This is actually pretty easy since fs/dlm already handles the bulk of the
work. The Ocfs2 userspace cluster stack module already uses fs/dlm as the
underlying lock manager, so I only had to add the right calls.

Cluster-aware POSIX locks ("plocks") can be turned off by the same means at
UNIX locks - mount with 'noflocks', or create a local-only Ocfs2 volume.
Internally, the file system uses two sets of file_operations, depending on
whether cluster aware plocks is required. This turns out to be easier than
implementing local-only versions of ->lock.
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

The ->hangup() call was only used to execute ocfs2_hb_ctl.  Now that
the generic stack glue code handles this, the underlying stack drivers
don't need to know about it.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

Take o2hb_stop() out of the o2cb code and make it part of the generic
stack glue as ocfs2_leave_group().  This also allows us to remove the
ocfs2_get_hb_ctl_path() function - everything to do with hb_ctl is now
part of stackglue.c.  o2cb no longer needs a ->hangup() function.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

ocfs2 needs to call out to the hb_ctl program at unmount for all cluster
stacks.  The first step is to move the hb_ctl_path sysctl out of the
o2cb code and into the generic stack glue.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

Add code to use fs/dlm.

[ Modified to be part of the stack_user module -- Joel ]
Signed-off-by: NDavid Teigland <teigland@redhat.com>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

Userspace can now query and specify the cluster stack in use via the
/sys/fs/ocfs2/cluster_stack file.  By default, it is 'o2cb', which is
the classic stack.  Thus, old tools that do not know how to modify this
file will work just fine.  The stack cannot be modified if there is a
live filesystem.

ocfs2_cluster_connect() now takes the expected cluster stack as an
argument.  This way, the filesystem and the stack glue ensure they are
speaking to the same backend.

If the stack is 'o2cb', the o2cb stack plugin is used.  For any other
value, the fsdlm stack plugin is selected.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

We define the ocfs2_stack_plugin structure to represent a stack driver.
The o2cb stack code is split into stack_o2cb.c.  This becomes the
ocfs2_stack_o2cb.ko module.

The stackglue generic functions are similarly split into the
ocfs2_stackglue.ko module.  This module now provides an interface to
register drivers.  The ocfs2_stack_o2cb driver registers itself.  As
part of this interface, ocfs2_stackglue can load drivers on demand.
This is accomplished in ocfs2_cluster_connect().

ocfs2_cluster_disconnect() is now notified when a _hangup() is pending.
If a hangup is pending, it will not release the driver module and will
let _hangup() do that.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

Define the ocfs2_stack_operations structure.  Build o2cb_stack_ops from
all of the o2cb-specific stack functions.  Change the generic stack glue
functions to call the stack_ops instead of the o2cb functions directly.

The o2cb functions are moved to stack_o2cb.c.  The headers are cleaned up
to where only needed headers are included.

In this code, stackglue.c and stack_o2cb.c refer to some shared
extern variables.  When they become modules, that will change.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

The stack glue initialization function needs a better name so that it can be
used cleanly when stackglue becomes a module.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

dlmglue.c was still referencing a raw o2dlm lksb in one instance.  Let's
create a generic ocfs2_dlm_dump_lksb() function.  This allows underlying
DLMs to print whatever they want about their lock.

We then move the o2dlm dump into stackglue.c where it belongs.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

The last bit of classic stack used directly in ocfs2 code is o2hb.
Specifically, the check for heartbeat during mount and the call to
ocfs2_hb_ctl during unmount.

We create an extra API, ocfs2_cluster_hangup(), to encapsulate the call
to ocfs2_hb_ctl.  Other stacks will just leave hangup() empty.

The check for heartbeat is moved into ocfs2_cluster_connect().  It will
be matched by a similar check for other stacks.

With this change, only stackglue.c includes cluster/ headers.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

ocfs2 asks the cluster stack for the local node's node number for two
reasons; to fill the slot map and to print it. While the slot map isn't
necessary for userspace cluster stacks, the printing is very nice for
debugging. Thus we add ocfs2_cluster_this_node() as a generic API to get
this value. It is anticipated that the slot map will not be used under a
userspace cluster stack, so validity checks of the node num only need to
exist in the slot map code. Otherwise, it just gets used and printed as an
opaque value.

[ Fixed up some "int" versus "unsigned int" issues and made osb->node_num
  truly opaque. --Mark ]
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

This step introduces a cluster stack agnostic API for initializing and
exiting.  fs/ocfs2/dlmglue.c no longer uses o2cb/o2dlm knowledge to
connect to the stack.  It is all handled in stackglue.c.

heartbeat.c no longer needs to know how it gets called.
ocfs2_do_node_down() is now a clean recovery trigger.

The big gotcha is the ordering of initializations and de-initializations done
underneath ocfs2_cluster_connect().  ocfs2_dlm_init() used to do all
o2dlm initialization in one block.  Thus, the o2dlm functionality of
ocfs2_cluster_connect() is very straightforward.  ocfs2_dlm_shutdown(),
however, did a few things between de-registration of the eviction
callback and actually shutting down the domain.  Now de-registration and
shutdown of the domain are wrapped within the single
ocfs2_cluster_disconnect() call.  I've checked the code paths to make
sure we can safely tear down things in ocfs2_dlm_shutdown() before
calling ocfs2_cluster_disconnect().  The filesystem has already set
itself to ignore the callback.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

Wrap the lock status block (lksb) in a union.  Later we will add a union
element for the fs/dlm lksb.  Create accessors for the status and lvb
fields.

Other than a debugging function, dlmglue.c does not directly reference
the o2dlm locking path anymore.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

Change the ocfs2_dlm_lock/unlock() functions to return -errno values.
This is the first step towards elminiating dlm_status in
fs/ocfs2/dlmglue.c.  The change also passes -errno values to
->unlock_ast().

[ Fix a return code in dlmglue.c and change the error translation table into
  an array of ints. --Mark ]
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

The ocfs2 generic code should use the values in <linux/dlmconstants.h>.
stackglue.c will convert them to o2dlm values.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

This is the first in a series of patches to isolate ocfs2 from the
underlying cluster stack. Here we wrap the dlm locking functions with
ocfs2-specific calls. Because ocfs2 always uses the same dlm lock status
callbacks, we can eliminate the callbacks from the filesystem visible
functions.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>