Contributing to ZFS on Linux

First of all, thank you for taking the time to contribute!

By using the following guidelines, you can help us make ZFS on Linux even better.

What should I know before I get started?

Get ZFS

You can build zfs packages by following these instructions, or install stable packages from your distribution's repository.

Debug ZFS

A variety of methods and tools are available to aid ZFS developers. It's strongly recommended that when developing a patch the --enable-debug configure option should be set. This will enable additional correctness checks and all the ASSERTs to help quickly catch potential issues.

In addition, there are numerous utilities and debugging files which provide visibility in to the inner workings of ZFS. The most useful of these tools are discussed in detail on the debugging ZFS wiki page.

Where can I ask for help?

The mailing list is the best place to ask for help.

How Can I Contribute?

Reporting Bugs

Please contact us via the mailing list if you aren't certain that you are experiencing a bug.

If you run into an issue, please search our issue tracker first to ensure the issue hasn't been reported before. Open a new issue only if you haven't found anything similar to your issue.

You can open a new issue and search existing issues using the public issue tracker.

When opening a new issue, please include the following information at the top of the issue:

What distribution (with version) you are using.
The spl and zfs versions you are using, installation method (repository or manual compilation).
Describe the issue you are experiencing.
Describe how to reproduce the issue.
Including any warning/errors/backtraces from the system logs.

When a new issue is opened, it is not uncommon for developers to request additional information.

In general, the more detail you share about a problem the quicker a developer can resolve it. For example, providing a simple test case is always exceptionally helpful.

Be prepared to work with the developers investigating your issue. Your assistance is crucial in providing a quick solution. They may ask for information like:

Your pool configuration as reported by zdb or zpool status.
Your hardware configuration, such as
- Number of CPUs.
- Amount of memory.
- Whether your system has ECC memory.
- Whether it is running under a VMM/Hypervisor.
- Kernel version.
- Values of the spl/zfs module parameters.
Stack traces which may be logged to dmesg.

Suggesting Enhancements

ZFS on Linux is a widely deployed production filesystem which is under active development. The team's primary focus is on fixing known issues, improving performance, and adding compelling new features.

You can view the list of proposed features by filtering the issue tracker by the "Feature" label. If you have an idea for a feature first check this list. If your idea already appears then add a +1 to the top most comment, this helps us gauge interest in that feature.

Otherwise, open a new issue and describe your proposed feature. Why is this feature needed? What problem does it solve?

Pull Requests

All pull requests must be based on the current master branch and apply without conflicts.
Please attempt to limit pull requests to a single commit which resolves one specific issue.
Make sure your commit messages are in the correct format. See the Commit Message Formats section for more information.
When updating a pull request squash multiple commits by performing a rebase (squash).
For large pull requests consider structuring your changes as a stack of logically independent patches which build on each other. This makes large changes easier to review and approve which speeds up the merging process.
Try to keep pull requests simple. Simple code with comments is much easier to review and approve.
Test cases should be provided when appropriate.
If your pull request improves performance, please include some benchmarks.
The pull request must pass all required ZFS Buildbot builders before being accepted. If you are experiencing intermittent TEST builder failures, you may be experiencing a test suite issue. There are also various buildbot options to control how changes are tested.
All proposed changes must be approved by a ZFS on Linux organization member.

Testing

All help is appreciated! If you're in a position to run the latest code consider helping us by reporting any functional problems, performance regressions or other suspected issues. By running the latest code to a wide range of realistic workloads, configurations and architectures we're better able quickly identify and resolve potential issues.

Users can also run the ZFS Test Suite on their systems to verify ZFS is behaving as intended.

Style Guides

Coding Conventions

We currently use C Style and Coding Standards for SunOS as our coding convention.

Commit Message Formats

New Changes

Commit messages for new changes must meet the following guidelines:

In 50 characters or less, provide a summary of the change as the first line in the commit message.
A body which provides a description of the change. If necessary, please summarize important information such as why the proposed approach was chosen or a brief description of the bug you are resolving. Each line of the body must be 72 characters or less.
The last line must be a Signed-off-by: tag with the developer's name followed by their email. This is the developer's certification that they have the right to submit the patch for inclusion into the code base and indicates agreement to the Developer's Certificate of Origin. Code without a proper signoff cannot be merged.

Git can append the Signed-off-by line to your commit messages. Simply provide the -s or --signoff option when performing a git commit. For more information about writing commit messages, visit How to Write a Git Commit Message. An example commit message is provided below.

This line is a brief summary of your change

Please provide at least a couple sentences describing the
change. If necessary, please summarize decisions such as
why the proposed approach was chosen or what bug you are
attempting to solve.

Signed-off-by: Contributor <contributor@email.com>

OpenZFS Patch Ports

If you are porting an OpenZFS patch, the commit message must meet the following guidelines:

The first line must be the summary line from the OpenZFS commit. It must begin with OpenZFS dddd - where dddd is the OpenZFS issue number.
Provides a Authored by: line to attribute the patch to the original author.
Provides the Reviewed by: and Approved by: lines from the original OpenZFS commit.
Provides a Ported-by: line with the developer's name followed by their email.
Provides a OpenZFS-issue: line which is a link to the original illumos issue.
Provides a OpenZFS-commit: line which links back to the original OpenZFS commit.
If necessary, provide some porting notes to describe any deviations from the original OpenZFS commit.

An example OpenZFS patch port commit message is provided below.

OpenZFS 1234 - Summary from the original OpenZFS commit

Authored by: Original Author <original@email.com>
Reviewed by: Reviewer One <reviewer1@email.com>
Reviewed by: Reviewer Two <reviewer2@email.com>
Approved by: Approver One <approver1@email.com>
Ported-by: ZFS Contributor <contributor@email.com>

Provide some porting notes here if necessary.

OpenZFS-issue: https://www.illumos.org/issues/1234
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/abcd1234

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