Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
[linux-2.6.git] / mm / backing-dev.c
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