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