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3fcfab16 AM |
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 | ||
b2e8fb6e PZ |
8 | int bdi_init(struct backing_dev_info *bdi) |
9 | { | |
10 | int i, j; | |
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 | for (j = 0; j < i; j++) | |
17 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
18 | break; | |
19 | } | |
20 | } | |
21 | ||
22 | return err; | |
23 | } | |
24 | EXPORT_SYMBOL(bdi_init); | |
25 | ||
26 | void bdi_destroy(struct backing_dev_info *bdi) | |
27 | { | |
28 | int i; | |
29 | ||
30 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) | |
31 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
32 | } | |
33 | EXPORT_SYMBOL(bdi_destroy); | |
34 | ||
3fcfab16 AM |
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]) | |
38 | }; | |
39 | ||
40 | ||
41 | void clear_bdi_congested(struct backing_dev_info *bdi, int rw) | |
42 | { | |
43 | enum bdi_state bit; | |
44 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
45 | ||
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)) | |
50 | wake_up(wqh); | |
51 | } | |
52 | EXPORT_SYMBOL(clear_bdi_congested); | |
53 | ||
54 | void set_bdi_congested(struct backing_dev_info *bdi, int rw) | |
55 | { | |
56 | enum bdi_state bit; | |
57 | ||
58 | bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; | |
59 | set_bit(bit, &bdi->state); | |
60 | } | |
61 | EXPORT_SYMBOL(set_bdi_congested); | |
62 | ||
63 | /** | |
64 | * congestion_wait - wait for a backing_dev to become uncongested | |
65 | * @rw: READ or WRITE | |
66 | * @timeout: timeout in jiffies | |
67 | * | |
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. | |
71 | */ | |
72 | long congestion_wait(int rw, long timeout) | |
73 | { | |
74 | long ret; | |
75 | DEFINE_WAIT(wait); | |
76 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
77 | ||
78 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
79 | ret = io_schedule_timeout(timeout); | |
80 | finish_wait(wqh, &wait); | |
81 | return ret; | |
82 | } | |
83 | EXPORT_SYMBOL(congestion_wait); |