fs/dlm/ast.c

   1 /******************************************************************************
   2 *******************************************************************************
   3 **
   4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   5 **  Copyright (C) 2004-2010 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 #include "dlm_internal.h"
  15 #include "lock.h"
  16 #include "user.h"
  17 #include "ast.h"
  18
  19 #define WAKE_ASTS  0
  20
  21 static uint64_t                 ast_seq_count;
  22 static struct list_head         ast_queue;
  23 static spinlock_t               ast_queue_lock;
  24 static struct task_struct *     astd_task;
  25 static unsigned long            astd_wakeflags;
  26 static struct mutex             astd_running;
  27
  28
  29 static void dlm_dump_lkb_callbacks(struct dlm_lkb *lkb)
  30 {
  31         int i;
  32
  33         log_print("last_bast %x %llu flags %x mode %d sb %d %x",
  34                   lkb->lkb_id,
  35                   (unsigned long long)lkb->lkb_last_bast.seq,
  36                   lkb->lkb_last_bast.flags,
  37                   lkb->lkb_last_bast.mode,
  38                   lkb->lkb_last_bast.sb_status,
  39                   lkb->lkb_last_bast.sb_flags);
  40
  41         log_print("last_cast %x %llu flags %x mode %d sb %d %x",
  42                   lkb->lkb_id,
  43                   (unsigned long long)lkb->lkb_last_cast.seq,
  44                   lkb->lkb_last_cast.flags,
  45                   lkb->lkb_last_cast.mode,
  46                   lkb->lkb_last_cast.sb_status,
  47                   lkb->lkb_last_cast.sb_flags);
  48
  49         for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
  50                 log_print("cb %x %llu flags %x mode %d sb %d %x",
  51                           lkb->lkb_id,
  52                           (unsigned long long)lkb->lkb_callbacks[i].seq,
  53                           lkb->lkb_callbacks[i].flags,
  54                           lkb->lkb_callbacks[i].mode,
  55                           lkb->lkb_callbacks[i].sb_status,
  56                           lkb->lkb_callbacks[i].sb_flags);
  57         }
  58 }
  59
  60 void dlm_del_ast(struct dlm_lkb *lkb)
  61 {
  62         spin_lock(&ast_queue_lock);
  63         if (!list_empty(&lkb->lkb_astqueue))
  64                 list_del_init(&lkb->lkb_astqueue);
  65         spin_unlock(&ast_queue_lock);
  66 }
  67
  68 int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
  69                          int status, uint32_t sbflags, uint64_t seq)
  70 {
  71         struct dlm_ls *ls = lkb->lkb_resource->res_ls;
  72         uint64_t prev_seq;
  73         int prev_mode;
  74         int i;
  75
  76         for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
  77                 if (lkb->lkb_callbacks[i].seq)
  78                         continue;
  79
  80                 /*
  81                  * Suppress some redundant basts here, do more on removal.
  82                  * Don't even add a bast if the callback just before it
  83                  * is a bast for the same mode or a more restrictive mode.
  84                  * (the addional > PR check is needed for PR/CW inversion)
  85                  */
  86
  87                 if ((i > 0) && (flags & DLM_CB_BAST) &&
  88                     (lkb->lkb_callbacks[i-1].flags & DLM_CB_BAST)) {
  89
  90                         prev_seq = lkb->lkb_callbacks[i-1].seq;
  91                         prev_mode = lkb->lkb_callbacks[i-1].mode;
  92
  93                         if ((prev_mode == mode) ||
  94                             (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {
  95
  96                                 log_debug(ls, "skip %x add bast %llu mode %d "
  97                                           "for bast %llu mode %d",
  98                                           lkb->lkb_id,
  99                                           (unsigned long long)seq,
 100                                           mode,
 101                                           (unsigned long long)prev_seq,
 102                                           prev_mode);
 103                                 return 0;
 104                         }
 105                 }
 106
 107                 lkb->lkb_callbacks[i].seq = seq;
 108                 lkb->lkb_callbacks[i].flags = flags;
 109                 lkb->lkb_callbacks[i].mode = mode;
 110                 lkb->lkb_callbacks[i].sb_status = status;
 111                 lkb->lkb_callbacks[i].sb_flags = (sbflags & 0x000000FF);
 112                 break;
 113         }
 114
 115         if (i == DLM_CALLBACKS_SIZE) {
 116                 log_error(ls, "no callbacks %x %llu flags %x mode %d sb %d %x",
 117                           lkb->lkb_id, (unsigned long long)seq,
 118                           flags, mode, status, sbflags);
 119                 dlm_dump_lkb_callbacks(lkb);
 120                 return -1;
 121         }
 122
 123         return 0;
 124 }
 125
 126 int dlm_rem_lkb_callback(struct dlm_ls *ls, struct dlm_lkb *lkb,
 127                          struct dlm_callback *cb, int *resid)
 128 {
 129         int i;
 130
 131         *resid = 0;
 132
 133         if (!lkb->lkb_callbacks[0].seq)
 134                 return -ENOENT;
 135
 136         /* oldest undelivered cb is callbacks[0] */
 137
 138         memcpy(cb, &lkb->lkb_callbacks[0], sizeof(struct dlm_callback));
 139         memset(&lkb->lkb_callbacks[0], 0, sizeof(struct dlm_callback));
 140
 141         /* shift others down */
 142
 143         for (i = 1; i < DLM_CALLBACKS_SIZE; i++) {
 144                 if (!lkb->lkb_callbacks[i].seq)
 145                         break;
 146                 memcpy(&lkb->lkb_callbacks[i-1], &lkb->lkb_callbacks[i],
 147                        sizeof(struct dlm_callback));
 148                 memset(&lkb->lkb_callbacks[i], 0, sizeof(struct dlm_callback));
 149                 (*resid)++;
 150         }
 151
 152         /* if cb is a bast, it should be skipped if the blocking mode is
 153            compatible with the last granted mode */
 154
 155         if ((cb->flags & DLM_CB_BAST) && lkb->lkb_last_cast.seq) {
 156                 if (dlm_modes_compat(cb->mode, lkb->lkb_last_cast.mode)) {
 157                         cb->flags |= DLM_CB_SKIP;
 158
 159                         log_debug(ls, "skip %x bast %llu mode %d "
 160                                   "for cast %llu mode %d",
 161                                   lkb->lkb_id,
 162                                   (unsigned long long)cb->seq,
 163                                   cb->mode,
 164                                   (unsigned long long)lkb->lkb_last_cast.seq,
 165                                   lkb->lkb_last_cast.mode);
 166                         return 0;
 167                 }
 168         }
 169
 170         if (cb->flags & DLM_CB_CAST) {
 171                 memcpy(&lkb->lkb_last_cast, cb, sizeof(struct dlm_callback));
 172                 lkb->lkb_last_cast_time = ktime_get();
 173         }
 174
 175         if (cb->flags & DLM_CB_BAST) {
 176                 memcpy(&lkb->lkb_last_bast, cb, sizeof(struct dlm_callback));
 177                 lkb->lkb_last_bast_time = ktime_get();
 178         }
 179
 180         return 0;
 181 }
 182
 183 void dlm_add_ast(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
 184                  uint32_t sbflags)
 185 {
 186         uint64_t seq;
 187         int rv;
 188
 189         spin_lock(&ast_queue_lock);
 190
 191         seq = ++ast_seq_count;
 192
 193         if (lkb->lkb_flags & DLM_IFL_USER) {
 194                 spin_unlock(&ast_queue_lock);
 195                 dlm_user_add_ast(lkb, flags, mode, status, sbflags, seq);
 196                 return;
 197         }
 198
 199         rv = dlm_add_lkb_callback(lkb, flags, mode, status, sbflags, seq);
 200         if (rv < 0) {
 201                 spin_unlock(&ast_queue_lock);
 202                 return;
 203         }
 204
 205         if (list_empty(&lkb->lkb_astqueue)) {
 206                 kref_get(&lkb->lkb_ref);
 207                 list_add_tail(&lkb->lkb_astqueue, &ast_queue);
 208         }
 209         spin_unlock(&ast_queue_lock);
 210
 211         set_bit(WAKE_ASTS, &astd_wakeflags);
 212         wake_up_process(astd_task);
 213 }
 214
 215 static void process_asts(void)
 216 {
 217         struct dlm_ls *ls = NULL;
 218         struct dlm_rsb *r = NULL;
 219         struct dlm_lkb *lkb;
 220         void (*castfn) (void *astparam);
 221         void (*bastfn) (void *astparam, int mode);
 222         struct dlm_callback callbacks[DLM_CALLBACKS_SIZE];
 223         int i, rv, resid;
 224
 225 repeat:
 226         spin_lock(&ast_queue_lock);
 227         list_for_each_entry(lkb, &ast_queue, lkb_astqueue) {
 228                 r = lkb->lkb_resource;
 229                 ls = r->res_ls;
 230
 231                 if (dlm_locking_stopped(ls))
 232                         continue;
 233
 234                 /* we remove from astqueue list and remove everything in
 235                    lkb_callbacks before releasing the spinlock so empty
 236                    lkb_astqueue is always consistent with empty lkb_callbacks */
 237
 238                 list_del_init(&lkb->lkb_astqueue);
 239
 240                 castfn = lkb->lkb_astfn;
 241                 bastfn = lkb->lkb_bastfn;
 242
 243                 memset(&callbacks, 0, sizeof(callbacks));
 244
 245                 for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
 246                         rv = dlm_rem_lkb_callback(ls, lkb, &callbacks[i], &resid);
 247                         if (rv < 0)
 248                                 break;
 249                 }
 250                 spin_unlock(&ast_queue_lock);
 251
 252                 if (resid) {
 253                         /* shouldn't happen, for loop should have removed all */
 254                         log_error(ls, "callback resid %d lkb %x",
 255                                   resid, lkb->lkb_id);
 256                 }
 257
 258                 for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
 259                         if (!callbacks[i].seq)
 260                                 break;
 261                         if (callbacks[i].flags & DLM_CB_SKIP) {
 262                                 continue;
 263                         } else if (callbacks[i].flags & DLM_CB_BAST) {
 264                                 bastfn(lkb->lkb_astparam, callbacks[i].mode);
 265                         } else if (callbacks[i].flags & DLM_CB_CAST) {
 266                                 lkb->lkb_lksb->sb_status = callbacks[i].sb_status;
 267                                 lkb->lkb_lksb->sb_flags = callbacks[i].sb_flags;
 268                                 castfn(lkb->lkb_astparam);
 269                         }
 270                 }
 271
 272                 /* removes ref for ast_queue, may cause lkb to be freed */
 273                 dlm_put_lkb(lkb);
 274
 275                 cond_resched();
 276                 goto repeat;
 277         }
 278         spin_unlock(&ast_queue_lock);
 279 }
 280
 281 static inline int no_asts(void)
 282 {
 283         int ret;
 284
 285         spin_lock(&ast_queue_lock);
 286         ret = list_empty(&ast_queue);
 287         spin_unlock(&ast_queue_lock);
 288         return ret;
 289 }
 290
 291 static int dlm_astd(void *data)
 292 {
 293         while (!kthread_should_stop()) {
 294                 set_current_state(TASK_INTERRUPTIBLE);
 295                 if (!test_bit(WAKE_ASTS, &astd_wakeflags))
 296                         schedule();
 297                 set_current_state(TASK_RUNNING);
 298
 299                 mutex_lock(&astd_running);
 300                 if (test_and_clear_bit(WAKE_ASTS, &astd_wakeflags))
 301                         process_asts();
 302                 mutex_unlock(&astd_running);
 303         }
 304         return 0;
 305 }
 306
 307 void dlm_astd_wake(void)
 308 {
 309         if (!no_asts()) {
 310                 set_bit(WAKE_ASTS, &astd_wakeflags);
 311                 wake_up_process(astd_task);
 312         }
 313 }
 314
 315 int dlm_astd_start(void)
 316 {
 317         struct task_struct *p;
 318         int error = 0;
 319
 320         INIT_LIST_HEAD(&ast_queue);
 321         spin_lock_init(&ast_queue_lock);
 322         mutex_init(&astd_running);
 323
 324         p = kthread_run(dlm_astd, NULL, "dlm_astd");
 325         if (IS_ERR(p))
 326                 error = PTR_ERR(p);
 327         else
 328                 astd_task = p;
 329         return error;
 330 }
 331
 332 void dlm_astd_stop(void)
 333 {
 334         kthread_stop(astd_task);
 335 }
 336
 337 void dlm_astd_suspend(void)
 338 {
 339         mutex_lock(&astd_running);
 340 }
 341
 342 void dlm_astd_resume(void)
 343 {
 344         mutex_unlock(&astd_running);
 345 }
 346