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 "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)
  37 {
  38         if (lkb->lkb_flags & DLM_IFL_USER) {
  39                 dlm_user_add_ast(lkb, type);
  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         spin_unlock(&ast_queue_lock);
  50
  51         set_bit(WAKE_ASTS, &astd_wakeflags);
  52         wake_up_process(astd_task);
  53 }
  54
  55 static void process_asts(void)
  56 {
  57         struct dlm_ls *ls = NULL;
  58         struct dlm_rsb *r = NULL;
  59         struct dlm_lkb *lkb;
  60         void (*cast) (void *astparam);
  61         void (*bast) (void *astparam, int mode);
  62         int type = 0, found, bmode;
  63
  64         for (;;) {
  65                 found = 0;
  66                 spin_lock(&ast_queue_lock);
  67                 list_for_each_entry(lkb, &ast_queue, lkb_astqueue) {
  68                         r = lkb->lkb_resource;
  69                         ls = r->res_ls;
  70
  71                         if (dlm_locking_stopped(ls))
  72                                 continue;
  73
  74                         list_del(&lkb->lkb_astqueue);
  75                         type = lkb->lkb_ast_type;
  76                         lkb->lkb_ast_type = 0;
  77                         found = 1;
  78                         break;
  79                 }
  80                 spin_unlock(&ast_queue_lock);
  81
  82                 if (!found)
  83                         break;
  84
  85                 cast = lkb->lkb_astfn;
  86                 bast = lkb->lkb_bastfn;
  87                 bmode = lkb->lkb_bastmode;
  88
  89                 if ((type & AST_COMP) && cast)
  90                         cast(lkb->lkb_astparam);
  91
  92                 /* FIXME: Is it safe to look at lkb_grmode here
  93                    without doing a lock_rsb() ?
  94                    Look at other checks in v1 to avoid basts. */
  95
  96                 if ((type & AST_BAST) && bast)
  97                         if (!dlm_modes_compat(lkb->lkb_grmode, bmode))
  98                                 bast(lkb->lkb_astparam, bmode);
  99
 100                 /* this removes the reference added by dlm_add_ast
 101                    and may result in the lkb being freed */
 102                 dlm_put_lkb(lkb);
 103
 104                 schedule();
 105         }
 106 }
 107
 108 static inline int no_asts(void)
 109 {
 110         int ret;
 111
 112         spin_lock(&ast_queue_lock);
 113         ret = list_empty(&ast_queue);
 114         spin_unlock(&ast_queue_lock);
 115         return ret;
 116 }
 117
 118 static int dlm_astd(void *data)
 119 {
 120         while (!kthread_should_stop()) {
 121                 set_current_state(TASK_INTERRUPTIBLE);
 122                 if (!test_bit(WAKE_ASTS, &astd_wakeflags))
 123                         schedule();
 124                 set_current_state(TASK_RUNNING);
 125
 126                 mutex_lock(&astd_running);
 127                 if (test_and_clear_bit(WAKE_ASTS, &astd_wakeflags))
 128                         process_asts();
 129                 mutex_unlock(&astd_running);
 130         }
 131         return 0;
 132 }
 133
 134 void dlm_astd_wake(void)
 135 {
 136         if (!no_asts()) {
 137                 set_bit(WAKE_ASTS, &astd_wakeflags);
 138                 wake_up_process(astd_task);
 139         }
 140 }
 141
 142 int dlm_astd_start(void)
 143 {
 144         struct task_struct *p;
 145         int error = 0;
 146
 147         INIT_LIST_HEAD(&ast_queue);
 148         spin_lock_init(&ast_queue_lock);
 149         mutex_init(&astd_running);
 150
 151         p = kthread_run(dlm_astd, NULL, "dlm_astd");
 152         if (IS_ERR(p))
 153                 error = PTR_ERR(p);
 154         else
 155                 astd_task = p;
 156         return error;
 157 }
 158
 159 void dlm_astd_stop(void)
 160 {
 161         kthread_stop(astd_task);
 162 }
 163
 164 void dlm_astd_suspend(void)
 165 {
 166         mutex_lock(&astd_running);
 167 }
 168
 169 void dlm_astd_resume(void)
 170 {
 171         mutex_unlock(&astd_running);
 172 }
 173