Provide initial ListNVMfRemoteNamespaces implementation.

[artek-koltun]

see #12

[glimchb]

not clear why we need it
Also I think Ben wanted to create and delete those namespaces in a forloop when spdk attaching and detaching from nvme bdev controller

[codecov]

Codecov Report

Merging #465 (6bc1b58) into main (17e5134) will decrease coverage by 1.03%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #465      +/-   ##
==========================================
- Coverage   65.16%   64.14%   -1.03%     
==========================================
  Files          21       22       +1     
  Lines        3207     3258      +51     
==========================================
  Hits         2090     2090              
- Misses        989     1040      +51     
  Partials      128      128              

Impacted Files	Coverage Δ
pkg/backend/nvme_namespace.go	0.00% <0.00%> (ø)

[artek-koltun]

Sorry, missed the comment.
My understanding is that ListNVMfRemoteNamespaces is needed for a client to get all discovered namespaces after a remote controller is connected, so we could assign them to middleend/frontend. It is also why we can only list them, but not create/delete.
@benlwalker could you please clarify?

[glimchb]

Sorry, missed the comment. My understanding is that ListNVMfRemoteNamespaces is needed for a client to get all discovered namespaces after a remote controller is connected, so we could assign them to middleend/frontend. It is also why we can only list them, but not create/delete. @benlwalker could you please clarify?

what I mean is we already call bdev_get_bdevs in several places... not sure I understand why we need yet another one... maybe if we show how to create those first, then list will make more sense... ?