This patch set is based on the following patch submission and email exchange: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V K. Y. Srinivasan kys at microsoft.com Sat Mar 12 21:52:48 UTC 2016 http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/2016-March/087116.html Included in the current storvsc driver for Hyper-V is the ability to access luns on an FC fabric via a virtualized fiber channel adapter exposed by the Hyper-V host. This was done to provide an interface for existing customer tools that was more consistent with a conventional FC device. The driver attaches to the FC transport to allow host and port names to be published under /sys/class/fc_host/hostX. A problem arose when attaching to the FC transport. The scsi_scan code attempts to call fc_user_scan which has basically become a no-op due to the virtualized nature of the FC host ( missing rports, vports, etc ). At this point you cannot refresh the scsi bus after mapping or unmapping luns on the SAN without a reboot. The patch above attempted to address the problem of not being able to scan FC hosts on a Hyper-V guest by setting fc_transport_template->user_scan = NULL but it was rejected in favor of a new "lightweight" version of the FC transport that only provides the bare minimum functionality of the standard FC model. This new transport option would be more suitable for FC transports running on a VM and provide some flexibility in the future. The patches below offer a method to incorporate the new lightweight FC option into the existing transport and storvsc drivers. Patch 1: scsi_transport_fc.h, scsi_transport_fc.c 1) Adds the lightweight_transport option to fc_function_template. Based on this selection the transport will either be lightweight or default to heavyweight. 2) Divides the applicable export functions into two sets. The lightweight functions involve FC attributes port_name and node name. The functions that deal with targets, rports, etc are not used. The heavyweight default contains the original standard physical FC hba attribute set. 3) All top level FC class directories such fc_remote_ports, fc_transport, and fc_vports are still created when the transport driver is loaded. They are just not populated when running in lightweight mode. Conceptually both lightweight and heavyweight clients could coexist. 4) fc_transport_template->user_scan is now null and the bus can be scanned. Patch 2: storvsc.c 1) storvsc elects to use the new lightweight FC host option by enabling it in fc_function_template. 2) Removes an original workaround dealing with replacing the eh_timed_out function. Patch 1 will not set the scsi_transport_template.eh_timed_out function directly during lightweight fc_attach_transport(). It instead relies on whatever was indicated as the scsi_host_template timeout handler during scsi_times_out() scsi_error.c. So the workaround is no longer necessary. It has been suggested that the word lightweight may not be the best choice of terms when describing the new FC transport option. I can offer a few new ones but I am not particularly imaginative. Virtual FC Mini FC Host only FC Changes from V1: Added more comments and documentation in the code regarding the lightweight feature. Cathy Avery (2): scsi: scsi_transport_fc: Provide a lightweight option for Virtual FC Hosts. scsi: storvsc: Add support for FC lightweight host. drivers/scsi/scsi_transport_fc.c | 144 +++++++++++++++++++++++++++++++++++++-- drivers/scsi/storvsc_drv.c | 12 ++-- include/scsi/scsi_transport_fc.h | 2 + 3 files changed, 149 insertions(+), 9 deletions(-) -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
