git.oblomov.eu Git - linux-2.6/blob - 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 v.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->fsdata, cb, &lp->lockname);
  45 }
  46
  47 static void process_complete(struct gdlm_lock *lp)
  48 {
  49         struct gdlm_ls *ls = lp->ls;
  50         struct lm_async_cb acb;
  51         int16_t prev_mode = lp->cur;
  52
  53         memset(&acb, 0, sizeof(acb));
  54
  55         if (lp->lksb.sb_status == -DLM_ECANCEL) {
  56                 log_info("complete dlm cancel %x,%llx flags %lx",
  57                          lp->lockname.ln_type, lp->lockname.ln_number,
  58                          lp->flags);
  59
  60                 lp->req = lp->cur;
  61                 acb.lc_ret |= LM_OUT_CANCELED;
  62                 if (lp->cur == DLM_LOCK_IV)
  63                         lp->lksb.sb_lkid = 0;
  64                 goto out;
  65         }
  66
  67         if (test_and_clear_bit(LFL_DLM_UNLOCK, &lp->flags)) {
  68                 if (lp->lksb.sb_status != -DLM_EUNLOCK) {
  69                         log_info("unlock sb_status %d %x,%llx flags %lx",
  70                                  lp->lksb.sb_status, lp->lockname.ln_type,
  71                                  lp->lockname.ln_number, lp->flags);
  72                         return;
  73                 }
  74
  75                 lp->cur = DLM_LOCK_IV;
  76                 lp->req = DLM_LOCK_IV;
  77                 lp->lksb.sb_lkid = 0;
  78
  79                 if (test_and_clear_bit(LFL_UNLOCK_DELETE, &lp->flags)) {
  80                         gdlm_delete_lp(lp);
  81                         return;
  82                 }
  83                 goto out;
  84         }
  85
  86         if (lp->lksb.sb_flags & DLM_SBF_VALNOTVALID)
  87                 memset(lp->lksb.sb_lvbptr, 0, GDLM_LVB_SIZE);
  88
  89         if (lp->lksb.sb_flags & DLM_SBF_ALTMODE) {
  90                 if (lp->req == DLM_LOCK_PR)
  91                         lp->req = DLM_LOCK_CW;
  92                 else if (lp->req == DLM_LOCK_CW)
  93                         lp->req = DLM_LOCK_PR;
  94         }
  95
  96         /*
  97          * A canceled lock request.  The lock was just taken off the delayed
  98          * list and was never even submitted to dlm.
  99          */
 100
 101         if (test_and_clear_bit(LFL_CANCEL, &lp->flags)) {
 102                 log_info("complete internal cancel %x,%llx",
 103                          lp->lockname.ln_type, lp->lockname.ln_number);
 104                 lp->req = lp->cur;
 105                 acb.lc_ret |= LM_OUT_CANCELED;
 106                 goto out;
 107         }
 108
 109         /*
 110          * An error occured.
 111          */
 112
 113         if (lp->lksb.sb_status) {
 114                 /* a "normal" error */
 115                 if ((lp->lksb.sb_status == -EAGAIN) &&
 116                     (lp->lkf & DLM_LKF_NOQUEUE)) {
 117                         lp->req = lp->cur;
 118                         if (lp->cur == DLM_LOCK_IV)
 119                                 lp->lksb.sb_lkid = 0;
 120                         goto out;
 121                 }
 122
 123                 /* this could only happen with cancels I think */
 124                 log_info("ast sb_status %d %x,%llx flags %lx",
 125                          lp->lksb.sb_status, lp->lockname.ln_type,
 126                          lp->lockname.ln_number, lp->flags);
 127                 return;
 128         }
 129
 130         /*
 131          * This is an AST for an EX->EX conversion for sync_lvb from GFS.
 132          */
 133
 134         if (test_and_clear_bit(LFL_SYNC_LVB, &lp->flags)) {
 135                 complete(&lp->ast_wait);
 136                 return;
 137         }
 138
 139         /*
 140          * A lock has been demoted to NL because it initially completed during
 141          * BLOCK_LOCKS.  Now it must be requested in the originally requested
 142          * mode.
 143          */
 144
 145         if (test_and_clear_bit(LFL_REREQUEST, &lp->flags)) {
 146                 gdlm_assert(lp->req == DLM_LOCK_NL, "%x,%llx",
 147                             lp->lockname.ln_type, lp->lockname.ln_number);
 148                 gdlm_assert(lp->prev_req > DLM_LOCK_NL, "%x,%llx",
 149                             lp->lockname.ln_type, lp->lockname.ln_number);
 150
 151                 lp->cur = DLM_LOCK_NL;
 152                 lp->req = lp->prev_req;
 153                 lp->prev_req = DLM_LOCK_IV;
 154                 lp->lkf &= ~DLM_LKF_CONVDEADLK;
 155
 156                 set_bit(LFL_NOCACHE, &lp->flags);
 157
 158                 if (test_bit(DFL_BLOCK_LOCKS, &ls->flags) &&
 159                     !test_bit(LFL_NOBLOCK, &lp->flags))
 160                         gdlm_queue_delayed(lp);
 161                 else
 162                         queue_submit(lp);
 163                 return;
 164         }
 165
 166         /*
 167          * A request is granted during dlm recovery.  It may be granted
 168          * because the locks of a failed node were cleared.  In that case,
 169          * there may be inconsistent data beneath this lock and we must wait
 170          * for recovery to complete to use it.  When gfs recovery is done this
 171          * granted lock will be converted to NL and then reacquired in this
 172          * granted state.
 173          */
 174
 175         if (test_bit(DFL_BLOCK_LOCKS, &ls->flags) &&
 176             !test_bit(LFL_NOBLOCK, &lp->flags) &&
 177             lp->req != DLM_LOCK_NL) {
 178
 179                 lp->cur = lp->req;
 180                 lp->prev_req = lp->req;
 181                 lp->req = DLM_LOCK_NL;
 182                 lp->lkf |= DLM_LKF_CONVERT;
 183                 lp->lkf &= ~DLM_LKF_CONVDEADLK;
 184
 185                 log_debug("rereq %x,%llx id %x %d,%d",
 186                           lp->lockname.ln_type, lp->lockname.ln_number,
 187                           lp->lksb.sb_lkid, lp->cur, lp->req);
 188
 189                 set_bit(LFL_REREQUEST, &lp->flags);
 190                 queue_submit(lp);
 191                 return;
 192         }
 193
 194         /*
 195          * DLM demoted the lock to NL before it was granted so GFS must be
 196          * told it cannot cache data for this lock.
 197          */
 198
 199         if (lp->lksb.sb_flags & DLM_SBF_DEMOTED)
 200                 set_bit(LFL_NOCACHE, &lp->flags);
 201
 202  out:
 203         /*
 204          * This is an internal lock_dlm lock
 205          */
 206
 207         if (test_bit(LFL_INLOCK, &lp->flags)) {
 208                 clear_bit(LFL_NOBLOCK, &lp->flags);
 209                 lp->cur = lp->req;
 210                 complete(&lp->ast_wait);
 211                 return;
 212         }
 213
 214         /*
 215          * Normal completion of a lock request.  Tell GFS it now has the lock.
 216          */
 217
 218         clear_bit(LFL_NOBLOCK, &lp->flags);
 219         lp->cur = lp->req;
 220
 221         acb.lc_name = lp->lockname;
 222         acb.lc_ret |= gdlm_make_lmstate(lp->cur);
 223
 224         if (!test_and_clear_bit(LFL_NOCACHE, &lp->flags) &&
 225             (lp->cur > DLM_LOCK_NL) && (prev_mode > DLM_LOCK_NL))
 226                 acb.lc_ret |= LM_OUT_CACHEABLE;
 227
 228         ls->fscb(ls->fsdata, LM_CB_ASYNC, &acb);
 229 }
 230
 231 static inline int no_work(struct gdlm_ls *ls, int blocking)
 232 {
 233         int ret;
 234
 235         spin_lock(&ls->async_lock);
 236         ret = list_empty(&ls->complete) && list_empty(&ls->submit);
 237         if (ret && blocking)
 238                 ret = list_empty(&ls->blocking);
 239         spin_unlock(&ls->async_lock);
 240
 241         return ret;
 242 }
 243
 244 static inline int check_drop(struct gdlm_ls *ls)
 245 {
 246         if (!ls->drop_locks_count)
 247                 return 0;
 248
 249         if (time_after(jiffies, ls->drop_time + ls->drop_locks_period * HZ)) {
 250                 ls->drop_time = jiffies;
 251                 if (ls->all_locks_count >= ls->drop_locks_count)
 252                         return 1;
 253         }
 254         return 0;
 255 }
 256
 257 static int gdlm_thread(void *data)
 258 {
 259         struct gdlm_ls *ls = (struct gdlm_ls *) data;
 260         struct gdlm_lock *lp = NULL;
 261         int blist = 0;
 262         uint8_t complete, blocking, submit, drop;
 263         DECLARE_WAITQUEUE(wait, current);
 264
 265         /* Only thread1 is allowed to do blocking callbacks since gfs
 266            may wait for a completion callback within a blocking cb. */
 267
 268         if (current == ls->thread1)
 269                 blist = 1;
 270
 271         while (!kthread_should_stop()) {
 272                 set_current_state(TASK_INTERRUPTIBLE);
 273                 add_wait_queue(&ls->thread_wait, &wait);
 274                 if (no_work(ls, blist))
 275                         schedule();
 276                 remove_wait_queue(&ls->thread_wait, &wait);
 277                 set_current_state(TASK_RUNNING);
 278
 279                 complete = blocking = submit = drop = 0;
 280
 281                 spin_lock(&ls->async_lock);
 282
 283                 if (blist && !list_empty(&ls->blocking)) {
 284                         lp = list_entry(ls->blocking.next, struct gdlm_lock,
 285                                         blist);
 286                         list_del_init(&lp->blist);
 287                         blocking = lp->bast_mode;
 288                         lp->bast_mode = 0;
 289                 } else if (!list_empty(&ls->complete)) {
 290                         lp = list_entry(ls->complete.next, struct gdlm_lock,
 291                                         clist);
 292                         list_del_init(&lp->clist);
 293                         complete = 1;
 294                 } else if (!list_empty(&ls->submit)) {
 295                         lp = list_entry(ls->submit.next, struct gdlm_lock,
 296                                         delay_list);
 297                         list_del_init(&lp->delay_list);
 298                         submit = 1;
 299                 }
 300
 301                 drop = check_drop(ls);
 302                 spin_unlock(&ls->async_lock);
 303
 304                 if (complete)
 305                         process_complete(lp);
 306
 307                 else if (blocking)
 308                         process_blocking(lp, blocking);
 309
 310                 else if (submit)
 311                         gdlm_do_lock(lp);
 312
 313                 if (drop)
 314                         ls->fscb(ls->fsdata, LM_CB_DROPLOCKS, NULL);
 315
 316                 schedule();
 317         }
 318
 319         return 0;
 320 }
 321
 322 int gdlm_init_threads(struct gdlm_ls *ls)
 323 {
 324         struct task_struct *p;
 325         int error;
 326
 327         p = kthread_run(gdlm_thread, ls, "lock_dlm1");
 328         error = IS_ERR(p);
 329         if (error) {
 330                 log_error("can't start lock_dlm1 thread %d", error);
 331                 return error;
 332         }
 333         ls->thread1 = p;
 334
 335         p = kthread_run(gdlm_thread, ls, "lock_dlm2");
 336         error = IS_ERR(p);
 337         if (error) {
 338                 log_error("can't start lock_dlm2 thread %d", error);
 339                 kthread_stop(ls->thread1);
 340                 return error;
 341         }
 342         ls->thread2 = p;
 343
 344         return 0;
 345 }
 346
 347 void gdlm_release_threads(struct gdlm_ls *ls)
 348 {
 349         kthread_stop(ls->thread1);
 350         kthread_stop(ls->thread2);
 351 }
 352