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SubmittingPatches: initial version

Largely based on Linux's version.  Includes the Signed-off-by stuff at
the top, and a bit more modern description of how to prepare/send patches
using git format-patch and send-email.

Signed-off-by: Sage Weil <>
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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 slightly. The patch signing
+procedures and definitions are unmodified.
+In order to keep the record of code attribution clean within the
+source repository, please 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
+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 <>
+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 him 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 <>
+ [ struct foo moved from foo.c to foo.h]
+ Signed-off-by: Lucky K Maintainer <>
+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
+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. Please
+note that 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.
+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.
+1) "git format-patch"
+The best way to generate a patch 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,
+ $ 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 necesarily have to be an ancestor of your current commit. You
+can do something like
+ $ 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
+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:
+2) Sending patches with "git send-email"
+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:
+ $ git send-email --to my.patch
+for a single patch, or
+ $ git send-email --to 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.
+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."
+The maintainer will thank you if you write your patch description in a
+form which can be easily pulled into Linux's source code management
+system, git, as a "commit log". See #15, below.
+If your description starts to get long, that's a sign that you probably
+need to split up your patch. See #3, next.
+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.
+If the patch fixes a logged bug entry, refer to that bug entry by
+number and URL.
+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) Style check your changes.
+Check your patch for basic style violations, details of which can be
+found in CodingStyle.
+6) 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.

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