[libvirt] [PATCH 0/8] storage_scsi: Stable SCSI host addressing

[John Ferlan]

Just over a year ago, Osier Yang submitted some patches to provide stable
SCSI host addressing support:

http://www.redhat.com/archives/libvir-list/2013-June/msg00396.html

Although reviewed - none of the patches were ever pushed and Osier never
got back to the work. I eventually inherited the changes and now after
languishing in the todo list - I took the time to rework things. There
is a bz associated:

https://bugzilla.redhat.com/show_bug.cgi?id=963817

Prior to leaving Red Hat, Osier and I spent some time revisiting the patch
series and hashing out new/different ideas to come up with the same answer.
My focus was to avoid the "generic recursive directory search" (patch 3),
to not require having to know whether the scsi_host was using udev or hal,
and to simplify as much as possible using existing data/information.

The generic directory search I believe was less generic than intended and
over complicated things. The old patches essentially used the output of
a 'virsh nodedev-list scsi_host' and then selecting a resulting entry ran
a 'virsh nodedev-dumpxml' to grab/use the resulting <parent> value. Taking
that value and optionally adding a unique_id value was the basis for the
design that would generate a PCI address (either in udev or hal format) and
recursively search through /sys/devices looking for a matching address in
either udev or hal format.

These patches replace the bulk of the directory traversal logic with a
more direct (and already in use) approach to scan the /sys/class/scsi_host
directories looking for a matching PCI address found in the symlink of
the files in the directory.

The changed logic will add a new XML element 'parentaddr' to describe the
scsi_host by it's PCI address. Additionally, the 'unique_id' has become a
required attribute. The code reuses the virDevicePCIAddressParseXML() in
order parse the required 'address' element. The 'address' will be in the
expect PCI Address format like other described host devices.

In order to help view the required unique_id value, the nodedev-dumpxml
output has been adjusted to provide the <unique_id> value. This value will
be an optional value on input.

The documentation is updated to describe how to generate the address from
the nodedev-dumpxml output.

The new scsihosttest creates the expected PCI infrastructure on the fly
since adding files with colons (':') is prohibited. There are multiple
directories and hosts within each to ensure the search logic worked as
expected.

Reviewer notes:

Patch 1 is new - it's just forcing the specific adapter.type checking
Patches 2 & 3 are the former patches 1 & 2 with some edits to adjust
   for new XML syntax (and changed associated structure)
Patch 4 is new - it's just utilizing the 'LINUX_SYSFS_SCSI_HOST_PREFIX'
   definition rather than using the hardcoded value
Patches 5 & 6 are new.  They handle the optional unique_id value (including
   using the new virNodeDevCapsDefParseIntOptional())
Patch 7 is similar to the former patch 5 insomuch as it's where the comparison
   of the PCI directory path and unique_id file is made.
Patch 8 is similar to the former patch 7 insomuch as it's where the link
   is made between the scsi_host host# and the loading/refreshing of the
   scsi_host adapter.

Former patches 3, 4, 6, and 8-11 are no longer used

Please check my XML schema (patch 3) - I think I figured out the right
syntax to use regarding using either "<name>" or "<parentaddr>" where
"<parentaddr>" is an element. The syntax passes the make check, but
it's not an area of expertise for me. Using parentaddr was preferred
over overloading the parent attribute.

John Ferlan (6):
  getAdapterName: check for SCSI_HOST
  scsi_backend: Use existing LINUX_SYSFS_SCSI_HOST_PREFIX definition
  virutil: Introduce virReadSCSIUniqueId
  Add unique_id to nodedev output
  scsi_host: Introduce virFindSCSIHostByPCI
  getAdapterName: Lookup stable scsi_host

Osier Yang (2):
  virStoragePoolSourceAdapter: Refine the SCSI_HOST adapter name
  storage: Introduce parentaddr into virStoragePoolSourceAdapter

 docs/formatnode.html.in                            |  11 +
 docs/formatstorage.html.in                         | 130 +++++++--
 docs/schemas/basictypes.rng                        |  24 +-
 docs/schemas/nodedev.rng                           |   6 +
 src/conf/node_device_conf.c                        |  23 +-
 src/conf/node_device_conf.h                        |   1 +
 src/conf/storage_conf.c                            | 111 +++++++-
 src/conf/storage_conf.h                            |   8 +-
 src/libvirt_private.syms                           |   2 +
 src/node_device/node_device_linux_sysfs.c          |   6 +
 src/phyp/phyp_driver.c                             |   8 +-
 src/storage/storage_backend_scsi.c                 |  53 +++-
 src/test/test_driver.c                             |   5 +-
 src/util/virutil.c                                 | 154 +++++++++++
 src/util/virutil.h                                 |   8 +
 tests/Makefile.am                                  |   7 +
 .../pci_8086_27c5_scsi_host_0_unique_id.xml        |   8 +
 tests/nodedevxml2xmltest.c                         |   1 +
 tests/scsihosttest.c                               | 308 +++++++++++++++++++++
 .../pool-scsi-type-scsi-host-stable.xml            |  19 ++
 .../pool-scsi-type-scsi-host-stable.xml            |  22 ++
 tests/storagepoolxml2xmltest.c                     |   1 +
 22 files changed, 855 insertions(+), 61 deletions(-)
 create mode 100644 tests/nodedevschemadata/pci_8086_27c5_scsi_host_0_unique_id.xml
 create mode 100644 tests/scsihosttest.c
 create mode 100644 tests/storagepoolxml2xmlin/pool-scsi-type-scsi-host-stable.xml
 create mode 100644 tests/storagepoolxml2xmlout/pool-scsi-type-scsi-host-stable.xml

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1.9.3