This patch does two things:
- Remove "vg_name" from _OP_REQP due to the introduction of
  --no-lvm-storage. Since vg_name option has as default now None and is
  only set to the DEFAULT_VG if lvm_storage is enabled, this is needed
- It changes LUInitCluster.CheckPrereq() to skip _HasValidVG check
  initializing the cluster with --no-lvm-storage. Furthermore it adds to
  the help message the statement of the possibility to use
  --no-lvm-storage if no 'xenvg' volume group is found.

Reviewed-by: iustinp

Add LUSetClusterParams, which is the LU to modify cluster options.
This includes checks:
- not to disable lvm storage when it's already disabled
- not to enable lvm storage when it is already enabled
- not to disable lvm when lvm-based instances are present
- that the specified volume group is valid on all cluster-nodes
  when lvm-storage is going to be enabled

Reviewed-by: iustinp

Reviewed-by: iustinp

This adds a check to fail instance creation if lvm-storage is disabled
(cluster-wide). If lvm-storage is disabled (by initializing the cluster
with --no-lvm-storage) only instances with disk template in frozenset
DTS_NOT_LVM are allowed to create.

Reviewed-by: iustinp

DTS_NOT_LVM:
This constant is needed when checking if an instance can be created with
the given disk template if no lvm-storage is available, i.e. the ganeti
cluster does not have a volume group

DEFAULT_VG:
'xenvg' has been hardcoded before.

Reviewed-by: iustinp

In the start and stop instance LUs, the configuration update is done
right at the end. This means that if, for example, the instance shutdown
succeeds, but the drive deactivation fails, the next run of the watcher
will start the instance again, as it's still marked in running mode.

This patch changes these two LUs so that first the update the
configuration to the desired state, and only then we proceed to update
the config. This ensures that the state saved is the desired state.

Because the config might be updated even though the LU failed, this
patch also modifies the mcpu.Processor.ExecOpCode method to run the
RunConfigUpdate hook in a finally: phase while the lu.Exec is done in
its try phase. This ensures that config update hooks (tries to) run at
all times when the config is updated.

Reviewed-by: schreiberal

Reviewed-by: iustinp

Reviewed-by: iustinp

Reviewed-by: iustinp

This patch removes the options that allow to create local_raid1 or
remote_raid1 instances. It also modifies the documentation and removes
these disk templates from burnin and from qa.

Reviewed-by: imsnah

These two operations are related to md/drbd7 code (remote_raid1). Remove
them as part of the md/drbd7 removal.

Reviewed-by: imsnah

This patch adds three things:
- it normalizes the file storage directory path passed to gnt-cluster init
- if the file-storage-path doesn't exist on the master node, ganeti
  tries to create it
- adds additional check if the passed file-storage-dir is not a directory

Reviewed-by: iustinp

The BlockDev.GetStatus() method and some associated constants were never
used in the rest of the code. This patch removes them.

Reviewed-by: imsnah

This patch adds a new top-level class (BaseJO) that is used for both
opcodes and a new Job class.

This new class and the related changes to the OpCode abstract class are
used to implement simple to-dict/from-dict transformations, so that we
can easily serialize the classes using json.

Reviewed-by: imsnah

Author: manuel.franceschini
Reviewed-by: iustinp

Author: manuel.franceschini
Reviewed-by: iustinp

Author: manuel.franceschini
Reviewed-by: iustinp

Author: manuel.franceschini
Reviewed-by: iustinp

Author: manuel.franceschini
Reviewed-by: iustinp

Reviewed-by: ultrotter

This replaces very old code.

Reviewed-by: ultrotter

Reviewed-by: ultrotter

Reviewed-by: ultrotter

This allows callers to allocate a pseudo-TTY easily.

Reviewed-by: ultrotter

Reviewed-by: ultrotter

This renames some functions and does some minor codestyle cleanup.

Reviewed-by: ultrotter

The whole Ganeti cluster has a single SSH key. Its fingerprint is
written to Ganeti's known_hosts file, together with an alias. This
allows us to always use that alias instead of the real hostname,
making management of the known_hosts file much easier.

This patch does not handle an upgrade from an earlier version.

Reviewed-by: ultrotter

Reviewed-by: imsnah

Previously if a shared thread was notified, together with the rest, and was not
fast enough in waking up and acquiring the lock, another one could release it,
decide there were no more sharers, and let an exclusive one in instead. With
this patch we make sure all the shared holders which were waiting have passed,
before declaring it's time to make an exclusive one pass.

This also allows us to reintroduce a slight variation of the assertion removed
in r665, which makes our code safer.

Reviewed-by: imsnah

Make the cluster init fail if the IP to which the cluster name resolved
is already reachable by the master node. This is not a foolproof
solution, but it allows a cheap method of detecting simple mistakes.

It will also disallow using the master node name as cluster name (which
is something good).

The only drawbacks that I see are:
  - you are not allowed to do this, which might come in handy in cluster
    upgrades; but since we support rename, this is mitigated
  - cluster init takes longer now (+the timeout value, set to 5
    seconds), but since this is a one-off operation, it should be ok

Reviewed-by: ultrotter

This patch modifies TcpPing and its callers to make the source address
selection optional. Usually, the kernel will know better what
source address to use, just in some cases we want to enforce a given
source address so it makes sense to make this optional.

Reviewed-by: ultrotter

Reviewed-by: ultrotter

Reviewed-by: ultrotter

A LockSet is mostly useful when it has some locks in it. On the other hand
there are cases in which it must function even when empty. For example if a
cluster has no instances in it there's no reason why locking all of them
shouldn't work anyway. This patch adds test code for that situation and
implements the necessary fixes to make it work.

Reviewed-by: imsnah

Reviewed-by: imsnah

r644 contained some cleanup code for LockSet. Among other things it removed a
syntax error that allowed an assertion that previously wan't really checked to
trigger. It turns out that even though the spirit of that assertion was correct
its actual implementation was wrong.

While it's true that no sharers must be waiting if an exclusive holder is not
present it might happen that when all the sharers wake up one of them releases
the lock before some other even has had a chance to run. In this case
__shr_wait would still be greater than 0, even if the sharer is not actually
waiting, just pending a wakeup to proceed.

Thus, removing the assertion in question.

Reviewed-by: imsnah

Reviewed-by: ultrotter

This new functionality makes it possible to acquire a whole set, by passing
"None" to the acquire() function as the list of elements. This will avoid new
additions to the set, and then acquire all the current elements. The list of
all elements acquired will be returned at the end.

Deletions can still happen during the acquire process and we'll deal with it by
just skipping the deleted elements: it's effectively as if they were deleted
before we called the function. After we've finished though we hold all the
elements, so no more deletes can be performed before we release them.

Any call to release() will then first of all release the "set-level" lock if
we're holding it, and then all or some of the locks we have.

Some new tests checks that this feature works as intended.

Reviewed-by: imsnah

This patch adds a try/except area around most of the acquire() code (everything
after the intial condition checks). Since the except: clause contains just a
'raise' nothing really changes except the indentation of the code.

This is done in a separate commit to insulate and make clearer what the real
code changes done in the upcoming patch are.

Reviewed-by: imsnah

Previously the private version of the __names function returned directly a set.
We'll keep this in the public interface but change the private version to a
list in order to be able to sort() its result and then loop on it, even though
we'll need to do this with the usual care that some keys may disappear in
between.

Reviewed-by: imsnah