aboutsummaryrefslogtreecommitdiffstats
path: root/mm/backing-dev.c
blob: a47065e084a472e89a624bf723338eff5d10f9ac (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83

#include <linux/wait.h>
#include <linux/backing-dev.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/module.h>

int bdi_init(struct backing_dev_info *bdi)
{
	int i, j;
	int err;

	for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
		err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
		if (err) {
			for (j = 0; j < i; j++)
				percpu_counter_destroy(&bdi->bdi_stat[i]);
			break;
		}
	}

	return err;
}
EXPORT_SYMBOL(bdi_init);

void bdi_destroy(struct backing_dev_info *bdi)
{
	int i;

	for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
		percpu_counter_destroy(&bdi->bdi_stat[i]);
}
EXPORT_SYMBOL(bdi_destroy);

static wait_queue_head_t congestion_wqh[2] = {
		__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
		__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
	};


void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
{
	enum bdi_state bit;
	wait_queue_head_t *wqh = &congestion_wqh[rw];

	bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
	clear_bit(bit, &bdi->state);
	smp_mb__after_clear_bit();
	if (waitqueue_active(wqh))
		wake_up(wqh);
}
EXPORT_SYMBOL(clear_bdi_congested);

void set_bdi_congested(struct backing_dev_info *bdi, int rw)
{
	enum bdi_state bit;

	bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
	set_bit(bit, &bdi->state);
}
EXPORT_SYMBOL(set_bdi_congested);

/**
 * congestion_wait - wait for a backing_dev to become uncongested
 * @rw: READ or WRITE
 * @timeout: timeout in jiffies
 *
 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
 * write congestion.  If no backing_devs are congested then just wait for the
 * next write to be completed.
 */
long congestion_wait(int rw, long timeout)
{
	long ret;
	DEFINE_WAIT(wait);
	wait_queue_head_t *wqh = &congestion_wqh[rw];

	prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
	ret = io_schedule_timeout(timeout);
	finish_wait(wqh, &wait);
	return ret;
}
EXPORT_SYMBOL(congestion_wait);