OpenZFS on Linux and FreeBSD
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George Wilson c15d36c674
Remove dependency on sharetab file and refactor sharing logic
== Motivation and Context

The current implementation of 'sharenfs' and 'sharesmb' relies on
the use of the sharetab file. The use of this file is os-specific
and not required by linux or freebsd. Currently the code must
maintain updates to this file which adds complexity and presents
a significant performance impact when sharing many datasets. In
addition, concurrently running 'zfs sharenfs' command results in
missing entries in the sharetab file leading to unexpected failures.

== Description

This change removes the sharetab logic from the linux and freebsd
implementation of 'sharenfs' and 'sharesmb'. It still preserves an
os-specific library which contains the logic required for sharing
NFS or SMB. The following entry points exist in the vastly simplified
libshare library:

- sa_enable_share -- shares a dataset but may not commit the change
- sa_disable_share -- unshares a dataset but may not commit the change
- sa_is_shared -- determine if a dataset is shared
- sa_commit_share -- notify NFS/SMB subsystem to commit the shares
- sa_validate_shareopts -- determine if sharing options are valid

The sa_commit_share entry point is provided as a performance enhancement
and is not required. The sa_enable_share/sa_disable_share may commit
the share as part of the implementation. Libshare provides a framework
for both NFS and SMB but some operating systems may not fully support
these protocols or all features of the protocol.

NFS Operation:
For linux, libshare updates /etc/exports.d/zfs.exports to add
and remove shares and then commits the changes by invoking
'exportfs -r'. This file, is automatically read by the kernel NFS
implementation which makes for better integration with the NFS systemd
service. For FreeBSD, libshare updates /etc/zfs/exports to add and
remove shares and then commits the changes by sending a SIGHUP to
mountd.

SMB Operation:
For linux, libshare adds and removes files in /var/lib/samba/usershares
by calling the 'net' command directly. There is no need to commit the
changes. FreeBSD does not support SMB.

== Performance Results

To test sharing performance we created a pool with an increasing number
of datasets and invoked various zfs actions that would enable and
disable sharing. The performance testing was limited to NFS sharing.
The following tests were performed on an 8 vCPU system with 128GB and
a pool comprised of 4 50GB SSDs:

Scale testing:
- Share all filesystems in parallel -- zfs sharenfs=on <dataset> &
- Unshare all filesystems in parallel -- zfs sharenfs=off <dataset> &

Functional testing:
- share each filesystem serially -- zfs share -a
- unshare each filesystem serially -- zfs unshare -a
- reset sharenfs property and unshare -- zfs inherit -r sharenfs <pool>

For 'zfs sharenfs=on' scale testing we saw an average reduction in time
of 89.43% and for 'zfs sharenfs=off' we saw an average reduction in time
of 83.36%.

Functional testing also shows a huge improvement:
- zfs share -- 97.97% reduction in time
- zfs unshare -- 96.47% reduction in time
- zfs inhert -r sharenfs -- 99.01% reduction in time

Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Bryant G. Ly <bryangly@gmail.com>
Signed-off-by: George Wilson <gwilson@delphix.com>
External-Issue: DLPX-68690
Closes #1603
Closes #7692
Closes #7943
Closes #10300
2020-07-13 09:19:18 -07:00
.github Move cppcheck suppressions out of .github 2020-06-27 17:40:15 -07:00
cmd Remove dependency on sharetab file and refactor sharing logic 2020-07-13 09:19:18 -07:00
config Fix up FIND_SYSTEM_LIBRARY to work with cross-compiling 2020-07-10 14:26:40 -07:00
contrib Use abs_top_builddir when referencing libraries 2020-07-10 14:26:32 -07:00
etc Remove dependency on sharetab file and refactor sharing logic 2020-07-13 09:19:18 -07:00
include Remove dependency on sharetab file and refactor sharing logic 2020-07-13 09:19:18 -07:00
lib Remove dependency on sharetab file and refactor sharing logic 2020-07-13 09:19:18 -07:00
man Add device rebuild feature 2020-07-03 11:05:50 -07:00
module filesystem_limit/snapshot_limit is incorrectly enforced against root 2020-07-11 17:18:02 -07:00
rpm Clean up lib dependencies 2020-07-10 14:26:00 -07:00
scripts Drop unnecessary srcdir paths 2020-06-24 18:20:18 -07:00
tests Remove dependency on sharetab file and refactor sharing logic 2020-07-13 09:19:18 -07:00
udev Fixes for make dist 2020-06-26 14:20:02 -07:00
.editorconfig Add an .editorconfig; document git whitespace settings 2020-01-27 13:32:52 -08:00
.gitignore Add FreeBSD support to OpenZFS 2020-04-14 11:36:28 -07:00
.gitmodules Add zimport.sh compatibility test script 2014-02-21 12:10:31 -08:00
.travis.yml Add .travis.yml 2017-11-13 09:18:18 -08:00
AUTHORS Update build system and packaging 2018-05-29 16:00:33 -07:00
CODE_OF_CONDUCT.md Add CODE_OF_CONDUCT.md 2019-04-30 10:58:45 -07:00
COPYRIGHT Fix typos 2020-06-09 21:24:09 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
META Linux 5.7 compat: blk_alloc_queue() 2020-04-09 09:16:46 -07:00
Makefile.am Add Makefile command to run checkbashisms on all /bin/sh scripts 2020-07-09 20:04:49 -07:00
NEWS Add NEWS file 2018-09-18 12:03:47 -07:00
NOTICE Update build system and packaging 2018-05-29 16:00:33 -07:00
README.md Update wiki links with new address 2020-06-03 19:46:31 -07:00
TEST Remove CI builder customization from TEST 2020-03-16 10:46:03 -07:00
autogen.sh Cause autogen.sh to fail if autoreconf fails 2018-07-06 09:27:37 -07:00
configure.ac Clean up lib dependencies 2020-07-10 14:26:00 -07:00
copy-builtin Move zfs_gitrev.h to build directory 2020-06-24 18:19:28 -07:00
cppcheck-suppressions.txt Move cppcheck suppressions out of .github 2020-06-27 17:40:15 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

README.md

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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite Linux distribution can be found at the ZoL Site.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS is released under a CDDL license. For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported Linux kernel versions.
  • Supported FreeBSD versions are 12-STABLE and 13-CURRENT.