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There is no real limit on the length of PR titles, other than whatever limit is imposed by the GitHub GUI/API. Signed-off-by: Nathan Cutler <ncutler@suse.com>
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521 lines
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==========================
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Submitting Patches to Ceph
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==========================
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This is based on Documentation/SubmittingPatches from the Linux kernel,
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but has pared down significantly and updated based on the Ceph project's
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best practices.
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The patch signing procedures and definitions are unmodified.
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SIGNING CONTRIBUTIONS
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=====================
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In order to keep the record of code attribution clean within the
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source repository, please follow these guidelines for signing
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patches submitted to the project. These definitions are taken
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from those used by the Linux kernel and many other open source
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projects.
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1. Sign your work
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-----------------
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To improve tracking of who did what, especially with patches that can
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percolate to their final resting place in the kernel through several
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layers of maintainers, we've introduced a "sign-off" procedure on
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patches that are being emailed around.
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The sign-off is a simple line at the end of the explanation for the
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patch, which certifies that you wrote it or otherwise have the right to
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pass it on as a open-source patch. The rules are pretty simple: if you
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can certify the below:
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Developer's Certificate of Origin 1.1
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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By making a contribution to this project, I certify that:
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(a) The contribution was created in whole or in part by me and I
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have the right to submit it under the open source license
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indicated in the file; or
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(b) The contribution is based upon previous work that, to the best
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of my knowledge, is covered under an appropriate open source
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license and I have the right under that license to submit that
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work with modifications, whether created in whole or in part
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by me, under the same open source license (unless I am
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permitted to submit under a different license), as indicated
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in the file; or
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(c) The contribution was provided directly to me by some other
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person who certified (a), (b) or (c) and I have not modified
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it.
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(d) I understand and agree that this project and the contribution
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are public and that a record of the contribution (including all
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personal information I submit with it, including my sign-off) is
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maintained indefinitely and may be redistributed consistent with
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this project or the open source license(s) involved.
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then you just add a line saying ::
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Signed-off-by: Random J Developer <random@developer.example.org>
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using your real name (sorry, no pseudonyms or anonymous contributions.)
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Some people also put extra tags at the end. They'll just be ignored for
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now, but you can do this to mark internal company procedures or just
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point out some special detail about the sign-off.
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If you are a subsystem or branch maintainer, sometimes you need to slightly
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modify patches you receive in order to merge them, because the code is not
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exactly the same in your tree and the submitters'. If you stick strictly to
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rule (c), you should ask the submitter to rediff, but this is a totally
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counter-productive waste of time and energy. Rule (b) allows you to adjust
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the code, but then it is very impolite to change one submitter's code and
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make them endorse your bugs. To solve this problem, it is recommended that
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you add a line between the last Signed-off-by header and yours, indicating
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the nature of your changes. While there is nothing mandatory about this, it
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seems like prepending the description with your mail and/or name, all
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enclosed in square brackets, is noticeable enough to make it obvious that
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you are responsible for last-minute changes. Example ::
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Signed-off-by: Random J Developer <random@developer.example.org>
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[lucky@maintainer.example.org: struct foo moved from foo.c to foo.h]
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Signed-off-by: Lucky K Maintainer <lucky@maintainer.example.org>
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This practise is particularly helpful if you maintain a stable branch and
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want at the same time to credit the author, track changes, merge the fix,
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and protect the submitter from complaints. Note that under no circumstances
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can you change the author's identity (the From header), as it is the one
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which appears in the changelog.
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Special note to back-porters: It seems to be a common and useful practise
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to insert an indication of the origin of a patch at the top of the commit
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message (just after the subject line) to facilitate tracking. For instance,
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here's what we see in 2.6-stable ::
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Date: Tue May 13 19:10:30 2008 +0000
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SCSI: libiscsi regression in 2.6.25: fix nop timer handling
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commit 4cf1043593db6a337f10e006c23c69e5fc93e722 upstream
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And here's what appears in 2.4 ::
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Date: Tue May 13 22:12:27 2008 +0200
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wireless, airo: waitbusy() won't delay
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[backport of 2.6 commit b7acbdfbd1f277c1eb23f344f899cfa4cd0bf36a]
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Whatever the format, this information provides a valuable help to people
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tracking your trees, and to people trying to trouble-shoot bugs in your
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tree.
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2. When to use ``Acked-by:`` and ``Cc:``
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----------------------------------------
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The ``Signed-off-by:`` tag indicates that the signer was involved in the
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development of the patch, or that he/she was in the patch's delivery path.
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If a person was not directly involved in the preparation or handling of a
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patch but wishes to signify and record their approval of it then they can
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arrange to have an ``Acked-by:`` line added to the patch's changelog.
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``Acked-by:`` is often used by the maintainer of the affected code when that
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maintainer neither contributed to nor forwarded the patch.
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``Acked-by:`` is not as formal as ``Signed-off-by:``. It is a record that the acker
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has at least reviewed the patch and has indicated acceptance. Hence patch
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mergers will sometimes manually convert an acker's "yep, looks good to me"
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into an ``Acked-by:``.
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``Acked-by:`` does not necessarily indicate acknowledgement of the entire patch.
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For example, if a patch affects multiple subsystems and has an ``Acked-by:`` from
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one subsystem maintainer then this usually indicates acknowledgement of just
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the part which affects that maintainer's code. Judgement should be used here.
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When in doubt people should refer to the original discussion in the mailing
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list archives.
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If a person has had the opportunity to comment on a patch, but has not
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provided such comments, you may optionally add a "Cc:" tag to the patch.
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This is the only tag which might be added without an explicit action by the
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person it names. This tag documents that potentially interested parties
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have been included in the discussion
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3. Using ``Reported-by:``, ``Tested-by:`` and ``Reviewed-by:``
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--------------------------------------------------------------
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If this patch fixes a problem reported by somebody else, consider adding a
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Reported-by: tag to credit the reporter for their contribution. Please
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note that this tag should not be added without the reporter's permission,
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especially if the problem was not reported in a public forum. That said,
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if we diligently credit our bug reporters, they will, hopefully, be
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inspired to help us again in the future.
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A ``Tested-by:`` tag indicates that the patch has been successfully tested (in
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some environment) by the person named. This tag informs maintainers that
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some testing has been performed, provides a means to locate testers for
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future patches, and ensures credit for the testers.
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``Reviewed-by:``, instead, indicates that the patch has been reviewed and found
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acceptable according to the Reviewer's Statement:
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Reviewer's statement of oversight
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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By offering my ``Reviewed-by:`` tag, I state that:
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(a) I have carried out a technical review of this patch to
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evaluate its appropriateness and readiness for inclusion into
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the mainline kernel.
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(b) Any problems, concerns, or questions relating to the patch
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have been communicated back to the submitter. I am satisfied
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with the submitter's response to my comments.
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(c) While there may be things that could be improved with this
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submission, I believe that it is, at this time, (1) a
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worthwhile modification to the kernel, and (2) free of known
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issues which would argue against its inclusion.
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(d) While I have reviewed the patch and believe it to be sound, I
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do not (unless explicitly stated elsewhere) make any
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warranties or guarantees that it will achieve its stated
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purpose or function properly in any given situation.
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A ``Reviewed-by`` tag is a statement of opinion that the patch is an
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appropriate modification of the kernel without any remaining serious
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technical issues. Any interested reviewer (who has done the work) can
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offer a ``Reviewed-by`` tag for a patch. This tag serves to give credit to
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reviewers and to inform maintainers of the degree of review which has been
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done on the patch. ``Reviewed-by:`` tags, when supplied by reviewers known to
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understand the subject area and to perform thorough reviews, will normally
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increase the likelihood of your patch getting into the kernel.
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PREPARING AND SENDING PATCHES
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=============================
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The upstream repository is managed by Git. You will find that it
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is easiest to work on the project and submit changes by using the
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git tools, both for managing your own code and for preparing and
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sending patches.
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The project will generally accept code either by pulling code directly from
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a published git tree (usually on github), or via patches emailed directly
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to the email list (ceph-devel@vger.kernel.org). For the kernel client,
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patches are expected to be reviewed in the email list. And for everything
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else, github is preferred due to the convenience of the 'pull request'
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feature.
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1. Github pull request
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----------------------
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The preferred way to submit code is by publishing your patches in a branch
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in your github fork of the ceph repository and then submitting a github
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pull request.
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For example, prepare your changes
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.. code-block:: bash
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# ...code furiously...
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$ git commit # git gui is also quite convenient
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$ git push origin mything
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Then submit a pull request at
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https://github.com/ceph/ceph/pulls
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and click 'New pull request'. See :ref:`_title_of_commit` for our naming
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convention of pull requests. The 'hub' command-line tool, available from
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https://github.com/github/hub
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allows you to submit pull requests directly from the command line
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.. code-block:: bash
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$ hub pull-request -b ceph:master -h you:mything
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Pull requests appear in the review queue at
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https://github.com/organizations/ceph/dashboard/pulls
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You may want to ping a developer in #ceph-devel on irc.oftc.net or on the
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email list to ensure your submission is noticed.
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When addressing review comments, can should either add additional patches to
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your branch or (better yet) squash those changes into the relevant commits so
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that the sequence of changes is "clean" and gets things right the first time.
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The 'git rebase -i' command is very helpful in this process. Once you have
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updated your local branch, you can simply force-push to the existing branch
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in your public repository that is referenced by the pull request with
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.. code-block:: bash
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$ git push -f origin mything
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and your changes will be visible from the existing pull-request. You may want
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to ping the reviewer again or comment on the pull request to ensure the updates
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are noticed.
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Sometimes your change could be based on an outdated parent commit and has
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conflicts with the latest target branch, then you need to fetch the updates
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from the remote branch, rebase your change onto it, and resolve the conflicts
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before doing the force-push
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.. code-block:: bash
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$ git pull --rebase origin target-branch
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So that the pull request does not contain any "merge" commit. Instead of "merging"
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the target branch, we expect a linear history in a pull request where you
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commit on top of the remote branch.
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Q: Which branch should I target in my pull request?
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A: The target branch depends on the nature of your change:
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If you are adding a feature, target the "master" branch in your pull
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request.
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If you are fixing a bug, target the named branch corresponding to the
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major version that is currently in development. For example, if
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Infernalis is the latest stable release and Jewel is development, target
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the "jewel" branch for bugfixes. The Ceph core developers will
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periodically merge this named branch into "master". When this happens,
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the master branch will contain your fix as well.
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If you are fixing a bug (see above) *and* the bug exists in older stable
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branches (for example, the "hammer" or "infernalis" branches), then you
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should file a Redmine ticket describing your issue and fill out the
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"Backport: <branchname>" form field. This will notify other developers that
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your commit should be cherry-picked to one or more stable branches. Then,
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target the "master" branch in your pull request.
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For example, you should set "Backport: jewel, kraken" in your Redmine ticket
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to indicate that you are fixing a bug that exists on the "jewel" and
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"kraken" branches and that you desire that your change be cherry-picked to
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those branches after it is merged into master.
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Q: How to include ``Reviewed-by: tag(s)`` in my pull request?
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A: You don't. If someone reviews your pull request, they should indicate they
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have done so by commenting on it with "+1", "looks good to me", "LGTM",
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and/or the entire "Reviewed-by: ..." line with their name and email address.
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The developer merging the pull request should note positive reviews and
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include the appropriate Reviewed-by: lines in the merge commit.
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2. Patch submission via ceph-devel@vger.kernel.org
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--------------------------------------------------
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The best way to generate a patch for manual submission is to work from
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a Git checkout of the Ceph source code. You can then generate patches
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with the 'git format-patch' command. For example,
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.. code-block:: bash
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$ git format-patch HEAD^^ -o mything
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will take the last two commits and generate patches in the mything/
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directory. The commit you specify on the command line is the
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'upstream' commit that you are diffing against. Note that it does
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not necesarily have to be an ancestor of your current commit. You
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can do something like
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.. code-block:: bash
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$ git checkout -b mything
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# ... do lots of stuff ...
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$ git fetch
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# ...find out that origin/unstable has also moved forward...
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$ git format-patch origin/unstable -o mything
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and the patches will be against origin/unstable.
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The ``-o`` dir is optional; if left off, the patch(es) will appear in
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the current directory. This can quickly get messy.
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You can also add ``--cover-letter`` and get a '0000' patch in the
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mything/ directory. That can be updated to include any overview
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stuff for a multipart patch series. If it's a single patch, don't
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bother.
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Make sure your patch does not include any extra files which do not
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belong in a patch submission. Make sure to review your patch -after-
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generated it with ``diff(1)``, to ensure accuracy.
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If your changes produce a lot of deltas, you may want to look into
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splitting them into individual patches which modify things in
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logical stages. This will facilitate easier reviewing by other
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kernel developers, very important if you want your patch accepted.
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There are a number of scripts which can aid in this.
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The ``git send-email`` command make it super easy to send patches
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(particularly those prepared with git format patch). It is careful to
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format the emails correctly so that you don't have to worry about your
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email client mangling whitespace or otherwise screwing things up. It
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works like so:
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.. code-block:: bash
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$ git send-email --to ceph-devel@vger.kernel.org my.patch
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for a single patch, or
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.. code-block:: bash
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$ git send-email --to ceph-devel@vger.kernel.org mything
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to send a whole patch series (prepared with, say, git format-patch).
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3. Describe your changes
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------------------------
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Describe the technical detail of the change(s) your patch includes.
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.. _title_of_commit:
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Title of pull requests and title of commits
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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The text up to the first empty line in a commit message is the commit
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title. Ideally it is a single short line of at most 72 characters,
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summarizing the change. It is required to prefix it with the
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subsystem or module you are changing. For instance, the prefix
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could be "doc:", "osd:", or "common:". One can use::
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git log
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for more examples. Please use this "subsystem: short description"
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convention for naming pull requests (PRs) also, as it feeds directly
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into the script that generates release notes and it's tedious to clean
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up at release time. This document places no limit on the length of PR
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titles, but be aware that they are subject to editing as part of the
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release process.
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Commit message
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^^^^^^^^^^^^^^
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Be as specific as possible. The WORST descriptions possible include
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things like "update driver X", "bug fix for driver X", or "this patch
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includes updates for subsystem X. Please apply."
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If your description starts to get long, that's a sign that you probably
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need to split up your patch. See :ref:`split_changes`.
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When you submit or resubmit a patch or patch series, include the
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complete patch description and justification for it. Don't just
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say that this is version N of the patch (series). Don't expect the
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patch merger to refer back to earlier patch versions or referenced
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URLs to find the patch description and put that into the patch.
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I.e., the patch (series) and its description should be self-contained.
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This benefits both the patch merger(s) and reviewers. Some reviewers
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probably didn't even receive earlier versions of the patch.
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Tag the commit
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^^^^^^^^^^^^^^
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If the patch fixes a logged bug entry, refer to that bug entry by
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URL. In particular, if this patch fixes one or more issues
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tracked by http://tracker.ceph.com, consider adding a ``Fixes:`` tag to
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connect this change to addressed issue(s). So a line saying ::
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Fixes: http://tracker.ceph.com/issues/12345
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is added before the ``Signed-off-by:`` line stating that this commit
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addresses http://tracker.ceph.com/issues/12345. It helps the reviewer to
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get more context of this bug, so she/he can hence update the issue on
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the bug tracker accordingly.
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So a typical commit message for revising the document could look like::
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doc: add "--foo" option to bar
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* update the man page for bar with the newly added "--foo" option.
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* fix a typo
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Fixes: http://tracker.ceph.com/issues/12345
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Signed-off-by: Random J Developer <random@developer.example.org>
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.. _split_changes:
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4. Separate your changes
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------------------------
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Separate *logical changes* into a single patch file.
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For example, if your changes include both bug fixes and performance
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enhancements for a single driver, separate those changes into two
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or more patches. If your changes include an API update, and a new
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driver which uses that new API, separate those into two patches.
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On the other hand, if you make a single change to numerous files,
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group those changes into a single patch. Thus a single logical change
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is contained within a single patch.
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If one patch depends on another patch in order for a change to be
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complete, that is OK. Simply note "this patch depends on patch X"
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in your patch description.
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If you cannot condense your patch set into a smaller set of patches,
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then only post say 15 or so at a time and wait for review and integration.
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5. Document your changes
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------------------------
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If you have added or modified any user-facing functionality, such
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as CLI commands or their output, then the patch series or pull request
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must include appropriate updates to documentation.
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It is the submitter's responsibility to make the changes, and the reviewer's
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responsibility to make sure they are not merging changes that do not
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have the needed updates to documentation.
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Where there are areas that have absent documentation, or there is no
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clear place to note the change that is being made, the reviewer should
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contact the component lead, who should arrange for the missing section
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to be created with sufficient detail for the patch submitter to
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document their changes.
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6. Style check your changes
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---------------------------
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Check your patch for basic style violations, details of which can be
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found in CodingStyle.
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7. No MIME, no links, no compression, no attachments. Just plain text
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----------------------------------------------------------------------
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Developers need to be able to read and comment on the changes you are
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submitting. It is important for a kernel developer to be able to
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"quote" your changes, using standard e-mail tools, so that they may
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comment on specific portions of your code.
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For this reason, all patches should be submitting e-mail "inline".
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WARNING: Be wary of your editor's word-wrap corrupting your patch,
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if you choose to cut-n-paste your patch.
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Do not attach the patch as a MIME attachment, compressed or not.
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|
Many popular e-mail applications will not always transmit a MIME
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|
attachment as plain text, making it impossible to comment on your
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code. A MIME attachment also takes Linus a bit more time to process,
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decreasing the likelihood of your MIME-attached change being accepted.
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Exception: If your mailer is mangling patches then someone may ask
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you to re-send them using MIME.
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