include/linux/dlm.h

   1 /******************************************************************************
   2 *******************************************************************************
   3 **
   4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   5 **  Copyright (C) 2004-2007 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_NODLCKWT
  89  *
  90  * Do not cancel the lock if it gets into conversion deadlock.
  91  * Exclude this lock from being monitored due to DLM_LSFL_TIMEWARN.
  92  *
  93  * DLM_LKF_NODLCKBLK
  94  *
  95  * net yet implemented
  96  *
  97  * DLM_LKF_EXPEDITE
  98  *
  99  * Used only with new requests for NL mode locks.  Tells the lock manager
 100  * to grant the lock, ignoring other locks in convert and wait queues.
 101  *
 102  * DLM_LKF_NOQUEUEBAST
 103  *
 104  * Send blocking AST's before returning -EAGAIN to the caller.  It is only
 105  * used along with the NOQUEUE flag.  Blocking AST's are not sent for failed
 106  * NOQUEUE requests otherwise.
 107  *
 108  * DLM_LKF_HEADQUE
 109  *
 110  * Add a lock to the head of the convert or wait queue rather than the tail.
 111  *
 112  * DLM_LKF_NOORDER
 113  *
 114  * Disregard the standard grant order rules and grant a lock as soon as it
 115  * is compatible with other granted locks.
 116  *
 117  * DLM_LKF_ORPHAN
 118  *
 119  * not yet implemented
 120  *
 121  * DLM_LKF_ALTPR
 122  *
 123  * If the requested mode cannot be granted immediately, try to grant the lock
 124  * in PR mode instead.  If this alternate mode is granted instead of the
 125  * requested mode, DLM_SBF_ALTMODE is returned in the lksb.
 126  *
 127  * DLM_LKF_ALTCW
 128  *
 129  * The same as ALTPR, but the alternate mode is CW.
 130  *
 131  * DLM_LKF_FORCEUNLOCK
 132  *
 133  * Unlock the lock even if it is converting or waiting or has sublocks.
 134  * Only really for use by the userland device.c code.
 135  *
 136  */
 137
 138 #define DLM_LKF_NOQUEUE         0x00000001
 139 #define DLM_LKF_CANCEL          0x00000002
 140 #define DLM_LKF_CONVERT         0x00000004
 141 #define DLM_LKF_VALBLK          0x00000008
 142 #define DLM_LKF_QUECVT          0x00000010
 143 #define DLM_LKF_IVVALBLK        0x00000020
 144 #define DLM_LKF_CONVDEADLK      0x00000040
 145 #define DLM_LKF_PERSISTENT      0x00000080
 146 #define DLM_LKF_NODLCKWT        0x00000100
 147 #define DLM_LKF_NODLCKBLK       0x00000200
 148 #define DLM_LKF_EXPEDITE        0x00000400
 149 #define DLM_LKF_NOQUEUEBAST     0x00000800
 150 #define DLM_LKF_HEADQUE         0x00001000
 151 #define DLM_LKF_NOORDER         0x00002000
 152 #define DLM_LKF_ORPHAN          0x00004000
 153 #define DLM_LKF_ALTPR           0x00008000
 154 #define DLM_LKF_ALTCW           0x00010000
 155 #define DLM_LKF_FORCEUNLOCK     0x00020000
 156 #define DLM_LKF_TIMEOUT         0x00040000
 157
 158 /*
 159  * Some return codes that are not in errno.h
 160  */
 161
 162 #define DLM_ECANCEL             0x10001
 163 #define DLM_EUNLOCK             0x10002
 164
 165 typedef void dlm_lockspace_t;
 166
 167 /*
 168  * Lock status block
 169  *
 170  * Use this structure to specify the contents of the lock value block.  For a
 171  * conversion request, this structure is used to specify the lock ID of the
 172  * lock.  DLM writes the status of the lock request and the lock ID assigned
 173  * to the request in the lock status block.
 174  *
 175  * sb_lkid: the returned lock ID.  It is set on new (non-conversion) requests.
 176  * It is available when dlm_lock returns.
 177  *
 178  * sb_lvbptr: saves or returns the contents of the lock's LVB according to rules
 179  * shown for the DLM_LKF_VALBLK flag.
 180  *
 181  * sb_flags: DLM_SBF_DEMOTED is returned if in the process of promoting a lock,
 182  * it was first demoted to NL to avoid conversion deadlock.
 183  * DLM_SBF_VALNOTVALID is returned if the resource's LVB is marked invalid.
 184  *
 185  * sb_status: the returned status of the lock request set prior to AST
 186  * execution.  Possible return values:
 187  *
 188  * 0 if lock request was successful
 189  * -EAGAIN if request would block and is flagged DLM_LKF_NOQUEUE
 190  * -ENOMEM if there is no memory to process request
 191  * -EINVAL if there are invalid parameters
 192  * -DLM_EUNLOCK if unlock request was successful
 193  * -DLM_ECANCEL if a cancel completed successfully
 194  */
 195
 196 #define DLM_SBF_DEMOTED         0x01
 197 #define DLM_SBF_VALNOTVALID     0x02
 198 #define DLM_SBF_ALTMODE         0x04
 199
 200 struct dlm_lksb {
 201         int      sb_status;
 202         uint32_t sb_lkid;
 203         char     sb_flags;
 204         char *   sb_lvbptr;
 205 };
 206
 207 #define DLM_LSFL_NODIR          0x00000001
 208 #define DLM_LSFL_TIMEWARN       0x00000002
 209 #define DLM_LSFL_FS             0x00000004
 210
 211 #ifdef __KERNEL__
 212
 213 /*
 214  * dlm_new_lockspace
 215  *
 216  * Starts a lockspace with the given name.  If the named lockspace exists in
 217  * the cluster, the calling node joins it.
 218  */
 219
 220 int dlm_new_lockspace(char *name, int namelen, dlm_lockspace_t **lockspace,
 221                       uint32_t flags, int lvblen);
 222
 223 /*
 224  * dlm_release_lockspace
 225  *
 226  * Stop a lockspace.
 227  */
 228
 229 int dlm_release_lockspace(dlm_lockspace_t *lockspace, int force);
 230
 231 /*
 232  * dlm_lock
 233  *
 234  * Make an asyncronous request to acquire or convert a lock on a named
 235  * resource.
 236  *
 237  * lockspace: context for the request
 238  * mode: the requested mode of the lock (DLM_LOCK_)
 239  * lksb: lock status block for input and async return values
 240  * flags: input flags (DLM_LKF_)
 241  * name: name of the resource to lock, can be binary
 242  * namelen: the length in bytes of the resource name (MAX_RESNAME_LEN)
 243  * parent: the lock ID of a parent lock or 0 if none
 244  * lockast: function DLM executes when it completes processing the request
 245  * astarg: argument passed to lockast and bast functions
 246  * bast: function DLM executes when this lock later blocks another request
 247  *
 248  * Returns:
 249  * 0 if request is successfully queued for processing
 250  * -EINVAL if any input parameters are invalid
 251  * -EAGAIN if request would block and is flagged DLM_LKF_NOQUEUE
 252  * -ENOMEM if there is no memory to process request
 253  * -ENOTCONN if there is a communication error
 254  *
 255  * If the call to dlm_lock returns an error then the operation has failed and
 256  * the AST routine will not be called.  If dlm_lock returns 0 it is still
 257  * possible that the lock operation will fail. The AST routine will be called
 258  * when the locking is complete and the status is returned in the lksb.
 259  *
 260  * If the AST routines or parameter are passed to a conversion operation then
 261  * they will overwrite those values that were passed to a previous dlm_lock
 262  * call.
 263  *
 264  * AST routines should not block (at least not for long), but may make
 265  * any locking calls they please.
 266  */
 267
 268 int dlm_lock(dlm_lockspace_t *lockspace,
 269              int mode,
 270              struct dlm_lksb *lksb,
 271              uint32_t flags,
 272              void *name,
 273              unsigned int namelen,
 274              uint32_t parent_lkid,
 275              void (*lockast) (void *astarg),
 276              void *astarg,
 277              void (*bast) (void *astarg, int mode));
 278
 279 /*
 280  * dlm_unlock
 281  *
 282  * Asynchronously release a lock on a resource.  The AST routine is called
 283  * when the resource is successfully unlocked.
 284  *
 285  * lockspace: context for the request
 286  * lkid: the lock ID as returned in the lksb
 287  * flags: input flags (DLM_LKF_)
 288  * lksb: if NULL the lksb parameter passed to last lock request is used
 289  * astarg: the arg used with the completion ast for the unlock
 290  *
 291  * Returns:
 292  * 0 if request is successfully queued for processing
 293  * -EINVAL if any input parameters are invalid
 294  * -ENOTEMPTY if the lock still has sublocks
 295  * -EBUSY if the lock is waiting for a remote lock operation
 296  * -ENOTCONN if there is a communication error
 297  */
 298
 299 int dlm_unlock(dlm_lockspace_t *lockspace,
 300                uint32_t lkid,
 301                uint32_t flags,
 302                struct dlm_lksb *lksb,
 303                void *astarg);
 304
 305 #endif                          /* __KERNEL__ */
 306
 307 #endif                          /* __DLM_DOT_H__ */
 308