As a regular kernel function, kern_path() returns errors as negative
errnos, such as -ELOOP. zfsctl_snapdir_vget() must convert these into
the positive errnos used throughout the ZFS code when it returns them
to other ZFS functions so that the ZFS code properly sees them as
errors.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chris Siebenmann <cks.git01@cs.toronto.edu>
Closes#7764Closes#7864
Re-adds a recalculation step for the ARC stats after the MRU
eviction so that we don't pathologically attempt to evict the MFU.
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Authored-by: Mark Johnston <markj@freebsd.org>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes#7855
This reverts commit a6214a0ae9.
Disabling zfs_admin_snapshot by default results in multiple ZTS
tests failing which depend on this functionality. Revert this
change until the relevant test cases can be updated.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #7838
It's disabled by default, update code to reflect
the documentation.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Gregor Kopka <gregor@kopka.net>
Signed-off-by: George Melikov <mail@gmelikov.ru>
Closes#7835Closes#7838
Relax allocation throttling for ditto blocks. Due to random imbalances
in allocation it tends to push block copies to one vdev, that looks
slightly better at the moment. Slightly less strict policy allows both
improve data security and surprisingly write performance, since we don't
need to touch extra metaslabs on each vdev to respect the min distance.
Sponsored by: iXsystems, Inc.
Authored by: mav <mav@FreeBSD.org>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://illumos.org/issues/9751
FreeBSD-commit: https://github.com/freebsd/freebsd/commit/8253837ac3Closes#7857
Use METASLAB_WEIGHT_CLAIM weight to allocate tertiary blocks.
Previous use of METASLAB_WEIGHT_SECONDARY for that caused errors
later on metaslab_activate_allocator() call, leading to massive
load of unneeded metaslabs and write freezes.
Authored by: mav <mav@FreeBSD.org>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://illumos.org/issues/9738
FreeBSD-commit: https://github.com/freebsd/freebsd/commit/63e7138Closes#7858
We want newer versions of libzfs_core to run against an existing
zfs kernel module (i.e. a deferred reboot or module reload after
an update).
Programmatically document, via a zfs_ioc_key_t, the valid arguments
for the ioc commands that rely on nvpair input arguments (i.e. non
legacy commands from libzfs_core). Automatically verify the expected
pairs before dispatching a command.
This initial phase focuses on the non-legacy ioctls. A follow-on
change can address the legacy ioctl input from the zfs_cmd_t.
The zfs_ioc_key_t for zfs_keys_channel_program looks like:
static const zfs_ioc_key_t zfs_keys_channel_program[] = {
{"program", DATA_TYPE_STRING, 0},
{"arg", DATA_TYPE_UNKNOWN, 0},
{"sync", DATA_TYPE_BOOLEAN_VALUE, ZK_OPTIONAL},
{"instrlimit", DATA_TYPE_UINT64, ZK_OPTIONAL},
{"memlimit", DATA_TYPE_UINT64, ZK_OPTIONAL},
};
Introduce four input errors to identify specific input failures
(in addition to generic argument value errors like EINVAL, ERANGE,
EBADF, and E2BIG).
ZFS_ERR_IOC_CMD_UNAVAIL the ioctl number is not supported by kernel
ZFS_ERR_IOC_ARG_UNAVAIL an input argument is not supported by kernel
ZFS_ERR_IOC_ARG_REQUIRED a required input argument is missing
ZFS_ERR_IOC_ARG_BADTYPE an input argument has an invalid type
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Don Brady <don.brady@delphix.com>
Closes#7780
This extends our sysfs '/sys/module/zfs' entry to include feature
and property attributes. The primary consumer of this information
is user processes, like the zfs CLI, that need to know what the
current loaded ZFS module supports. The libzfs binary will consult
this information when instantiating the zfs and zpool property
tables and the pool features table.
This introduces 4 kernel objects (dirs) into '/sys/module/zfs'
with corresponding attributes (files):
features.runtime
features.pool
properties.dataset
properties.pool
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Don Brady <don.brady@delphix.com>
Closes#7706
The checkpoint space map object may not be accessible from the
vdev's ZAP when it has been damaged. This may be the case when
performing an extreme rewind when importing the pool.
Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#7809Closes#7853
We can simplify the dbuf_hold code by allocating dbuf_hold_arg_t's on
demand, rather than allocating a big array of them up front. While this
can occasionally increase the number of allocations, typically only one
allocation is needed since the indirect block is already cached.
The performance test suite gets the same results with this change.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#7841
Assertion failed in arc_buf_destroy() when concurrently reading
block with checksum error.
Porting notes:
* The ability to zinject decompression errors has been added, but
this only works at the zio_decompress() level, where we have all
of the info we need to match against the user's zinject options.
* The decompress_fault test has been added to test the new zinject
functionality
* We attempted to set zio_decompress_fail_fraction to (1 << 18) in
ztest for further test coverage. Although this did uncover a few
low priority issues, this unfortuantely also causes ztest to
ASSERT in many locations where the code is working correctly since
it is designed to fail on IO errors. Developers can manually set
this variable with the '-o' option to find and debug issues.
Authored by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Matt Ahrens <mahrens@delphix.com>
Ported-by: Tom Caputi <tcaputi@datto.com>
OpenZFS-issue: https://illumos.org/issues/9403
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/fa98e487a9Closes#7822
Currently, when unmounting a filesystem, ZFS will only wait for
a txg sync if the dataset is dirty and not readonly. However, this
can be problematic in cases where a dataset is remounted readonly
immediately before being unmounted, which often happens when the
system is being shut down. Since encrypted datasets require that
all I/O is completed before the dataset is disowned, this issue
causes problems when write I/Os leak into the txgs after the
dataset is disowned, which can happen when sync=disabled.
While looking into fixes for this issue, it was discovered that
dsl_dataset_is_dirty() does not return B_TRUE when the dataset has
been removed from the txg dirty datasets list, but has not actually
been processed yet. Furthermore, the implementation is comletely
different from dmu_objset_is_dirty(), adding to the confusion.
Rather than relying on this function, this patch forces the umount
code path (and the remount readonly code path) to always perform a
txg sync on read-write datasets and removes the function altogether.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#7753Closes#7795
This patch simply adds some missing locking to the txg_list
functions and refactors txg_verify() so that it is only compiled
in for debug builds.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#7795
Direct IO via the O_DIRECT flag was originally introduced in XFS by
IRIX for database workloads. Its purpose was to allow the database
to bypass the page and buffer caches to prevent unnecessary IO
operations (e.g. readahead) while preventing contention for system
memory between the database and kernel caches.
On Illumos, there is a library function called directio(3C) that
allows user space to provide a hint to the file system that Direct IO
is useful, but the file system is free to ignore it. The semantics
are also entirely a file system decision. Those that do not
implement it return ENOTTY.
Since the semantics were never defined in any standard, O_DIRECT is
implemented such that it conforms to the behavior described in the
Linux open(2) man page as follows.
1. Minimize cache effects of the I/O.
By design the ARC is already scan-resistant which helps mitigate
the need for special O_DIRECT handling. Data which is only
accessed once will be the first to be evicted from the cache.
This behavior is in consistent with Illumos and FreeBSD.
Future performance work may wish to investigate the benefits of
immediately evicting data from the cache which has been read or
written with the O_DIRECT flag. Functionally this behavior is
very similar to applying the 'primarycache=metadata' property
per open file.
2. O_DIRECT _MAY_ impose restrictions on IO alignment and length.
No additional alignment or length restrictions are imposed.
3. O_DIRECT _MAY_ perform unbuffered IO operations directly
between user memory and block device.
No unbuffered IO operations are currently supported. In order
to support features such as transparent compression, encryption,
and checksumming a copy must be made to transform the data.
4. O_DIRECT _MAY_ imply O_DSYNC (XFS).
O_DIRECT does not imply O_DSYNC for ZFS. Callers must provide
O_DSYNC to request synchronous semantics.
5. O_DIRECT _MAY_ disable file locking that serializes IO
operations. Applications should avoid mixing O_DIRECT
and normal IO or mmap(2) IO to the same file. This is
particularly true for overlapping regions.
All I/O in ZFS is locked for correctness and this locking is not
disabled by O_DIRECT. However, concurrently mixing O_DIRECT,
mmap(2), and normal I/O on the same file is not recommended.
This change is implemented by layering the aops->direct_IO operations
on the existing AIO operations. Code already existed in ZFS on Linux
for bypassing the page cache when O_DIRECT is specified.
References:
* http://xfs.org/docs/xfsdocs-xml-dev/XFS_User_Guide/tmp/en-US/html/ch02s09.html
* https://blogs.oracle.com/roch/entry/zfs_and_directio
* https://ext4.wiki.kernel.org/index.php/Clarifying_Direct_IO's_Semantics
* https://illumos.org/man/3c/directio
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#224Closes#7823
Using VERIFY3S allows to view the unexpected error value in the system
log.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Don Brady <don.brady@delphix.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
Issue #7809Closes#7818
This patch fixes 2 issues with raw, deduplicated send streams. The
first is that datasets who had been completely received earlier in
the stream were not still marked as raw receives. This caused
problems when newly received datasets attempted to fetch raw data
from these datasets without this flag set.
The second problem was that the arc freeze checksum code was not
consistent about which locks needed to be held while performing
its asserts. The proper locking needed to run these asserts is
actually fairly nuanced, since the asserts touch the linked list
of buffers (requiring the header lock), the arc_state (requiring
the b_evict_lock), and the b_freeze_cksum (requiring the
b_freeze_lock). This seems like a large performance sacrifice and
a lot of unneeded complexity to verify that this relatively small
debug feature is working as intended, so this patch simply removes
these asserts instead.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#7701
The following patch introduces a few statistics on reads and writes
grouped by dataset. These statistics are implemented as kstats
(backed by aggregate sums for performance) and can be retrieved by
using the dataset objset ID number. The motivation for this change is
to provide some preliminary analytics on dataset usage/performance.
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Closes#7705
The error path must free the memory allocated by this function or
it will be leaked. In practice, this would leak only a few bytes
of memory under rare circumstances and thus is unlikely to have
caused any real problems. This issue was caught by the kmemleak.
Reviewed-by: Giuseppe Di Natale <guss80@gmail.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#7791
This patch fixes a bug where attempting to receive a send stream
with embedded data into an encrypted dataset would not cleanup
that dataset when the error was reached. The check was moved into
dmu_recv_begin_check(), preventing this issue.
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#7650
One small integration that was absent from b52563 was
support for zfs recv -o / -x with regards to encryption
parameters. The main use cases of this are as follows:
* Receiving an unencrypted stream as encrypted without
needing to create a "dummy" encrypted parent so that
encryption can be inheritted.
* Allowing users to change their keylocation on receive,
so long as the receiving dataset is an encryption root.
* Allowing users to explicitly exclude or override the
encryption property from an unencrypted properties stream,
allowing it to be received as encrypted.
* Receiving a recursive heirarchy of unencrypted datasets,
encrypting the top-level one and forcing all children to
inherit the encryption.
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#7650
Fix comment on calculating blkid at level n within dnode's blkptrs.
"(2^(level*(indblkshift - SPA_BLKPTRSHIFT)" is part of divisor
in this division.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@osnexus.com>
Closes#7768
This change modifies how 'checksum' and 'dedup' properties are verified
in zfs_check_settable() handling the case where they are explicitly
inherited in the dataset hierarchy when receiving a recursive send
stream.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#7755Closes#7576Closes#7757
Reviewed by: Thomas Caputi <tcaputi@datto.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Don Brady <don.brady@delphix.com>
Closes#7759
When doing a read from disk, ZFS creates 3 ZIO's: a zio_null(), the
logical zio_read(), and then a physical zio. Currently, each of these
results in a separate taskq_dispatch(zio_execute).
On high-read-iops workloads, this causes a significant performance
impact. By processing all 3 ZIO's in a single taskq entry, we reduce the
overhead on taskq locking and context switching. We accomplish this by
allowing zio_done() to return a "next zio to execute" to zio_execute().
This results in a ~12% performance increase for random reads, from
96,000 iops to 108,000 iops (with recordsize=8k, on SSD's).
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: George Wilson <george.wilson@delphix.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
External-issue: DLPX-59292
Closes#7736
Linux specific zpl_* entry points, such as xattrs, must include
the same unmounted and sa handle checks as the common zfs_ entry
points. The additional ZPL_* wrappers are identical to their
ZFS_ counterparts except the errno is negated since they are
expected to be used at the zpl_ layer.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: John Gallagher <john.gallagher@delphix.com>
Closes#5866Closes#7761
This change reintroduces logic required by OpenZFS 9577. When
OpenZFS 9337, zfs get all is slow due to uncached metadata, was
merged in it ended up removing logic required by OpenZFS 9577,
remove zfs_dbuf_evict_key, and inadvertently reintroduced the
bug that 9577 was designed to fix.
This change re-enables the "evicting" flag to dbuf_rele_and_unlock
and dnode_rele_and_unlock and updates all callers to provide the
correct parameter.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Wilson <george.wilson@delphix.com>
Closes#7758
zfs umount -> zfsctl_destroy() takes the zfs_snapshot_lock as a
writer and calls zfsctl_snapshot_unmount_cancel(), which waits
for snapentry_expire() if present (when snap is automounted).
This snapentry_expire() itself then waits for zfs_snapshot_lock
as a reader, resulting in a deadlock.
The fix is to only hold the zfs_snapshot_lock over the tree
lookup and removal. After a successful lookup the lock can
be dropped and zfs_snapentry_t will remain valid until the
reference taken by the lookup is released.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rohan Puri <rohan.puri15@gmail.com>
Closes#7751Closes#7752
Overview
========
We parallelize the allocation process by creating the concept of
"allocators". There are a certain number of allocators per metaslab
group, defined by the value of a tunable at pool open time. Each
allocator for a given metaslab group has up to 2 active metaslabs; one
"primary", and one "secondary". The primary and secondary weight mean
the same thing they did in in the pre-allocator world; primary metaslabs
are used for most allocations, secondary metaslabs are used for ditto
blocks being allocated in the same metaslab group. There is also the
CLAIM weight, which has been separated out from the other weights, but
that is less important to understanding the patch. The active metaslabs
for each allocator are moved from their normal place in the metaslab
tree for the group to the back of the tree. This way, they will not be
selected for use by other allocators searching for new metaslabs unless
all the passive metaslabs are unsuitable for allocations. If that does
happen, the allocators will "steal" from each other to ensure that IOs
don't fail until there is truly no space left to perform allocations.
In addition, the alloc queue for each metaslab group has been broken
into a separate queue for each allocator. We don't want to dramatically
increase the number of inflight IOs on low-end systems, because it can
significantly increase txg times. On the other hand, we want to ensure
that there are enough IOs for each allocator to allow for good
coalescing before sending the IOs to the disk. As a result, we take a
compromise path; each allocator's alloc queue max depth starts at a
certain value for every txg. Every time an IO completes, we increase the
max depth. This should hopefully provide a good balance between the two
failure modes, while not dramatically increasing complexity.
We also parallelize the spa_alloc_tree and spa_alloc_lock, which cause
very similar contention when selecting IOs to allocate. This
parallelization uses the same allocator scheme as metaslab selection.
Performance Results
===================
Performance improvements from this change can vary significantly based
on the number of CPUs in the system, whether or not the system has a
NUMA architecture, the speed of the drives, the values for the various
tunables, and the workload being performed. For an fio async sequential
write workload on a 24 core NUMA system with 256 GB of RAM and 8 128 GB
SSDs, there is a roughly 25% performance improvement.
Future Work
===========
Analysis of the performance of the system with this patch applied shows
that a significant new bottleneck is the vdev disk queues, which also
need to be parallelized. Prototyping of this change has occurred, and
there was a performance improvement, but more work needs to be done
before its stability has been verified and it is ready to be upstreamed.
Authored by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Alexander Motin <mav@FreeBSD.org>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Gordon Ross <gwr@nexenta.com>
Ported-by: Paul Dagnelie <pcd@delphix.com>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Porting Notes:
* Fix reservation test failures by increasing tolerance.
OpenZFS-issue: https://illumos.org/issues/9112
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/3f3cc3c3Closes#7682
In the case of one pool being built on another pool, we want
to make sure we don't end up throttling the lower (backing)
pool when the upper pool is the majority contributor to dirty
data. To insure we make forward progress during throttling, we
also check the current pool's net dirty data and only throttle
if it exceeds zfs_arc_pool_dirty_percent of the anonymous dirty
data in the cache.
Authored by: Don Brady <don.brady@delphix.com>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed by: Prashanth Sreenivasa <pks@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Porting Notes:
* The new global variables zfs_arc_dirty_limit_percent,
zfs_arc_anon_limit_percent, and zfs_arc_pool_dirty_percent
were intentially not added as tunable module parameters.
OpenZFS-issue: https://illumos.org/issues/9465
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/d6a4c3efCloses#7749
= Motivation
While dealing with another performance issue (see 126118f) we noticed
that we spend a lot of time in various places in the kernel when
constructing long nvlists. The problem is that when an nvlist is created
with the NV_UNIQUE_NAME set (which is the case most of the time), we do
a linear search through the whole list to ensure uniqueness for every
entry we add.
An example of the above scenario can be seen in the following
flamegraph, where more than have the time of the zfsdev_ioctl() is spent
on constructing nvlists. Flamegraph:
https://sdimitro.github.io/img/flame/sdimitro_snap_unmount3.svg
Adding a table to speed up lookups will help situations where we just
construct an nvlist (like the scenario above), in addition to regular
lookups and removals.
= What this patch does
In this diff we've implemented a hash-table on top of the nvlist code
that converts most nvlist operations from O(# number of entries) to
O(1)* (the start is for amortized time as the hash-table grows and
shrinks depending on the # of entries - plain lookup is strictly O(1)).
= Performance Analysis
To analyze the performance improvement I just used the setup from the
snapshot deletion issue mentioned above in the Motivation section.
Basically I created 10K filesystems with one snapshot each and then I
just used the API of libZFS_Core to pass down an nvlist of all the
snapshots to have them deleted. The reason I used my own driver program
was to have clean performance results of what actually happens in the
kernel. The flamegraphs and wall clock times mentioned below were
gathered from the start to the end of the driver program's run. Between
trials the testpool used was completely destroyed, the system was
rebooted and the testpool was completely recreated. The reason for this
dance was to get consistent results.
== Results (before patch):
=== Sampling Flamegraphs
[Trial 1] https://sdimitro.github.io/img/flame/DLPX-53417/trial-A.svg
[Trial 2] https://sdimitro.github.io/img/flame/DLPX-53417/trial-A2.svg
[Trial 3] https://sdimitro.github.io/img/flame/DLPX-53417/trial-A3.svg
=== Wall clock times (in seconds)
```
[Trial 4]
real 5.3
user 0.4
sys 2.3
[Trial 5]
real 8.2
user 0.4
sys 2.4
[Trial 6]
real 6.0
user 0.5
sys 2.3
```
== Results (after patch):
=== Sampling Flamegraphs
[Trial 1] https://sdimitro.github.io/img/flame/DLPX-53417/trial-Ae.svg
[Trial 2] https://sdimitro.github.io/img/flame/DLPX-53417/trial-A2e.svg
[Trial 3] https://sdimitro.github.io/img/flame/DLPX-53417/trial-A3e.svg
=== Wall clock times (in seconds)
```
[Trial 4]
real 4.9
user 0.0
sys 0.9
[Trial 5]
real 3.8
user 0.0
sys 0.9
[Trial 6]
real 3.6
user 0.0
sys 0.9
```
== Analysis
The results between the trials are consistent so in this sections I will
only talk about the flamegraph results from trial-1 and the wall-clock
results from trial-4.
From trial-1 we can see that zfs_dev_ioctl() goes from 2,331 to 996
samples counts. Specifically, the samples from fnvlist_add_nvlist() and
spa_history_log_nvl() are almost gone (~500 & ~800 to 5 & 5 samples),
leaving zfs_ioc_destroy_snaps() to dominate most samples from
zfs_dev_ioctl().
From trial-4 we see that the user time dropped to 0 secods. I believe
the consistent 0.4 seconds before my patch was applied was due to my
driver program constructing the long nvlist of snapshots so it can pass
it to the kernel. As for the system time, the effect there is more clear
(2.3 down to 0.9 seconds).
Porting Notes:
* DATA_TYPE_DONTCARE case added to switch in fm_nvprintr() and
zpool_do_events_nvprint().
Authored by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/9580
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/b5eca7b1Closes#7748
Follow up commit for OpenZFS 9438. See the OpenZFS-issue link below
for a complete analysis.
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://illumos.org/issues/9439
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/779220d
External-issue: DLPX-46861
Closes#7746
As reported by https://github.com/zfsonlinux/zfs/issues/4996, there is
yet another hole birth issue. In this one, if a block is entirely holes,
but the birth times are not all the same, we lose that information by
creating one hole with the current txg as its birth time.
The ZoL PR's fix approach is incorrect. Ultimately, the problem here is
that when you truncate and write a file in the same transaction group,
the dbuf for the indirect block will be zeroed out to deal with the
truncation, and then written for the write. During this process, we will
lose hole birth time information for any holes in the range. In the case
where a dnode is being freed, we need to determine whether the block
should be converted to a higher-level hole in the zio pipeline, and if
so do it when the dnode is being synced out.
Porting Notes:
* The DMU_OBJECT_END change in zfs_znode.c was already applied.
* Added test cases from #5675 provided by @rincebrain for hole_birth
issues. These test cases should be pushed upstream to OpenZFS.
* Updated mk_files which is used by several rsend tests so the
files created are a little more interesting and may contain holes.
Authored by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/9438
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/738e2a3c
External-issue: DLPX-46861
Closes#7746
Porting notes:
* As of grub-2.02 these checksums are not supported. However, as
pointed out in #6501 there are alternatives such as EFISTUB which
work and have no such restriction. A warning was added to the
checksum property section of the zfs.8 man page.
Authored by: Toomas Soome <tsoome@me.com>
Reviewed by: C Fraire <cfraire@me.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Yuri Pankov <yuripv@yuripv.net>
Approved by: Dan McDonald <danmcd@joyent.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://illumos.org/issues/8906
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7dec52fCloses#6501Closes#7714
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Albert Lee <trisk@forkgnu.org>
Reviewed by: Igor Kozhukhov <igor@dilos.org>
Reviewed by: George Melikov <mail@gmelikov.ru>
Approved by: Dan McDonald <danmcd@joyent.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Updates to indirect blocks of spacemaps can contribute significantly to
write inflation. Therefore we want to reduce the indirect block size of
spacemaps from 128K to 16K.
Porting notes:
* Refactored to allow the dmu_object_alloc(), dmu_object_alloc_ibs()
and dmu_object_alloc_dnsize() functions to use a common shared
dmu_object_alloc_impl() function.
OpenZFS-issue: https://www.illumos.org/issues/9442
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/0c2e6408bCloses#7712
It is helpful to tune zfs_per_txg_dirty_frees_percent for commit
539d33c7(OpenZFS 6569 - large file delete can starve out write ops).
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Richard Elling <Richard.Elling@RichardElling.com>
Signed-off-by: Feng Sun <loyou85@gmail.com>
Closes#7718
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prashanth Sreenivasa <pks@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Giuseppe Di Natale <guss80@gmail.com>
Reviewed by: George Melikov <mail@gmelikov.ru>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
While investigating a different problem, I noticed that moved dnodes
(those processed by dnode_move_impl() via kmem_move()) have an incorrect
dn_next_type. This could cause the on-disk dn_type to be changed to an
invalid value. The fix to copy the dn_next_type in dnode_move_impl().
Porting notes:
* For the moment this potential issue cannot occur on Linux since
the SPL does not provide the kmem_move() functionality.
OpenZFS-issue: https://illumos.org/issues/9338
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/0717e6f13Closes#7715
The arc_hdr_realloc_crypt() function is responsible for converting
a "full" arc header to an extended "crypt" header and visa versa.
This code was originally written with a bcopy() so that any new
members added to arc headers would automatically be included
without requiring a code change. However, in practice this (along
with small differences in kmem_cache implementations between
various platforms) has caused a number of hard-to-find problems in
ports to other operating systems. This patch solves this problem
by making all member copies explicit and adding ASSERTs for fields
that cannot be set during the transfer. It also manually resets the
old header after the reallocation is finished so it can be properly
reallocated and reused.
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#7711
We were doing count_block() twice inside this function, once
unconditionally at the beginning (intended to catch the embedded block
case) and once near the end after processing the block.
The double-accounting caused the "zpool scrub" progress statistics in
"zpool status" to climb from 0% to 200% instead of 0% to 100%, and
showed double the I/O rate it was actually seeing.
This was apparently a regression introduced in commit 00c405b4b5,
which was an incorrect port of this OpenZFS commit:
https://github.com/openzfs/openzfs/commit/d8a447a7
Reviewed by: Thomas Caputi <tcaputi@datto.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Closes#7720Closes#7738
While the autoexpand property may seem like a small feature it
depends on a significant amount of system infrastructure. Enough
of that infrastructure is now in place that with a few modifications
for Linux it can be supported.
Auto-expand works as follows; when a block device is modified
(re-sized, closed after being open r/w, etc) a change uevent is
generated for udev. The ZED, which is monitoring udev events,
passes the change event along to zfs_deliver_dle() if the disk
or partition contains a zfs_member as identified by blkid.
From here the device is matched against all imported pool vdevs
using the vdev_guid which was read from the label by blkid. If
a match is found the ZED reopens the pool vdev. This re-opening
is important because it allows the vdev to be briefly closed so
the disk partition table can be re-read. Otherwise, it wouldn't
be possible to report the maximum possible expansion size.
Finally, if the property autoexpand=on a vdev expansion will be
attempted. After performing some sanity checks on the disk to
verify that it is safe to expand, the primary partition (-part1)
will be expanded and the partition table updated. The partition
is then re-opened (again) to detect the updated size which allows
the new capacity to be used.
In order to make all of the above possible the following changes
were required:
* Updated the zpool_expand_001_pos and zpool_expand_003_pos tests.
These tests now create a pool which is layered on a loopback,
scsi_debug, and file vdev. This allows for testing of non-
partitioned block device (loopback), a partition block device
(scsi_debug), and a file which does not receive udev change
events. This provided for better test coverage, and by removing
the layering on ZFS volumes there issues surrounding layering
one pool on another are avoided.
* zpool_find_vdev_by_physpath() updated to accept a vdev guid.
This allows for matching by guid rather than path which is a
more reliable way for the ZED to reference a vdev.
* Fixed zfs_zevent_wait() signal handling which could result
in the ZED spinning when a signal was not handled.
* Removed vdev_disk_rrpart() functionality which can be abandoned
in favor of kernel provided blkdev_reread_part() function.
* Added a rwlock which is held as a writer while a disk is being
reopened. This is important to prevent errors from occurring
for any configuration related IOs which bypass the SCL_ZIO lock.
The zpool_reopen_007_pos.ksh test case was added to verify IO
error are never observed when reopening. This is not expected
to impact IO performance.
Additional fixes which aren't critical but were discovered and
resolved in the course of developing this functionality.
* Added PHYS_PATH="/dev/zvol/dataset" to the vdev configuration for
ZFS volumes. This is as good as a unique physical path, while the
volumes are not used in the test cases anymore for other reasons
this improvement was included.
Reviewed by: Richard Elling <Richard.Elling@RichardElling.com>
Signed-off-by: Sara Hartse <sara.hartse@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#120Closes#2437Closes#5771Closes#7366Closes#7582Closes#7629
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). There are two parts:
The dbuf_metadata_cache. We identify what to put into the cache based on
the object type of each dbuf. Caching objset properties os
{version,normalization,utf8only,casesensitivity} in the objset_t. The reason
these needed to be cached is that although they are queried frequently,
they aren't stored in a dbuf type which we can easily recognize and cache in
the dbuf layer; instead, we have to explicitly store them. There's already
existing infrastructure for maintaining cached properties in the objset
setup code, so I simply used that.
Performance Testing:
- Disabled kmem_flags
- Tuned dbuf_cache_max_bytes very low (128K)
- Tuned zfs_arc_max very low (64M)
Created test pool with 400 filesystems, and 100 snapshots per filesystem.
Later on in testing, added 600 more filesystems (with no snapshots) to make
sure scaling didn't look different between snapshots and filesystems.
Results:
| Test | Time (trunk / diff) | I/Os (trunk / diff) |
+------------------------+---------------------+---------------------+
| zpool import | 0:05 / 0:06 | 12.9k / 12.9k |
| zfs get all (uncached) | 1:36 / 0:53 | 16.7k / 5.7k |
| zfs get all (cached) | 1:36 / 0:51 | 16.0k / 6.0k |
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Thomas Caputi <tcaputi@datto.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Richard Lowe <richlowe@richlowe.net>
Ported-by: Alek Pinchuk <apinchuk@datto.com>
Signed-off-by: Alek Pinchuk <apinchuk@datto.com>
OpenZFS-issue: https://illumos.org/issues/9337
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7dec52fCloses#7668
Commit 93b43af10 inadvertently introduced the following scenario which
can result in a deadlock. This issue was most easily reproduced by
LXD containers using a ZFS storage backend but should be reproducible
under any workload which is frequently mounting and unmounting.
-- THREAD A --
spa_sync()
spa_sync_upgrades()
rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG); <- Waiting on B
-- THREAD B --
mount_fs()
zpl_mount()
zpl_mount_impl()
dmu_objset_hold()
dmu_objset_hold_flags()
dsl_pool_hold()
dsl_pool_config_enter()
rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
sget()
sget_userns()
grab_super()
down_write(&s->s_umount); <- Waiting on C
-- THREAD C --
cleanup_mnt()
deactivate_super()
down_write(&s->s_umount);
deactivate_locked_super()
zpl_kill_sb()
kill_anon_super()
generic_shutdown_super()
sync_filesystem()
zpl_sync_fs()
zfs_sync()
zil_commit()
txg_wait_synced() <- Waiting on A
Reviewed by: Alek Pinchuk <apinchuk@datto.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#7598Closes#7659Closes#7691Closes#7693
Update the SA_COPY_DATA macro to check if architecture supports
efficient unaligned memory accesses at compile time. Otherwise
fallback to using the sa_copy_data() function.
The kernel provided CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is
used to determine availability in kernel space. In user space
the x86_64, x86, powerpc, and sometimes arm architectures will
define the HAVE_EFFICIENT_UNALIGNED_ACCESS macro.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#7642Closes#7684
Ztest failed with the following crash.
::status
debugging core file of ztest (64-bit) from clone-dc-slave-280-bc7947b1.dcenter
file: /usr/bin/amd64/ztest
initial argv: /usr/bin/amd64/ztest
threading model: raw lwps
status: process terminated by SIGABRT (Abort), pid=2150 uid=1025 code=-1
panic message: failure for thread 0xfffffd7fff112a40, thread-id 1: unprotected error in call to Lua API (Invalid
value type 'function' for key 'error')
::stack
libc.so.1`_lwp_kill+0xa()
libc.so.1`_assfail+0x182(fffffd7fffdfe8d0, 0, 0)
libc.so.1`assfail+0x19(fffffd7fffdfe8d0, 0, 0)
libzpool.so.1`vpanic+0x3d(fffffd7ffaa58c20, fffffd7fffdfeb00)
0xfffffd7ffaa28146()
0xfffffd7ffaa0a109()
libzpool.so.1`luaD_throw+0x86(3011a48, 2)
0xfffffd7ffa9350d3()
0xfffffd7ffa93e3f1()
libzpool.so.1`zcp_lua_to_nvlist+0x33(3011a48, 1, 2686470, fffffd7ffaa2e2c3)
libzpool.so.1`zcp_convert_return_values+0xa4(3011a48, 2686470, fffffd7ffaa2e2c3, fffffd7fffdfedd0)
libzpool.so.1`zcp_pool_error+0x59(fffffd7fffdfedd0, 1e0f450)
libzpool.so.1`zcp_eval+0x6f8(1e0f450, fffffd7ffaa483f8, 1, 0, 6400000, 1d33b30)
libzpool.so.1`dsl_destroy_snapshots_nvl+0x12c(2786b60, 0, 484750)
libzpool.so.1`dsl_destroy_snapshot+0x4f(fffffd7fffdfef70, 0)
ztest_dsl_dataset_cleanup+0xea(fffffd7fffdff4c0, 1)
ztest_dataset_destroy+0x53(1)
ztest_run+0x59f(fffffd7fff0e0498)
main+0x7ff(1, fffffd7fffdffa88)
_start+0x6c()
The problem is that zcp_convert_return_values() assumes that there's
exactly one value on the stack, but that isn't always true. It ends up
putting the wrong thing on the stack which is then consumed by
zcp_convert_return values, which either adds the wrong message to the
nvlist, or blows up.
The fix is to make sure that callers of zcp_convert_return_values()
clear the stack before pushing their error message, and
zcp_convert_return_values() should VERIFY that the stack is the expected
size.
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Don Brady <don.brady@delphix.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Robert Mustacchi <rm@joyent.com>
OpenZFS-issue: https://www.illumos.org/issues/9424
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/eb7e57429Closes#7696
When we do a scrub or resilver, ZFS counts the different types of blocks,
which can be printed by the ::zfs_blkstats mdb dcmd. However, it fails to
count embedded blocks.
Porting notes:
* Commit d4a72f23 moved count_blocks under a BP_IS_EMBEDDED conditional
as part of the sequential resilver functionality. Since phys_birth
would be zero that case should never happen as described above. This
is confirmed by the code coverage analysis. Remove the conditional
to realign that aspect of this function with OpenZFS.
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: George Melikov <mail@gmelikov.ru>
Reviewed by: Tom Caputi <tcaputi@datto.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Robert Mustacchi <rm@joyent.com>
OpenZFS-issue: https://www.illumos.org/issues/9454
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/d8a447a7Closes#7697
Problem
=======
Illumos bug 8373 was integrated, which now presents a code path where
"dmu_tx_assign" can fail. When "dmu_tx_assign" fails, it will not issue
the lwb that was passed in to "zil_lwb_write_issue". As a result, when
"zil_lwb_write_issue" returns, the lwb will still be in the "opened"
state, just as it was when "zil_lwb_write_issue" was originally called.
Solution
========
As a result of this new call path, the failed assertion needs to be
modified to be aware of this new possibility. Thus, we can only assert
that the lwb is no longer in the "opened" state if the returned lwb is
non-null, since we cannot differentiate between the case of
"dmu_tx_assign" failing or "zio_alloc_zil" failing within the call to
"zil_lwb_write_issue".
Authored by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: George Melikov <mail@gmelikov.ru>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Matt Ahrens <mahrens@delphix.com>
OpenZFS-issue: https://www.illumos.org/issues/9456
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/a8b09f4eCloses#7695
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.
The problem can be seen by attempting to create a dataset using the -p
option with many levels:
panic[cpu0]/thread=ffffff01cd282c20: BAD TRAP: type=8 (#df Double fault) rp=ffffffff
fffffffffbc3aa60 unix:die+100 ()
fffffffffbc3ab70 unix:trap+157d ()
ffffff00083d7020 unix:_patch_xrstorq_rbx+196 ()
ffffff00083d7050 zfs:dbuf_rele+2e ()
...
ffffff00083d7080 zfs:dsl_dir_close+32 ()
ffffff00083d70b0 zfs:dsl_dir_evict+30 ()
ffffff00083d70d0 zfs:dbuf_evict_user+4a ()
ffffff00083d7100 zfs:dbuf_rele_and_unlock+87 ()
ffffff00083d7130 zfs:dbuf_rele+2e ()
... The block above repeats once per directory in the ...
... create -p command, working towards the root ...
ffffff00083db9f0 zfs:dsl_dataset_drop_ref+19 ()
ffffff00083dba20 zfs:dsl_dataset_rele+42 ()
ffffff00083dba70 zfs:dmu_objset_prefetch+e4 ()
ffffff00083dbaa0 zfs:findfunc+23 ()
ffffff00083dbb80 zfs:dmu_objset_find_spa+38c ()
ffffff00083dbbc0 zfs:dmu_objset_find+40 ()
ffffff00083dbc20 zfs:zfs_ioc_snapshot_list_next+4b ()
ffffff00083dbcc0 zfs:zfsdev_ioctl+347 ()
ffffff00083dbd00 genunix:cdev_ioctl+45 ()
ffffff00083dbd40 specfs:spec_ioctl+5a ()
ffffff00083dbdc0 genunix:fop_ioctl+7b ()
ffffff00083dbec0 genunix:ioctl+18e ()
ffffff00083dbf10 unix:brand_sys_sysenter+1c9 ()
Porting notes:
* Added zfs_max_dataset_nesting module option with documentation.
* Updated zfs_rename_014_neg.ksh for Linux.
* Increase the zfs.sh stack warning to 15K. Enough time has passed
that 16K can be reasonably assumed to be the default value. It
was increased in the 3.15 kernel released in June of 2014.
Authored by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Garrett D'Amore <garrett@damore.org>
OpenZFS-issue: https://www.illumos.org/issues/9330
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/757a75aCloses#7681
Motivation
==========
The current space map encoding has the following disadvantages:
[1] Assuming 512 sector size each entry can represent at most 16MB for a segment.
This makes the encoding very inefficient for large regions of space.
[2] As vdev-wide space maps have started to be used by new features (i.e.
device removal, zpool checkpoint) we've started imposing limits in the
vdevs that can be used with them based on the maximum addressable offset
(currently 64PB for a top-level vdev).
New encoding
============
The layout can be found at space_map.h and it remains backwards compatible with
the old one. The introduced two-word entry format, besides extending the limits
imposed by the single-entry layout, also includes a vdev field and some extra
padding after its prefix.
The extra padding after the prefix should is reserved for future usage (e.g.
new prefixes for future encodings or new fields for flags). The new vdev field
not only makes the space maps more self-descriptive, but also opens the doors
for pool-wide space maps (expected to be used in the log spacemap project).
One final important note is that the number of bits used for vdevs is reduced
to 24 bits for blkptrs. That was decided as we don't know of any setups that
use more than 16M vdevs for the time being and we wanted to fit the vdev field
in the space map. In addition that gives us some extra bits in dva_t.
Other references:
=================
The new encoding is also discussed towards the end of the Log Space Map
presentation from 2017's OpenZFS summit.
Link: https://www.youtube.com/watch?v=jj2IxRkl5bQ
Authored by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <gwilson@zfsmail.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Gordon Ross <gwr@nexenta.com>
Ported-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/90a56e6d
OpenZFS-issue: https://www.illumos.org/issues/9238Closes#7665
