linux/fs/ocfs2/stackglue.h
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   1/* -*- mode: c; c-basic-offset: 8; -*-
   2 * vim: noexpandtab sw=8 ts=8 sts=0:
   3 *
   4 * stackglue.h
   5 *
   6 * Glue to the underlying cluster stack.
   7 *
   8 * Copyright (C) 2007 Oracle.  All rights reserved.
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public
  12 * License as published by the Free Software Foundation, version 2.
  13 *
  14 * This program is distributed in the hope that it will be useful,
  15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17 * General Public License for more details.
  18 */
  19
  20
  21#ifndef STACKGLUE_H
  22#define STACKGLUE_H
  23
  24#include <linux/types.h>
  25#include <linux/list.h>
  26#include <linux/dlmconstants.h>
  27
  28#include "dlm/dlmapi.h"
  29#include <linux/dlm.h>
  30
  31/* Needed for plock-related prototypes */
  32struct file;
  33struct file_lock;
  34
  35/*
  36 * dlmconstants.h does not have a LOCAL flag.  We hope to remove it
  37 * some day, but right now we need it.  Let's fake it.  This value is larger
  38 * than any flag in dlmconstants.h.
  39 */
  40#define DLM_LKF_LOCAL           0x00100000
  41
  42/*
  43 * This shadows DLM_LOCKSPACE_LEN in fs/dlm/dlm_internal.h.  That probably
  44 * wants to be in a public header.
  45 */
  46#define GROUP_NAME_MAX          64
  47
  48
  49/*
  50 * ocfs2_protocol_version changes when ocfs2 does something different in
  51 * its inter-node behavior.  See dlmglue.c for more information.
  52 */
  53struct ocfs2_protocol_version {
  54        u8 pv_major;
  55        u8 pv_minor;
  56};
  57
  58/*
  59 * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
  60 * has a pointer to separately allocated lvb space.  This struct exists only to
  61 * include in the lksb union to make space for a combined dlm_lksb and lvb.
  62 */
  63struct fsdlm_lksb_plus_lvb {
  64        struct dlm_lksb lksb;
  65        char lvb[DLM_LVB_LEN];
  66};
  67
  68/*
  69 * A union of all lock status structures.  We define it here so that the
  70 * size of the union is known.  Lock status structures are embedded in
  71 * ocfs2 inodes.
  72 */
  73struct ocfs2_cluster_connection;
  74struct ocfs2_dlm_lksb {
  75         union {
  76                 struct dlm_lockstatus lksb_o2dlm;
  77                 struct dlm_lksb lksb_fsdlm;
  78                 struct fsdlm_lksb_plus_lvb padding;
  79         };
  80         struct ocfs2_cluster_connection *lksb_conn;
  81};
  82
  83/*
  84 * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
  85 */
  86struct ocfs2_locking_protocol {
  87        struct ocfs2_protocol_version lp_max_version;
  88        void (*lp_lock_ast)(struct ocfs2_dlm_lksb *lksb);
  89        void (*lp_blocking_ast)(struct ocfs2_dlm_lksb *lksb, int level);
  90        void (*lp_unlock_ast)(struct ocfs2_dlm_lksb *lksb, int error);
  91};
  92
  93
  94/*
  95 * A cluster connection.  Mostly opaque to ocfs2, the connection holds
  96 * state for the underlying stack.  ocfs2 does use cc_version to determine
  97 * locking compatibility.
  98 */
  99struct ocfs2_cluster_connection {
 100        char cc_name[GROUP_NAME_MAX];
 101        int cc_namelen;
 102        struct ocfs2_protocol_version cc_version;
 103        struct ocfs2_locking_protocol *cc_proto;
 104        void (*cc_recovery_handler)(int node_num, void *recovery_data);
 105        void *cc_recovery_data;
 106        void *cc_lockspace;
 107        void *cc_private;
 108};
 109
 110/*
 111 * Each cluster stack implements the stack operations structure.  Not used
 112 * in the ocfs2 code, the stackglue code translates generic cluster calls
 113 * into stack operations.
 114 */
 115struct ocfs2_stack_operations {
 116        /*
 117         * The fs code calls ocfs2_cluster_connect() to attach a new
 118         * filesystem to the cluster stack.  The ->connect() op is passed
 119         * an ocfs2_cluster_connection with the name and recovery field
 120         * filled in.
 121         *
 122         * The stack must set up any notification mechanisms and create
 123         * the filesystem lockspace in the DLM.  The lockspace should be
 124         * stored on cc_lockspace.  Any other information can be stored on
 125         * cc_private.
 126         *
 127         * ->connect() must not return until it is guaranteed that
 128         *
 129         *  - Node down notifications for the filesystem will be received
 130         *    and passed to conn->cc_recovery_handler().
 131         *  - Locking requests for the filesystem will be processed.
 132         */
 133        int (*connect)(struct ocfs2_cluster_connection *conn);
 134
 135        /*
 136         * The fs code calls ocfs2_cluster_disconnect() when a filesystem
 137         * no longer needs cluster services.  All DLM locks have been
 138         * dropped, and recovery notification is being ignored by the
 139         * fs code.  The stack must disengage from the DLM and discontinue
 140         * recovery notification.
 141         *
 142         * Once ->disconnect() has returned, the connection structure will
 143         * be freed.  Thus, a stack must not return from ->disconnect()
 144         * until it will no longer reference the conn pointer.
 145         *
 146         * Once this call returns, the stack glue will be dropping this
 147         * connection's reference on the module.
 148         */
 149        int (*disconnect)(struct ocfs2_cluster_connection *conn);
 150
 151        /*
 152         * ->this_node() returns the cluster's unique identifier for the
 153         * local node.
 154         */
 155        int (*this_node)(unsigned int *node);
 156
 157        /*
 158         * Call the underlying dlm lock function.  The ->dlm_lock()
 159         * callback should convert the flags and mode as appropriate.
 160         *
 161         * ast and bast functions are not part of the call because the
 162         * stack will likely want to wrap ast and bast calls before passing
 163         * them to stack->sp_proto.  There is no astarg.  The lksb will
 164         * be passed back to the ast and bast functions.  The caller can
 165         * use this to find their object.
 166         */
 167        int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
 168                        int mode,
 169                        struct ocfs2_dlm_lksb *lksb,
 170                        u32 flags,
 171                        void *name,
 172                        unsigned int namelen);
 173
 174        /*
 175         * Call the underlying dlm unlock function.  The ->dlm_unlock()
 176         * function should convert the flags as appropriate.
 177         *
 178         * The unlock ast is not passed, as the stack will want to wrap
 179         * it before calling stack->sp_proto->lp_unlock_ast().  There is
 180         * no astarg.  The lksb will be passed back to the unlock ast
 181         * function.  The caller can use this to find their object.
 182         */
 183        int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
 184                          struct ocfs2_dlm_lksb *lksb,
 185                          u32 flags);
 186
 187        /*
 188         * Return the status of the current lock status block.  The fs
 189         * code should never dereference the union.  The ->lock_status()
 190         * callback pulls out the stack-specific lksb, converts the status
 191         * to a proper errno, and returns it.
 192         */
 193        int (*lock_status)(struct ocfs2_dlm_lksb *lksb);
 194
 195        /*
 196         * Return non-zero if the LVB is valid.
 197         */
 198        int (*lvb_valid)(struct ocfs2_dlm_lksb *lksb);
 199
 200        /*
 201         * Pull the lvb pointer off of the stack-specific lksb.
 202         */
 203        void *(*lock_lvb)(struct ocfs2_dlm_lksb *lksb);
 204
 205        /*
 206         * Cluster-aware posix locks
 207         *
 208         * This is NULL for stacks which do not support posix locks.
 209         */
 210        int (*plock)(struct ocfs2_cluster_connection *conn,
 211                     u64 ino,
 212                     struct file *file,
 213                     int cmd,
 214                     struct file_lock *fl);
 215
 216        /*
 217         * This is an optoinal debugging hook.  If provided, the
 218         * stack can dump debugging information about this lock.
 219         */
 220        void (*dump_lksb)(struct ocfs2_dlm_lksb *lksb);
 221};
 222
 223/*
 224 * Each stack plugin must describe itself by registering a
 225 * ocfs2_stack_plugin structure.  This is only seen by stackglue and the
 226 * stack driver.
 227 */
 228struct ocfs2_stack_plugin {
 229        char *sp_name;
 230        struct ocfs2_stack_operations *sp_ops;
 231        struct module *sp_owner;
 232
 233        /* These are managed by the stackglue code. */
 234        struct list_head sp_list;
 235        unsigned int sp_count;
 236        struct ocfs2_protocol_version sp_max_proto;
 237};
 238
 239
 240/* Used by the filesystem */
 241int ocfs2_cluster_connect(const char *stack_name,
 242                          const char *group,
 243                          int grouplen,
 244                          struct ocfs2_locking_protocol *lproto,
 245                          void (*recovery_handler)(int node_num,
 246                                                   void *recovery_data),
 247                          void *recovery_data,
 248                          struct ocfs2_cluster_connection **conn);
 249/*
 250 * Used by callers that don't store their stack name.  They must ensure
 251 * all nodes have the same stack.
 252 */
 253int ocfs2_cluster_connect_agnostic(const char *group,
 254                                   int grouplen,
 255                                   struct ocfs2_locking_protocol *lproto,
 256                                   void (*recovery_handler)(int node_num,
 257                                                            void *recovery_data),
 258                                   void *recovery_data,
 259                                   struct ocfs2_cluster_connection **conn);
 260int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 261                             int hangup_pending);
 262void ocfs2_cluster_hangup(const char *group, int grouplen);
 263int ocfs2_cluster_this_node(unsigned int *node);
 264
 265struct ocfs2_lock_res;
 266int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
 267                   int mode,
 268                   struct ocfs2_dlm_lksb *lksb,
 269                   u32 flags,
 270                   void *name,
 271                   unsigned int namelen);
 272int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
 273                     struct ocfs2_dlm_lksb *lksb,
 274                     u32 flags);
 275
 276int ocfs2_dlm_lock_status(struct ocfs2_dlm_lksb *lksb);
 277int ocfs2_dlm_lvb_valid(struct ocfs2_dlm_lksb *lksb);
 278void *ocfs2_dlm_lvb(struct ocfs2_dlm_lksb *lksb);
 279void ocfs2_dlm_dump_lksb(struct ocfs2_dlm_lksb *lksb);
 280
 281int ocfs2_stack_supports_plocks(void);
 282int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
 283                struct file *file, int cmd, struct file_lock *fl);
 284
 285void ocfs2_stack_glue_set_max_proto_version(struct ocfs2_protocol_version *max_proto);
 286
 287
 288/* Used by stack plugins */
 289int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
 290void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
 291
 292#endif  /* STACKGLUE_H */
 293
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