This is an effort of removing ocfs2_controld.pcmk and getting ocfs2 DLM
handling up to the times with respect to DLM (>=4.0.1) and corosync
(2.3.x).  AFAIK, cman also is being phased out for a unified corosync
cluster stack.

fs/dlm performs all the functions with respect to fencing and node
management and provides the API's to do so for ocfs2.  For all future
references, DLM stands for fs/dlm code.

The advantages are:
 + No need to run an additional userspace daemon (ocfs2_controld)
 + No controld device handling and controld protocol
 + Shifting responsibilities of node management to DLM layer

For backward compatibility, we are keeping the controld handling code.
Once enough time has passed we can remove a significant portion of the
code.  This was tested by using the kernel with changes on older
unmodified tools.  The kernel used ocfs2_controld as expected, and
displayed the appropriate warning message.

This feature requires modification in the userspace ocfs2-tools.  The
changes can be found at: https://github.com/goldwynr/ocfs2-tools branch:
nocontrold Currently, not many checks are present in the userspace code,
but that would change soon.

This patch (of 6):

Add clustername to cluster connection.
Signed-off-by: NGoldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: NMark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

Unlike ocfs2, dlmfs has no permanent storage.  It can't store off a
cluster stack it is supposed to be using.  So it can't specify the stack
name in ocfs2_cluster_connect().

Instead, we create ocfs2_cluster_connect_agnostic(), which simply uses
the stack that is currently enabled.  This is find for dlmfs, which will
rely on the stack initialization.

We add the "stackglue" capability to dlmfs's capability list.  This lets
userspace know dlmfs can be used with all cluster stacks.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

Inside the stackglue, the locking protocol structure is hanging off of
the ocfs2_cluster_connection.  This takes it one further; the locking
protocol is passed into ocfs2_cluster_connect().  Now different cluster
connections can have different locking protocols with distinct asts.
Note that all locking protocols have to keep their maximum protocol
version in lock-step.

With the protocol structure set in ocfs2_cluster_connect(), there is no
need for the stackglue to have a static pointer to a specific protocol
structure.  We can change initialization to only pass in the maximum
protocol version.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

With the full ocfs2_locking_protocol hanging off of the
ocfs2_cluster_connection, ast wrappers can get the ast/bast pointers
there.  They don't need to get them from their plugin structure.

The user plugin still needs the maximum locking protocol version,
though.  This changes the plugin structure so that it only holds the max
version, not the entire ocfs2_locking_protocol pointer.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

With the ocfs2_cluster_connection hanging off of the ocfs2_dlm_lksb, we
have access to it in the ast and bast wrapper functions.  Attach the
ocfs2_locking_protocol to the conn.

Now, instead of refering to a static variable for ast/bast pointers, the
wrappers can look at the connection.  This means different connections
can have different ast/bast pointers, and it reduces the need for the
static pointer.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

We're going to want it in the ast functions, so we convert union
ocfs2_dlm_lksb to struct ocfs2_dlm_lksb and let it carry the connection.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

The stackglue ast and bast functions tried to maintain the fiction that
their arguments were void pointers.  In reality, stack_user.c had to
know that the argument was an ocfs2_lock_res in order to get the status
off of the lksb.  That's ugly.

This changes stackglue to always pass the lksb as the argument to ast
and bast functions.  The caller can always use container_of() to get the
ocfs2_lock_res or user_dlm_lock_res.  The net effect to the caller is
zero.  They still get back the lockres in their ast.  stackglue gets
cleaner, and now can use the lksb itself.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>

The Lock Value Block (LVB) of a DLM lock can be lost when nodes die and
the DLM cannot reconstruct its state.  Clients of the DLM need to know
this.

ocfs2's internal DLM, o2dlm, explicitly zeroes out the LVB when it loses
track of the state.  This is not a standard behavior, but ocfs2 has
always relied on it.  Thus, an o2dlm LVB is always "valid".

ocfs2 now supports both o2dlm and fs/dlm via the stack glue.  When
fs/dlm loses track of an LVBs state, it sets a flag
(DLM_SBF_VALNOTVALID) on the Lock Status Block (LKSB).  The contents of
the LVB may be garbage or merely stale.

ocfs2 doesn't want to try to guess at the validity of the stale LVB.
Instead, it should be checking the VALNOTVALID flag.  As this is the
'standard' way of treating LVBs, we will promote this behavior.

We add a stack glue API ocfs2_dlm_lvb_valid().  It returns non-zero when
the LVB is valid.  o2dlm will always return valid, while fs/dlm will
check VALNOTVALID.
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
Acked-by: NMark Fasheh <mfasheh@suse.com>

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>