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 /* This shadows  OCFS2_CLUSTER_NAME_LEN */
  49 #define CLUSTER_NAME_MAX        16
  50
  51
  52 /*
  53  * ocfs2_protocol_version changes when ocfs2 does something different in
  54  * its inter-node behavior.  See dlmglue.c for more information.
  55  */
  56 struct ocfs2_protocol_version {
  57         u8 pv_major;
  58         u8 pv_minor;
  59 };
  60
  61 /*
  62  * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
  63  * has a pointer to separately allocated lvb space.  This struct exists only to
  64  * include in the lksb union to make space for a combined dlm_lksb and lvb.
  65  */
  66 struct fsdlm_lksb_plus_lvb {
  67         struct dlm_lksb lksb;
  68         char lvb[DLM_LVB_LEN];
  69 };
  70
  71 /*
  72  * A union of all lock status structures.  We define it here so that the
  73  * size of the union is known.  Lock status structures are embedded in
  74  * ocfs2 inodes.
  75  */
  76 struct ocfs2_cluster_connection;
  77 struct ocfs2_dlm_lksb {
  78          union {
  79                  struct dlm_lockstatus lksb_o2dlm;
  80                  struct dlm_lksb lksb_fsdlm;
  81                  struct fsdlm_lksb_plus_lvb padding;
  82          };
  83          struct ocfs2_cluster_connection *lksb_conn;
  84 };
  85
  86 /*
  87  * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
  88  */
  89 struct ocfs2_locking_protocol {
  90         struct ocfs2_protocol_version lp_max_version;
  91         void (*lp_lock_ast)(struct ocfs2_dlm_lksb *lksb);
  92         void (*lp_blocking_ast)(struct ocfs2_dlm_lksb *lksb, int level);
  93         void (*lp_unlock_ast)(struct ocfs2_dlm_lksb *lksb, int error);
  94 };
  95
  96
  97 /*
  98  * A cluster connection.  Mostly opaque to ocfs2, the connection holds
  99  * state for the underlying stack.  ocfs2 does use cc_version to determine
 100  * locking compatibility.
 101  */
 102 struct ocfs2_cluster_connection {
 103         char cc_name[GROUP_NAME_MAX + 1];
 104         int cc_namelen;
 105         char cc_cluster_name[CLUSTER_NAME_MAX + 1];
 106         int cc_cluster_name_len;
 107         struct ocfs2_protocol_version cc_version;
 108         struct ocfs2_locking_protocol *cc_proto;
 109         void (*cc_recovery_handler)(int node_num, void *recovery_data);
 110         void *cc_recovery_data;
 111         void *cc_lockspace;
 112         void *cc_private;
 113 };
 114
 115 /*
 116  * Each cluster stack implements the stack operations structure.  Not used
 117  * in the ocfs2 code, the stackglue code translates generic cluster calls
 118  * into stack operations.
 119  */
 120 struct ocfs2_stack_operations {
 121         /*
 122          * The fs code calls ocfs2_cluster_connect() to attach a new
 123          * filesystem to the cluster stack.  The ->connect() op is passed
 124          * an ocfs2_cluster_connection with the name and recovery field
 125          * filled in.
 126          *
 127          * The stack must set up any notification mechanisms and create
 128          * the filesystem lockspace in the DLM.  The lockspace should be
 129          * stored on cc_lockspace.  Any other information can be stored on
 130          * cc_private.
 131          *
 132          * ->connect() must not return until it is guaranteed that
 133          *
 134          *  - Node down notifications for the filesystem will be received
 135          *    and passed to conn->cc_recovery_handler().
 136          *  - Locking requests for the filesystem will be processed.
 137          */
 138         int (*connect)(struct ocfs2_cluster_connection *conn);
 139
 140         /*
 141          * The fs code calls ocfs2_cluster_disconnect() when a filesystem
 142          * no longer needs cluster services.  All DLM locks have been
 143          * dropped, and recovery notification is being ignored by the
 144          * fs code.  The stack must disengage from the DLM and discontinue
 145          * recovery notification.
 146          *
 147          * Once ->disconnect() has returned, the connection structure will
 148          * be freed.  Thus, a stack must not return from ->disconnect()
 149          * until it will no longer reference the conn pointer.
 150          *
 151          * Once this call returns, the stack glue will be dropping this
 152          * connection's reference on the module.
 153          */
 154         int (*disconnect)(struct ocfs2_cluster_connection *conn);
 155
 156         /*
 157          * ->this_node() returns the cluster's unique identifier for the
 158          * local node.
 159          */
 160         int (*this_node)(struct ocfs2_cluster_connection *conn,
 161                          unsigned int *node);
 162
 163         /*
 164          * Call the underlying dlm lock function.  The ->dlm_lock()
 165          * callback should convert the flags and mode as appropriate.
 166          *
 167          * ast and bast functions are not part of the call because the
 168          * stack will likely want to wrap ast and bast calls before passing
 169          * them to stack->sp_proto.  There is no astarg.  The lksb will
 170          * be passed back to the ast and bast functions.  The caller can
 171          * use this to find their object.
 172          */
 173         int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
 174                         int mode,
 175                         struct ocfs2_dlm_lksb *lksb,
 176                         u32 flags,
 177                         void *name,
 178                         unsigned int namelen);
 179
 180         /*
 181          * Call the underlying dlm unlock function.  The ->dlm_unlock()
 182          * function should convert the flags as appropriate.
 183          *
 184          * The unlock ast is not passed, as the stack will want to wrap
 185          * it before calling stack->sp_proto->lp_unlock_ast().  There is
 186          * no astarg.  The lksb will be passed back to the unlock ast
 187          * function.  The caller can use this to find their object.
 188          */
 189         int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
 190                           struct ocfs2_dlm_lksb *lksb,
 191                           u32 flags);
 192
 193         /*
 194          * Return the status of the current lock status block.  The fs
 195          * code should never dereference the union.  The ->lock_status()
 196          * callback pulls out the stack-specific lksb, converts the status
 197          * to a proper errno, and returns it.
 198          */
 199         int (*lock_status)(struct ocfs2_dlm_lksb *lksb);
 200
 201         /*
 202          * Return non-zero if the LVB is valid.
 203          */
 204         int (*lvb_valid)(struct ocfs2_dlm_lksb *lksb);
 205
 206         /*
 207          * Pull the lvb pointer off of the stack-specific lksb.
 208          */
 209         void *(*lock_lvb)(struct ocfs2_dlm_lksb *lksb);
 210
 211         /*
 212          * Cluster-aware posix locks
 213          *
 214          * This is NULL for stacks which do not support posix locks.
 215          */
 216         int (*plock)(struct ocfs2_cluster_connection *conn,
 217                      u64 ino,
 218                      struct file *file,
 219                      int cmd,
 220                      struct file_lock *fl);
 221
 222         /*
 223          * This is an optoinal debugging hook.  If provided, the
 224          * stack can dump debugging information about this lock.
 225          */
 226         void (*dump_lksb)(struct ocfs2_dlm_lksb *lksb);
 227 };
 228
 229 /*
 230  * Each stack plugin must describe itself by registering a
 231  * ocfs2_stack_plugin structure.  This is only seen by stackglue and the
 232  * stack driver.
 233  */
 234 struct ocfs2_stack_plugin {
 235         char *sp_name;
 236         struct ocfs2_stack_operations *sp_ops;
 237         struct module *sp_owner;
 238
 239         /* These are managed by the stackglue code. */
 240         struct list_head sp_list;
 241         unsigned int sp_count;
 242         struct ocfs2_protocol_version sp_max_proto;
 243 };
 244
 245
 246 /* Used by the filesystem */
 247 int ocfs2_cluster_connect(const char *stack_name,
 248                           const char *cluster_name,
 249                           int cluster_name_len,
 250                           const char *group,
 251                           int grouplen,
 252                           struct ocfs2_locking_protocol *lproto,
 253                           void (*recovery_handler)(int node_num,
 254                                                    void *recovery_data),
 255                           void *recovery_data,
 256                           struct ocfs2_cluster_connection **conn);
 257 /*
 258  * Used by callers that don't store their stack name.  They must ensure
 259  * all nodes have the same stack.
 260  */
 261 int ocfs2_cluster_connect_agnostic(const char *group,
 262                                    int grouplen,
 263                                    struct ocfs2_locking_protocol *lproto,
 264                                    void (*recovery_handler)(int node_num,
 265                                                             void *recovery_data),
 266                                    void *recovery_data,
 267                                    struct ocfs2_cluster_connection **conn);
 268 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 269                              int hangup_pending);
 270 void ocfs2_cluster_hangup(const char *group, int grouplen);
 271 int ocfs2_cluster_this_node(struct ocfs2_cluster_connection *conn,
 272                             unsigned int *node);
 273
 274 struct ocfs2_lock_res;
 275 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
 276                    int mode,
 277                    struct ocfs2_dlm_lksb *lksb,
 278                    u32 flags,
 279                    void *name,
 280                    unsigned int namelen);
 281 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
 282                      struct ocfs2_dlm_lksb *lksb,
 283                      u32 flags);
 284
 285 int ocfs2_dlm_lock_status(struct ocfs2_dlm_lksb *lksb);
 286 int ocfs2_dlm_lvb_valid(struct ocfs2_dlm_lksb *lksb);
 287 void *ocfs2_dlm_lvb(struct ocfs2_dlm_lksb *lksb);
 288 void ocfs2_dlm_dump_lksb(struct ocfs2_dlm_lksb *lksb);
 289
 290 int ocfs2_stack_supports_plocks(void);
 291 int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
 292                 struct file *file, int cmd, struct file_lock *fl);
 293
 294 void ocfs2_stack_glue_set_max_proto_version(struct ocfs2_protocol_version *max_proto);
 295
 296
 297 /* Used by stack plugins */
 298 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
 299 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
 300
 301 #endif  /* STACKGLUE_H */