Suppress AIO kmem warnings

The new zpl_aio_write() and zpl_aio_read() functions use kmem_alloc()
to allocate enough memory to hold the vectorized IO.  While this
allocation will be small it's been observed in practice to sometimes
slightly exceed the 8K warning threshold by a few kilobytes.
Therefore, the KM_NODEBUG flag has been added to suppress warning.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Closes #2774
Illumos 4924 - LZ4 Compression for metadata

Reviewed by Matthew Ahrens <mahrens@delphix.com>
Reviewed by Saso Kiselkov <skiselkov.ml@gmail.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://github.com/illumos/illumos-gate/commit/b8289d2
  https://www.illumos.org/issues/3756

Porting notes:

The static function zfs_prop_activate_feature() was removed because
this change removes the only caller.  The function was not removed
from Illumos but instead left as dead code.  However, to keep gcc
happy it was removed from Linux and may be easily restored if needed.

Ported by: DHE <git@dehacked.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1540
Don't perform ACL-to-mode translation on empty ACL

In zfs_acl_chown_setattr(), the zfs_mode_comput() function is used to
create a traditional mode value based on an ACL.  If no ACL exists, this
processing shouldn't be done.  Problems caused by this were most evident
on version 4 filesystems which not only don't have system attributes,
and also frequently have empty ACLs. On such filesystems, performing a
chown() operation could have the effect of dirtying the mode bits in
memory but not on the file system as follows:

	# create a file with typical mode of 664
	echo test > test
	chown anyuser test
	ls -l test

and the mode will show up as all zeroes.  Unmounting/mounting and/or
exporting/importing the filesystem will reveal the proper mode again.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1264
Illumos 3693 - restore_object uses at least two transactions to restore an object

Restore_object should not use two transactions to restore an object:
  * one transaction is used for dmu_object_claim
  * another transaction is used to set compression, checksum and most
    importantly bonus data
  * furthermore dmu_object_reclaim internally uses multiple transactions
  * dmu_free_long_range frees chunks in separate transactions
  * dnode_reallocate is executed in a distinct transaction

The fact the dnode_allocate/dnode_reallocate are executed in one
transaction and bonus (re-)population is executed in a different
transaction may lead to violation of ZFS consistency assertions if the
transactions are assigned to different transaction groups.  Also, if
the first transaction group is successfully written to a permanent
storage, but the second transaction is lost, then an invalid dnode may
be created on the stable storage.

3693 restore_object uses at least two transactions to restore an object
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Andriy Gapon <andriy.gapon@hybridcluster.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Original authors: Matthew Ahrens and Andriy Gapon

References:
  https://www.illumos.org/issues/3693
  https://github.com/illumos/illumos-gate/commit/e77d42e

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2689
Illumos 5150 - zfs clone of a defer_destroy snapshot causes strangeness

When a clone is created of a snapshot that has been marked for
deferred destroy (with "zfs destroy -d"), the clone "inherits" the
defer_destroy flag from the origin, and any snapshots of the clone
"inherit" the defer_destroy flag from the clone. This causes a strange
situation where the clone's snapshots are marked for defer_destroy but
they have no holds or clones. If the clone's snapshot gets a hold or
clone, which is then deleted, we will honor the incorrectly-set
defer_destroy flag and delete the snapshot!

Steps to reproduce:

  * zpool create test c1t1d0
  * zfs create test/fs
  * zfs snapshot test/fs@a
  * zfs clone test/fs@a test/clone
  * zfs destroy -d test/fs@a
  * zfs clone test/fs@a test/clone2
  * zfs snapshot test/clone2@a
  * zfs hold hld test/clone2@a
  * zfs release hld test/clone2@a
  * zfs list -r -t all test

  <test/clone2@a has been destroyed>

We noticed that this causes dcenter to get very confused, because it
treats snapshots that are marked defer_destroy as not existing. So it
won't see any snapshots of the clone that's marked defer_destroy.

5150 - zfs clone of a defer_destroy snapshot causes strangeness
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Max Grossman <max.grossman@delphix.com>
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Robert Mustacchi <rm@joyent.com>

References:
  https://www.illumos.org/projects/illumos-gate//issues/5150
  https://github.com/illumos/illumos-gate/commit/42fcb65

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2690
Illumos 5162 - zfs recv should use loaned arc buffer to avoid copy

5162 zfs recv should use loaned arc buffer to avoid copy
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Bayard Bell <Bayard.Bell@nexenta.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  https://www.illumos.org/issues/5162
  https://github.com/illumos/illumos-gate/commit/8a90470

Porting notes:
  Fix spelling error 's/arena/area/' in dmu.c.
  In restore_write() declare bonus and abuf at the top of the function.

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2696
Remove checks for mandatory locks

The Linux VFS handles mandatory locks generically so we shouldn't
need to check for conflicting locks in zfs_read(), zfs_write(), or
zfs_freesp().  Linux 3.18 removed the lock_may_read() and
lock_may_write() interfaces which we were relying on for this
purpose.  Rather than emulating those interfaces we remove the
redundant checks.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2804
Handle block pointers with a corrupt logical size

The general strategy used by ZFS to verify that blocks are valid is
to checksum everything.  This has the advantage of being extremely
robust and generically applicable regardless of the contents of
the block.  If a blocks checksum is valid then its contents are
trusted by the higher layers.

This system works exceptionally well as long as bad data is never
written with a valid checksum.  If this does somehow occur due to
a software bug or a memory bit-flip on a non-ECC system it may
result in kernel panic.

One such place where this could occur is if somehow the logical
size stored in a block pointer exceeds the maximum block size.
This will result in an attempt to allocate a buffer greater than
the maximum block size causing a system panic.

To prevent this from happening the arc_read() function has been
updated to detect this specific case.  If a block pointer with an
invalid logical size is passed it will treat the block as if it
contained a checksum error.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2678
Fix zpool create -t ENOENT bug.

In userland we need to switch over to the temporary name once the
pool has been created, otherwise the root dataset won't mount
and the error "cannot open 'the_real_name': dataset does not exist"
is printed.

Signed-off-by: ilovezfs <ilovezfs@icloud.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2760
Illumos 5178 - zdb -vvvvv on old-format pool fails in dump_deadlist()

5178 zdb -vvvvv on old-format pool fails in dump_deadlist()
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Reviewed by: Alek Pinchuk <alek.pinchuk@nexenta.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  https://www.illumos.org/issues/5178
  https://github.com/illumos/illumos-gate/commit/90c76c6

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2713
Illumos 5169-5171 - zdb fixes

5169 zdb should limit its ARC size
5170 zdb -c should create more scrub i/os by default
5171 zdb should print status while loading metaslabs for leak detection
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Bayard Bell <Bayard.Bell@nexenta.com>
Approved by: Robert Mustacchi <rm@joyent.com>

References:
  https://www.illumos.org/issues/5169
  https://www.illumos.org/issues/5170
  https://www.illumos.org/issues/5171
  https://github.com/illumos/illumos-gate/commit/06be980

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2707
Fix zdb segfault

On 32-bit systems setting 'zfs_arc_max = 256M' in zdb results in the
following segmentation fault.  Rather than reverting 0ec0724 which
introduced this flaw this code is only used for 64-bit builds.

Segmentation fault (core dumped)
ztest: '/sbin/zdb -bcc -d -U /var/tmp/zpool.cache ztest' exit code 139
child exited with code 3

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Illumos 4958 zdb trips assert on pools with ashift >= 0xe

4958 zdb trips assert on pools with ashift >= 0xe
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Max Grossman <max.grossman@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  https://www.illumos.org/issues/4958
  https://github.com/illumos/illumos-gate/commit/2a104a5

Porting notes:

Keep the ZIO_FLAG_FASTWRITE define.  This is for a feature present
in Linux but not yet in *BSD.

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2697
Illumos 5164-5165 - space map fixes

5164 space_map_max_blksz causes panic, does not work
5165 zdb fails assertion when run on pool with recently-enabled
     space map_histogram feature
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>

References:
  https://www.illumos.org/issues/5164
  https://www.illumos.org/issues/5165
  https://github.com/illumos/illumos-gate/commit/b1be289

Porting Notes:

The metaslab_fragmentation() hunk was dropped from this patch
because it was already resolved by commit 8b0a084.

The comment modified in metaslab.c was updated to use the correct
variable name, space_map_blksz.  The upstream commit incorrectly
used space_map_blksize.

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2697