[RFC PATCH 0/3] FC subsystem update

[Robert Love <robert.w.love@intel.com>]

This series represents the continuation of the RFC archived here:
http://marc.info/?l=linux-scsi&m=126463466126962&w=2. The sysfs organization has
taken shape and object allocations make more sense than the previous RFC. The
patches have undergone my own developer testing, which has mostly focused on
NPIV port creation and deletion and some I/O.

This series creates a Fibre Channel subsystem that has an improved sysfs device
tree (the port's view of the fabric) and begins to abstract itself from SCSI.

This RFC is to solicit any feedback before I continue to refine these patches.
I've created two diagrams to help people understand the change. The first shows
the current sysfs device layout and the second shows the allocation scheme for
libfc and fcoe's primary data structures.

http://open-fcoe.org/rwlove/fc_sysfs.jpg
http://open-fcoe.org/rwlove/libfc_alloc.jpg

These patches apply to scsi-misc + the recently submitted fcoe patches, which
is the same as the fcoe-next tree on open-fcoe.org.

Overview of N_Port creation/login (for fcoe.ko):

1) First, fc.ko is installed and then scsi_transport_fcp.ko is installed.
   scsi_transport_fcp.ko registers itself (SCSI initiator) as a FC4 with
   fc.ko.

2) When a fcoe port is "created" from
   'echo ethX > /sys/module/fcoe/parameters/create' a fcport is allocated and
   added to sysfs. All of the port's physical properties are added as
   attributes.

<PCI root>/fcport_0

3) At this point libfc/libfcoe/fcoe needs an lport and an fcoe_port. The lport
   and fcoe_ports are private data of a fcvport so a fcvport is allocated,
   but not added to sysfs.

4) libfcoe.ko discovers FCFs and allocates/adds them as fcfabrics to sysfs
   as they are discovered.

   [ I think that we may want to revisit the idea of having a fcfport between
     the fcport and fcfabric. Right now I'm creating a fcfabric for each FCF
     that is discovered at the FIP phase, but that doesn't make much sense
     since multiple FCFs on the same fabric can be discovered. Adding a fcfport
     for each FCF discovered might be more correct. ]

<PCI root>/fcport_0/fcfabric_0

5) libfc.ko will FLOGI into the fabric and upon the FLOGI ACC the fcvport
   will be added to sysfs.

<PCI root>/fcport_0/fcfabric_0/fcvport_0

5.1) The FC layer will call fc4_init_add in the fc4_template. If SCSI
     is the FC4, fcp_init_add (scsi_transport_fcp) will be called. This
     routine calls scsi_host_alloc/scsi_add_host. There is also a callback
     down to the LLD so that it can setup any SCSI-FCP private data.

     [ I'm not sure how non-FCoE HBAs will do this. I imagine they will just
       create all three sysfs devices (fcport, fcfabric and fcvport) on the
       FLOGI ACC since they do not rely on a discovery protocol. ]

<PCI root>/fcport_0/fcfabric_0/fcvport_0/fcpinit_X/hostX

6) libfc will start discovery and as remote ports are discovered libfc will
   notify FC to create and add fcrports to sysfs.

<PCI root>/fcport_0/fcfabric_0/fcvport_0/fcpinit_X/hostX
					/fcrport_0

6.1) When the fcrports are created the FC layer will call fc4_targ_add in
     the fc4_template. If SCSI is the FC4, fcp_targ_add (scsi_transport_fcp)
     will be called. This routine will allocate a fcptarg device, add it to
     sysfs and notify SCSI to scan it.

<PCI root>/fcport_0/fcfabric_0/fcvport_0/fcpinit_X/hostX
					/fcrport_0/fcptargX:0-0


The current series shortcomings are:

1) The FC4 interface needs work to become more FC4 agnostic.
   (end of include/fc/fc.h)

2) Point-to-Point mode needs to be addressed

3) BSG needs to be tested and STGT should become another FC4 that is
   registered with FC. Since libfc/fcoe doesn't plug into STGT yet this
   will be a challenge.

4) user space updates - For the fcoe-utils package, libhbalinux (user
   space HBA API library) needs to be updated to read the new layout before
   heavy testing of the new layout can be done.

5) Miscellaneous problems like error handling, fcfabric deletion cleaning
   up vports, using attribute containers / scsi transport style for
   SCSI-FCP devices, warnings, etc...

6) FCoE attributes...

Other thoughts:

I would love to collaborate with someone who maintains a HBA that supports
native FC since I'm not aware of the specific needs of traditional HBAs.

I would hope that this new layout could be added to the kernel (when
ready) and the existing FC Transport deprecated as I'm not sure how to get
all HBA maintainers to switch their drivers at the same time. I think that
only adding FCoE attributes to this layout would be an incentive to get LLDs
to migrate.

I've tried to keep this covermail brief, so there are plenty of details
left out. Please ask if you have a question.

Thanks, //Rob

---

Robert Love (3):
      libfc, libfcoe, fcoe: Make use of FC subsystem
      scsi_transport_fcp: Create FC/SCSI interaction layer
      fc: Create FC sybsystem


 drivers/Kconfig                   |    2 
 drivers/Makefile                  |    1 
 drivers/fc/Kconfig                |    8 
 drivers/fc/Makefile               |    7 
 drivers/fc/fcfabric.c             |  425 ++++++++++
 drivers/fc/fcport.c               |  205 +++++
 drivers/fc/fcrport.c              | 1034 ++++++++++++++++++++++++
 drivers/fc/fcsysfs.c              |  180 ++++
 drivers/fc/fcsysfs.h              |   76 ++
 drivers/fc/fcvport.c              |  714 +++++++++++++++++
 drivers/scsi/Kconfig              |   11 
 drivers/scsi/Makefile             |    1 
 drivers/scsi/fcoe/fcoe.c          |  619 ++++++++------
 drivers/scsi/fcoe/libfcoe.c       |  167 +++-
 drivers/scsi/libfc/fc_disc.c      |    4 
 drivers/scsi/libfc/fc_exch.c      |    2 
 drivers/scsi/libfc/fc_fcp.c       |  130 +--
 drivers/scsi/libfc/fc_libfc.h     |   28 -
 drivers/scsi/libfc/fc_lport.c     |  195 ++---
 drivers/scsi/libfc/fc_npiv.c      |   44 -
 drivers/scsi/libfc/fc_rport.c     |   15 
 drivers/scsi/scsi_transport_fcp.c | 1598 +++++++++++++++++++++++++++++++++++++
 include/fc/fc.h                   |  843 ++++++++++++++++++++
 include/scsi/fc_encode.h          |   34 -
 include/scsi/libfc.h              |  119 +--
 include/scsi/libfcoe.h            |   17 
 include/scsi/scsi_transport_fcp.h |  325 ++++++++
 27 files changed, 6241 insertions(+), 563 deletions(-)
 create mode 100644 drivers/fc/Kconfig
 create mode 100644 drivers/fc/Makefile
 create mode 100644 drivers/fc/fcfabric.c
 create mode 100644 drivers/fc/fcport.c
 create mode 100644 drivers/fc/fcrport.c
 create mode 100644 drivers/fc/fcsysfs.c
 create mode 100644 drivers/fc/fcsysfs.h
 create mode 100644 drivers/fc/fcvport.c
 create mode 100644 drivers/scsi/scsi_transport_fcp.c
 create mode 100644 include/fc/fc.h
 create mode 100644 include/scsi/scsi_transport_fcp.h

--