projects/linux·blob v2.6.21 · refs

85 lines · 2.0 KiB

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);