fs/dlm/ast.c

   1 /******************************************************************************
   2 *******************************************************************************
   3 **
   4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   5 **  Copyright (C) 2004-2005 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 "ast.h"
  17
  18 #define WAKE_ASTS  0
  19
  20 static struct list_head         ast_queue;
  21 static spinlock_t               ast_queue_lock;
  22 static struct task_struct *     astd_task;
  23 static unsigned long            astd_wakeflags;
  24 static struct mutex             astd_running;
  25
  26
  27 void dlm_del_ast(struct dlm_lkb *lkb)
  28 {
  29         spin_lock(&ast_queue_lock);
  30         if (lkb->lkb_ast_type & (AST_COMP | AST_BAST))
  31                 list_del(&lkb->lkb_astqueue);
  32         spin_unlock(&ast_queue_lock);
  33 }
  34
  35 void dlm_add_ast(struct dlm_lkb *lkb, int type)
  36 {
  37         spin_lock(&ast_queue_lock);
  38         if (!(lkb->lkb_ast_type & (AST_COMP | AST_BAST))) {
  39                 kref_get(&lkb->lkb_ref);
  40                 list_add_tail(&lkb->lkb_astqueue, &ast_queue);
  41         }
  42         lkb->lkb_ast_type |= type;
  43         spin_unlock(&ast_queue_lock);
  44
  45         set_bit(WAKE_ASTS, &astd_wakeflags);
  46         wake_up_process(astd_task);
  47 }
  48
  49 static void process_asts(void)
  50 {
  51         struct dlm_ls *ls = NULL;
  52         struct dlm_rsb *r = NULL;
  53         struct dlm_lkb *lkb;
  54         void (*cast) (long param);
  55         void (*bast) (long param, int mode);
  56         int type = 0, found, bmode;
  57
  58         for (;;) {
  59                 found = 0;
  60                 spin_lock(&ast_queue_lock);
  61                 list_for_each_entry(lkb, &ast_queue, lkb_astqueue) {
  62                         r = lkb->lkb_resource;
  63                         ls = r->res_ls;
  64
  65                         if (dlm_locking_stopped(ls))
  66                                 continue;
  67
  68                         list_del(&lkb->lkb_astqueue);
  69                         type = lkb->lkb_ast_type;
  70                         lkb->lkb_ast_type = 0;
  71                         found = 1;
  72                         break;
  73                 }
  74                 spin_unlock(&ast_queue_lock);
  75
  76                 if (!found)
  77                         break;
  78
  79                 cast = lkb->lkb_astaddr;
  80                 bast = lkb->lkb_bastaddr;
  81                 bmode = lkb->lkb_bastmode;
  82
  83                 if ((type & AST_COMP) && cast)
  84                         cast(lkb->lkb_astparam);
  85
  86                 /* FIXME: Is it safe to look at lkb_grmode here
  87                    without doing a lock_rsb() ?
  88                    Look at other checks in v1 to avoid basts. */
  89
  90                 if ((type & AST_BAST) && bast)
  91                         if (!dlm_modes_compat(lkb->lkb_grmode, bmode))
  92                                 bast(lkb->lkb_astparam, bmode);
  93
  94                 /* this removes the reference added by dlm_add_ast
  95                    and may result in the lkb being freed */
  96                 dlm_put_lkb(lkb);
  97
  98                 schedule();
  99         }
 100 }
 101
 102 static inline int no_asts(void)
 103 {
 104         int ret;
 105
 106         spin_lock(&ast_queue_lock);
 107         ret = list_empty(&ast_queue);
 108         spin_unlock(&ast_queue_lock);
 109         return ret;
 110 }
 111
 112 static int dlm_astd(void *data)
 113 {
 114         while (!kthread_should_stop()) {
 115                 set_current_state(TASK_INTERRUPTIBLE);
 116                 if (!test_bit(WAKE_ASTS, &astd_wakeflags))
 117                         schedule();
 118                 set_current_state(TASK_RUNNING);
 119
 120                 mutex_lock(&astd_running);
 121                 if (test_and_clear_bit(WAKE_ASTS, &astd_wakeflags))
 122                         process_asts();
 123                 mutex_unlock(&astd_running);
 124         }
 125         return 0;
 126 }
 127
 128 void dlm_astd_wake(void)
 129 {
 130         if (!no_asts()) {
 131                 set_bit(WAKE_ASTS, &astd_wakeflags);
 132                 wake_up_process(astd_task);
 133         }
 134 }
 135
 136 int dlm_astd_start(void)
 137 {
 138         struct task_struct *p;
 139         int error = 0;
 140
 141         INIT_LIST_HEAD(&ast_queue);
 142         spin_lock_init(&ast_queue_lock);
 143         mutex_init(&astd_running);
 144
 145         p = kthread_run(dlm_astd, NULL, "dlm_astd");
 146         if (IS_ERR(p))
 147                 error = PTR_ERR(p);
 148         else
 149                 astd_task = p;
 150         return error;
 151 }
 152
 153 void dlm_astd_stop(void)
 154 {
 155         kthread_stop(astd_task);
 156 }
 157
 158 void dlm_astd_suspend(void)
 159 {
 160         mutex_lock(&astd_running);
 161 }
 162
 163 void dlm_astd_resume(void)
 164 {
 165         mutex_unlock(&astd_running);
 166 }
 167