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 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  */
  63 struct 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  */
  73 struct ocfs2_cluster_connection;
  74 struct 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  */
  86 struct 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  */
  99 struct 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  */
 115 struct 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 recieved
 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  */
 228 struct 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_locking_protocol *sp_proto;
 237 };
 238
 239
 240 /* Used by the filesystem */
 241 int ocfs2_cluster_connect(const char *stack_name,
 242                           const char *group,
 243                           int grouplen,
 244                           void (*recovery_handler)(int node_num,
 245                                                    void *recovery_data),
 246                           void *recovery_data,
 247                           struct ocfs2_cluster_connection **conn);
 248 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 249                              int hangup_pending);
 250 void ocfs2_cluster_hangup(const char *group, int grouplen);
 251 int ocfs2_cluster_this_node(unsigned int *node);
 252
 253 struct ocfs2_lock_res;
 254 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
 255                    int mode,
 256                    struct ocfs2_dlm_lksb *lksb,
 257                    u32 flags,
 258                    void *name,
 259                    unsigned int namelen);
 260 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
 261                      struct ocfs2_dlm_lksb *lksb,
 262                      u32 flags);
 263
 264 int ocfs2_dlm_lock_status(struct ocfs2_dlm_lksb *lksb);
 265 int ocfs2_dlm_lvb_valid(struct ocfs2_dlm_lksb *lksb);
 266 void *ocfs2_dlm_lvb(struct ocfs2_dlm_lksb *lksb);
 267 void ocfs2_dlm_dump_lksb(struct ocfs2_dlm_lksb *lksb);
 268
 269 int ocfs2_stack_supports_plocks(void);
 270 int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
 271                 struct file *file, int cmd, struct file_lock *fl);
 272
 273 void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);
 274
 275
 276 /* Used by stack plugins */
 277 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
 278 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
 279
 280 #endif  /* STACKGLUE_H */