include/linux/dlm.h

   1 /******************************************************************************
   2 *******************************************************************************
   3 **
   4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   5 **  Copyright (C) 2004-2005 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 /*
  23  * Lock Modes
  24  */
  25
  26 #define DLM_LOCK_IV             -1      /* invalid */
  27 #define DLM_LOCK_NL             0       /* null */
  28 #define DLM_LOCK_CR             1       /* concurrent read */
  29 #define DLM_LOCK_CW             2       /* concurrent write */
  30 #define DLM_LOCK_PR             3       /* protected read */
  31 #define DLM_LOCK_PW             4       /* protected write */
  32 #define DLM_LOCK_EX             5       /* exclusive */
  33
  34 /*
  35  * Maximum size in bytes of a dlm_lock name
  36  */
  37
  38 #define DLM_RESNAME_MAXLEN      64
  39
  40 /*
  41  * Flags to dlm_lock
  42  *
  43  * DLM_LKF_NOQUEUE
  44  *
  45  * Do not queue the lock request on the wait queue if it cannot be granted
  46  * immediately.  If the lock cannot be granted because of this flag, DLM will
  47  * either return -EAGAIN from the dlm_lock call or will return 0 from
  48  * dlm_lock and -EAGAIN in the lock status block when the AST is executed.
  49  *
  50  * DLM_LKF_CANCEL
  51  *
  52  * Used to cancel a pending lock request or conversion.  A converting lock is
  53  * returned to its previously granted mode.
  54  *
  55  * DLM_LKF_CONVERT
  56  *
  57  * Indicates a lock conversion request.  For conversions the name and namelen
  58  * are ignored and the lock ID in the LKSB is used to identify the lock.
  59  *
  60  * DLM_LKF_VALBLK
  61  *
  62  * Requests DLM to return the current contents of the lock value block in the
  63  * lock status block.  When this flag is set in a lock conversion from PW or EX
  64  * modes, DLM assigns the value specified in the lock status block to the lock
  65  * value block of the lock resource.  The LVB is a DLM_LVB_LEN size array
  66  * containing application-specific information.
  67  *
  68  * DLM_LKF_QUECVT
  69  *
  70  * Force a conversion request to be queued, even if it is compatible with
  71  * the granted modes of other locks on the same resource.
  72  *
  73  * DLM_LKF_IVVALBLK
  74  *
  75  * Invalidate the lock value block.
  76  *
  77  * DLM_LKF_CONVDEADLK
  78  *
  79  * Allows the dlm to resolve conversion deadlocks internally by demoting the
  80  * granted mode of a converting lock to NL.  The DLM_SBF_DEMOTED flag is
  81  * returned for a conversion that's been effected by this.
  82  *
  83  * DLM_LKF_PERSISTENT
  84  *
  85  * Only relevant to locks originating in userspace.  A persistent lock will not
  86  * be removed if the process holding the lock exits.
  87  *
  88  * DLM_LKF_NODLKWT
  89  * DLM_LKF_NODLCKBLK
  90  *
  91  * net yet implemented
  92  *
  93  * DLM_LKF_EXPEDITE
  94  *
  95  * Used only with new requests for NL mode locks.  Tells the lock manager
  96  * to grant the lock, ignoring other locks in convert and wait queues.
  97  *
  98  * DLM_LKF_NOQUEUEBAST
  99  *
 100  * Send blocking AST's before returning -EAGAIN to the caller.  It is only
 101  * used along with the NOQUEUE flag.  Blocking AST's are not sent for failed
 102  * NOQUEUE requests otherwise.
 103  *
 104  * DLM_LKF_HEADQUE
 105  *
 106  * Add a lock to the head of the convert or wait queue rather than the tail.
 107  *
 108  * DLM_LKF_NOORDER
 109  *
 110  * Disregard the standard grant order rules and grant a lock as soon as it
 111  * is compatible with other granted locks.
 112  *
 113  * DLM_LKF_ORPHAN
 114  *
 115  * not yet implemented
 116  *
 117  * DLM_LKF_ALTPR
 118  *
 119  * If the requested mode cannot be granted immediately, try to grant the lock
 120  * in PR mode instead.  If this alternate mode is granted instead of the
 121  * requested mode, DLM_SBF_ALTMODE is returned in the lksb.
 122  *
 123  * DLM_LKF_ALTCW
 124  *
 125  * The same as ALTPR, but the alternate mode is CW.
 126  *
 127  * DLM_LKF_FORCEUNLOCK
 128  *
 129  * Unlock the lock even if it is converting or waiting or has sublocks.
 130  * Only really for use by the userland device.c code.
 131  *
 132  */
 133
 134 #define DLM_LKF_NOQUEUE         0x00000001
 135 #define DLM_LKF_CANCEL          0x00000002
 136 #define DLM_LKF_CONVERT         0x00000004
 137 #define DLM_LKF_VALBLK          0x00000008
 138 #define DLM_LKF_QUECVT          0x00000010
 139 #define DLM_LKF_IVVALBLK        0x00000020
 140 #define DLM_LKF_CONVDEADLK      0x00000040
 141 #define DLM_LKF_PERSISTENT      0x00000080
 142 #define DLM_LKF_NODLCKWT        0x00000100
 143 #define DLM_LKF_NODLCKBLK       0x00000200
 144 #define DLM_LKF_EXPEDITE        0x00000400
 145 #define DLM_LKF_NOQUEUEBAST     0x00000800
 146 #define DLM_LKF_HEADQUE         0x00001000
 147 #define DLM_LKF_NOORDER         0x00002000
 148 #define DLM_LKF_ORPHAN          0x00004000
 149 #define DLM_LKF_ALTPR           0x00008000
 150 #define DLM_LKF_ALTCW           0x00010000
 151 #define DLM_LKF_FORCEUNLOCK     0x00020000
 152
 153 /*
 154  * Some return codes that are not in errno.h
 155  */
 156
 157 #define DLM_ECANCEL             0x10001
 158 #define DLM_EUNLOCK             0x10002
 159
 160 typedef void dlm_lockspace_t;
 161
 162 /*
 163  * Lock status block
 164  *
 165  * Use this structure to specify the contents of the lock value block.  For a
 166  * conversion request, this structure is used to specify the lock ID of the
 167  * lock.  DLM writes the status of the lock request and the lock ID assigned
 168  * to the request in the lock status block.
 169  *
 170  * sb_lkid: the returned lock ID.  It is set on new (non-conversion) requests.
 171  * It is available when dlm_lock returns.
 172  *
 173  * sb_lvbptr: saves or returns the contents of the lock's LVB according to rules
 174  * shown for the DLM_LKF_VALBLK flag.
 175  *
 176  * sb_flags: DLM_SBF_DEMOTED is returned if in the process of promoting a lock,
 177  * it was first demoted to NL to avoid conversion deadlock.
 178  * DLM_SBF_VALNOTVALID is returned if the resource's LVB is marked invalid.
 179  *
 180  * sb_status: the returned status of the lock request set prior to AST
 181  * execution.  Possible return values:
 182  *
 183  * 0 if lock request was successful
 184  * -EAGAIN if request would block and is flagged DLM_LKF_NOQUEUE
 185  * -ENOMEM if there is no memory to process request
 186  * -EINVAL if there are invalid parameters
 187  * -DLM_EUNLOCK if unlock request was successful
 188  * -DLM_ECANCEL if a cancel completed successfully
 189  */
 190
 191 #define DLM_SBF_DEMOTED         0x01
 192 #define DLM_SBF_VALNOTVALID     0x02
 193 #define DLM_SBF_ALTMODE         0x04
 194
 195 struct dlm_lksb {
 196         int      sb_status;
 197         uint32_t sb_lkid;
 198         char     sb_flags;
 199         char *   sb_lvbptr;
 200 };
 201
 202
 203 #ifdef __KERNEL__
 204
 205 #define DLM_LSFL_NODIR          0x00000001
 206
 207 /*
 208  * dlm_new_lockspace
 209  *
 210  * Starts a lockspace with the given name.  If the named lockspace exists in
 211  * the cluster, the calling node joins it.
 212  */
 213
 214 int dlm_new_lockspace(char *name, int namelen, dlm_lockspace_t **lockspace,
 215                       uint32_t flags, int lvblen);
 216
 217 /*
 218  * dlm_release_lockspace
 219  *
 220  * Stop a lockspace.
 221  */
 222
 223 int dlm_release_lockspace(dlm_lockspace_t *lockspace, int force);
 224
 225 /*
 226  * dlm_lock
 227  *
 228  * Make an asyncronous request to acquire or convert a lock on a named
 229  * resource.
 230  *
 231  * lockspace: context for the request
 232  * mode: the requested mode of the lock (DLM_LOCK_)
 233  * lksb: lock status block for input and async return values
 234  * flags: input flags (DLM_LKF_)
 235  * name: name of the resource to lock, can be binary
 236  * namelen: the length in bytes of the resource name (MAX_RESNAME_LEN)
 237  * parent: the lock ID of a parent lock or 0 if none
 238  * lockast: function DLM executes when it completes processing the request
 239  * astarg: argument passed to lockast and bast functions
 240  * bast: function DLM executes when this lock later blocks another request
 241  *
 242  * Returns:
 243  * 0 if request is successfully queued for processing
 244  * -EINVAL if any input parameters are invalid
 245  * -EAGAIN if request would block and is flagged DLM_LKF_NOQUEUE
 246  * -ENOMEM if there is no memory to process request
 247  * -ENOTCONN if there is a communication error
 248  *
 249  * If the call to dlm_lock returns an error then the operation has failed and
 250  * the AST routine will not be called.  If dlm_lock returns 0 it is still
 251  * possible that the lock operation will fail. The AST routine will be called
 252  * when the locking is complete and the status is returned in the lksb.
 253  *
 254  * If the AST routines or parameter are passed to a conversion operation then
 255  * they will overwrite those values that were passed to a previous dlm_lock
 256  * call.
 257  *
 258  * AST routines should not block (at least not for long), but may make
 259  * any locking calls they please.
 260  */
 261
 262 int dlm_lock(dlm_lockspace_t *lockspace,
 263              int mode,
 264              struct dlm_lksb *lksb,
 265              uint32_t flags,
 266              void *name,
 267              unsigned int namelen,
 268              uint32_t parent_lkid,
 269              void (*lockast) (void *astarg),
 270              void *astarg,
 271              void (*bast) (void *astarg, int mode));
 272
 273 /*
 274  * dlm_unlock
 275  *
 276  * Asynchronously release a lock on a resource.  The AST routine is called
 277  * when the resource is successfully unlocked.
 278  *
 279  * lockspace: context for the request
 280  * lkid: the lock ID as returned in the lksb
 281  * flags: input flags (DLM_LKF_)
 282  * lksb: if NULL the lksb parameter passed to last lock request is used
 283  * astarg: the arg used with the completion ast for the unlock
 284  *
 285  * Returns:
 286  * 0 if request is successfully queued for processing
 287  * -EINVAL if any input parameters are invalid
 288  * -ENOTEMPTY if the lock still has sublocks
 289  * -EBUSY if the lock is waiting for a remote lock operation
 290  * -ENOTCONN if there is a communication error
 291  */
 292
 293 int dlm_unlock(dlm_lockspace_t *lockspace,
 294                uint32_t lkid,
 295                uint32_t flags,
 296                struct dlm_lksb *lksb,
 297                void *astarg);
 298
 299 #endif                          /* __KERNEL__ */
 300
 301 #endif                          /* __DLM_DOT_H__ */
 302