fs/gfs2/locking/dlm/lock.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
   4  *
   5  * This copyrighted material is made available to anyone wishing to use,
   6  * modify, copy, or redistribute it subject to the terms and conditions
   7  * of the GNU General Public License v.2.
   8  */
   9
  10 #include "lock_dlm.h"
  11
  12 static char junk_lvb[GDLM_LVB_SIZE];
  13
  14 static void queue_complete(struct gdlm_lock *lp)
  15 {
  16         struct gdlm_ls *ls = lp->ls;
  17
  18         clear_bit(LFL_ACTIVE, &lp->flags);
  19
  20         spin_lock(&ls->async_lock);
  21         list_add_tail(&lp->clist, &ls->complete);
  22         spin_unlock(&ls->async_lock);
  23         wake_up(&ls->thread_wait);
  24 }
  25
  26 static inline void gdlm_ast(void *astarg)
  27 {
  28         queue_complete((struct gdlm_lock *) astarg);
  29 }
  30
  31 static inline void gdlm_bast(void *astarg, int mode)
  32 {
  33         struct gdlm_lock *lp = astarg;
  34         struct gdlm_ls *ls = lp->ls;
  35
  36         if (!mode) {
  37                 printk(KERN_INFO "lock_dlm: bast mode zero %x,%llx\n",
  38                         lp->lockname.ln_type, lp->lockname.ln_number);
  39                 return;
  40         }
  41
  42         spin_lock(&ls->async_lock);
  43         if (!lp->bast_mode) {
  44                 list_add_tail(&lp->blist, &ls->blocking);
  45                 lp->bast_mode = mode;
  46         } else if (lp->bast_mode < mode)
  47                 lp->bast_mode = mode;
  48         spin_unlock(&ls->async_lock);
  49         wake_up(&ls->thread_wait);
  50 }
  51
  52 void gdlm_queue_delayed(struct gdlm_lock *lp)
  53 {
  54         struct gdlm_ls *ls = lp->ls;
  55
  56         spin_lock(&ls->async_lock);
  57         list_add_tail(&lp->delay_list, &ls->delayed);
  58         spin_unlock(&ls->async_lock);
  59 }
  60
  61 /* convert gfs lock-state to dlm lock-mode */
  62
  63 static int16_t make_mode(int16_t lmstate)
  64 {
  65         switch (lmstate) {
  66         case LM_ST_UNLOCKED:
  67                 return DLM_LOCK_NL;
  68         case LM_ST_EXCLUSIVE:
  69                 return DLM_LOCK_EX;
  70         case LM_ST_DEFERRED:
  71                 return DLM_LOCK_CW;
  72         case LM_ST_SHARED:
  73                 return DLM_LOCK_PR;
  74         }
  75         gdlm_assert(0, "unknown LM state %d", lmstate);
  76         return -1;
  77 }
  78
  79 /* convert dlm lock-mode to gfs lock-state */
  80
  81 int16_t gdlm_make_lmstate(int16_t dlmmode)
  82 {
  83         switch (dlmmode) {
  84         case DLM_LOCK_IV:
  85         case DLM_LOCK_NL:
  86                 return LM_ST_UNLOCKED;
  87         case DLM_LOCK_EX:
  88                 return LM_ST_EXCLUSIVE;
  89         case DLM_LOCK_CW:
  90                 return LM_ST_DEFERRED;
  91         case DLM_LOCK_PR:
  92                 return LM_ST_SHARED;
  93         }
  94         gdlm_assert(0, "unknown DLM mode %d", dlmmode);
  95         return -1;
  96 }
  97
  98 /* verify agreement with GFS on the current lock state, NB: DLM_LOCK_NL and
  99    DLM_LOCK_IV are both considered LM_ST_UNLOCKED by GFS. */
 100
 101 static void check_cur_state(struct gdlm_lock *lp, unsigned int cur_state)
 102 {
 103         int16_t cur = make_mode(cur_state);
 104         if (lp->cur != DLM_LOCK_IV)
 105                 gdlm_assert(lp->cur == cur, "%d, %d", lp->cur, cur);
 106 }
 107
 108 static inline unsigned int make_flags(struct gdlm_lock *lp,
 109                                       unsigned int gfs_flags,
 110                                       int16_t cur, int16_t req)
 111 {
 112         unsigned int lkf = 0;
 113
 114         if (gfs_flags & LM_FLAG_TRY)
 115                 lkf |= DLM_LKF_NOQUEUE;
 116
 117         if (gfs_flags & LM_FLAG_TRY_1CB) {
 118                 lkf |= DLM_LKF_NOQUEUE;
 119                 lkf |= DLM_LKF_NOQUEUEBAST;
 120         }
 121
 122         if (gfs_flags & LM_FLAG_PRIORITY) {
 123                 lkf |= DLM_LKF_NOORDER;
 124                 lkf |= DLM_LKF_HEADQUE;
 125         }
 126
 127         if (gfs_flags & LM_FLAG_ANY) {
 128                 if (req == DLM_LOCK_PR)
 129                         lkf |= DLM_LKF_ALTCW;
 130                 else if (req == DLM_LOCK_CW)
 131                         lkf |= DLM_LKF_ALTPR;
 132         }
 133
 134         if (lp->lksb.sb_lkid != 0) {
 135                 lkf |= DLM_LKF_CONVERT;
 136
 137                 /* Conversion deadlock avoidance by DLM */
 138
 139                 if (!test_bit(LFL_FORCE_PROMOTE, &lp->flags) &&
 140                     !(lkf & DLM_LKF_NOQUEUE) &&
 141                     cur > DLM_LOCK_NL && req > DLM_LOCK_NL && cur != req)
 142                         lkf |= DLM_LKF_CONVDEADLK;
 143         }
 144
 145         if (lp->lvb)
 146                 lkf |= DLM_LKF_VALBLK;
 147
 148         return lkf;
 149 }
 150
 151 /* make_strname - convert GFS lock numbers to a string */
 152
 153 static inline void make_strname(struct lm_lockname *lockname,
 154                                 struct gdlm_strname *str)
 155 {
 156         sprintf(str->name, "%8x%16llx", lockname->ln_type,
 157                 lockname->ln_number);
 158         str->namelen = GDLM_STRNAME_BYTES;
 159 }
 160
 161 int gdlm_create_lp(struct gdlm_ls *ls, struct lm_lockname *name,
 162                    struct gdlm_lock **lpp)
 163 {
 164         struct gdlm_lock *lp;
 165
 166         lp = kzalloc(sizeof(struct gdlm_lock), GFP_KERNEL);
 167         if (!lp)
 168                 return -ENOMEM;
 169
 170         lp->lockname = *name;
 171         lp->ls = ls;
 172         lp->cur = DLM_LOCK_IV;
 173         lp->lvb = NULL;
 174         lp->hold_null = NULL;
 175         init_completion(&lp->ast_wait);
 176         INIT_LIST_HEAD(&lp->clist);
 177         INIT_LIST_HEAD(&lp->blist);
 178         INIT_LIST_HEAD(&lp->delay_list);
 179
 180         spin_lock(&ls->async_lock);
 181         list_add(&lp->all_list, &ls->all_locks);
 182         ls->all_locks_count++;
 183         spin_unlock(&ls->async_lock);
 184
 185         *lpp = lp;
 186         return 0;
 187 }
 188
 189 void gdlm_delete_lp(struct gdlm_lock *lp)
 190 {
 191         struct gdlm_ls *ls = lp->ls;
 192
 193         spin_lock(&ls->async_lock);
 194         if (!list_empty(&lp->clist))
 195                 list_del_init(&lp->clist);
 196         if (!list_empty(&lp->blist))
 197                 list_del_init(&lp->blist);
 198         if (!list_empty(&lp->delay_list))
 199                 list_del_init(&lp->delay_list);
 200         gdlm_assert(!list_empty(&lp->all_list),
 201                     "%x,%llx", lp->lockname.ln_type, lp->lockname.ln_number);
 202         list_del_init(&lp->all_list);
 203         ls->all_locks_count--;
 204         spin_unlock(&ls->async_lock);
 205
 206         kfree(lp);
 207 }
 208
 209 int gdlm_get_lock(lm_lockspace_t *lockspace, struct lm_lockname *name,
 210                   lm_lock_t **lockp)
 211 {
 212         struct gdlm_lock *lp;
 213         int error;
 214
 215         error = gdlm_create_lp((struct gdlm_ls *) lockspace, name, &lp);
 216
 217         *lockp = (lm_lock_t *) lp;
 218         return error;
 219 }
 220
 221 void gdlm_put_lock(lm_lock_t *lock)
 222 {
 223         gdlm_delete_lp((struct gdlm_lock *) lock);
 224 }
 225
 226 unsigned int gdlm_do_lock(struct gdlm_lock *lp)
 227 {
 228         struct gdlm_ls *ls = lp->ls;
 229         struct gdlm_strname str;
 230         int error, bast = 1;
 231
 232         /*
 233          * When recovery is in progress, delay lock requests for submission
 234          * once recovery is done.  Requests for recovery (NOEXP) and unlocks
 235          * can pass.
 236          */
 237
 238         if (test_bit(DFL_BLOCK_LOCKS, &ls->flags) &&
 239             !test_bit(LFL_NOBLOCK, &lp->flags) && lp->req != DLM_LOCK_NL) {
 240                 gdlm_queue_delayed(lp);
 241                 return LM_OUT_ASYNC;
 242         }
 243
 244         /*
 245          * Submit the actual lock request.
 246          */
 247
 248         if (test_bit(LFL_NOBAST, &lp->flags))
 249                 bast = 0;
 250
 251         make_strname(&lp->lockname, &str);
 252
 253         set_bit(LFL_ACTIVE, &lp->flags);
 254
 255         log_debug("lk %x,%llx id %x %d,%d %x", lp->lockname.ln_type,
 256                   lp->lockname.ln_number, lp->lksb.sb_lkid,
 257                   lp->cur, lp->req, lp->lkf);
 258
 259         error = dlm_lock(ls->dlm_lockspace, lp->req, &lp->lksb, lp->lkf,
 260                          str.name, str.namelen, 0, gdlm_ast, (void *) lp,
 261                          bast ? gdlm_bast : NULL);
 262
 263         if ((error == -EAGAIN) && (lp->lkf & DLM_LKF_NOQUEUE)) {
 264                 lp->lksb.sb_status = -EAGAIN;
 265                 queue_complete(lp);
 266                 error = 0;
 267         }
 268
 269         if (error) {
 270                 log_debug("%s: gdlm_lock %x,%llx err=%d cur=%d req=%d lkf=%x "
 271                           "flags=%lx", ls->fsname, lp->lockname.ln_type,
 272                           lp->lockname.ln_number, error, lp->cur, lp->req,
 273                           lp->lkf, lp->flags);
 274                 return LM_OUT_ERROR;
 275         }
 276         return LM_OUT_ASYNC;
 277 }
 278
 279 unsigned int gdlm_do_unlock(struct gdlm_lock *lp)
 280 {
 281         struct gdlm_ls *ls = lp->ls;
 282         unsigned int lkf = 0;
 283         int error;
 284
 285         set_bit(LFL_DLM_UNLOCK, &lp->flags);
 286         set_bit(LFL_ACTIVE, &lp->flags);
 287
 288         if (lp->lvb)
 289                 lkf = DLM_LKF_VALBLK;
 290
 291         log_debug("un %x,%llx %x %d %x", lp->lockname.ln_type,
 292                   lp->lockname.ln_number, lp->lksb.sb_lkid, lp->cur, lkf);
 293
 294         error = dlm_unlock(ls->dlm_lockspace, lp->lksb.sb_lkid, lkf, NULL, lp);
 295
 296         if (error) {
 297                 log_debug("%s: gdlm_unlock %x,%llx err=%d cur=%d req=%d lkf=%x "
 298                           "flags=%lx", ls->fsname, lp->lockname.ln_type,
 299                           lp->lockname.ln_number, error, lp->cur, lp->req,
 300                           lp->lkf, lp->flags);
 301                 return LM_OUT_ERROR;
 302         }
 303         return LM_OUT_ASYNC;
 304 }
 305
 306 unsigned int gdlm_lock(lm_lock_t *lock, unsigned int cur_state,
 307                        unsigned int req_state, unsigned int flags)
 308 {
 309         struct gdlm_lock *lp = (struct gdlm_lock *) lock;
 310
 311         clear_bit(LFL_DLM_CANCEL, &lp->flags);
 312         if (flags & LM_FLAG_NOEXP)
 313                 set_bit(LFL_NOBLOCK, &lp->flags);
 314
 315         check_cur_state(lp, cur_state);
 316         lp->req = make_mode(req_state);
 317         lp->lkf = make_flags(lp, flags, lp->cur, lp->req);
 318
 319         return gdlm_do_lock(lp);
 320 }
 321
 322 unsigned int gdlm_unlock(lm_lock_t *lock, unsigned int cur_state)
 323 {
 324         struct gdlm_lock *lp = (struct gdlm_lock *) lock;
 325
 326         clear_bit(LFL_DLM_CANCEL, &lp->flags);
 327         if (lp->cur == DLM_LOCK_IV)
 328                 return 0;
 329         return gdlm_do_unlock(lp);
 330 }
 331
 332 void gdlm_cancel(lm_lock_t *lock)
 333 {
 334         struct gdlm_lock *lp = (struct gdlm_lock *) lock;
 335         struct gdlm_ls *ls = lp->ls;
 336         int error, delay_list = 0;
 337
 338         if (test_bit(LFL_DLM_CANCEL, &lp->flags))
 339                 return;
 340
 341         log_info("gdlm_cancel %x,%llx flags %lx",
 342                  lp->lockname.ln_type, lp->lockname.ln_number, lp->flags);
 343
 344         spin_lock(&ls->async_lock);
 345         if (!list_empty(&lp->delay_list)) {
 346                 list_del_init(&lp->delay_list);
 347                 delay_list = 1;
 348         }
 349         spin_unlock(&ls->async_lock);
 350
 351         if (delay_list) {
 352                 set_bit(LFL_CANCEL, &lp->flags);
 353                 set_bit(LFL_ACTIVE, &lp->flags);
 354                 queue_complete(lp);
 355                 return;
 356         }
 357
 358         if (!test_bit(LFL_ACTIVE, &lp->flags) ||
 359             test_bit(LFL_DLM_UNLOCK, &lp->flags))       {
 360                 log_info("gdlm_cancel skip %x,%llx flags %lx",
 361                          lp->lockname.ln_type, lp->lockname.ln_number,
 362                          lp->flags);
 363                 return;
 364         }
 365
 366         /* the lock is blocked in the dlm */
 367
 368         set_bit(LFL_DLM_CANCEL, &lp->flags);
 369         set_bit(LFL_ACTIVE, &lp->flags);
 370
 371         error = dlm_unlock(ls->dlm_lockspace, lp->lksb.sb_lkid, DLM_LKF_CANCEL,
 372                            NULL, lp);
 373
 374         log_info("gdlm_cancel rv %d %x,%llx flags %lx", error,
 375                  lp->lockname.ln_type, lp->lockname.ln_number, lp->flags);
 376
 377         if (error == -EBUSY)
 378                 clear_bit(LFL_DLM_CANCEL, &lp->flags);
 379 }
 380
 381 int gdlm_add_lvb(struct gdlm_lock *lp)
 382 {
 383         char *lvb;
 384
 385         lvb = kzalloc(GDLM_LVB_SIZE, GFP_KERNEL);
 386         if (!lvb)
 387                 return -ENOMEM;
 388
 389         lp->lksb.sb_lvbptr = lvb;
 390         lp->lvb = lvb;
 391         return 0;
 392 }
 393
 394 void gdlm_del_lvb(struct gdlm_lock *lp)
 395 {
 396         kfree(lp->lvb);
 397         lp->lvb = NULL;
 398         lp->lksb.sb_lvbptr = NULL;
 399 }
 400
 401 /* This can do a synchronous dlm request (requiring a lock_dlm thread to get
 402    the completion) because gfs won't call hold_lvb() during a callback (from
 403    the context of a lock_dlm thread). */
 404
 405 static int hold_null_lock(struct gdlm_lock *lp)
 406 {
 407         struct gdlm_lock *lpn = NULL;
 408         int error;
 409
 410         if (lp->hold_null) {
 411                 printk(KERN_INFO "lock_dlm: lvb already held\n");
 412                 return 0;
 413         }
 414
 415         error = gdlm_create_lp(lp->ls, &lp->lockname, &lpn);
 416         if (error)
 417                 goto out;
 418
 419         lpn->lksb.sb_lvbptr = junk_lvb;
 420         lpn->lvb = junk_lvb;
 421
 422         lpn->req = DLM_LOCK_NL;
 423         lpn->lkf = DLM_LKF_VALBLK | DLM_LKF_EXPEDITE;
 424         set_bit(LFL_NOBAST, &lpn->flags);
 425         set_bit(LFL_INLOCK, &lpn->flags);
 426
 427         init_completion(&lpn->ast_wait);
 428         gdlm_do_lock(lpn);
 429         wait_for_completion(&lpn->ast_wait);
 430         error = lp->lksb.sb_status;
 431         if (error) {
 432                 printk(KERN_INFO "lock_dlm: hold_null_lock dlm error %d\n",
 433                        error);
 434                 gdlm_delete_lp(lpn);
 435                 lpn = NULL;
 436         }
 437  out:
 438         lp->hold_null = lpn;
 439         return error;
 440 }
 441
 442 /* This cannot do a synchronous dlm request (requiring a lock_dlm thread to get
 443    the completion) because gfs may call unhold_lvb() during a callback (from
 444    the context of a lock_dlm thread) which could cause a deadlock since the
 445    other lock_dlm thread could be engaged in recovery. */
 446
 447 static void unhold_null_lock(struct gdlm_lock *lp)
 448 {
 449         struct gdlm_lock *lpn = lp->hold_null;
 450
 451         gdlm_assert(lpn, "%x,%llx",
 452                     lp->lockname.ln_type, lp->lockname.ln_number);
 453         lpn->lksb.sb_lvbptr = NULL;
 454         lpn->lvb = NULL;
 455         set_bit(LFL_UNLOCK_DELETE, &lpn->flags);
 456         gdlm_do_unlock(lpn);
 457         lp->hold_null = NULL;
 458 }
 459
 460 /* Acquire a NL lock because gfs requires the value block to remain
 461    intact on the resource while the lvb is "held" even if it's holding no locks
 462    on the resource. */
 463
 464 int gdlm_hold_lvb(lm_lock_t *lock, char **lvbp)
 465 {
 466         struct gdlm_lock *lp = (struct gdlm_lock *) lock;
 467         int error;
 468
 469         error = gdlm_add_lvb(lp);
 470         if (error)
 471                 return error;
 472
 473         *lvbp = lp->lvb;
 474
 475         error = hold_null_lock(lp);
 476         if (error)
 477                 gdlm_del_lvb(lp);
 478
 479         return error;
 480 }
 481
 482 void gdlm_unhold_lvb(lm_lock_t *lock, char *lvb)
 483 {
 484         struct gdlm_lock *lp = (struct gdlm_lock *) lock;
 485
 486         unhold_null_lock(lp);
 487         gdlm_del_lvb(lp);
 488 }
 489
 490 void gdlm_sync_lvb(lm_lock_t *lock, char *lvb)
 491 {
 492         struct gdlm_lock *lp = (struct gdlm_lock *) lock;
 493
 494         if (lp->cur != DLM_LOCK_EX)
 495                 return;
 496
 497         init_completion(&lp->ast_wait);
 498         set_bit(LFL_SYNC_LVB, &lp->flags);
 499
 500         lp->req = DLM_LOCK_EX;
 501         lp->lkf = make_flags(lp, 0, lp->cur, lp->req);
 502
 503         gdlm_do_lock(lp);
 504         wait_for_completion(&lp->ast_wait);
 505 }
 506
 507 void gdlm_submit_delayed(struct gdlm_ls *ls)
 508 {
 509         struct gdlm_lock *lp, *safe;
 510
 511         spin_lock(&ls->async_lock);
 512         list_for_each_entry_safe(lp, safe, &ls->delayed, delay_list) {
 513                 list_del_init(&lp->delay_list);
 514                 list_add_tail(&lp->delay_list, &ls->submit);
 515         }
 516         spin_unlock(&ls->async_lock);
 517         wake_up(&ls->thread_wait);
 518 }
 519
 520 int gdlm_release_all_locks(struct gdlm_ls *ls)
 521 {
 522         struct gdlm_lock *lp, *safe;
 523         int count = 0;
 524
 525         spin_lock(&ls->async_lock);
 526         list_for_each_entry_safe(lp, safe, &ls->all_locks, all_list) {
 527                 list_del_init(&lp->all_list);
 528
 529                 if (lp->lvb && lp->lvb != junk_lvb)
 530                         kfree(lp->lvb);
 531                 kfree(lp);
 532                 count++;
 533         }
 534         spin_unlock(&ls->async_lock);
 535
 536         return count;
 537 }
 538