add cmd_time_out option to /disks create command

[zhuozh]

Provide a cmd_time_out option to make configfs attribute
cmd_time_out optionally configrable when adding a disk node
to the configuration.

Signed-off-by: Zhang Zhuoyu zhangzhuoyu@cmss.chinamobile.com

[zhuozh]

This PR base on ceph/ceph-iscsi-config#36

[pcuzner]

Tuning specific lun's is a great idea. Maybe instead of adding it to a disk create, we should consider adding a 'ui_command_set' method to the storage.Disk class to specifically handle attrib changes, and set sensible defaults for the majority of luns we create. Thoughts?

[xiubli]

@pcuzner

Yes, good idea.

As we discussed with Mike in tcmu-runner PRs, this could be like what the targetcli/rtslib to do, for attributes and parameters the kernel has supported then we could just do the set attribute/parameter command, as you mentioned above.

[zhuozh]

@pcuzner ui_command_set sounds good, But for now, if disk is created, LUN will also be added to TPGs, and export_count in kernel is increased, which makes cmd_time_out attribute unmodifiable, maybe we should break the coupling between disk creation and adding LUN TPGs, to make 'ui_command_set' possible?

[mikechristie]

@zhuozh Sorry for the late reply. I was waiting on the targetcli discussion.

At the rtslib level we are going to break up the creation of the object, setting attributes, config settings and parameters, and then enabling it. Here is outline of how it would look like with targetcli:

open-iscsi/targetcli-fb#95 (comment)

We would probably want to do a similar separate of steps in gwcli and ceph-iscsi-config.