LU-1415 tests: Basic support for ZFS-based servers

LU-1415 tests: Basic support for ZFS-based servers

This patch extends Test Framework to support formatting and mounting
ZFS-based servers.

Current global FSTYPE is no longer flexible enough, as different
facets can use different types of back ends.  Such "mixed-fstype"
configurations are firstly resulted from the incremental landing of
Orion changes.  For example, when we have OFD and ZFS OSD, although
OSTs will be able to use ZFS, MGS and MDTs can still only use LDiskFS.
Secondly, to reduce the test matrix, we may also want to have both
OSTs using LDiskFS and OSTs using ZFS in the same test cluster.
Hence, this patch makes back end file system type a per-facet
attribute.  The flexible configuration variables in local.sh are
reserved for users; all other scripts shall use facet_fstype()
instead.

The major differences between using an LDiskFS-based target and a
ZFS-based one are on the mkfs.lustre(8) command line:

  - ZFS-based targets shall have "--backfstype=zfs", while
    LDiskFS-based ones shall have "--backfstype=ldiskfs".

  - LDiskFS-specific "--mkfsoptions" arguments shall not be given to
    ZFS-based targets, and vice versa.

  - ZFS-based targets have different device specifications.  See
    mkfs.lustre(8).

In addition, we will make "--index" mandatory.  Naturally, format
options have to be generated for each facet dynamically, based on its
back end type, index, etc.  This patch changes mkfs_opts() to do
exactly that.  All test scripts shall use mkfs_opts() instead of
reading related environment variables directly.

Similarly, mount options should also be generated on a per-facet, or
at least per-fstype, basis.  Nevertheless, this patch takes a shortcut
by keeping current per-facet-type {MGS,MDS,OST}_MOUNT_OPTSs and
generating the "loop" mount option dynamically in mount_facet().  I
believe this solution introduces fewer changes comparing to a pure
per-facet one and is sufficient for current use cases.

This patch is based on Brian Behlendorf's work under ORI-155.  See
http://review.whamcloud.com/1417.

Change-Id: Ifcce9b10179dd1b4992a30d10df13ea10bc34548
Whamcloud-bug-id: ORI-155
Test-Parameters: testgroup=full
Test-Parameters: testgroup=full envdefinitions=USE_OFD=yes,LOAD_MODULES_REMOTE=true
Signed-off-by: Li Wei <liwei@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/2907
Tested-by: Hudson
Reviewed-by: Yu Jian <yujian@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>