[PATCH v3] nvme-tcp: Print actual source IP address through sysfs "address" attr

[Sagi Grimberg]

> From: Martin Belanger <martin.belanger at dell.com>
> 
> TCP transport relies on the routing table to determine which source
> address and interface to use when making a connection. Currently,
> there is no way to tell from userspace where a connection was made.
> This patch exposes the actual source address using a new field named
> "src_addr=" in the "address" attribute.
> 
> This is needed to diagnose and identify connectivity issues. With
> the source address we can infer the interface associated with each
> connection.
> 
> This was tested with nvme-cli 2.0 to verify it does not have any
> adverse effect. The new "src_addr=" field will simply be displayed in
> the output of the "list-subsys" or "list -v" commands as shown here.
> 
> $ nvme list-subsys
> nvme-subsys0 - NQN=nqn.2014-08.org.nvmexpress.discovery
> \
>   +- nvme0 tcp traddr=192.168.56.1,trsvcid=8009,src_addr=192.168.56.101 live

I wonder how this works with udev events etc for auto-connect? and also
for uniqueness checks...