fs/dlm/ast.c

   1 /******************************************************************************
   2 *******************************************************************************
   3 **
   4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   5 **  Copyright (C) 2004-2008 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 struct list_head         ast_queue;
  22 static spinlock_t               ast_queue_lock;
  23 static struct task_struct *     astd_task;
  24 static unsigned long            astd_wakeflags;
  25 static struct mutex             astd_running;
  26
  27
  28 void dlm_del_ast(struct dlm_lkb *lkb)
  29 {
  30         spin_lock(&ast_queue_lock);
  31         if (lkb->lkb_ast_type & (AST_COMP | AST_BAST))
  32                 list_del(&lkb->lkb_astqueue);
  33         spin_unlock(&ast_queue_lock);
  34 }
  35
  36 void dlm_add_ast(struct dlm_lkb *lkb, int type, int bastmode)
  37 {
  38         if (lkb->lkb_flags & DLM_IFL_USER) {
  39                 dlm_user_add_ast(lkb, type, bastmode);
  40                 return;
  41         }
  42
  43         spin_lock(&ast_queue_lock);
  44         if (!(lkb->lkb_ast_type & (AST_COMP | AST_BAST))) {
  45                 kref_get(&lkb->lkb_ref);
  46                 list_add_tail(&lkb->lkb_astqueue, &ast_queue);
  47         }
  48         lkb->lkb_ast_type |= type;
  49         if (bastmode)
  50                 lkb->lkb_bastmode = bastmode;
  51         spin_unlock(&ast_queue_lock);
  52
  53         set_bit(WAKE_ASTS, &astd_wakeflags);
  54         wake_up_process(astd_task);
  55 }
  56
  57 static void process_asts(void)
  58 {
  59         struct dlm_ls *ls = NULL;
  60         struct dlm_rsb *r = NULL;
  61         struct dlm_lkb *lkb;
  62         void (*cast) (void *astparam);
  63         void (*bast) (void *astparam, int mode);
  64         int type = 0, found, bastmode;
  65
  66         for (;;) {
  67                 found = 0;
  68                 spin_lock(&ast_queue_lock);
  69                 list_for_each_entry(lkb, &ast_queue, lkb_astqueue) {
  70                         r = lkb->lkb_resource;
  71                         ls = r->res_ls;
  72
  73                         if (dlm_locking_stopped(ls))
  74                                 continue;
  75
  76                         list_del(&lkb->lkb_astqueue);
  77                         type = lkb->lkb_ast_type;
  78                         lkb->lkb_ast_type = 0;
  79                         bastmode = lkb->lkb_bastmode;
  80                         found = 1;
  81                         break;
  82                 }
  83                 spin_unlock(&ast_queue_lock);
  84
  85                 if (!found)
  86                         break;
  87
  88                 cast = lkb->lkb_astfn;
  89                 bast = lkb->lkb_bastfn;
  90
  91                 if ((type & AST_COMP) && cast)
  92                         cast(lkb->lkb_astparam);
  93
  94                 if ((type & AST_BAST) && bast)
  95                         bast(lkb->lkb_astparam, bastmode);
  96
  97                 /* this removes the reference added by dlm_add_ast
  98                    and may result in the lkb being freed */
  99                 dlm_put_lkb(lkb);
 100
 101                 cond_resched();
 102         }
 103 }
 104
 105 static inline int no_asts(void)
 106 {
 107         int ret;
 108
 109         spin_lock(&ast_queue_lock);
 110         ret = list_empty(&ast_queue);
 111         spin_unlock(&ast_queue_lock);
 112         return ret;
 113 }
 114
 115 static int dlm_astd(void *data)
 116 {
 117         while (!kthread_should_stop()) {
 118                 set_current_state(TASK_INTERRUPTIBLE);
 119                 if (!test_bit(WAKE_ASTS, &astd_wakeflags))
 120                         schedule();
 121                 set_current_state(TASK_RUNNING);
 122
 123                 mutex_lock(&astd_running);
 124                 if (test_and_clear_bit(WAKE_ASTS, &astd_wakeflags))
 125                         process_asts();
 126                 mutex_unlock(&astd_running);
 127         }
 128         return 0;
 129 }
 130
 131 void dlm_astd_wake(void)
 132 {
 133         if (!no_asts()) {
 134                 set_bit(WAKE_ASTS, &astd_wakeflags);
 135                 wake_up_process(astd_task);
 136         }
 137 }
 138
 139 int dlm_astd_start(void)
 140 {
 141         struct task_struct *p;
 142         int error = 0;
 143
 144         INIT_LIST_HEAD(&ast_queue);
 145         spin_lock_init(&ast_queue_lock);
 146         mutex_init(&astd_running);
 147
 148         p = kthread_run(dlm_astd, NULL, "dlm_astd");
 149         if (IS_ERR(p))
 150                 error = PTR_ERR(p);
 151         else
 152                 astd_task = p;
 153         return error;
 154 }
 155
 156 void dlm_astd_stop(void)
 157 {
 158         kthread_stop(astd_task);
 159 }
 160
 161 void dlm_astd_suspend(void)
 162 {
 163         mutex_lock(&astd_running);
 164 }
 165
 166 void dlm_astd_resume(void)
 167 {
 168         mutex_unlock(&astd_running);
 169 }
 170