fs/ocfs2/stackglue.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /* -*- mode: c; c-basic-offset: 8; -*-
   3  * vim: noexpandtab sw=8 ts=8 sts=0:
   4  *
   5  * stackglue.h
   6  *
   7  * Glue to the underlying cluster stack.
   8  *
   9  * Copyright (C) 2007 Oracle.  All rights reserved.
  10  */
  11
  12
  13 #ifndef STACKGLUE_H
  14 #define STACKGLUE_H
  15
  16 #include <linux/types.h>
  17 #include <linux/list.h>
  18 #include <linux/dlmconstants.h>
  19
  20 #include "dlm/dlmapi.h"
  21 #include <linux/dlm.h>
  22
  23 /* Needed for plock-related prototypes */
  24 struct file;
  25 struct file_lock;
  26
  27 /*
  28  * dlmconstants.h does not have a LOCAL flag.  We hope to remove it
  29  * some day, but right now we need it.  Let's fake it.  This value is larger
  30  * than any flag in dlmconstants.h.
  31  */
  32 #define DLM_LKF_LOCAL           0x00100000
  33
  34 /*
  35  * This shadows DLM_LOCKSPACE_LEN in fs/dlm/dlm_internal.h.  That probably
  36  * wants to be in a public header.
  37  */
  38 #define GROUP_NAME_MAX          64
  39
  40 /* This shadows  OCFS2_CLUSTER_NAME_LEN */
  41 #define CLUSTER_NAME_MAX        16
  42
  43
  44 /*
  45  * ocfs2_protocol_version changes when ocfs2 does something different in
  46  * its inter-node behavior.  See dlmglue.c for more information.
  47  */
  48 struct ocfs2_protocol_version {
  49         u8 pv_major;
  50         u8 pv_minor;
  51 };
  52
  53 /*
  54  * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
  55  * has a pointer to separately allocated lvb space.  This struct exists only to
  56  * include in the lksb union to make space for a combined dlm_lksb and lvb.
  57  */
  58 struct fsdlm_lksb_plus_lvb {
  59         struct dlm_lksb lksb;
  60         char lvb[DLM_LVB_LEN];
  61 };
  62
  63 /*
  64  * A union of all lock status structures.  We define it here so that the
  65  * size of the union is known.  Lock status structures are embedded in
  66  * ocfs2 inodes.
  67  */
  68 struct ocfs2_cluster_connection;
  69 struct ocfs2_dlm_lksb {
  70          union {
  71                  struct dlm_lockstatus lksb_o2dlm;
  72                  struct dlm_lksb lksb_fsdlm;
  73                  struct fsdlm_lksb_plus_lvb padding;
  74          };
  75          struct ocfs2_cluster_connection *lksb_conn;
  76 };
  77
  78 /*
  79  * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
  80  */
  81 struct ocfs2_locking_protocol {
  82         struct ocfs2_protocol_version lp_max_version;
  83         void (*lp_lock_ast)(struct ocfs2_dlm_lksb *lksb);
  84         void (*lp_blocking_ast)(struct ocfs2_dlm_lksb *lksb, int level);
  85         void (*lp_unlock_ast)(struct ocfs2_dlm_lksb *lksb, int error);
  86 };
  87
  88
  89 /*
  90  * A cluster connection.  Mostly opaque to ocfs2, the connection holds
  91  * state for the underlying stack.  ocfs2 does use cc_version to determine
  92  * locking compatibility.
  93  */
  94 struct ocfs2_cluster_connection {
  95         char cc_name[GROUP_NAME_MAX + 1];
  96         int cc_namelen;
  97         char cc_cluster_name[CLUSTER_NAME_MAX + 1];
  98         int cc_cluster_name_len;
  99         struct ocfs2_protocol_version cc_version;
 100         struct ocfs2_locking_protocol *cc_proto;
 101         void (*cc_recovery_handler)(int node_num, void *recovery_data);
 102         void *cc_recovery_data;
 103         void *cc_lockspace;
 104         void *cc_private;
 105 };
 106
 107 /*
 108  * Each cluster stack implements the stack operations structure.  Not used
 109  * in the ocfs2 code, the stackglue code translates generic cluster calls
 110  * into stack operations.
 111  */
 112 struct ocfs2_stack_operations {
 113         /*
 114          * The fs code calls ocfs2_cluster_connect() to attach a new
 115          * filesystem to the cluster stack.  The ->connect() op is passed
 116          * an ocfs2_cluster_connection with the name and recovery field
 117          * filled in.
 118          *
 119          * The stack must set up any notification mechanisms and create
 120          * the filesystem lockspace in the DLM.  The lockspace should be
 121          * stored on cc_lockspace.  Any other information can be stored on
 122          * cc_private.
 123          *
 124          * ->connect() must not return until it is guaranteed that
 125          *
 126          *  - Node down notifications for the filesystem will be received
 127          *    and passed to conn->cc_recovery_handler().
 128          *  - Locking requests for the filesystem will be processed.
 129          */
 130         int (*connect)(struct ocfs2_cluster_connection *conn);
 131
 132         /*
 133          * The fs code calls ocfs2_cluster_disconnect() when a filesystem
 134          * no longer needs cluster services.  All DLM locks have been
 135          * dropped, and recovery notification is being ignored by the
 136          * fs code.  The stack must disengage from the DLM and discontinue
 137          * recovery notification.
 138          *
 139          * Once ->disconnect() has returned, the connection structure will
 140          * be freed.  Thus, a stack must not return from ->disconnect()
 141          * until it will no longer reference the conn pointer.
 142          *
 143          * Once this call returns, the stack glue will be dropping this
 144          * connection's reference on the module.
 145          */
 146         int (*disconnect)(struct ocfs2_cluster_connection *conn);
 147
 148         /*
 149          * ->this_node() returns the cluster's unique identifier for the
 150          * local node.
 151          */
 152         int (*this_node)(struct ocfs2_cluster_connection *conn,
 153                          unsigned int *node);
 154
 155         /*
 156          * Call the underlying dlm lock function.  The ->dlm_lock()
 157          * callback should convert the flags and mode as appropriate.
 158          *
 159          * ast and bast functions are not part of the call because the
 160          * stack will likely want to wrap ast and bast calls before passing
 161          * them to stack->sp_proto.  There is no astarg.  The lksb will
 162          * be passed back to the ast and bast functions.  The caller can
 163          * use this to find their object.
 164          */
 165         int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
 166                         int mode,
 167                         struct ocfs2_dlm_lksb *lksb,
 168                         u32 flags,
 169                         void *name,
 170                         unsigned int namelen);
 171
 172         /*
 173          * Call the underlying dlm unlock function.  The ->dlm_unlock()
 174          * function should convert the flags as appropriate.
 175          *
 176          * The unlock ast is not passed, as the stack will want to wrap
 177          * it before calling stack->sp_proto->lp_unlock_ast().  There is
 178          * no astarg.  The lksb will be passed back to the unlock ast
 179          * function.  The caller can use this to find their object.
 180          */
 181         int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
 182                           struct ocfs2_dlm_lksb *lksb,
 183                           u32 flags);
 184
 185         /*
 186          * Return the status of the current lock status block.  The fs
 187          * code should never dereference the union.  The ->lock_status()
 188          * callback pulls out the stack-specific lksb, converts the status
 189          * to a proper errno, and returns it.
 190          */
 191         int (*lock_status)(struct ocfs2_dlm_lksb *lksb);
 192
 193         /*
 194          * Return non-zero if the LVB is valid.
 195          */
 196         int (*lvb_valid)(struct ocfs2_dlm_lksb *lksb);
 197
 198         /*
 199          * Pull the lvb pointer off of the stack-specific lksb.
 200          */
 201         void *(*lock_lvb)(struct ocfs2_dlm_lksb *lksb);
 202
 203         /*
 204          * Cluster-aware posix locks
 205          *
 206          * This is NULL for stacks which do not support posix locks.
 207          */
 208         int (*plock)(struct ocfs2_cluster_connection *conn,
 209                      u64 ino,
 210                      struct file *file,
 211                      int cmd,
 212                      struct file_lock *fl);
 213
 214         /*
 215          * This is an optoinal debugging hook.  If provided, the
 216          * stack can dump debugging information about this lock.
 217          */
 218         void (*dump_lksb)(struct ocfs2_dlm_lksb *lksb);
 219 };
 220
 221 /*
 222  * Each stack plugin must describe itself by registering a
 223  * ocfs2_stack_plugin structure.  This is only seen by stackglue and the
 224  * stack driver.
 225  */
 226 struct ocfs2_stack_plugin {
 227         char *sp_name;
 228         struct ocfs2_stack_operations *sp_ops;
 229         struct module *sp_owner;
 230
 231         /* These are managed by the stackglue code. */
 232         struct list_head sp_list;
 233         unsigned int sp_count;
 234         struct ocfs2_protocol_version sp_max_proto;
 235 };
 236
 237
 238 /* Used by the filesystem */
 239 int ocfs2_cluster_connect(const char *stack_name,
 240                           const char *cluster_name,
 241                           int cluster_name_len,
 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  */
 253 int 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);
 260 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 261                              int hangup_pending);
 262 void ocfs2_cluster_hangup(const char *group, int grouplen);
 263 int ocfs2_cluster_this_node(struct ocfs2_cluster_connection *conn,
 264                             unsigned int *node);
 265
 266 struct ocfs2_lock_res;
 267 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
 268                    int mode,
 269                    struct ocfs2_dlm_lksb *lksb,
 270                    u32 flags,
 271                    void *name,
 272                    unsigned int namelen);
 273 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
 274                      struct ocfs2_dlm_lksb *lksb,
 275                      u32 flags);
 276
 277 int ocfs2_dlm_lock_status(struct ocfs2_dlm_lksb *lksb);
 278 int ocfs2_dlm_lvb_valid(struct ocfs2_dlm_lksb *lksb);
 279 void *ocfs2_dlm_lvb(struct ocfs2_dlm_lksb *lksb);
 280 void ocfs2_dlm_dump_lksb(struct ocfs2_dlm_lksb *lksb);
 281
 282 int ocfs2_stack_supports_plocks(void);
 283 int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
 284                 struct file *file, int cmd, struct file_lock *fl);
 285
 286 void ocfs2_stack_glue_set_max_proto_version(struct ocfs2_protocol_version *max_proto);
 287
 288
 289 /* Used by stack plugins */
 290 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
 291 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
 292
 293 extern struct kset *ocfs2_kset;
 294
 295 #endif  /* STACKGLUE_H */