[PATCH V4 2/2] nvme-core: use xarray for ctrl ns tracking

[Sagi Grimberg]

>> This patch replaces the ctrl->namespaces tracking from linked list to
>> xarray and improves the performance. For host even though
>> nvme_find_get_ns() doesn't fall into the fast path yet it does for
>> NVMeOF passthru patch-series which is currently under review. This
>> prepares us to improve performance for future NVMeOF passthru backend
>> since nvme_find_get_ns() uses same data structure as it does in target
>> to find namespace in I/O patch from nsid specified in the nvme_rw_cmd.
> 
> І'm still not really sold on that rationale..

I think that your suggestion to have a passthru_q is a much more
elegant solution (although it probably cannot be unified with the
connect_q which should be able to make forward progress on a quiesced
queue as well for fabrics).