LXR linux/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
   8static wait_queue_head_t congestion_wqh[2] = {
   9                __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
  10                __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
  11        };
  12
  13
  14void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
  15{
  16        enum bdi_state bit;
  17        wait_queue_head_t *wqh = &congestion_wqh[rw];
  18
  19        bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
  20        clear_bit(bit, &bdi->state);
  21        smp_mb__after_clear_bit();
  22        if (waitqueue_active(wqh))
  23                wake_up(wqh);
  24}
  25EXPORT_SYMBOL(clear_bdi_congested);
  26
  27void set_bdi_congested(struct backing_dev_info *bdi, int rw)
  28{
  29        enum bdi_state bit;
  30
  31        bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
  32        set_bit(bit, &bdi->state);
  33}
  34EXPORT_SYMBOL(set_bdi_congested);
  35
  36/**
  37 * congestion_wait - wait for a backing_dev to become uncongested
  38 * @rw: READ or WRITE
  39 * @timeout: timeout in jiffies
  40 *
  41 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
  42 * write congestion.  If no backing_devs are congested then just wait for the
  43 * next write to be completed.
  44 */
  45long congestion_wait(int rw, long timeout)
  46{
  47        long ret;
  48        DEFINE_WAIT(wait);
  49        wait_queue_head_t *wqh = &congestion_wqh[rw];
  50
  51        prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
  52        ret = io_schedule_timeout(timeout);
  53        finish_wait(wqh, &wait);
  54        return ret;
  55}
  56EXPORT_SYMBOL(congestion_wait);
  57
  58long congestion_wait_interruptible(int rw, long timeout)
  59{
  60        long ret;
  61        DEFINE_WAIT(wait);
  62        wait_queue_head_t *wqh = &congestion_wqh[rw];
  63
  64        prepare_to_wait(wqh, &wait, TASK_INTERRUPTIBLE);
  65        if (signal_pending(current))
  66                ret = -ERESTARTSYS;
  67        else
  68                ret = io_schedule_timeout(timeout);
  69        finish_wait(wqh, &wait);
  70        return ret;
  71}
  72EXPORT_SYMBOL(congestion_wait_interruptible);
  73
  74/**
  75 * congestion_end - wake up sleepers on a congested backing_dev_info
  76 * @rw: READ or WRITE
  77 */
  78void congestion_end(int rw)
  79{
  80        wait_queue_head_t *wqh = &congestion_wqh[rw];
  81
  82        if (waitqueue_active(wqh))
  83                wake_up(wqh);
  84}
  85EXPORT_SYMBOL(congestion_end);
  86