fs/gfs2/locking/dlm/thread.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 version 2.
   8  */
   9
  10 #include "lock_dlm.h"
  11
  12 /* A lock placed on this queue is re-submitted to DLM as soon as the lock_dlm
  13    thread gets to it. */
  14
  15 static void queue_submit(struct gdlm_lock *lp)
  16 {
  17         struct gdlm_ls *ls = lp->ls;
  18
  19         spin_lock(&ls->async_lock);
  20         list_add_tail(&lp->delay_list, &ls->submit);
  21         spin_unlock(&ls->async_lock);
  22         wake_up(&ls->thread_wait);
  23 }
  24
  25 static void process_blocking(struct gdlm_lock *lp, int bast_mode)
  26 {
  27         struct gdlm_ls *ls = lp->ls;
  28         unsigned int cb = 0;
  29
  30         switch (gdlm_make_lmstate(bast_mode)) {
  31         case LM_ST_EXCLUSIVE:
  32                 cb = LM_CB_NEED_E;
  33                 break;
  34         case LM_ST_DEFERRED:
  35                 cb = LM_CB_NEED_D;
  36                 break;
  37         case LM_ST_SHARED:
  38                 cb = LM_CB_NEED_S;
  39                 break;
  40         default:
  41                 gdlm_assert(0, "unknown bast mode %u", lp->bast_mode);
  42         }
  43
  44         ls->fscb(ls->sdp, cb, &lp->lockname);
  45 }
  46
  47 static void wake_up_ast(struct gdlm_lock *lp)
  48 {
  49         clear_bit(LFL_AST_WAIT, &lp->flags);
  50         smp_mb__after_clear_bit();
  51         wake_up_bit(&lp->flags, LFL_AST_WAIT);
  52 }
  53
  54 static void process_complete(struct gdlm_lock *lp)
  55 {
  56         struct gdlm_ls *ls = lp->ls;
  57         struct lm_async_cb acb;
  58         s16 prev_mode = lp->cur;
  59
  60         memset(&acb, 0, sizeof(acb));
  61
  62         if (lp->lksb.sb_status == -DLM_ECANCEL) {
  63                 log_info("complete dlm cancel %x,%llx flags %lx",
  64                          lp->lockname.ln_type,
  65                          (unsigned long long)lp->lockname.ln_number,
  66                          lp->flags);
  67
  68                 lp->req = lp->cur;
  69                 acb.lc_ret |= LM_OUT_CANCELED;
  70                 if (lp->cur == DLM_LOCK_IV)
  71                         lp->lksb.sb_lkid = 0;
  72                 goto out;
  73         }
  74
  75         if (test_and_clear_bit(LFL_DLM_UNLOCK, &lp->flags)) {
  76                 if (lp->lksb.sb_status != -DLM_EUNLOCK) {
  77                         log_info("unlock sb_status %d %x,%llx flags %lx",
  78                                  lp->lksb.sb_status, lp->lockname.ln_type,
  79                                  (unsigned long long)lp->lockname.ln_number,
  80                                  lp->flags);
  81                         return;
  82                 }
  83
  84                 lp->cur = DLM_LOCK_IV;
  85                 lp->req = DLM_LOCK_IV;
  86                 lp->lksb.sb_lkid = 0;
  87
  88                 if (test_and_clear_bit(LFL_UNLOCK_DELETE, &lp->flags)) {
  89                         gdlm_delete_lp(lp);
  90                         return;
  91                 }
  92                 goto out;
  93         }
  94
  95         if (lp->lksb.sb_flags & DLM_SBF_VALNOTVALID)
  96                 memset(lp->lksb.sb_lvbptr, 0, GDLM_LVB_SIZE);
  97
  98         if (lp->lksb.sb_flags & DLM_SBF_ALTMODE) {
  99                 if (lp->req == DLM_LOCK_PR)
 100                         lp->req = DLM_LOCK_CW;
 101                 else if (lp->req == DLM_LOCK_CW)
 102                         lp->req = DLM_LOCK_PR;
 103         }
 104
 105         /*
 106          * A canceled lock request.  The lock was just taken off the delayed
 107          * list and was never even submitted to dlm.
 108          */
 109
 110         if (test_and_clear_bit(LFL_CANCEL, &lp->flags)) {
 111                 log_info("complete internal cancel %x,%llx",
 112                          lp->lockname.ln_type,
 113                          (unsigned long long)lp->lockname.ln_number);
 114                 lp->req = lp->cur;
 115                 acb.lc_ret |= LM_OUT_CANCELED;
 116                 goto out;
 117         }
 118
 119         /*
 120          * An error occured.
 121          */
 122
 123         if (lp->lksb.sb_status) {
 124                 /* a "normal" error */
 125                 if ((lp->lksb.sb_status == -EAGAIN) &&
 126                     (lp->lkf & DLM_LKF_NOQUEUE)) {
 127                         lp->req = lp->cur;
 128                         if (lp->cur == DLM_LOCK_IV)
 129                                 lp->lksb.sb_lkid = 0;
 130                         goto out;
 131                 }
 132
 133                 /* this could only happen with cancels I think */
 134                 log_info("ast sb_status %d %x,%llx flags %lx",
 135                          lp->lksb.sb_status, lp->lockname.ln_type,
 136                          (unsigned long long)lp->lockname.ln_number,
 137                          lp->flags);
 138                 return;
 139         }
 140
 141         /*
 142          * This is an AST for an EX->EX conversion for sync_lvb from GFS.
 143          */
 144
 145         if (test_and_clear_bit(LFL_SYNC_LVB, &lp->flags)) {
 146                 wake_up_ast(lp);
 147                 return;
 148         }
 149
 150         /*
 151          * A lock has been demoted to NL because it initially completed during
 152          * BLOCK_LOCKS.  Now it must be requested in the originally requested
 153          * mode.
 154          */
 155
 156         if (test_and_clear_bit(LFL_REREQUEST, &lp->flags)) {
 157                 gdlm_assert(lp->req == DLM_LOCK_NL, "%x,%llx",
 158                             lp->lockname.ln_type,
 159                             (unsigned long long)lp->lockname.ln_number);
 160                 gdlm_assert(lp->prev_req > DLM_LOCK_NL, "%x,%llx",
 161                             lp->lockname.ln_type,
 162                             (unsigned long long)lp->lockname.ln_number);
 163
 164                 lp->cur = DLM_LOCK_NL;
 165                 lp->req = lp->prev_req;
 166                 lp->prev_req = DLM_LOCK_IV;
 167                 lp->lkf &= ~DLM_LKF_CONVDEADLK;
 168
 169                 set_bit(LFL_NOCACHE, &lp->flags);
 170
 171                 if (test_bit(DFL_BLOCK_LOCKS, &ls->flags) &&
 172                     !test_bit(LFL_NOBLOCK, &lp->flags))
 173                         gdlm_queue_delayed(lp);
 174                 else
 175                         queue_submit(lp);
 176                 return;
 177         }
 178
 179         /*
 180          * A request is granted during dlm recovery.  It may be granted
 181          * because the locks of a failed node were cleared.  In that case,
 182          * there may be inconsistent data beneath this lock and we must wait
 183          * for recovery to complete to use it.  When gfs recovery is done this
 184          * granted lock will be converted to NL and then reacquired in this
 185          * granted state.
 186          */
 187
 188         if (test_bit(DFL_BLOCK_LOCKS, &ls->flags) &&
 189             !test_bit(LFL_NOBLOCK, &lp->flags) &&
 190             lp->req != DLM_LOCK_NL) {
 191
 192                 lp->cur = lp->req;
 193                 lp->prev_req = lp->req;
 194                 lp->req = DLM_LOCK_NL;
 195                 lp->lkf |= DLM_LKF_CONVERT;
 196                 lp->lkf &= ~DLM_LKF_CONVDEADLK;
 197
 198                 log_debug("rereq %x,%llx id %x %d,%d",
 199                           lp->lockname.ln_type,
 200                           (unsigned long long)lp->lockname.ln_number,
 201                           lp->lksb.sb_lkid, lp->cur, lp->req);
 202
 203                 set_bit(LFL_REREQUEST, &lp->flags);
 204                 queue_submit(lp);
 205                 return;
 206         }
 207
 208         /*
 209          * DLM demoted the lock to NL before it was granted so GFS must be
 210          * told it cannot cache data for this lock.
 211          */
 212
 213         if (lp->lksb.sb_flags & DLM_SBF_DEMOTED)
 214                 set_bit(LFL_NOCACHE, &lp->flags);
 215
 216 out:
 217         /*
 218          * This is an internal lock_dlm lock
 219          */
 220
 221         if (test_bit(LFL_INLOCK, &lp->flags)) {
 222                 clear_bit(LFL_NOBLOCK, &lp->flags);
 223                 lp->cur = lp->req;
 224                 wake_up_ast(lp);
 225                 return;
 226         }
 227
 228         /*
 229          * Normal completion of a lock request.  Tell GFS it now has the lock.
 230          */
 231
 232         clear_bit(LFL_NOBLOCK, &lp->flags);
 233         lp->cur = lp->req;
 234
 235         acb.lc_name = lp->lockname;
 236         acb.lc_ret |= gdlm_make_lmstate(lp->cur);
 237
 238         if (!test_and_clear_bit(LFL_NOCACHE, &lp->flags) &&
 239             (lp->cur > DLM_LOCK_NL) && (prev_mode > DLM_LOCK_NL))
 240                 acb.lc_ret |= LM_OUT_CACHEABLE;
 241
 242         ls->fscb(ls->sdp, LM_CB_ASYNC, &acb);
 243 }
 244
 245 static inline int no_work(struct gdlm_ls *ls, int blocking)
 246 {
 247         int ret;
 248
 249         spin_lock(&ls->async_lock);
 250         ret = list_empty(&ls->complete) && list_empty(&ls->submit);
 251         if (ret && blocking)
 252                 ret = list_empty(&ls->blocking);
 253         spin_unlock(&ls->async_lock);
 254
 255         return ret;
 256 }
 257
 258 static inline int check_drop(struct gdlm_ls *ls)
 259 {
 260         if (!ls->drop_locks_count)
 261                 return 0;
 262
 263         if (time_after(jiffies, ls->drop_time + ls->drop_locks_period * HZ)) {
 264                 ls->drop_time = jiffies;
 265                 if (ls->all_locks_count >= ls->drop_locks_count)
 266                         return 1;
 267         }
 268         return 0;
 269 }
 270
 271 static int gdlm_thread(void *data, int blist)
 272 {
 273         struct gdlm_ls *ls = (struct gdlm_ls *) data;
 274         struct gdlm_lock *lp = NULL;
 275         uint8_t complete, blocking, submit, drop;
 276
 277         /* Only thread1 is allowed to do blocking callbacks since gfs
 278            may wait for a completion callback within a blocking cb. */
 279
 280         while (!kthread_should_stop()) {
 281                 wait_event_interruptible(ls->thread_wait,
 282                                 !no_work(ls, blist) || kthread_should_stop());
 283
 284                 complete = blocking = submit = drop = 0;
 285
 286                 spin_lock(&ls->async_lock);
 287
 288                 if (blist && !list_empty(&ls->blocking)) {
 289                         lp = list_entry(ls->blocking.next, struct gdlm_lock,
 290                                         blist);
 291                         list_del_init(&lp->blist);
 292                         blocking = lp->bast_mode;
 293                         lp->bast_mode = 0;
 294                 } else if (!list_empty(&ls->complete)) {
 295                         lp = list_entry(ls->complete.next, struct gdlm_lock,
 296                                         clist);
 297                         list_del_init(&lp->clist);
 298                         complete = 1;
 299                 } else if (!list_empty(&ls->submit)) {
 300                         lp = list_entry(ls->submit.next, struct gdlm_lock,
 301                                         delay_list);
 302                         list_del_init(&lp->delay_list);
 303                         submit = 1;
 304                 }
 305
 306                 drop = check_drop(ls);
 307                 spin_unlock(&ls->async_lock);
 308
 309                 if (complete)
 310                         process_complete(lp);
 311
 312                 else if (blocking)
 313                         process_blocking(lp, blocking);
 314
 315                 else if (submit)
 316                         gdlm_do_lock(lp);
 317
 318                 if (drop)
 319                         ls->fscb(ls->sdp, LM_CB_DROPLOCKS, NULL);
 320
 321                 schedule();
 322         }
 323
 324         return 0;
 325 }
 326
 327 static int gdlm_thread1(void *data)
 328 {
 329         return gdlm_thread(data, 1);
 330 }
 331
 332 static int gdlm_thread2(void *data)
 333 {
 334         return gdlm_thread(data, 0);
 335 }
 336
 337 int gdlm_init_threads(struct gdlm_ls *ls)
 338 {
 339         struct task_struct *p;
 340         int error;
 341
 342         p = kthread_run(gdlm_thread1, ls, "lock_dlm1");
 343         error = IS_ERR(p);
 344         if (error) {
 345                 log_error("can't start lock_dlm1 thread %d", error);
 346                 return error;
 347         }
 348         ls->thread1 = p;
 349
 350         p = kthread_run(gdlm_thread2, ls, "lock_dlm2");
 351         error = IS_ERR(p);
 352         if (error) {
 353                 log_error("can't start lock_dlm2 thread %d", error);
 354                 kthread_stop(ls->thread1);
 355                 return error;
 356         }
 357         ls->thread2 = p;
 358
 359         return 0;
 360 }
 361
 362 void gdlm_release_threads(struct gdlm_ls *ls)
 363 {
 364         kthread_stop(ls->thread1);
 365         kthread_stop(ls->thread2);
 366 }
 367