MFC r337567 (by mmacy):
Performance optimization of AVL tree comparator functions

MFV:
commit ee36c709c3d5f7040e1bd11f5c75318aa03e789f
Author: Gvozden Neskovic <neskovic@gmail.com>
Date: Sat Aug 27 20:12:53 2016 +0200

perf: 2.75x faster ddt_entry_compare()
First 256bits of ddt_key_t is a block checksum, which are expected
to be close to random data. Hence, on average, comparison only needs to
look at first few bytes of the keys. To reduce number of conditional
jump instructions, the result is computed as: sign(memcmp(k1, k2)).

Sign of an integer 'a' can be obtained as: `(0 < a) - (a < 0)` := {-1, 0, 1} ,
which is computed efficiently. Synthetic performance evaluation of
original and new algorithm over 1G random keys on 2.6GHz Intel(R) Xeon(R)
CPU E5-2660 v3:

old 6.85789 s
new 2.49089 s

perf: 2.8x faster vdev_queue_offset_compare() and vdev_queue_timestamp_compare()
Compute the result directly instead of using conditionals

perf: zfs_range_compare()
Speedup between 1.1x - 2.5x, depending on compiler version and
optimization level.

perf: spa_error_entry_compare()
`bcmp()` is not suitable for comparator use. Use `memcmp()` instead.

perf: 2.8x faster metaslab_compare() and metaslab_rangesize_compare()
perf: 2.8x faster zil_bp_compare()
perf: 2.8x faster mze_compare()
perf: faster dbuf_compare()
perf: faster compares in spa_misc
perf: 2.8x faster layout_hash_compare()
perf: 2.8x faster space_reftree_compare()
perf: libzfs: faster avl tree comparators
perf: guid_compare()
perf: dsl_deadlist_compare()
perf: perm_set_compare()
perf: 2x faster range_tree_seg_compare()
perf: faster unique_compare()
perf: faster vdev_cache _compare()
perf: faster vdev_uberblock_compare()
perf: faster fuid _compare()
perf: faster zfs_znode_hold_compare()

Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Signed-off-by: Richard Elling <richard.elling@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #5033

MFC r305209: MFV r302660: 6314 buffer overflow in dsl_dataset_name

illumos/illumos-gate@9adfa60d484ce2435f5af77cc99dcd4e692b6660
https://github.com/illumos/illumos-gate/commit/9adfa60d484ce2435f5af77cc99dcd4e6
92b6660

https://www.illumos.org/issues/6314
Callers of dsl_dataset_name pass a buffer of size ZFS_MAXNAMELEN, but
dsl_dataset_name copies the datasets' name PLUS the snapshot name to it,
resulting in a max of 2 * ZFS_MAXNAMELEN + '@'.

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Matthew Ahrens <mahrens@delphix.com>

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

MFV r277428: 5056 ZFS deadlock on db_mtx and dn_holds

Reviewed by: Will Andrews <willa@spectralogic.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Justin Gibbs <justing@spectralogic.com>

illumos/illumos-gate@bc9014e6a81272073b9854d9f65dd59e18d18c35

MFV r275551:

Remove "dbuf phys" db->db_data pointer aliases.

Use function accessors that cast db->db_data to the appropriate
"phys" type, removing the need for clients of the dmu buf user
API to keep properly typed pointer aliases to db->db_data in order
to conveniently access their data.

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap_leaf.c:
In zap_leaf() and zap_leaf_byteswap, now that the pointer alias
field l_phys has been removed, use the db_data field in an on
stack dmu_buf_t to point to the leaf's phys data.

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dbuf.c:
Remove the db_user_data_ptr_ptr field from dbuf and all logic
to maintain it.

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dbuf.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dbuf.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dmu.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sa.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap_micro.c:
Modify the DMU buf user API to remove the ability to specify
a db_data aliasing pointer (db_user_data_ptr_ptr).

cddl/contrib/opensolaris/cmd/zdb/zdb.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_diff.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_objset.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_send.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_traverse.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_bookmark.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_deadlist.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_deleg.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_destroy.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_pool.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_prop.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_synctask.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_userhold.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sa.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_history.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap_leaf.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap_micro.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dsl_dataset.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dsl_dir.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zap_impl.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zap_leaf.h:
Create and use the new "phys data" accessor functions
dsl_dir_phys(), dsl_dataset_phys(), zap_m_phys(),
zap_f_phys(), and zap_leaf_phys().

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dsl_dataset.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dsl_dir.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zap_impl.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zap_leaf.h:
Remove now unused "phys pointer" aliases to db->db_data
from clients of the DMU buf user API.

Illumos issue:
5314 Remove "dbuf phys" db->db_data pointer aliases in ZFS

MFC after: 2 weeks

MFV r268455:

Use reserved space for ZFS administrative commands.

We reserve 1/2^spa_slop_shift = 1/32 or 3.125% of pool space (or 32MB at
least) for system use. Most ZPL operations, e.g. write(2), creat(2), will
fail with ENOSPC if we fall below this.

Certain operations, e.g. file removal and most administrative actions,
still permitted until half of the slop space is used. This would allow
users to use these operations to free up space in the pool when pool is
close to full but half of slop space is still free.

A very restricted set of operations that frees up space or change quota
are always permitted, regardless of the amount of free space.

MFC after: 2 weeks

MFV r248217:
Merge change from vendor to reduce diff only.
ZFS dtrace probes are not supported on FreeBSD yet.

Illumos ZFS issues:
3598 want to dtrace when errors are generated in zfs

MFC after: 3 weeks

Merge libzfs_core branch:
includes MFV 238590, 238592, 247580

MFV 238590, 238592:
In the first zfs ioctl restructuring phase, the libzfs_core library was
introduced. It is a new thin library that wraps around kernel ioctl's.
The idea is to provide a forward-compatible way of dealing with new
features. Arguments are passed in nvlists and not random zfs_cmd fields,
new-style ioctls are logged to pool history using a new method of
history logging.

http://blog.delphix.com/matt/2012/01/17/the-future-of-libzfs/

MFV 247580 [1]:
To address issues of several deadlocks and race conditions the locking
code around dsl_dataset was rewritten and the interface to synctasks
was changed.

User-Visible Changes:
"zfs snapshot" can create more arbitrary snapshots at once (atomically)
"zfs destroy" destroys multiple snapshots at once
"zfs recv" has improved performance

Backward Compatibility:
I have extended the compatibility layer to support full backward
compatibility by remapping or rewriting the responsible ioctl arguments.
Old utilities are fully supported by the new kernel module.

Forward Compatibility:
New utilities work with old kernels with the following restrictions:
- creating, destroying, holding and releasing of multiple snapshots
at once is not supported, this includes recursive (-r) commands

Illumos ZFS issues:
2882 implement libzfs_core
2900 "zfs snapshot" should be able to create multiple,
arbitrary snapshots at once
3464 zfs synctask code needs restructuring

References:
https://www.illumos.org/issues/2882
https://www.illumos.org/issues/2900
https://www.illumos.org/issues/3464 [1]

MFC after: 1 month
Sponsored by: Hybrid Logic Inc. [1]

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

Merge new ZFS features from illumos:

1644 add ZFS "clones" property
https://www.illumos.org/issues/1644

1645 add ZFS "written" and "written@..." properties
https://www.illumos.org/issues/1645

1646 "zfs send" should estimate size of stream
https://www.illumos.org/issues/1646

1647 "zfs destroy" should determine space reclaimed by destroying multiple
snapshots
https://www.illumos.org/issues/1647

1693 persistent 'comment' field for a zpool
https://www.illumos.org/issues/1693

1708 adjust size of zpool history data
https://www.illumos.org/issues/1708

1748 desire support for reguid in zfs
https://www.illumos.org/issues/1748

Obtained from: illumos (changesets 13514, 13524, 13525)
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

Consider snapshots as descendants via zfs allow -d

OpenSolaris onnv changeset: 9847:2f3ba86e857a

Approved by: pjd, delphij (mentor)
Obtained from: OpenSolaris (Bug ID 6809340)
MFC after: 1 week

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