Dear Ceph Community, I hope you are doing well. I am trying to understand how Ceph OSD interacts with the Linux kernel. The Linux I/O stack consists of layers such as VFS, filesystem, block layer, and device driver, but since Ceph does not use a traditional filesystem and instead relies on BlueStore as its storage backend, I am struggling to find details on how it interacts with the kernel. Specifically, I would like to understand: - What are the layers in the Linux I/O stack that a Ceph OSD request passes through? - Does BlueStore use submit_bio() to enter the block layer, or does it bypass it and interact directly with the device driver? - Where can I find resources or documentation that explain this in detail? Any insights, documentation links, or pointers to relevant parts of the Ceph source code would be greatly appreciated. Thank you in advance for your help! Best regards.