fs/ocfs2/stackglue.h

   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 /*
  32  * dlmconstants.h does not have a LOCAL flag.  We hope to remove it
  33  * some day, but right now we need it.  Let's fake it.  This value is larger
  34  * than any flag in dlmconstants.h.
  35  */
  36 #define DLM_LKF_LOCAL           0x00100000
  37
  38 /*
  39  * This shadows DLM_LOCKSPACE_LEN in fs/dlm/dlm_internal.h.  That probably
  40  * wants to be in a public header.
  41  */
  42 #define GROUP_NAME_MAX          64
  43
  44
  45 /*
  46  * ocfs2_protocol_version changes when ocfs2 does something different in
  47  * its inter-node behavior.  See dlmglue.c for more information.
  48  */
  49 struct ocfs2_protocol_version {
  50         u8 pv_major;
  51         u8 pv_minor;
  52 };
  53
  54 /*
  55  * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
  56  */
  57 struct ocfs2_locking_protocol {
  58         struct ocfs2_protocol_version lp_max_version;
  59         void (*lp_lock_ast)(void *astarg);
  60         void (*lp_blocking_ast)(void *astarg, int level);
  61         void (*lp_unlock_ast)(void *astarg, int error);
  62 };
  63
  64
  65 /*
  66  * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
  67  * has a pointer to separately allocated lvb space.  This struct exists only to
  68  * include in the lksb union to make space for a combined dlm_lksb and lvb.
  69  */
  70 struct fsdlm_lksb_plus_lvb {
  71         struct dlm_lksb lksb;
  72         char lvb[DLM_LVB_LEN];
  73 };
  74
  75 /*
  76  * A union of all lock status structures.  We define it here so that the
  77  * size of the union is known.  Lock status structures are embedded in
  78  * ocfs2 inodes.
  79  */
  80 union ocfs2_dlm_lksb {
  81         struct dlm_lockstatus lksb_o2dlm;
  82         struct dlm_lksb lksb_fsdlm;
  83         struct fsdlm_lksb_plus_lvb padding;
  84 };
  85
  86 /*
  87  * A cluster connection.  Mostly opaque to ocfs2, the connection holds
  88  * state for the underlying stack.  ocfs2 does use cc_version to determine
  89  * locking compatibility.
  90  */
  91 struct ocfs2_cluster_connection {
  92         char cc_name[GROUP_NAME_MAX];
  93         int cc_namelen;
  94         struct ocfs2_protocol_version cc_version;
  95         void (*cc_recovery_handler)(int node_num, void *recovery_data);
  96         void *cc_recovery_data;
  97         void *cc_lockspace;
  98         void *cc_private;
  99 };
 100
 101 /*
 102  * Each cluster stack implements the stack operations structure.  Not used
 103  * in the ocfs2 code, the stackglue code translates generic cluster calls
 104  * into stack operations.
 105  */
 106 struct ocfs2_stack_operations {
 107         /*
 108          * The fs code calls ocfs2_cluster_connect() to attach a new
 109          * filesystem to the cluster stack.  The ->connect() op is passed
 110          * an ocfs2_cluster_connection with the name and recovery field
 111          * filled in.
 112          *
 113          * The stack must set up any notification mechanisms and create
 114          * the filesystem lockspace in the DLM.  The lockspace should be
 115          * stored on cc_lockspace.  Any other information can be stored on
 116          * cc_private.
 117          *
 118          * ->connect() must not return until it is guaranteed that
 119          *
 120          *  - Node down notifications for the filesystem will be recieved
 121          *    and passed to conn->cc_recovery_handler().
 122          *  - Locking requests for the filesystem will be processed.
 123          */
 124         int (*connect)(struct ocfs2_cluster_connection *conn);
 125
 126         /*
 127          * The fs code calls ocfs2_cluster_disconnect() when a filesystem
 128          * no longer needs cluster services.  All DLM locks have been
 129          * dropped, and recovery notification is being ignored by the
 130          * fs code.  The stack must disengage from the DLM and discontinue
 131          * recovery notification.
 132          *
 133          * Once ->disconnect() has returned, the connection structure will
 134          * be freed.  Thus, a stack must not return from ->disconnect()
 135          * until it will no longer reference the conn pointer.
 136          *
 137          * Once this call returns, the stack glue will be dropping this
 138          * connection's reference on the module.
 139          */
 140         int (*disconnect)(struct ocfs2_cluster_connection *conn);
 141
 142         /*
 143          * ->this_node() returns the cluster's unique identifier for the
 144          * local node.
 145          */
 146         int (*this_node)(unsigned int *node);
 147
 148         /*
 149          * Call the underlying dlm lock function.  The ->dlm_lock()
 150          * callback should convert the flags and mode as appropriate.
 151          *
 152          * ast and bast functions are not part of the call because the
 153          * stack will likely want to wrap ast and bast calls before passing
 154          * them to stack->sp_proto.
 155          */
 156         int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
 157                         int mode,
 158                         union ocfs2_dlm_lksb *lksb,
 159                         u32 flags,
 160                         void *name,
 161                         unsigned int namelen,
 162                         void *astarg);
 163
 164         /*
 165          * Call the underlying dlm unlock function.  The ->dlm_unlock()
 166          * function should convert the flags as appropriate.
 167          *
 168          * The unlock ast is not passed, as the stack will want to wrap
 169          * it before calling stack->sp_proto->lp_unlock_ast().
 170          */
 171         int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
 172                           union ocfs2_dlm_lksb *lksb,
 173                           u32 flags,
 174                           void *astarg);
 175
 176         /*
 177          * Return the status of the current lock status block.  The fs
 178          * code should never dereference the union.  The ->lock_status()
 179          * callback pulls out the stack-specific lksb, converts the status
 180          * to a proper errno, and returns it.
 181          */
 182         int (*lock_status)(union ocfs2_dlm_lksb *lksb);
 183
 184         /*
 185          * Pull the lvb pointer off of the stack-specific lksb.
 186          */
 187         void *(*lock_lvb)(union ocfs2_dlm_lksb *lksb);
 188
 189         /*
 190          * This is an optoinal debugging hook.  If provided, the
 191          * stack can dump debugging information about this lock.
 192          */
 193         void (*dump_lksb)(union ocfs2_dlm_lksb *lksb);
 194 };
 195
 196 /*
 197  * Each stack plugin must describe itself by registering a
 198  * ocfs2_stack_plugin structure.  This is only seen by stackglue and the
 199  * stack driver.
 200  */
 201 struct ocfs2_stack_plugin {
 202         char *sp_name;
 203         struct ocfs2_stack_operations *sp_ops;
 204         struct module *sp_owner;
 205
 206         /* These are managed by the stackglue code. */
 207         struct list_head sp_list;
 208         unsigned int sp_count;
 209         struct ocfs2_locking_protocol *sp_proto;
 210 };
 211
 212
 213 /* Used by the filesystem */
 214 int ocfs2_cluster_connect(const char *stack_name,
 215                           const char *group,
 216                           int grouplen,
 217                           void (*recovery_handler)(int node_num,
 218                                                    void *recovery_data),
 219                           void *recovery_data,
 220                           struct ocfs2_cluster_connection **conn);
 221 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 222                              int hangup_pending);
 223 void ocfs2_cluster_hangup(const char *group, int grouplen);
 224 int ocfs2_cluster_this_node(unsigned int *node);
 225
 226 struct ocfs2_lock_res;
 227 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
 228                    int mode,
 229                    union ocfs2_dlm_lksb *lksb,
 230                    u32 flags,
 231                    void *name,
 232                    unsigned int namelen,
 233                    struct ocfs2_lock_res *astarg);
 234 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
 235                      union ocfs2_dlm_lksb *lksb,
 236                      u32 flags,
 237                      struct ocfs2_lock_res *astarg);
 238
 239 int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb);
 240 void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb);
 241 void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);
 242
 243 void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);
 244
 245
 246 /* Used by stack plugins */
 247 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
 248 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
 249
 250 #endif  /* STACKGLUE_H */