves
   zfs_mount_label_policy, which does not exist in the Linux port.
Illumos #3743

3743 zfs needs a refcount audit
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://www.illumos.org/issues/3743
  illumos/illumos-gate@b287be1ba86043996f49b1cc34c80cc620f9b841

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Illumos #3744

3744 zfs shouldn't ignore errors unmounting snapshots
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://www.illumos.org/issues/3744
  illumos/illumos-gate@fc7a6e3fefc649cb65c8e2a35d194781445008b0

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775

Porting notes:

1. There is no clear way to distinguish between a failure when we
   tried to unmount the snapdir of a zvol (which does not exist)
   and the failure when we try to unmount a snapdir of a dataset,
   so the changes to zfs_unmount_snap() were dropped in favor of
   an altered Linux function that unconditionally returns 0.
Illumos #3745, #3811

3745 zpool create should treat -O mountpoint and -m the same
3811 zpool create -o altroot=/xyz -O mountpoint=/mnt ignores
     the mountpoint option
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://www.illumos.org/issues/3745
  https://www.illumos.org/issues/3811
  illumos/illumos-gate@8b713775314bbbf24edd503b4869342d8711ce95

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Illumos #3740

3740 Poor ZFS send / receive performance due to snapshot
     hold / release processing
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://www.illumos.org/issues/3740
  illumos/illumos-gate@a7a845e4bf22fd1b2a284729ccd95c7370a0438c

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775

Porting notes:

1. 13fe019870c8779bf2f5b3ff731b512cf89133ef introduced a merge conflict
   in dsl_dataset_user_release_tmp where some variables were moved
   outside of the preprocessor directive.

2. dea9dfefdd747534b3846845629d2200f0616dad made the previous merge
   conflict worse by switching KM_SLEEP to KM_PUSHPAGE. This is notable
   because this commit refactors the code, adding a new KM_SLEEP
   allocation. It is not clear to me whether this should be converted
   to KM_PUSHPAGE.

3. We had a merge conflict in libzfs_sendrecv.c because of copyright
   notices.

4. Several small C99 compatibility fixed were made.
Illumos #3818

3818 zpool status -x should report pools with removed l2arc devices
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>
Reviewed by: George Wilson <gwilson@zfsmail.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://www.illumos.org/issues/3818
  illumos/illumos-gate@7f2416ef64fb43dab18d9b36c0da64bea37c0df3

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Illumos #3829

3829 fix for 3740 changed behavior of zfs destroy/hold/release ioctl
Reviewed by: Matt Amdur <matt.amdur@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/3829
  illumos/illumos-gate@bb6e70758d0c30c09f148026d6e686e21cfc8d18

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Illumos #3894

3894 zfs should not allow snapshot of inconsistent dataset
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Gordon Ross <gwr@nexenta.com>

References:
  https://www.illumos.org/issues/3894
  illumos/illumos-gate@ca48f36f20f6098ceb19d5b084b6b3d4b8eca9fa

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775
Illumos #3888

3888 zfs recv -F should destroy any snapshots created since
     the incremental source
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Peng Dai <peng.dai@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/3888
  illumos/illumos-gate@34f2f8cf94052481c81be2e134b94a00b501bf21

Porting notes:

1. Commit 1fde1e37208c2f56c72c70a06676676f04b65998 wrapped a
   declaration in dsl_dataset_modified_since_lastsnap in ASSERTV().
   The ASSERTV() and local variable have been removed to avoid an
   unused variable warning.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Richard Yao <ryao@gentoo.org>
Issue #1775
Illumos #3875

3875 panic in zfs_root() after failed rollback
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Gordon Ross <gwr@nexenta.com>

References:
  https://www.illumos.org/issues/3875
  illumos/illumos-gate@91948b51b8e978ddc88a36b2bc3ae83c20cdc9aa

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775