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 /* Needed for plock-related prototypes */
  32 struct file;
  33 struct 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  */
  53 struct ocfs2_protocol_version {
  54         u8 pv_major;
  55         u8 pv_minor;
  56 };
  57
  58 /*
  59  * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
  60  */
  61 struct ocfs2_locking_protocol {
  62         struct ocfs2_protocol_version lp_max_version;
  63         void (*lp_lock_ast)(void *astarg);
  64         void (*lp_blocking_ast)(void *astarg, int level);
  65         void (*lp_unlock_ast)(void *astarg, int error);
  66 };
  67
  68
  69 /*
  70  * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
  71  * has a pointer to separately allocated lvb space.  This struct exists only to
  72  * include in the lksb union to make space for a combined dlm_lksb and lvb.
  73  */
  74 struct fsdlm_lksb_plus_lvb {
  75         struct dlm_lksb lksb;
  76         char lvb[DLM_LVB_LEN];
  77 };
  78
  79 /*
  80  * A union of all lock status structures.  We define it here so that the
  81  * size of the union is known.  Lock status structures are embedded in
  82  * ocfs2 inodes.
  83  */
  84 union ocfs2_dlm_lksb {
  85         struct dlm_lockstatus lksb_o2dlm;
  86         struct dlm_lksb lksb_fsdlm;
  87         struct fsdlm_lksb_plus_lvb padding;
  88 };
  89
  90 /*
  91  * A cluster connection.  Mostly opaque to ocfs2, the connection holds
  92  * state for the underlying stack.  ocfs2 does use cc_version to determine
  93  * locking compatibility.
  94  */
  95 struct ocfs2_cluster_connection {
  96         char cc_name[GROUP_NAME_MAX];
  97         int cc_namelen;
  98         struct ocfs2_protocol_version cc_version;
  99         void (*cc_recovery_handler)(int node_num, void *recovery_data);
 100         void *cc_recovery_data;
 101         void *cc_lockspace;
 102         void *cc_private;
 103 };
 104
 105 /*
 106  * Each cluster stack implements the stack operations structure.  Not used
 107  * in the ocfs2 code, the stackglue code translates generic cluster calls
 108  * into stack operations.
 109  */
 110 struct ocfs2_stack_operations {
 111         /*
 112          * The fs code calls ocfs2_cluster_connect() to attach a new
 113          * filesystem to the cluster stack.  The ->connect() op is passed
 114          * an ocfs2_cluster_connection with the name and recovery field
 115          * filled in.
 116          *
 117          * The stack must set up any notification mechanisms and create
 118          * the filesystem lockspace in the DLM.  The lockspace should be
 119          * stored on cc_lockspace.  Any other information can be stored on
 120          * cc_private.
 121          *
 122          * ->connect() must not return until it is guaranteed that
 123          *
 124          *  - Node down notifications for the filesystem will be recieved
 125          *    and passed to conn->cc_recovery_handler().
 126          *  - Locking requests for the filesystem will be processed.
 127          */
 128         int (*connect)(struct ocfs2_cluster_connection *conn);
 129
 130         /*
 131          * The fs code calls ocfs2_cluster_disconnect() when a filesystem
 132          * no longer needs cluster services.  All DLM locks have been
 133          * dropped, and recovery notification is being ignored by the
 134          * fs code.  The stack must disengage from the DLM and discontinue
 135          * recovery notification.
 136          *
 137          * Once ->disconnect() has returned, the connection structure will
 138          * be freed.  Thus, a stack must not return from ->disconnect()
 139          * until it will no longer reference the conn pointer.
 140          *
 141          * Once this call returns, the stack glue will be dropping this
 142          * connection's reference on the module.
 143          */
 144         int (*disconnect)(struct ocfs2_cluster_connection *conn);
 145
 146         /*
 147          * ->this_node() returns the cluster's unique identifier for the
 148          * local node.
 149          */
 150         int (*this_node)(unsigned int *node);
 151
 152         /*
 153          * Call the underlying dlm lock function.  The ->dlm_lock()
 154          * callback should convert the flags and mode as appropriate.
 155          *
 156          * ast and bast functions are not part of the call because the
 157          * stack will likely want to wrap ast and bast calls before passing
 158          * them to stack->sp_proto.
 159          */
 160         int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
 161                         int mode,
 162                         union ocfs2_dlm_lksb *lksb,
 163                         u32 flags,
 164                         void *name,
 165                         unsigned int namelen,
 166                         void *astarg);
 167
 168         /*
 169          * Call the underlying dlm unlock function.  The ->dlm_unlock()
 170          * function should convert the flags as appropriate.
 171          *
 172          * The unlock ast is not passed, as the stack will want to wrap
 173          * it before calling stack->sp_proto->lp_unlock_ast().
 174          */
 175         int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
 176                           union ocfs2_dlm_lksb *lksb,
 177                           u32 flags,
 178                           void *astarg);
 179
 180         /*
 181          * Return the status of the current lock status block.  The fs
 182          * code should never dereference the union.  The ->lock_status()
 183          * callback pulls out the stack-specific lksb, converts the status
 184          * to a proper errno, and returns it.
 185          */
 186         int (*lock_status)(union ocfs2_dlm_lksb *lksb);
 187
 188         /*
 189          * Pull the lvb pointer off of the stack-specific lksb.
 190          */
 191         void *(*lock_lvb)(union ocfs2_dlm_lksb *lksb);
 192
 193         /*
 194          * Cluster-aware posix locks
 195          *
 196          * This is NULL for stacks which do not support posix locks.
 197          */
 198         int (*plock)(struct ocfs2_cluster_connection *conn,
 199                      u64 ino,
 200                      struct file *file,
 201                      int cmd,
 202                      struct file_lock *fl);
 203
 204         /*
 205          * This is an optoinal debugging hook.  If provided, the
 206          * stack can dump debugging information about this lock.
 207          */
 208         void (*dump_lksb)(union ocfs2_dlm_lksb *lksb);
 209 };
 210
 211 /*
 212  * Each stack plugin must describe itself by registering a
 213  * ocfs2_stack_plugin structure.  This is only seen by stackglue and the
 214  * stack driver.
 215  */
 216 struct ocfs2_stack_plugin {
 217         char *sp_name;
 218         struct ocfs2_stack_operations *sp_ops;
 219         struct module *sp_owner;
 220
 221         /* These are managed by the stackglue code. */
 222         struct list_head sp_list;
 223         unsigned int sp_count;
 224         struct ocfs2_locking_protocol *sp_proto;
 225 };
 226
 227
 228 /* Used by the filesystem */
 229 int ocfs2_cluster_connect(const char *stack_name,
 230                           const char *group,
 231                           int grouplen,
 232                           void (*recovery_handler)(int node_num,
 233                                                    void *recovery_data),
 234                           void *recovery_data,
 235                           struct ocfs2_cluster_connection **conn);
 236 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 237                              int hangup_pending);
 238 void ocfs2_cluster_hangup(const char *group, int grouplen);
 239 int ocfs2_cluster_this_node(unsigned int *node);
 240
 241 struct ocfs2_lock_res;
 242 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
 243                    int mode,
 244                    union ocfs2_dlm_lksb *lksb,
 245                    u32 flags,
 246                    void *name,
 247                    unsigned int namelen,
 248                    struct ocfs2_lock_res *astarg);
 249 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
 250                      union ocfs2_dlm_lksb *lksb,
 251                      u32 flags,
 252                      struct ocfs2_lock_res *astarg);
 253
 254 int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb);
 255 void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb);
 256 void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);
 257
 258 int ocfs2_stack_supports_plocks(void);
 259 int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
 260                 struct file *file, int cmd, struct file_lock *fl);
 261
 262 void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);
 263
 264
 265 /* Used by stack plugins */
 266 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
 267 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
 268
 269 #endif  /* STACKGLUE_H */