fs/dlm/ast.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /******************************************************************************
   3 *******************************************************************************
   4 **
   5 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   6 **  Copyright (C) 2004-2010 Red Hat, Inc.  All rights reserved.
   7 **
   8 **
   9 *******************************************************************************
  10 ******************************************************************************/
  11
  12 #include <trace/events/dlm.h>
  13
  14 #include "dlm_internal.h"
  15 #include "memory.h"
  16 #include "lock.h"
  17 #include "user.h"
  18 #include "ast.h"
  19
  20 void dlm_release_callback(struct kref *ref)
  21 {
  22         struct dlm_callback *cb = container_of(ref, struct dlm_callback, ref);
  23
  24         dlm_free_cb(cb);
  25 }
  26
  27 void dlm_callback_set_last_ptr(struct dlm_callback **from,
  28                                struct dlm_callback *to)
  29 {
  30         if (*from)
  31                 kref_put(&(*from)->ref, dlm_release_callback);
  32
  33         if (to)
  34                 kref_get(&to->ref);
  35
  36         *from = to;
  37 }
  38
  39 void dlm_purge_lkb_callbacks(struct dlm_lkb *lkb)
  40 {
  41         struct dlm_callback *cb, *safe;
  42
  43         list_for_each_entry_safe(cb, safe, &lkb->lkb_callbacks, list) {
  44                 list_del(&cb->list);
  45                 kref_put(&cb->ref, dlm_release_callback);
  46         }
  47
  48         clear_bit(DLM_IFL_CB_PENDING_BIT, &lkb->lkb_iflags);
  49
  50         /* invalidate */
  51         dlm_callback_set_last_ptr(&lkb->lkb_last_cast, NULL);
  52         dlm_callback_set_last_ptr(&lkb->lkb_last_cb, NULL);
  53         lkb->lkb_last_bast_mode = -1;
  54 }
  55
  56 int dlm_enqueue_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
  57                              int status, uint32_t sbflags)
  58 {
  59         struct dlm_ls *ls = lkb->lkb_resource->res_ls;
  60         int rv = DLM_ENQUEUE_CALLBACK_SUCCESS;
  61         struct dlm_callback *cb;
  62         int prev_mode;
  63
  64         if (flags & DLM_CB_BAST) {
  65                 /* if cb is a bast, it should be skipped if the blocking mode is
  66                  * compatible with the last granted mode
  67                  */
  68                 if (lkb->lkb_last_cast) {
  69                         if (dlm_modes_compat(mode, lkb->lkb_last_cast->mode)) {
  70                                 log_debug(ls, "skip %x bast mode %d for cast mode %d",
  71                                           lkb->lkb_id, mode,
  72                                           lkb->lkb_last_cast->mode);
  73                                 goto out;
  74                         }
  75                 }
  76
  77                 /*
  78                  * Suppress some redundant basts here, do more on removal.
  79                  * Don't even add a bast if the callback just before it
  80                  * is a bast for the same mode or a more restrictive mode.
  81                  * (the addional > PR check is needed for PR/CW inversion)
  82                  */
  83                 if (lkb->lkb_last_cb && lkb->lkb_last_cb->flags & DLM_CB_BAST) {
  84                         prev_mode = lkb->lkb_last_cb->mode;
  85
  86                         if ((prev_mode == mode) ||
  87                             (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {
  88                                 log_debug(ls, "skip %x add bast mode %d for bast mode %d",
  89                                           lkb->lkb_id, mode, prev_mode);
  90                                 goto out;
  91                         }
  92                 }
  93         }
  94
  95         cb = dlm_allocate_cb();
  96         if (!cb) {
  97                 rv = DLM_ENQUEUE_CALLBACK_FAILURE;
  98                 goto out;
  99         }
 100
 101         cb->flags = flags;
 102         cb->mode = mode;
 103         cb->sb_status = status;
 104         cb->sb_flags = (sbflags & 0x000000FF);
 105         kref_init(&cb->ref);
 106         if (!test_and_set_bit(DLM_IFL_CB_PENDING_BIT, &lkb->lkb_iflags))
 107                 rv = DLM_ENQUEUE_CALLBACK_NEED_SCHED;
 108
 109         list_add_tail(&cb->list, &lkb->lkb_callbacks);
 110
 111         if (flags & DLM_CB_CAST)
 112                 dlm_callback_set_last_ptr(&lkb->lkb_last_cast, cb);
 113
 114         dlm_callback_set_last_ptr(&lkb->lkb_last_cb, cb);
 115
 116  out:
 117         return rv;
 118 }
 119
 120 int dlm_dequeue_lkb_callback(struct dlm_lkb *lkb, struct dlm_callback **cb)
 121 {
 122         /* oldest undelivered cb is callbacks first entry */
 123         *cb = list_first_entry_or_null(&lkb->lkb_callbacks,
 124                                        struct dlm_callback, list);
 125         if (!*cb)
 126                 return DLM_DEQUEUE_CALLBACK_EMPTY;
 127
 128         /* remove it from callbacks so shift others down */
 129         list_del(&(*cb)->list);
 130         if (list_empty(&lkb->lkb_callbacks))
 131                 return DLM_DEQUEUE_CALLBACK_LAST;
 132
 133         return DLM_DEQUEUE_CALLBACK_SUCCESS;
 134 }
 135
 136 void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
 137                 uint32_t sbflags)
 138 {
 139         struct dlm_ls *ls = lkb->lkb_resource->res_ls;
 140         int rv;
 141
 142         if (test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
 143                 dlm_user_add_ast(lkb, flags, mode, status, sbflags);
 144                 return;
 145         }
 146
 147         spin_lock(&lkb->lkb_cb_lock);
 148         rv = dlm_enqueue_lkb_callback(lkb, flags, mode, status, sbflags);
 149         switch (rv) {
 150         case DLM_ENQUEUE_CALLBACK_NEED_SCHED:
 151                 kref_get(&lkb->lkb_ref);
 152
 153                 spin_lock(&ls->ls_cb_lock);
 154                 if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
 155                         list_add(&lkb->lkb_cb_list, &ls->ls_cb_delay);
 156                 } else {
 157                         queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
 158                 }
 159                 spin_unlock(&ls->ls_cb_lock);
 160                 break;
 161         case DLM_ENQUEUE_CALLBACK_FAILURE:
 162                 WARN_ON_ONCE(1);
 163                 break;
 164         case DLM_ENQUEUE_CALLBACK_SUCCESS:
 165                 break;
 166         default:
 167                 WARN_ON_ONCE(1);
 168                 break;
 169         }
 170         spin_unlock(&lkb->lkb_cb_lock);
 171 }
 172
 173 void dlm_callback_work(struct work_struct *work)
 174 {
 175         struct dlm_lkb *lkb = container_of(work, struct dlm_lkb, lkb_cb_work);
 176         struct dlm_ls *ls = lkb->lkb_resource->res_ls;
 177         void (*castfn) (void *astparam);
 178         void (*bastfn) (void *astparam, int mode);
 179         struct dlm_callback *cb;
 180         int rv;
 181
 182         spin_lock(&lkb->lkb_cb_lock);
 183         rv = dlm_dequeue_lkb_callback(lkb, &cb);
 184         spin_unlock(&lkb->lkb_cb_lock);
 185
 186         if (WARN_ON_ONCE(rv == DLM_DEQUEUE_CALLBACK_EMPTY))
 187                 goto out;
 188
 189         for (;;) {
 190                 castfn = lkb->lkb_astfn;
 191                 bastfn = lkb->lkb_bastfn;
 192
 193                 if (cb->flags & DLM_CB_BAST) {
 194                         trace_dlm_bast(ls, lkb, cb->mode);
 195                         lkb->lkb_last_bast_time = ktime_get();
 196                         lkb->lkb_last_bast_mode = cb->mode;
 197                         bastfn(lkb->lkb_astparam, cb->mode);
 198                 } else if (cb->flags & DLM_CB_CAST) {
 199                         lkb->lkb_lksb->sb_status = cb->sb_status;
 200                         lkb->lkb_lksb->sb_flags = cb->sb_flags;
 201                         trace_dlm_ast(ls, lkb);
 202                         lkb->lkb_last_cast_time = ktime_get();
 203                         castfn(lkb->lkb_astparam);
 204                 }
 205
 206                 kref_put(&cb->ref, dlm_release_callback);
 207
 208                 spin_lock(&lkb->lkb_cb_lock);
 209                 rv = dlm_dequeue_lkb_callback(lkb, &cb);
 210                 if (rv == DLM_DEQUEUE_CALLBACK_EMPTY) {
 211                         clear_bit(DLM_IFL_CB_PENDING_BIT, &lkb->lkb_iflags);
 212                         spin_unlock(&lkb->lkb_cb_lock);
 213                         break;
 214                 }
 215                 spin_unlock(&lkb->lkb_cb_lock);
 216         }
 217
 218 out:
 219         /* undo kref_get from dlm_add_callback, may cause lkb to be freed */
 220         dlm_put_lkb(lkb);
 221 }
 222
 223 int dlm_callback_start(struct dlm_ls *ls)
 224 {
 225         ls->ls_callback_wq = alloc_workqueue("dlm_callback",
 226                                              WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
 227         if (!ls->ls_callback_wq) {
 228                 log_print("can't start dlm_callback workqueue");
 229                 return -ENOMEM;
 230         }
 231         return 0;
 232 }
 233
 234 void dlm_callback_stop(struct dlm_ls *ls)
 235 {
 236         if (ls->ls_callback_wq)
 237                 destroy_workqueue(ls->ls_callback_wq);
 238 }
 239
 240 void dlm_callback_suspend(struct dlm_ls *ls)
 241 {
 242         if (ls->ls_callback_wq) {
 243                 spin_lock(&ls->ls_cb_lock);
 244                 set_bit(LSFL_CB_DELAY, &ls->ls_flags);
 245                 spin_unlock(&ls->ls_cb_lock);
 246
 247                 flush_workqueue(ls->ls_callback_wq);
 248         }
 249 }
 250
 251 #define MAX_CB_QUEUE 25
 252
 253 void dlm_callback_resume(struct dlm_ls *ls)
 254 {
 255         struct dlm_lkb *lkb, *safe;
 256         int count = 0, sum = 0;
 257         bool empty;
 258
 259         if (!ls->ls_callback_wq)
 260                 return;
 261
 262 more:
 263         spin_lock(&ls->ls_cb_lock);
 264         list_for_each_entry_safe(lkb, safe, &ls->ls_cb_delay, lkb_cb_list) {
 265                 list_del_init(&lkb->lkb_cb_list);
 266                 queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
 267                 count++;
 268                 if (count == MAX_CB_QUEUE)
 269                         break;
 270         }
 271         empty = list_empty(&ls->ls_cb_delay);
 272         if (empty)
 273                 clear_bit(LSFL_CB_DELAY, &ls->ls_flags);
 274         spin_unlock(&ls->ls_cb_lock);
 275
 276         sum += count;
 277         if (!empty) {
 278                 count = 0;
 279                 cond_resched();
 280                 goto more;
 281         }
 282
 283         if (sum)
 284                 log_rinfo(ls, "%s %d", __func__, sum);
 285 }
 286