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 err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
15 if (err)
16 goto err;
17 }
18
19 bdi->dirty_exceeded = 0;
20 err = prop_local_init_percpu(&bdi->completions);
21
22 if (err) {
23 err:
24 while (i--)
25 percpu_counter_destroy(&bdi->bdi_stat[i]);
26 }
27
28 return err;
29 }
30 EXPORT_SYMBOL(bdi_init);
31
32 void bdi_destroy(struct backing_dev_info *bdi)
33 {
34 int i;
35
36 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
37 percpu_counter_destroy(&bdi->bdi_stat[i]);
38
39 prop_local_destroy_percpu(&bdi->completions);
40 }
41 EXPORT_SYMBOL(bdi_destroy);
42
43 static wait_queue_head_t congestion_wqh[2] = {
44 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
45 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
46 };
47
48
49 void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
50 {
51 enum bdi_state bit;
52 wait_queue_head_t *wqh = &congestion_wqh[rw];
53
54 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
55 clear_bit(bit, &bdi->state);
56 smp_mb__after_clear_bit();
57 if (waitqueue_active(wqh))
58 wake_up(wqh);
59 }
60 EXPORT_SYMBOL(clear_bdi_congested);
61
62 void set_bdi_congested(struct backing_dev_info *bdi, int rw)
63 {
64 enum bdi_state bit;
65
66 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
67 set_bit(bit, &bdi->state);
68 }
69 EXPORT_SYMBOL(set_bdi_congested);
70
71 /**
72 * congestion_wait - wait for a backing_dev to become uncongested
73 * @rw: READ or WRITE
74 * @timeout: timeout in jiffies
75 *
76 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
77 * write congestion. If no backing_devs are congested then just wait for the
78 * next write to be completed.
79 */
80 long congestion_wait(int rw, long timeout)
81 {
82 long ret;
83 DEFINE_WAIT(wait);
84 wait_queue_head_t *wqh = &congestion_wqh[rw];
85
86 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
87 ret = io_schedule_timeout(timeout);
88 finish_wait(wqh, &wait);
89 return ret;
90 }
91 EXPORT_SYMBOL(congestion_wait);
92
93
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