MFC r329732: MFV r329502: 7614 zfs device evacuation/removal

illumos/illumos-gate@5cabbc6b49070407fb9610cfe73d4c0e0dea3e77

https://www.illumos.org/issues/7614:
This project allows top-level vdevs to be removed from the storage pool with
“zpool remove”, reducing the total amount of storage in the pool. This
operation copies all allocated regions of the device to be removed onto other
devices, recording the mapping from old to new location. After the removal is
complete, read and free operations to the removed (now “indirect”) vdev must
be remapped and performed at the new location on disk. The indirect mapping
table is kept in memory whenever the pool is loaded, so there is minimal
performance overhead when doing operations on the indirect vdev.

The size of the in-memory mapping table will be reduced when its entries
become “obsolete” because they are no longer used by any block pointers in
the pool. An entry becomes obsolete when all the blocks that use it are
freed. An entry can also become obsolete when all the snapshots that
reference it are deleted, and the block pointers that reference it have been
“remapped” in all filesystems/zvols (and clones). Whenever an indirect block
is written, all the block pointers in it will be “remapped” to their new
(concrete) locations if possible. This process can be accelerated by using
the “zfs remap” command to proactively rewrite all indirect blocks that
reference indirect (removed) vdevs.

Note that when a device is removed, we do not verify the checksum of the data
that is copied. This makes the process much faster, but if it were used on
redundant vdevs (i.e. mirror or raidz vdevs), it would be possible to copy
the wrong data, when we have the correct data on e.g. the other side of the
mirror. Therefore, mirror and raidz devices can not be removed.

Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Richard Laager <rlaager@wiktel.com>
Reviewed by: Tim Chase <tim@chase2k.com>
Approved by: Garrett D'Amore <garrett@damore.org>
Author: Prashanth Sreenivasa <pks@delphix.com>

MFC r328254:
MFV r328253: 8835 Speculative prefetch in ZFS not working for misaligned reads

illumos/illumos-gate@5cb8d943bc8513c6230589aad5a409d58b0297cb

https://www.illumos.org/issues/8835:
Sequential reads not aligned to block size are not detected by ZFS
prefetcher as sequential, killing prefetch and severely hurting
performance. It is caused by dmu_zfetch() in case of misaligned
sequential accesses being called with overlap of one block.

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Allan Jude <allanjude@freebsd.org>
Approved by: Gordon Ross <gwr@nexenta.com>
Author: Alexander Motin <mav@FreeBSD.org>

MFC r309833: Add missed vfs.zfs.zfetch.max_idistance sysctl.

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 r297831: 6322 ZFS indirect block predictive prefetch

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Author: Alexander Motin <mav@FreeBSD.org>

Improve speculative prefetch of indirect blocks.

Scalability of many operations on wide ZFS pool can be limited by
requirement to prefetch indirect blocks first. Recently added
asynchronous indirect block read partially helped, but did not
solve the problem completely. This patch extends existing prefetcher
functionality to explicitly work with indirect blocks.

Before this change prefetcher issued reads for up to 8MB of data in
advance. With this change it also issues indirect block reads
for up to 64MB of data in advance, so that when it will be time to
actually read those data, it can be done immediately. Alike effect
can be achieved by just increasing maximal data prefetch distance,
but at higher memory cost.

Also this change introduces indirect block prefetch for rewrite
operations, that was never done before. Previously ARC miss for
Indirect blocks regularly blocked rewrites, converting perfectly
aligned asynchronous operations into synchronous read-write pairs,
significantly reducing maximal rewrite speed.

While being there this issue was also fixed:
- prefetch was done always, even if caching for the dataset was
completely disabled.

Testing on FreeBSD with zvol on top of 6x striped 2x mirrored pool
of 12 assorted HDDs shown me such performance numbers:
------- BEFORE --------
Write 491363677 bytes/sec
Read 312430631 bytes/sec
Rewrite 97680464 bytes/sec
-------- AFTER --------
Write 493524146 bytes/sec
Read 438598079 bytes/sec
Rewrite 277506044 bytes/sec

Closes #65
Closes #80

openzfs/openzfs@792fd28ac04f78cc5e43ead2d72a96f244ea84e8

MFV r289188: 6281 prefetching should apply to 1MB reads

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Alexander Motin <mav@freebsd.org>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Justin Gibbs <gibbs@scsiguy.com>
Reviewed by: Xin Li <delphij@freebsd.org>
Approved by: Gordon Ross <gordon.ross@nexenta.com>
Author: George Wilson <george.wilson@delphix.com>

illumos/illumos-gate@632802744ef6d17e06d6980a95f631615c3b060f

MFV r287624: 5987 zfs prefetch code needs work

Rewrite the ZFS prefetch code to detect only forward, sequential
streams.

The following kstats have been added:

kstat.zfs.misc.arcstats.sync_wait_for_async

How many sync reads have waited for async read
to complete. (less is better)

kstat.zfs.misc.arcstats.demand_hit_predictive_prefetch

How many demand read didn't have to wait for I/O
because of predictive prefetch. (more is better)

zfetch kstats have been similified to hits, misses, and max_streams,
with max_streams representing times when we were not able to create
new stream because we already have the maximum number of sequences
for a file.

The sysctl variable/loader tunable vfs.zfs.zfetch.block_cap have been
replaced by vfs.zfs.zfetch.max_distance, which controls maximum bytes
to prefetch per stream.

illumos/illumos-gate@cf6106c8a0d6598b045811f9650d66e07eb332af

Illumos ZFS issues:

5987 zfs prefetch code needs work
https://www.illumos.org/issues/5987

MFV r286704: 5960 zfs recv should prefetch indirect blocks
5925 zfs receive -o origin=

Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Author: Paul Dagnelie <pcd@delphix.com>

While running 'zfs recv' we noticed that every 128th 8K block required a
read. We were seeing that restore_write() was calling dmu_tx_hold_write()
and the indirect block was not cached. We should prefetch upcoming indirect
blocks to avoid having to go to disk and blocking the restore_write().

Allow an incremental send stream to be received as a clone, even if the
stream does not mark it as a clone.

Make sysctls under vfs.zfs.zfetch writeable.

I don't see any reason for them to be read-only, while tuning them without
reboot is much more convenient for experiments.

MFC after: 2 weeks

Pull in r267961 and r267973 again. Fix for issues reported will follow.

Revert r267961, r267973:

These changes prevent sysctl(8) from returning proper output,
such as:

1) no output from sysctl(8)
2) erroneously returning ENOMEM with tools like truss(1)
or uname(1)
truss: can not get etype: Cannot allocate memory

Extend the meaning of the CTLFLAG_TUN flag to automatically check if
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.

Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.

MFC after: 2 weeks
Sponsored by: Mellanox Technologies

In dmu_zfetch_stream_reclaim() replace division with multiplication and
move it out of the loop and lock.

MFV r255255: 4045 zfs write throttle & i/o scheduler performance work

illumos/illumos-gate@69962b5647e4a8b9b14998733b765925381b727e

Please note the following changes:
- zio_ioctl has lost its priority parameter and now TRIM is executed
with 'now' priority
- some knobs are gone and some new knobs are added; not all of them are
exposed as tunables / sysctls yet

MFC after: 10 days
Sponsored by: HybridCluster [merge]

MFV r251619:

ZFS needs better comments.

Illumos ZFS issues:
3741 zfs needs better comments

MFC after: 2 weeks

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

Re-commit the zfs sysctl(9) type-safety changes.

Thanks to dim and pjd for the pointer to zfs_context.h for building
userland.

Revert cddl changes for sysctl(9) until I understand why this isn't
building on universe.

sysctl(9) cleanup checkpoint: amd64 GENERIC builds cleanly.

Commit the zfs piece.

Fix perfomance problem with ZFS prefetch caching [1]
Add statistics for ZFS prefetch (sysctl kstat.zfs.misc.zfetchstats)

Partial import of OpenSolaris onnv revision 10474:0e96dd3b905a

Reported by: jhell@dataix.net (private e-mail) [1]
Approved by: pjd, delphij (mentor)
Obtained from: OpenSolaris (Bug ID 6859997, 6868951)
MFC after: 3 days

Don't bottleneck on acquiring the stream locks - this avoids a massive
drop off in throughput with large numbers of simultaneous reads

MFC after: 7 days

pjd has requested that I keep the tunable as zfs_prefetch_disable to minimize gratuitous
differences with Opensolaris' ZFS

Sorry for the churn

check against prefetch_enable

use default policy for enabling prefetching unless the TUNABLE is set

As far as I can tell systems that have less than 4GB are more often hurt
by prefetched than helped. On i386 systems and systems with less than 4GB,
prefetch is now disabled by default. I've added a prefetch enable tunable, to
enable prefetching for those systems. The prefetch disable tunable will continue
to unconditionally disable prefetching.

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

We want to use LBOLT instead of lbolt on FreeBSD.
I've this already fixed in p4, but the fix was never integrated into HEAD.

Reported by: ed

Forced commit to note that these files were repo copied.

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/)