release/src-rt-6.x/linux/linux-2.6/mm/backing-dev.c

   1
   2 #include <linux/wait.h>
   3 #include <linux/backing-dev.h>
   4 #include <linux/fs.h>
   5 #include <linux/sched.h>
   6 #include <linux/module.h>
   7
   8 int bdi_init(struct backing_dev_info *bdi)
   9 {
  10         int i;
  11         int err;
  12
  13         for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
  14                 percpu_counter_init(&bdi->bdi_stat[i], 0);
  15         }
  16
  17         bdi->dirty_exceeded = 0;
  18         err = prop_local_init_percpu(&bdi->completions);
  19
  20
  21         return err;
  22 }
  23 EXPORT_SYMBOL(bdi_init);
  24
  25 void bdi_destroy(struct backing_dev_info *bdi)
  26 {
  27         int i;
  28
  29         for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
  30                 percpu_counter_destroy(&bdi->bdi_stat[i]);
  31
  32         prop_local_destroy_percpu(&bdi->completions);
  33 }
  34 EXPORT_SYMBOL(bdi_destroy);
  35
  36 static wait_queue_head_t congestion_wqh[2] = {
  37                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
  38                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
  39         };
  40
  41
  42 void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
  43 {
  44         enum bdi_state bit;
  45         wait_queue_head_t *wqh = &congestion_wqh[rw];
  46
  47         bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
  48         clear_bit(bit, &bdi->state);
  49         smp_mb__after_clear_bit();
  50         if (waitqueue_active(wqh))
  51                 wake_up(wqh);
  52 }
  53 EXPORT_SYMBOL(clear_bdi_congested);
  54
  55 void set_bdi_congested(struct backing_dev_info *bdi, int rw)
  56 {
  57         enum bdi_state bit;
  58
  59         bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
  60         set_bit(bit, &bdi->state);
  61 }
  62 EXPORT_SYMBOL(set_bdi_congested);
  63
  64 /**
  65  * congestion_wait - wait for a backing_dev to become uncongested
  66  * @rw: READ or WRITE
  67  * @timeout: timeout in jiffies
  68  *
  69  * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
  70  * write congestion.  If no backing_devs are congested then just wait for the
  71  * next write to be completed.
  72  */
  73 long congestion_wait(int rw, long timeout)
  74 {
  75         long ret;
  76         DEFINE_WAIT(wait);
  77         wait_queue_head_t *wqh = &congestion_wqh[rw];
  78
  79         prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
  80         ret = io_schedule_timeout(timeout);
  81         finish_wait(wqh, &wait);
  82         return ret;
  83 }
  84 EXPORT_SYMBOL(congestion_wait);