linux/include/linux/dlm.h
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   1/******************************************************************************
   2*******************************************************************************
   3**
   4**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   5**  Copyright (C) 2004-2011 Red Hat, Inc.  All rights reserved.
   6**
   7**  This copyrighted material is made available to anyone wishing to use,
   8**  modify, copy, or redistribute it subject to the terms and conditions
   9**  of the GNU General Public License v.2.
  10**
  11*******************************************************************************
  12******************************************************************************/
  13
  14#ifndef __DLM_DOT_H__
  15#define __DLM_DOT_H__
  16
  17/*
  18 * Interface to Distributed Lock Manager (DLM)
  19 * routines and structures to use DLM lockspaces
  20 */
  21
  22/* Lock levels and flags are here */
  23#include <linux/dlmconstants.h>
  24#include <linux/types.h>
  25
  26typedef void dlm_lockspace_t;
  27
  28/*
  29 * Lock status block
  30 *
  31 * Use this structure to specify the contents of the lock value block.  For a
  32 * conversion request, this structure is used to specify the lock ID of the
  33 * lock.  DLM writes the status of the lock request and the lock ID assigned
  34 * to the request in the lock status block.
  35 *
  36 * sb_lkid: the returned lock ID.  It is set on new (non-conversion) requests.
  37 * It is available when dlm_lock returns.
  38 *
  39 * sb_lvbptr: saves or returns the contents of the lock's LVB according to rules
  40 * shown for the DLM_LKF_VALBLK flag.
  41 *
  42 * sb_flags: DLM_SBF_DEMOTED is returned if in the process of promoting a lock,
  43 * it was first demoted to NL to avoid conversion deadlock.
  44 * DLM_SBF_VALNOTVALID is returned if the resource's LVB is marked invalid.
  45 *
  46 * sb_status: the returned status of the lock request set prior to AST
  47 * execution.  Possible return values:
  48 *
  49 * 0 if lock request was successful
  50 * -EAGAIN if request would block and is flagged DLM_LKF_NOQUEUE
  51 * -DLM_EUNLOCK if unlock request was successful
  52 * -DLM_ECANCEL if a cancel completed successfully
  53 * -EDEADLK if a deadlock was detected
  54 * -ETIMEDOUT if the lock request was canceled due to a timeout
  55 */
  56
  57#define DLM_SBF_DEMOTED         0x01
  58#define DLM_SBF_VALNOTVALID     0x02
  59#define DLM_SBF_ALTMODE         0x04
  60
  61struct dlm_lksb {
  62        int      sb_status;
  63        __u32    sb_lkid;
  64        char     sb_flags;
  65        char *   sb_lvbptr;
  66};
  67
  68/* dlm_new_lockspace() flags */
  69
  70#define DLM_LSFL_TIMEWARN       0x00000002
  71#define DLM_LSFL_FS             0x00000004
  72#define DLM_LSFL_NEWEXCL        0x00000008
  73
  74#ifdef __KERNEL__
  75
  76struct dlm_slot {
  77        int nodeid; /* 1 to MAX_INT */
  78        int slot;   /* 1 to MAX_INT */
  79};
  80
  81/*
  82 * recover_prep: called before the dlm begins lock recovery.
  83 *   Notfies lockspace user that locks from failed members will be granted.
  84 * recover_slot: called after recover_prep and before recover_done.
  85 *   Identifies a failed lockspace member.
  86 * recover_done: called after the dlm completes lock recovery.
  87 *   Identifies lockspace members and lockspace generation number.
  88 */
  89
  90struct dlm_lockspace_ops {
  91        void (*recover_prep) (void *ops_arg);
  92        void (*recover_slot) (void *ops_arg, struct dlm_slot *slot);
  93        void (*recover_done) (void *ops_arg, struct dlm_slot *slots,
  94                              int num_slots, int our_slot, uint32_t generation);
  95};
  96
  97/*
  98 * dlm_new_lockspace
  99 *
 100 * Create/join a lockspace.
 101 *
 102 * name: lockspace name, null terminated, up to DLM_LOCKSPACE_LEN (not
 103 *   including terminating null).
 104 *
 105 * cluster: cluster name, null terminated, up to DLM_LOCKSPACE_LEN (not
 106 *   including terminating null).  Optional.  When cluster is null, it
 107 *   is not used.  When set, dlm_new_lockspace() returns -EBADR if cluster
 108 *   is not equal to the dlm cluster name.
 109 *
 110 * flags:
 111 * DLM_LSFL_NODIR
 112 *   The dlm should not use a resource directory, but statically assign
 113 *   resource mastery to nodes based on the name hash that is otherwise
 114 *   used to select the directory node.  Must be the same on all nodes.
 115 * DLM_LSFL_TIMEWARN
 116 *   The dlm should emit netlink messages if locks have been waiting
 117 *   for a configurable amount of time.  (Unused.)
 118 * DLM_LSFL_FS
 119 *   The lockspace user is in the kernel (i.e. filesystem).  Enables
 120 *   direct bast/cast callbacks.
 121 * DLM_LSFL_NEWEXCL
 122 *   dlm_new_lockspace() should return -EEXIST if the lockspace exists.
 123 *
 124 * lvblen: length of lvb in bytes.  Must be multiple of 8.
 125 *   dlm_new_lockspace() returns an error if this does not match
 126 *   what other nodes are using.
 127 *
 128 * ops: callbacks that indicate lockspace recovery points so the
 129 *   caller can coordinate its recovery and know lockspace members.
 130 *   This is only used by the initial dlm_new_lockspace() call.
 131 *   Optional.
 132 *
 133 * ops_arg: arg for ops callbacks.
 134 *
 135 * ops_result: tells caller if the ops callbacks (if provided) will
 136 *   be used or not.  0: will be used, -EXXX will not be used.
 137 *   -EOPNOTSUPP: the dlm does not have recovery_callbacks enabled.
 138 *
 139 * lockspace: handle for dlm functions
 140 */
 141
 142int dlm_new_lockspace(const char *name, const char *cluster,
 143                      uint32_t flags, int lvblen,
 144                      const struct dlm_lockspace_ops *ops, void *ops_arg,
 145                      int *ops_result, dlm_lockspace_t **lockspace);
 146
 147/*
 148 * dlm_release_lockspace
 149 *
 150 * Stop a lockspace.
 151 */
 152
 153int dlm_release_lockspace(dlm_lockspace_t *lockspace, int force);
 154
 155/*
 156 * dlm_lock
 157 *
 158 * Make an asyncronous request to acquire or convert a lock on a named
 159 * resource.
 160 *
 161 * lockspace: context for the request
 162 * mode: the requested mode of the lock (DLM_LOCK_)
 163 * lksb: lock status block for input and async return values
 164 * flags: input flags (DLM_LKF_)
 165 * name: name of the resource to lock, can be binary
 166 * namelen: the length in bytes of the resource name (MAX_RESNAME_LEN)
 167 * parent: the lock ID of a parent lock or 0 if none
 168 * lockast: function DLM executes when it completes processing the request
 169 * astarg: argument passed to lockast and bast functions
 170 * bast: function DLM executes when this lock later blocks another request
 171 *
 172 * Returns:
 173 * 0 if request is successfully queued for processing
 174 * -EINVAL if any input parameters are invalid
 175 * -EAGAIN if request would block and is flagged DLM_LKF_NOQUEUE
 176 * -ENOMEM if there is no memory to process request
 177 * -ENOTCONN if there is a communication error
 178 *
 179 * If the call to dlm_lock returns an error then the operation has failed and
 180 * the AST routine will not be called.  If dlm_lock returns 0 it is still
 181 * possible that the lock operation will fail. The AST routine will be called
 182 * when the locking is complete and the status is returned in the lksb.
 183 *
 184 * If the AST routines or parameter are passed to a conversion operation then
 185 * they will overwrite those values that were passed to a previous dlm_lock
 186 * call.
 187 *
 188 * AST routines should not block (at least not for long), but may make
 189 * any locking calls they please.
 190 */
 191
 192int dlm_lock(dlm_lockspace_t *lockspace,
 193             int mode,
 194             struct dlm_lksb *lksb,
 195             uint32_t flags,
 196             void *name,
 197             unsigned int namelen,
 198             uint32_t parent_lkid,
 199             void (*lockast) (void *astarg),
 200             void *astarg,
 201             void (*bast) (void *astarg, int mode));
 202
 203/*
 204 * dlm_unlock
 205 *
 206 * Asynchronously release a lock on a resource.  The AST routine is called
 207 * when the resource is successfully unlocked.
 208 *
 209 * lockspace: context for the request
 210 * lkid: the lock ID as returned in the lksb
 211 * flags: input flags (DLM_LKF_)
 212 * lksb: if NULL the lksb parameter passed to last lock request is used
 213 * astarg: the arg used with the completion ast for the unlock
 214 *
 215 * Returns:
 216 * 0 if request is successfully queued for processing
 217 * -EINVAL if any input parameters are invalid
 218 * -ENOTEMPTY if the lock still has sublocks
 219 * -EBUSY if the lock is waiting for a remote lock operation
 220 * -ENOTCONN if there is a communication error
 221 */
 222
 223int dlm_unlock(dlm_lockspace_t *lockspace,
 224               uint32_t lkid,
 225               uint32_t flags,
 226               struct dlm_lksb *lksb,
 227               void *astarg);
 228
 229#endif                          /* __KERNEL__ */
 230
 231#endif                          /* __DLM_DOT_H__ */
 232
 233
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