MFC r359303

MFOpenZFS: ZVOLs should not be allowed to have children

zfs create, receive and rename can bypass this hierarchy rule. Update
both userland and kernel module to prevent this issue and use pyzfs
unit tests to exercise the ioctls directly.

Note: this commit slightly changes zfs_ioc_create() ABI. This allow to
differentiate a generic error (EINVAL) from the specific case where we
tried to create a dataset below a ZVOL (ZFS_ERR_WRONG_PARENT).

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>

Approved by: mav (mentor)
openzfs/zfs@d8d418ff0cc90776182534bce10b01e9487b63e4

MFC r349381: Avoid extra taskq_dispatch() calls by DMU.

DMU sync code calls taskq_dispatch() for each sublist of os_dirty_dnodes
and os_synced_dnodes. Since the number of sublists by default is equal
to number of CPUs, it will dispatch equal, potentially large, number of
tasks, waking up many CPUs to handle them, even if only one or few of
sublists actually have any work to do.

This change adds check for empty sublists to avoid this.

MFC r337183:
MFV r337182: 9330 stack overflow when creating a deeply nested dataset

Datasets that are deeply nested (~100 levels) are impractical. We just put
a limit of 50 levels to newly created datasets. Existing datasets should
work without a problem.

illumos/illumos-gate@5ac95da7d61660aa299c287a39277cb0372be959

Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Approved by: Garrett D'Amore <garrett@damore.org>
Author: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>

MFC r336959: MFV r336958: 9337 zfs get all is slow due to uncached metadata

This project's goal is to make read-heavy channel programs and zfs(1m)
administrative commands faster by caching all the metadata that they will
need in the dbuf layer. This will prevent the data from being evicted, so
that any future call to i.e. zfs get all won't have to go to disk (very
much).

illumos/illumos-gate@adb52d9262f45a04318fc6e188fe2b7f59d989a5

Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Thomas Caputi <tcaputi@datto.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
Author: Matthew Ahrens <mahrens@delphix.com>

MFC r334844, r336180, r336458

r334844

This originated from ZFS On Linux, as
https://github.com/zfsonlinux/zfs/commit/d4a72f23863382bdf6d0ae33196f5b5decbc48fd

During scans (scrubs or resilvers), it sorts the blocks in each transaction
group by block offset; the result can be a significant improvement. (On my
test system just now, which I put some effort to introduce fragmentation into
the pool since I set it up yesterday, a scrub went from 1h2m to 33.5m with the
changes.) I've seen similar rations on production systems.

r336180

Fix up some missed and mis-merges from the sequential scan code
(r334844). Most of the changes involve moving some code around to
reduce conflicts with future merges. One of the missing changes
included a notification on scrub cancellation.

r336458

Fix a couple of typos in r334844 noticed by Richard Kojedzinszky

Approved by: mav
Sponsored by: iXsystems, Inc

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 r330974: MFV r330973: 9164 assert: newds == os->os_dsl_dataset

PR: 225877

MFC r319748: MFV r319738: 8155 simplify dmu_write_policy handling of pre-compressed buffers

illumos/illumos-gate@adaec86ad212d9fd756bee322934fa54d1258605
https://github.com/illumos/illumos-gate/commit/adaec86ad212d9fd756bee322934fa54d1258605

https://www.illumos.org/issues/8155
When writing pre-compressed buffers, arc_write() requires that the compression
algorithm used to compress the buffer matches the compression algorithm
requested by the zio_prop_t, which is set by dmu_write_policy().
This makes dmu_write_policy() and its callers a bit more complicated.
We can simplify this by making arc_write() trust the caller to supply the type
of pre-compressed buffer that it wants to write, and override the compression
setting in the zio_prop_t.

Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Matthew Ahrens <mahrens@delphix.com>

MFC r318828: MFV r316917: 7968 multi-threaded spa_sync()

illumos/illumos-gate@94c2d0eb22e9624151ee84a7edbf7178e1bf4087
https://github.com/illumos/illumos-gate/commit/94c2d0eb22e9624151ee84a7edbf7178e1bf4087

https://www.illumos.org/issues/7968
spa_sync() iterates over all the dirty dnodes and processes each of them by
calling dnode_sync(). If there are many dirty dnodes (e.g. because we created
or removed a lot of files), the single thread of spa_sync() calling
dnode_sync() can become a bottleneck. Additionally, if many dnodes are dirtied
concurrently in open context (e.g. due to concurrent file creation), the
os_lock will experience lock contention via dnode_setdirty().
The solution is to track dirty dnodes on a multilist_t, and for spa_sync() to
use separate threads to process each of the sublists in the multilist.
On the concurrent file creation microbenchmark, the performance improvement
from dnode_setdirty() is up to 7%. Additionally, the wall clock time spent in
spa_sync() is reduced to 15%-40% of the single-threaded case. In terms of cost/
reward, once the other bottlenecks are addressed, fixing this bug will provide
a medium-large performance gain and require a medium amount of effort to
implement.

Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Reviewed by: Saso Kiselkov <saso.kiselkov@nexenta.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Matthew Ahrens <mahrens@delphix.com>

MFC r318821: MFV r316912: 7793 ztest fails assertion in dmu_tx_willuse_space

illumos/illumos-gate@61e255ce7267b52208af9daf434b77d37fb75622
https://github.com/illumos/illumos-gate/commit/61e255ce7267b52208af9daf434b77d37
fb75622

https://www.illumos.org/issues/7793
Background information: This assertion about tx_space_* verifies that we
are not dirtying more stuff than we thought we would. We “need” to know
how much we will dirty so that we can check if we should fail this
transaction with ENOSPC/EDQUOT, in dmu_tx_assign(). While the
transaction is open (i.e. between dmu_tx_assign() and dmu_tx_commit() —
typically less than a millisecond), we call dbuf_dirty() on the exact
blocks that will be modified. Once this happens, the temporary
accounting in tx_space_* is unnecessary, because we know exactly what
blocks are newly dirtied; we call dnode_willuse_space() to track this
more exact accounting.
The fundamental problem causing this bug is that dmu_tx_hold_*() relies
on the current state in the DMU (e.g. dn_nlevels) to predict how much
will be dirtied by this transaction, but this state can change before we
actually perform the transaction (i.e. call dbuf_dirty()).
This bug will be fixed by removing the assertion that the tx_space_*
accounting is perfectly accurate (i.e. we never dirty more than was
predicted by dmu_tx_hold_*()). By removing the requirement that this
accounting be perfectly accurate, we can also vastly simplify it, e.g.
removing most of the logic in dmu_tx_count_*().
The new tx space accounting will be very approximate, and may be more or
less than what is actually dirtied. It will still be used to determine
if this transaction will put us over quota. Transactions that are marked
by dmu_tx_mark_netfree() will be excepted from this check. We won’t make
an attempt to determine how much space will be freed by the transaction
— this was rarely accurate enough to determine if a transaction should
be permitted when we are over quota, which is why dmu_tx_mark_netfree()
was introduced in 2014.
We also won’t attempt to give “credit” when overwriting existing blocks,
if those blocks may be freed. This allows us to remove the
do_free_accounting logic in dbuf_dirty(), and associated routines. This

Reviewed by: Steve Gonczi <steve.gonczi@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Matthew Ahrens <mahrens@delphix.com>

MFC r318818: MFV r316907: 1300 filename normalization doesn't work for removes

illumos/illumos-gate@1c17160ac558f98048951327f4e9248d8f46acc0
https://github.com/illumos/illumos-gate/commit/1c17160ac558f98048951327f4e9248d8f46acc0

https://www.illumos.org/issues/1300

FreeBSD note: recent FreeBSD was not affected by the issue fixed as the
name cache is completely bypassed when normalization is enabled.
The change is imported for the sake of ZAP infrastructure modifications.

Reviewed by: Yuri Pankov <yuri.pankov@nexenta.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Kevin Crowe <kevin.crowe@nexenta.com>

MFC r317507: MFV 316895

7606 dmu_objset_find_dp() takes a long time while importing pool

illumos/illumos-gate@7588687e6ba67c47bf7c9805086dec4a97fcac7b
https://github.com/illumos/illumos-gate/commit/7588687e6ba67c47bf7c9805086dec4a97fcac7b

https://www.illumos.org/issues/7606
When importing a pool with a large number of filesystems within the same
parent filesystem, we see that dmu_objset_find_dp() takes a long time.
It is called from 3 places: spa_check_logs(), spa_ld_claim_log_blocks(),
and spa_load_verify().
There are several ways to improve performance here:
1. We don't really need to do spa_check_logs() or
spa_ld_claim_log_blocks() if the pool was closed cleanly.
2. spa_load_verify() uses dmu_objset_find_dp() to check that no
datasets have too long of names.
3. dmu_objset_find_dp() is slow because it's doing
zap_value_search() (which is O(N sibling datasets)) to determine
the name of each dsl_dir when it's opened. In this case we
actually know the name when we are opening it, so we can provide
it and avoid the lookup.
This change implements fix #3 from the above list; i.e. make
dmu_objset_find_dp() provide the name of the dataset so that we don't
have to search for it.

Reviewed by: Steve Gonczi <steve.gonczi@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Prashanth Sreenivasa <prashksp@gmail.com>
Approved by: Gordon Ross <gordon.w.ross@gmail.com>
Author: Matthew Ahrens <mahrens@delphix.com>

MFC r317414: MFV 316894

7252 7628 compressed zfs send / receive

illumos/illumos-gate@5602294fda888d923d57a78bafdaf48ae6223dea
https://github.com/illumos/illumos-gate/commit/5602294fda888d923d57a78bafdaf48ae6223dea

https://www.illumos.org/issues/7252
This feature includes code to allow a system with compressed ARC enabled to
send data in its compressed form straight out of the ARC, and receive data in
its compressed form directly into the ARC.

https://www.illumos.org/issues/7628
We should have longer, more readable versions of the ZFS send / recv options.

7628 create long versions of ZFS send / receive options

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed by: David Quigley <dpquigl@davequigley.com>
Reviewed by: Thomas Caputi <tcaputi@datto.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Dan Kimmel <dan.kimmel@delphix.com>

MFC r317235: MFV 316868

7430 Backfill metadnode more intelligently

illumos/illumos-gate@af346df58864e8fe897b1ff1a3a4c12f9294391b
https://github.com/illumos/illumos-gate/commit/af346df58864e8fe897b1ff1a3a4c12f9
294391b

https://www.illumos.org/issues/7430
Description and patch from brought over from the following ZoL commit: https:/
/
github.com/zfsonlinux/zfs/commit/68cbd56e182ab949f58d004778d463aeb3f595c6
Only attempt to backfill lower metadnode object numbers if at least
4096 objects have been freed since the last rescan, and at most once
per transaction group. This avoids a pathology in dmu_object_alloc()
that caused O(N^2) behavior for create-heavy workloads and
substantially improves object creation rates. As summarized by
@mahrens in #4636:
"Normally, the object allocator simply checks to see if the next
object is available. The slow calls happened when dmu_object_alloc()
checks to see if it can backfill lower object numbers. This happens
every time we move on to a new L1 indirect block (i.e. every 32 *
128 = 4096 objects). When re-checking lower object numbers, we use
the on-disk fill count (blkptr_t:blk_fill) to quickly skip over
indirect blocks that don?t have enough free dnodes (defined as an L2
with at least 393,216 of 524,288 dnodes free). Therefore, we may
find that a block of dnodes has a low (or zero) fill count, and yet
we can?t allocate any of its dnodes, because they've been allocated
in memory but not yet written to disk. In this case we have to hold
each of the dnodes and then notice that it has been allocated in
memory.
The end result is that allocating N objects in the same TXG can
require CPU usage proportional to N^2."
Add a tunable dmu_rescan_dnode_threshold to define the number of
objects that must be freed before a rescan is performed. Don't bother
to export this as a module option because testing doesn't show a
compelling reason to change it. The vast majority of the performance
gain comes from limit the rescan to at most once per TXG.

Reviewed by: Alek Pinchuk <alek@nexenta.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Gordon Ross <gordon.w.ross@gmail.com>
Author: Ned Bass <bass6@llnl.gov>

MFC r307318: MFV r307314:
6988 spa_sync() spends half its time in dmu_objset_do_userquota_updates

Using a benchmark which creates 2 million files in one TXG, I observe
that the thread running spa_sync() is on CPU almost the entire time we
are syncing, and therefore can be a performance bottleneck. About 50% of
the time in spa_sync() is in dmu_objset_do_userquota_updates().

The problem is that dmu_objset_do_userquota_updates() calls
zap_increment_int(DMU_USERUSED_OBJECT) once for every file that was
modified (or created). In this benchmark, all the files are owned by the
same user/group, so all 2 million calls to zap_increment_int() are
modifying the same entry in the zap. The same issue exists for the
DMU_GROUPUSED_OBJECT.

We should keep an in-memory map from user to space delta while we are
syncing, and when we finish, iterate over the in-memory map and modify
the ZAP once per entry. This reduces the number of calls to
zap_increment_int() from "number of objects modified" to "number of
owners/groups of modified files".

This reduced the time spent in spa_sync() in the file create benchmark
by ~33%, from 11 seconds to 7 seconds.

Closes #107

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Steve Gonczi <steve.gonczi@delphix.com>
Reviewed by: Ned Bass <bass6@llnl.gov>
Reviewed by: Jinshan Xiong <jinshan.xiong@intel.com>
Author: Matthew Ahrens <mahrens@delphix.com>

openzfs/openzfs@5fc46359c569369d87728ca09f8705cdff6cc8e2

MFC r306424: MFV r306422:
7254 ztest failed assertion in ztest_dataset_dirobj_verify: dirobjs + 1 == usedobjs

dsl_dataset_space is looking at the ds_bp's fill count while
dmu_objset_write_ready() is concurrently modifying it. This fix adds an
rrwlock to protect the ds_bp.

Closes #180

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Steve Gonczi <steve.gonczi@delphix.com>
Author: Paul Dagnelie <pcd@delphix.com>

MFC r305323: MFV r302991: 6950 ARC should cache compressed data

illumos/illumos-gate@dcbf3bd6a1f1360fc1afcee9e22c6dcff7844bf2
https://github.com/illumos/illumos-gate/commit/dcbf3bd6a1f1360fc1afcee9e22c6dcff7844bf2

https://www.illumos.org/issues/6950
When reading compressed data from disk, the ARC should keep the compressed
block cached and only decompress it when consumers access the block. The
uncompressed data should be short-lived allowing the ARC to cache a much larger
amount of data. The DMU would also maintain a smaller cache of uncompressed
blocks to minimize the impact of decompressing frequently accessed blocks.

Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Don Brady <don.brady@intel.com>
Reviewed by: Richard Elling <Richard.Elling@RichardElling.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
Author: George Wilson <george.wilson@delphix.com>

MFC r305222: MFV r302993: 7104 increase indirect block size

illumos/illumos-gate@4b5c8e93cab28d3c65ba9d407fd8f46e3be1db1c
https://github.com/illumos/illumos-gate/commit/4b5c8e93cab28d3c65ba9d407fd8f46e3
be1db1c

https://www.illumos.org/issues/7104
The current default indirect block size is 16KB. We can improve
performance by increasing it to 128KB. This is especially helpful for
any workload that needs to read most of the metadata, e.g.
scrub/resilver, file deletion, filesystem deletion, and zfs send.
We also need to fix a few space estimation errors to make the tests
pass.

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Matthew Ahrens <mahrens@delphix.com>

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>

MFC r302838: 6513 partially filled holes lose birth time