MFC ZFS version 28 and related revisions:

MFC ZFS version 28 and related revisions:
208682, 211900, 212543, 213791, 216378, 218007, 218725, 219089, 219090,
219092, 219316, 219317, 219320, 219404, 219636, 219703, 219959, 219973,
220447, 220575, 221112, 221177, 221263, 221409, 222050, 222267, 222268

MFC r208682 (pjd):
Fix panic when reading label from provider with non power of 2 sector size.

MFC r211900 (pjd):
Use ZFS_CTLDIR_NAME instead of hardcoding ".zfs".

MFC r212543 (imp):
Simplify atomic selection

MFC r213791 (rpaulo):
Pass a format string to panic() and to taskqueue_start_threads().

Found with:	clang

MFC r216378 (pjd):
Remove redundant semicolon and empty like.

MFC r218007 (jchandra):
CDDL fixes for MIPS n32.

Provide 64 bit atomic ops, and use 32 bit pointer.

MFC r218725 (dim):
When building libzpool on ia64 or sparc64, don't add the .note.GNU-stack
section.

MFC r219089 (pjd):
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 r219090 (pjd):
Commit two more files missed in r219089.

MFC r219092 (pjd):
Use proper lock in assertion.

MFC r219316 (pjd):
Simplify zvol_remove_minors() a bit.

MFC r219317 (pjd):
Make renaming of a ZVOL, ZVOL's parent directory and ZVOL snapshot work.

MFC r219320 (pjd):
Fix libzpool build.

MFC r219404 (pjd):
Correct readdir over ZFS handling.

MFC r219636 (pjd):
Fix potential panic in dbuf_sync_list() relate to spill blocks handling.

MFC r219703 (ae):
The size of zfsboot2 grown up to 64 Kbytes in r219089.
Increase NSECT up to 128 sectors too.

MFC r219959 (pjd):
Properly print characters larger than 127.

MFC r219973 (pjd):
Checking file access on size change is bogus. The checks are done earlier by
VFS where we know if this is truncate(2) or ftruncate(2). If this is the
latter we should depend on the mode the file was opened and not on the current
permission.

MFC r220447 (mm):
Partially fix ZFS compat code for sparc64.
Some endianess bugs still need to be resolved.

MFC r220575 (pjd):
Fix 'zfs list <path>' handling. If the path was found, the 'ret' variable was
uninitialized.

MFC r221112 (marcel):
Fix copy-paste bug.

MFC r221177 (jhb):
Due to space constraints, the UFS boot2 and boot1 use an evil hack where
boot2 calls back into boot1 to perform disk reads.  The ZFS MBR boot blocks
do not have the same space constraints, so remove this hack for ZFS.
While here, remove commented out code to support C/H/S addressing from
zfsldr.  The ZFS and GPT bootstraps always just use EDD LBA addressing.

MFC r221263 (mm):
Fix deduplicated zfs receive
(dmu_recv_stream builds incomplete guid_to_ds_map)

Illumos-gate changeset: 13329:c48b8bf84ab7

MFC r221409 (marius):
Convert the last use of xcopyout() to ddi_copyout() and remove the now
unused xcopyin() as well as xcopyout().

MFC r222050 (mm):
Restore old (v15) behaviour for a recursive snapshot destroy.
(zfs destroy -r pool/dataset@snapshot)

To destroy all descendent snapshots with the same name the top level
snapshot was not required to exist. So if the top level snapshot does
not exist, check permissions of the parent dataset instead.

Filed as Illumos Bug #1043

MFC r222267 (pjd):
Don't access task structure once we call task function.
The task structure might be no longer available.
This also allows to eliminates the need for two tasks in the zio structure.

MFC r222268 (pjd):
Don't pass pointer to name buffer which is on the stack to another thread,
because the stack might be paged out once the other thread tries to use the
data. Instead, just allocate memory.

Discussed with:		pjd

git-svn-id: svn://svn.freebsd.org/base/stable/8@222741 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f