This patch adds support for a new storage backend with RBD support.

RBD is the RADOS Block Device and is part of the Ceph distributed storage
system.

It comes in two flavours: Qemu-RBD and Kernel RBD, this storage backend only
supports Qemu-RBD, thus limiting the use of this storage driver to Qemu only.

To function this backend relies on librbd and librados being present on the
local system.

The backend also supports Cephx authentication for safe authentication with
the Ceph cluster.

For storing credentials it uses the built-in secret mechanism of libvirt.
Signed-off-by: NWido den Hollander <wido@widodh.nl>

Make it obvious to 'dumpxml' readers what unit we are using,
since our default of KiB for memory (1024) differs from qemu's
default of MiB; and differs from our use of bytes for storage.

Tests were updated via:

$ find tests/*data tests/*out -name '*.xml' | \
  xargs sed -i 's/<\(memory\|currentMemory\|hard_limit\|soft_limit\|min_guarantee\|swap_hard_limit\)>/<\1 unit='"'KiB'>/"
$ find tests/*data tests/*out -name '*.xml' | \
  xargs sed -i 's/<\(capacity\|allocation\|available\)>/<\1 unit='"'bytes'>/"

followed by a few fixes for the stragglers.

Note that with this patch, the RNG for <memory> still forbids
validation of anything except unit='KiB', since the code silently
ignores the attribute; a later patch will expand <memory> to allow
scaled input in the code and update the RNG to match.

* docs/schemas/basictypes.rng (unit): Add 'bytes'.
(scaledInteger): New define.
* docs/schemas/storagevol.rng (sizing): Use it.
* docs/schemas/storagepool.rng (sizing): Likewise.
* docs/schemas/domaincommon.rng (memoryKBElement): New define; use
for memory elements.
* src/conf/storage_conf.c (virStoragePoolDefFormat)
(virStorageVolDefFormat): Likewise.
* src/conf/domain_conf.h (_virDomainDef): Document unit used
internally.
* src/conf/storage_conf.h (_virStoragePoolDef, _virStorageVolDef):
Likewise.
* tests/*data/*.xml: Update all tests.
* tests/*out/*.xml: Likewise.
* tests/define-dev-segfault: Likewise.
* tests/openvzutilstest.c (testReadNetworkConf): Likewise.
* tests/qemuargv2xmltest.c (blankProblemElements): Likewise.

The code supported unit='E' for "exabyte", but the RNG did not;
conversely, the RNG supported "z" and "y" but the code did not
(I'm jealous if you have that much storage, particularly since
it won't fit in 64-bit off_t).  Also, the code supported
<allocation unit='...'>, but not the RNG.

In an effort to make 'unit' more worthwhile in future patches,
it's easier to share it between files.

In making this factorization, note that absFilePath is more
permissive than 'path', so storage pools and storage volumes
will now validate with a wider set of file names than before.
I don't think this should be a problem in practice.

* docs/schemas/storagepool.rng: Include basic types, rather than
repeating things here.
* docs/schemas/storagevol.rng: Likewise.
* docs/schemas/basictypes.rng: Add 'unsignedLong', 'unit', and fix
to match storage code.

The XML docs describe a 'port' attribute for the
storage source <host> element, but the parser never
handled it.

* docs/schemas/storagepool.rng: Define port attribute
* src/conf/storage_conf.c: Add missing parsing/formatting
  of host port number
* src/conf/storage_conf.h: Remove bogus/unused 'protocol' field

I wrote a patch to add support for listing the Vendor and Model of a
storage pool in the storage pool XML.  This would allow vendor
extensions of specific devices.  The patch includes a test for the new
attributes as well.

Patrick Dignan

* Fix broken rng schema
* Add test input & output files

* docs/schemas/capability.rng: Likewise.
* docs/schemas/network.rng: Likewise.
* docs/schemas/nodedev.rng: Likewise.
* docs/schemas/storagepool.rng: Likewise.
* docs/schemas/storagevol.rng: Likewise.
Use these commands:
t=$'\t'
git ls-files | grep '\.rng$' | xargs grep -lE "^ *$t" \
  | xargs perl -MText::Tabs -ni -le \
    '$m=/^( *\t[ \t]*)(.*)/; print $m ? expand($1) . $2 : $_'

Allows the initiator to use a variety of IQNs rather than just the
system IQN when creating iSCSI pools.
* docs/schemas/storagepool.rng: extends the syntax with <iqn name="..."/>
* src/conf/storage_conf.[ch]: read and stores the iqn name
* src/storage/storage_backend_iscsi.[ch]: implement the IQN selection
  when detected

* src/conf/storage_conf.c src/conf/storage_conf.h: extend the enums
  and values
* docs/schemas/storagepool.rng: add to the list of storage pool type
  formats

- mpath pools weren't listed
- scsi pools were missing an adapter section
- iscsi pools were missing an auth section
- Logical pools do not require a source name to be specified

* docs/schemas/*.rng: the comments were wrong
* src/qemu_conf.c: typo in an error message