2 #include <linux/wait.h>
3 #include <linux/backing-dev.h>
5 #include <linux/sched.h>
6 #include <linux/module.h>
8 int bdi_init(struct backing_dev_info *bdi)
13 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
14 err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
16 for (j = 0; j < i; j++)
17 percpu_counter_destroy(&bdi->bdi_stat[i]);
24 EXPORT_SYMBOL(bdi_init);
26 void bdi_destroy(struct backing_dev_info *bdi)
30 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
31 percpu_counter_destroy(&bdi->bdi_stat[i]);
33 EXPORT_SYMBOL(bdi_destroy);
35 static wait_queue_head_t congestion_wqh[2] = {
36 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
37 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
41 void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
44 wait_queue_head_t *wqh = &congestion_wqh[rw];
46 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
47 clear_bit(bit, &bdi->state);
48 smp_mb__after_clear_bit();
49 if (waitqueue_active(wqh))
52 EXPORT_SYMBOL(clear_bdi_congested);
54 void set_bdi_congested(struct backing_dev_info *bdi, int rw)
58 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
59 set_bit(bit, &bdi->state);
61 EXPORT_SYMBOL(set_bdi_congested);
64 * congestion_wait - wait for a backing_dev to become uncongested
66 * @timeout: timeout in jiffies
68 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
69 * write congestion. If no backing_devs are congested then just wait for the
70 * next write to be completed.
72 long congestion_wait(int rw, long timeout)
76 wait_queue_head_t *wqh = &congestion_wqh[rw];
78 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
79 ret = io_schedule_timeout(timeout);
80 finish_wait(wqh, &wait);
83 EXPORT_SYMBOL(congestion_wait);