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diff --git a/SubmittingPatches.rst b/SubmittingPatches.rst new file mode 100644 index 00000000..a13191d8 --- /dev/null +++ b/SubmittingPatches.rst @@ -0,0 +1,521 @@ +========================== +Submitting Patches to Ceph +========================== + +This is based on Documentation/SubmittingPatches from the Linux kernel, +but has pared down significantly and updated based on the Ceph project's +best practices. + +The patch signing procedures and definitions are unmodified. + + +SIGNING CONTRIBUTIONS +===================== + +In order to keep the record of code attribution clean within the source +repository, follow these guidelines for signing patches submitted to the +project. These definitions are taken from those used by the Linux kernel +and many other open source projects. + + +1. Sign your work +----------------- + +To improve tracking of who did what, especially with patches that can +percolate to their final resting place in the kernel through several +layers of maintainers, we've introduced a "sign-off" procedure on +patches that are being emailed around. + +The sign-off is a simple line at the end of the explanation for the +patch, which certifies that you wrote it or otherwise have the right to +pass it on as a open-source patch. The rules are pretty simple: if you +can certify the below: + +Developer's Certificate of Origin 1.1 +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +By making a contribution to this project, I certify that: + + (a) The contribution was created in whole or in part by me and I + have the right to submit it under the open source license + indicated in the file; or + + (b) The contribution is based upon previous work that, to the best + of my knowledge, is covered under an appropriate open source + license and I have the right under that license to submit that + work with modifications, whether created in whole or in part + by me, under the same open source license (unless I am + permitted to submit under a different license), as indicated + in the file; or + + (c) The contribution was provided directly to me by some other + person who certified (a), (b) or (c) and I have not modified + it. + + (d) I understand and agree that this project and the contribution + are public and that a record of the contribution (including all + personal information I submit with it, including my sign-off) is + maintained indefinitely and may be redistributed consistent with + this project or the open source license(s) involved. + +then you just add a line saying :: + + Signed-off-by: Random J Developer <random@developer.example.org> + + +using your real name (sorry, no pseudonyms or anonymous contributions.) + +Some people also put extra tags at the end. They'll just be ignored for +now, but you can do this to mark internal company procedures or just +point out some special detail about the sign-off. + +If you are a subsystem or branch maintainer, sometimes you need to slightly +modify patches you receive in order to merge them, because the code is not +exactly the same in your tree and the submitters'. If you stick strictly to +rule (c), you should ask the submitter to rediff, but this is a totally +counter-productive waste of time and energy. Rule (b) allows you to adjust +the code, but then it is very impolite to change one submitter's code and +make them endorse your bugs. To solve this problem, it is recommended that +you add a line between the last Signed-off-by header and yours, indicating +the nature of your changes. While there is nothing mandatory about this, it +seems like prepending the description with your mail and/or name, all +enclosed in square brackets, is noticeable enough to make it obvious that +you are responsible for last-minute changes. Example :: + + Signed-off-by: Random J Developer <random@developer.example.org> + [lucky@maintainer.example.org: struct foo moved from foo.c to foo.h] + Signed-off-by: Lucky K Maintainer <lucky@maintainer.example.org> + +This practise is particularly helpful if you maintain a stable branch and +want at the same time to credit the author, track changes, merge the fix, +and protect the submitter from complaints. Note that under no circumstances +can you change the author's identity (the From header), as it is the one +which appears in the changelog. + +Special note to back-porters: It seems to be a common and useful practise +to insert an indication of the origin of a patch at the top of the commit +message (just after the subject line) to facilitate tracking. For instance, +here's what we see in 2.6-stable :: + + Date: Tue May 13 19:10:30 2008 +0000 + + SCSI: libiscsi regression in 2.6.25: fix nop timer handling + + commit 4cf1043593db6a337f10e006c23c69e5fc93e722 upstream + +And here's what appears in 2.4 :: + + Date: Tue May 13 22:12:27 2008 +0200 + + wireless, airo: waitbusy() won't delay + + [backport of 2.6 commit b7acbdfbd1f277c1eb23f344f899cfa4cd0bf36a] + +Whatever the format, this information provides a valuable help to people +tracking your trees, and to people trying to trouble-shoot bugs in your +tree. + + +2. When to use ``Acked-by:`` and ``Cc:`` +---------------------------------------- + +The ``Signed-off-by:`` tag indicates that the signer was involved in the +development of the patch, or that he/she was in the patch's delivery path. + +If a person was not directly involved in the preparation or handling of a +patch but wishes to signify and record their approval of it then they can +arrange to have an ``Acked-by:`` line added to the patch's changelog. + +``Acked-by:`` is often used by the maintainer of the affected code when that +maintainer neither contributed to nor forwarded the patch. + +``Acked-by:`` is not as formal as ``Signed-off-by:``. It is a record that the acker +has at least reviewed the patch and has indicated acceptance. Hence patch +mergers will sometimes manually convert an acker's "yep, looks good to me" +into an ``Acked-by:``. + +``Acked-by:`` does not necessarily indicate acknowledgement of the entire patch. +For example, if a patch affects multiple subsystems and has an ``Acked-by:`` from +one subsystem maintainer then this usually indicates acknowledgement of just +the part which affects that maintainer's code. Judgement should be used here. +When in doubt people should refer to the original discussion in the mailing +list archives. + +If a person has had the opportunity to comment on a patch, but has not +provided such comments, you may optionally add a "Cc:" tag to the patch. +This is the only tag which might be added without an explicit action by the +person it names. This tag documents that potentially interested parties +have been included in the discussion + + +3. Using ``Reported-by:``, ``Tested-by:`` and ``Reviewed-by:`` +-------------------------------------------------------------- + +If this patch fixes a problem reported by somebody else, consider adding a +``Reported-by:`` tag to credit the reporter for their contribution. This tag should +not be added without the reporter's permission, especially if the problem was +not reported in a public forum. That said, if we diligently credit our bug +reporters, they will, hopefully, be inspired to help us again in the future. + +A ``Tested-by:`` tag indicates that the patch has been successfully tested (in +some environment) by the person named. This tag informs maintainers that +some testing has been performed, provides a means to locate testers for +future patches, and ensures credit for the testers. + +``Reviewed-by:``, instead, indicates that the patch has been reviewed and found +acceptable according to the Reviewer's Statement: + +Reviewer's statement of oversight +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +By offering my ``Reviewed-by:`` tag, I state that: + + (a) I have carried out a technical review of this patch to + evaluate its appropriateness and readiness for inclusion into + the mainline kernel. + + (b) Any problems, concerns, or questions relating to the patch + have been communicated back to the submitter. I am satisfied + with the submitter's response to my comments. + + (c) While there may be things that could be improved with this + submission, I believe that it is, at this time, (1) a + worthwhile modification to the kernel, and (2) free of known + issues which would argue against its inclusion. + + (d) While I have reviewed the patch and believe it to be sound, I + do not (unless explicitly stated elsewhere) make any + warranties or guarantees that it will achieve its stated + purpose or function properly in any given situation. + +A ``Reviewed-by`` tag is a statement of opinion that the patch is an +appropriate modification of the kernel without any remaining serious +technical issues. Any interested reviewer (who has done the work) can +offer a ``Reviewed-by`` tag for a patch. This tag serves to give credit to +reviewers and to inform maintainers of the degree of review which has been +done on the patch. ``Reviewed-by:`` tags, when supplied by reviewers known to +understand the subject area and to perform thorough reviews, will normally +increase the likelihood of your patch getting into the kernel. + + +PREPARING AND SENDING PATCHES +============================= + +The upstream repository is managed by Git. You will find that it +is easiest to work on the project and submit changes by using the +git tools, both for managing your own code and for preparing and +sending patches. + +The project will generally accept code either by pulling code directly from +a published git tree (usually on github), or via patches emailed directly +to the email list (ceph-devel@vger.kernel.org). For the kernel client, +patches are expected to be reviewed in the email list. And for everything +else, github is preferred due to the convenience of the 'pull request' +feature. + + +1. Github pull request +---------------------- + +The preferred way to submit code is by publishing your patches in a branch +in your github fork of the ceph repository and then submitting a github +pull request. + +For example, prepare your changes + +.. code-block:: bash + + # ...code furiously... + $ git commit # git gui is also quite convenient + $ git push origin mything + +Then submit a pull request at + + https://github.com/ceph/ceph/pulls + +and click 'New pull request'. See :ref:`_title_of_commit` for our naming +convention of pull requests. The 'hub' command-line tool, available from + + https://github.com/github/hub + +allows you to submit pull requests directly from the command line + +.. code-block:: bash + + $ hub pull-request -b ceph:master -h you:mything + +Pull requests appear in the review queue at + + https://github.com/organizations/ceph/dashboard/pulls + +You may want to ping a developer in #ceph-devel on irc.oftc.net or on the +email list to ensure your submission is noticed. + +When addressing review comments, can should either add additional patches to +your branch or (better yet) squash those changes into the relevant commits so +that the sequence of changes is "clean" and gets things right the first time. +The ``git rebase -i`` command is very helpful in this process. Once you have +updated your local branch, you can simply force-push to the existing branch +in your public repository that is referenced by the pull request with + +.. code-block:: bash + + $ git push -f origin mything + +and your changes will be visible from the existing pull-request. You may want +to ping the reviewer again or comment on the pull request to ensure the updates +are noticed. + +Sometimes your change could be based on an outdated parent commit and has +conflicts with the latest target branch, then you need to fetch the updates +from the remote branch, rebase your change onto it, and resolve the conflicts +before doing the force-push + +.. code-block:: bash + + $ git pull --rebase origin target-branch + +So that the pull request does not contain any "merge" commit. Instead of "merging" +the target branch, we expect a linear history in a pull request where you +commit on top of the remote branch. + +Q: Which branch should I target in my pull request? + +A: The target branch depends on the nature of your change: + + If you are adding a feature, target the "master" branch in your pull + request. + + If you are fixing a bug, target the named branch corresponding to the + major version that is currently in development. For example, if + Infernalis is the latest stable release and Jewel is development, target + the "jewel" branch for bugfixes. The Ceph core developers will + periodically merge this named branch into "master". When this happens, + the master branch will contain your fix as well. + + If you are fixing a bug (see above) *and* the bug exists in older stable + branches (for example, the "hammer" or "infernalis" branches), then you + should file a Redmine ticket describing your issue and fill out the + "Backport: <branchname>" form field. This will notify other developers that + your commit should be cherry-picked to one or more stable branches. Then, + target the "master" branch in your pull request. + + For example, you should set "Backport: jewel, kraken" in your Redmine ticket + to indicate that you are fixing a bug that exists on the "jewel" and + "kraken" branches and that you desire that your change be cherry-picked to + those branches after it is merged into master. + +Q: How to include ``Reviewed-by: tag(s)`` in my pull request? + +A: You don't. If someone reviews your pull request, they should indicate they + have done so by commenting on it with "+1", "looks good to me", "LGTM", + and/or the entire "Reviewed-by: ..." line with their name and email address. + + The developer merging the pull request should note positive reviews and + include the appropriate Reviewed-by: lines in the merge commit. + + +2. Patch submission via ceph-devel@vger.kernel.org +-------------------------------------------------- + +The best way to generate a patch for manual submission is to work from +a Git checkout of the Ceph source code. You can then generate patches +with the 'git format-patch' command. For example, + +.. code-block:: bash + + $ git format-patch HEAD^^ -o mything + +will take the last two commits and generate patches in the mything/ +directory. The commit you specify on the command line is the +'upstream' commit that you are diffing against. Note that it does +not necessarily have to be an ancestor of your current commit. You +can do something like + +.. code-block:: bash + + $ git checkout -b mything + # ... do lots of stuff ... + $ git fetch + # ...find out that origin/unstable has also moved forward... + $ git format-patch origin/unstable -o mything + +and the patches will be against origin/unstable. + +The ``-o`` dir is optional; if left off, the patch(es) will appear in +the current directory. This can quickly get messy. + +You can also add ``--cover-letter`` and get a '0000' patch in the +mything/ directory. That can be updated to include any overview +stuff for a multipart patch series. If it's a single patch, don't +bother. + +Make sure your patch does not include any extra files which do not +belong in a patch submission. Make sure to review your patch -after- +generated it with ``diff(1)``, to ensure accuracy. + +If your changes produce a lot of deltas, you may want to look into +splitting them into individual patches which modify things in +logical stages. This will facilitate easier reviewing by other +kernel developers, very important if you want your patch accepted. +There are a number of scripts which can aid in this. + +The ``git send-email`` command make it super easy to send patches +(particularly those prepared with git format patch). It is careful to +format the emails correctly so that you don't have to worry about your +email client mangling whitespace or otherwise screwing things up. It +works like so: + +.. code-block:: bash + + $ git send-email --to ceph-devel@vger.kernel.org my.patch + +for a single patch, or + +.. code-block:: bash + + $ git send-email --to ceph-devel@vger.kernel.org mything + +to send a whole patch series (prepared with, say, git format-patch). + + +3. Describe your changes +------------------------ + +Describe the technical detail of the change(s) your patch includes. + +.. _title_of_commit: + +Title of pull requests and title of commits +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The text up to the first empty line in a commit message is the commit +title. Ideally it is a single short line of at most 72 characters, +summarizing the change. It is required to prefix it with the +subsystem or module you are changing. For instance, the prefix +could be "doc:", "osd:", or "common:". One can use:: + + git log + +for more examples. Please use this "subsystem: short description" +convention for naming pull requests (PRs) also, as it feeds directly +into the script that generates release notes and it's tedious to clean +up at release time. This document places no limit on the length of PR +titles, but be aware that they are subject to editing as part of the +release process. + +Commit message +^^^^^^^^^^^^^^ + +Be as specific as possible. The WORST descriptions possible include +things like "update driver X", "bug fix for driver X", or "this patch +includes updates for subsystem X. Please apply." + +If your description starts to get long, that's a sign that you probably +need to split up your patch. See :ref:`split_changes`. + +When you submit or resubmit a patch or patch series, include the +complete patch description and justification for it. Don't just +say that this is version N of the patch (series). Don't expect the +patch merger to refer back to earlier patch versions or referenced +URLs to find the patch description and put that into the patch. +I.e., the patch (series) and its description should be self-contained. +This benefits both the patch merger(s) and reviewers. Some reviewers +probably didn't even receive earlier versions of the patch. + +Tag the commit +^^^^^^^^^^^^^^ + +If the patch fixes a logged bug entry, refer to that bug entry by +URL. In particular, if this patch fixes one or more issues +tracked by http://tracker.ceph.com, consider adding a ``Fixes:`` tag to +connect this change to addressed issue(s). So a line saying :: + + Fixes: http://tracker.ceph.com/issues/12345 + +is added before the ``Signed-off-by:`` line stating that this commit +addresses http://tracker.ceph.com/issues/12345. It helps the reviewer to +get more context of this bug, so she/he can hence update the issue on +the bug tracker accordingly. + +So a typical commit message for revising the document could look like:: + + doc: add "--foo" option to bar + + * update the man page for bar with the newly added "--foo" option. + * fix a typo + + Fixes: http://tracker.ceph.com/issues/12345 + Signed-off-by: Random J Developer <random@developer.example.org> + +.. _split_changes: + +4. Separate your changes +------------------------ + +Separate *logical changes* into a single patch file. + +For example, if your changes include both bug fixes and performance +enhancements for a single driver, separate those changes into two +or more patches. If your changes include an API update, and a new +driver which uses that new API, separate those into two patches. + +On the other hand, if you make a single change to numerous files, +group those changes into a single patch. Thus a single logical change +is contained within a single patch. + +If one patch depends on another patch in order for a change to be +complete, that is OK. Simply note "this patch depends on patch X" +in your patch description. + +If you cannot condense your patch set into a smaller set of patches, +then only post say 15 or so at a time and wait for review and integration. + +5. Document your changes +------------------------ + +If you have added or modified any user-facing functionality, such +as CLI commands or their output, then the patch series or pull request +must include appropriate updates to documentation. + +It is the submitter's responsibility to make the changes, and the reviewer's +responsibility to make sure they are not merging changes that do not +have the needed updates to documentation. + +Where there are areas that have absent documentation, or there is no +clear place to note the change that is being made, the reviewer should +contact the component lead, who should arrange for the missing section +to be created with sufficient detail for the patch submitter to +document their changes. + +When writing and/or editing documentation, follow the Google Developer +Documentation Style Guide: https://developers.google.com/style/ + +6. Style check your changes +--------------------------- + +Check your patch for basic style violations, details of which can be +found in CodingStyle. + + +7. No MIME, no links, no compression, no attachments. Just plain text +---------------------------------------------------------------------- + +Developers need to be able to read and comment on the changes you are +submitting. It is important for a kernel developer to be able to +"quote" your changes, using standard e-mail tools, so that they may +comment on specific portions of your code. + +For this reason, all patches should be submitting e-mail "inline". +WARNING: Be wary of your editor's word-wrap corrupting your patch, +if you choose to cut-n-paste your patch. + +Do not attach the patch as a MIME attachment, compressed or not. +Many popular e-mail applications will not always transmit a MIME +attachment as plain text, making it impossible to comment on your +code. A MIME attachment also takes Linus a bit more time to process, +decreasing the likelihood of your MIME-attached change being accepted. + +Exception: If your mailer is mangling patches then someone may ask +you to re-send them using MIME. + |