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![Joel Becker](/assets/img/avatar_default.png)
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: Joel Becker <joel.becker@oracle.com> Acked-by: Mark Fasheh <mfasheh@suse.com>
275 lines
8.1 KiB
C
275 lines
8.1 KiB
C
/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* stackglue.h
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*
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* Glue to the underlying cluster stack.
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*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#ifndef STACKGLUE_H
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#define STACKGLUE_H
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#include <linux/types.h>
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#include <linux/list.h>
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#include <linux/dlmconstants.h>
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#include "dlm/dlmapi.h"
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#include <linux/dlm.h>
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/* Needed for plock-related prototypes */
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struct file;
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struct file_lock;
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/*
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* dlmconstants.h does not have a LOCAL flag. We hope to remove it
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* some day, but right now we need it. Let's fake it. This value is larger
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* than any flag in dlmconstants.h.
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*/
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#define DLM_LKF_LOCAL 0x00100000
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/*
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* This shadows DLM_LOCKSPACE_LEN in fs/dlm/dlm_internal.h. That probably
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* wants to be in a public header.
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*/
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#define GROUP_NAME_MAX 64
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/*
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* ocfs2_protocol_version changes when ocfs2 does something different in
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* its inter-node behavior. See dlmglue.c for more information.
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*/
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struct ocfs2_protocol_version {
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u8 pv_major;
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u8 pv_minor;
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};
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/*
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* The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
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*/
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struct ocfs2_locking_protocol {
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struct ocfs2_protocol_version lp_max_version;
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void (*lp_lock_ast)(void *astarg);
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void (*lp_blocking_ast)(void *astarg, int level);
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void (*lp_unlock_ast)(void *astarg, int error);
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};
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/*
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* The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
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* has a pointer to separately allocated lvb space. This struct exists only to
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* include in the lksb union to make space for a combined dlm_lksb and lvb.
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*/
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struct fsdlm_lksb_plus_lvb {
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struct dlm_lksb lksb;
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char lvb[DLM_LVB_LEN];
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};
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/*
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* A union of all lock status structures. We define it here so that the
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* size of the union is known. Lock status structures are embedded in
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* ocfs2 inodes.
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*/
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union ocfs2_dlm_lksb {
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struct dlm_lockstatus lksb_o2dlm;
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struct dlm_lksb lksb_fsdlm;
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struct fsdlm_lksb_plus_lvb padding;
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};
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/*
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* A cluster connection. Mostly opaque to ocfs2, the connection holds
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* state for the underlying stack. ocfs2 does use cc_version to determine
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* locking compatibility.
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*/
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struct ocfs2_cluster_connection {
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char cc_name[GROUP_NAME_MAX];
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int cc_namelen;
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struct ocfs2_protocol_version cc_version;
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void (*cc_recovery_handler)(int node_num, void *recovery_data);
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void *cc_recovery_data;
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void *cc_lockspace;
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void *cc_private;
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};
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/*
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* Each cluster stack implements the stack operations structure. Not used
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* in the ocfs2 code, the stackglue code translates generic cluster calls
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* into stack operations.
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*/
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struct ocfs2_stack_operations {
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/*
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* The fs code calls ocfs2_cluster_connect() to attach a new
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* filesystem to the cluster stack. The ->connect() op is passed
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* an ocfs2_cluster_connection with the name and recovery field
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* filled in.
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*
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* The stack must set up any notification mechanisms and create
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* the filesystem lockspace in the DLM. The lockspace should be
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* stored on cc_lockspace. Any other information can be stored on
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* cc_private.
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*
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* ->connect() must not return until it is guaranteed that
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*
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* - Node down notifications for the filesystem will be recieved
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* and passed to conn->cc_recovery_handler().
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* - Locking requests for the filesystem will be processed.
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*/
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int (*connect)(struct ocfs2_cluster_connection *conn);
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/*
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* The fs code calls ocfs2_cluster_disconnect() when a filesystem
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* no longer needs cluster services. All DLM locks have been
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* dropped, and recovery notification is being ignored by the
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* fs code. The stack must disengage from the DLM and discontinue
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* recovery notification.
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*
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* Once ->disconnect() has returned, the connection structure will
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* be freed. Thus, a stack must not return from ->disconnect()
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* until it will no longer reference the conn pointer.
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*
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* Once this call returns, the stack glue will be dropping this
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* connection's reference on the module.
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*/
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int (*disconnect)(struct ocfs2_cluster_connection *conn);
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/*
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* ->this_node() returns the cluster's unique identifier for the
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* local node.
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*/
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int (*this_node)(unsigned int *node);
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/*
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* Call the underlying dlm lock function. The ->dlm_lock()
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* callback should convert the flags and mode as appropriate.
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*
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* ast and bast functions are not part of the call because the
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* stack will likely want to wrap ast and bast calls before passing
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* them to stack->sp_proto.
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*/
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int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
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int mode,
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union ocfs2_dlm_lksb *lksb,
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u32 flags,
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void *name,
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unsigned int namelen,
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void *astarg);
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/*
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* Call the underlying dlm unlock function. The ->dlm_unlock()
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* function should convert the flags as appropriate.
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*
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* The unlock ast is not passed, as the stack will want to wrap
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* it before calling stack->sp_proto->lp_unlock_ast().
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*/
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int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
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union ocfs2_dlm_lksb *lksb,
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u32 flags,
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void *astarg);
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/*
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* Return the status of the current lock status block. The fs
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* code should never dereference the union. The ->lock_status()
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* callback pulls out the stack-specific lksb, converts the status
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* to a proper errno, and returns it.
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*/
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int (*lock_status)(union ocfs2_dlm_lksb *lksb);
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/*
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* Return non-zero if the LVB is valid.
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*/
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int (*lvb_valid)(union ocfs2_dlm_lksb *lksb);
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/*
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* Pull the lvb pointer off of the stack-specific lksb.
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*/
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void *(*lock_lvb)(union ocfs2_dlm_lksb *lksb);
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/*
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* Cluster-aware posix locks
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*
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* This is NULL for stacks which do not support posix locks.
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*/
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int (*plock)(struct ocfs2_cluster_connection *conn,
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u64 ino,
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struct file *file,
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int cmd,
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struct file_lock *fl);
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/*
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* This is an optoinal debugging hook. If provided, the
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* stack can dump debugging information about this lock.
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*/
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void (*dump_lksb)(union ocfs2_dlm_lksb *lksb);
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};
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/*
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* Each stack plugin must describe itself by registering a
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* ocfs2_stack_plugin structure. This is only seen by stackglue and the
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* stack driver.
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*/
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struct ocfs2_stack_plugin {
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char *sp_name;
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struct ocfs2_stack_operations *sp_ops;
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struct module *sp_owner;
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/* These are managed by the stackglue code. */
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struct list_head sp_list;
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unsigned int sp_count;
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struct ocfs2_locking_protocol *sp_proto;
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};
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/* Used by the filesystem */
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int ocfs2_cluster_connect(const char *stack_name,
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const char *group,
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int grouplen,
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void (*recovery_handler)(int node_num,
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void *recovery_data),
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void *recovery_data,
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struct ocfs2_cluster_connection **conn);
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int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
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int hangup_pending);
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void ocfs2_cluster_hangup(const char *group, int grouplen);
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int ocfs2_cluster_this_node(unsigned int *node);
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struct ocfs2_lock_res;
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int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
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int mode,
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union ocfs2_dlm_lksb *lksb,
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u32 flags,
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void *name,
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unsigned int namelen,
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struct ocfs2_lock_res *astarg);
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int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
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union ocfs2_dlm_lksb *lksb,
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u32 flags,
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struct ocfs2_lock_res *astarg);
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int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb);
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int ocfs2_dlm_lvb_valid(union ocfs2_dlm_lksb *lksb);
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void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb);
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void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);
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int ocfs2_stack_supports_plocks(void);
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int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
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struct file *file, int cmd, struct file_lock *fl);
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void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);
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/* Used by stack plugins */
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int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
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void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
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#endif /* STACKGLUE_H */
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