enhancement: Support regular NVMe read/write (0x01, 0x02) in OCSSD 2.0 spec

[lovers-under-moon]

FEMU OCSSD2.0 do not support NVMe read/write (0x01, 0x02).

[huaicheng]

The regular NVMe READ/WRITE commands are not really meaningful for directly accessing an OC device (I might miss something). For the SPDK+OCSSD2.0 case, does the SPDK FTL soly rely on NVMe READ/WRITE to function? (no use of the VECTOR read/write/erase at all?)

SPDK might expect an "NVME_SUCCESS" or other types of return values instead of "NVME_DNR" for the regular read/write commands, or it might have issued the I/O and mgmt commands in an order that's not the same as LightNVM+kernel-NVMe driver, thus FEMU is not able to correctly handle it.

PRs are welcome, otherwise, I work on this when I have time (timing not guaranteed).

[huaicheng]

Let me know if above patch works for you. Feel free to re-open the issue. I will mark it closed for now.