Recently we meet a requirement about Zlib windowBits for compression.

In the source code, we found that the zlib windowBits is hard code as -15[1]. While in zlib, it's a parameter that can be setting to different value.[2] According to zlib guide, windowBits can be set to [-15, -8) for raw deflate, (8, 15] for compression with header and trailer and [16,) for optional gzip encoding. Now we want to set it to 15 in Ceph to satisfy our requirement. Is it possible for Ceph Upstream to make it configurable, so that users can change it with their different use case? Or any other way to support it?

Hope to get community's feedback. And I have registered a feature[3] as well. Feel free to leave any comment.

Xiyuan Wang

[1]: https://github.com/ceph/ceph/blob/master/src/compressor/zlib/ZlibCompressor.cc#L43
[2]: https://github.com/madler/zlib/blob/cacf7f1d4e3d44d871b605da3b647f07d718623f/zlib.h#L552-L576
[3]: https://tracker.ceph.com/issues/43324