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+==========================
+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.
+