mm: bdi: expose the BDI object in sysfs for FUSE
[linux-2.6-block.git] / mm / backing-dev.c
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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>
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7#include <linux/writeback.h>
8#include <linux/device.h>
9
10
11static struct class *bdi_class;
12
13static ssize_t read_ahead_kb_store(struct device *dev,
14 struct device_attribute *attr,
15 const char *buf, size_t count)
16{
17 struct backing_dev_info *bdi = dev_get_drvdata(dev);
18 char *end;
19 unsigned long read_ahead_kb;
20 ssize_t ret = -EINVAL;
21
22 read_ahead_kb = simple_strtoul(buf, &end, 10);
23 if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
24 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
25 ret = count;
26 }
27 return ret;
28}
29
30#define K(pages) ((pages) << (PAGE_SHIFT - 10))
31
32#define BDI_SHOW(name, expr) \
33static ssize_t name##_show(struct device *dev, \
34 struct device_attribute *attr, char *page) \
35{ \
36 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
37 \
38 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
39}
40
41BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
42
43BDI_SHOW(reclaimable_kb, K(bdi_stat(bdi, BDI_RECLAIMABLE)))
44BDI_SHOW(writeback_kb, K(bdi_stat(bdi, BDI_WRITEBACK)))
45
46static inline unsigned long get_dirty(struct backing_dev_info *bdi, int i)
47{
48 unsigned long thresh[3];
49
50 get_dirty_limits(&thresh[0], &thresh[1], &thresh[2], bdi);
51
52 return thresh[i];
53}
54
55BDI_SHOW(dirty_kb, K(get_dirty(bdi, 1)))
56BDI_SHOW(bdi_dirty_kb, K(get_dirty(bdi, 2)))
57
58#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
59
60static struct device_attribute bdi_dev_attrs[] = {
61 __ATTR_RW(read_ahead_kb),
62 __ATTR_RO(reclaimable_kb),
63 __ATTR_RO(writeback_kb),
64 __ATTR_RO(dirty_kb),
65 __ATTR_RO(bdi_dirty_kb),
66 __ATTR_NULL,
67};
68
69static __init int bdi_class_init(void)
70{
71 bdi_class = class_create(THIS_MODULE, "bdi");
72 bdi_class->dev_attrs = bdi_dev_attrs;
73 return 0;
74}
75
76core_initcall(bdi_class_init);
77
78int bdi_register(struct backing_dev_info *bdi, struct device *parent,
79 const char *fmt, ...)
80{
81 char *name;
82 va_list args;
83 int ret = 0;
84 struct device *dev;
85
86 va_start(args, fmt);
87 name = kvasprintf(GFP_KERNEL, fmt, args);
88 va_end(args);
89
90 if (!name)
91 return -ENOMEM;
92
93 dev = device_create(bdi_class, parent, MKDEV(0, 0), name);
94 if (IS_ERR(dev)) {
95 ret = PTR_ERR(dev);
96 goto exit;
97 }
98
99 bdi->dev = dev;
100 dev_set_drvdata(bdi->dev, bdi);
101
102exit:
103 kfree(name);
104 return ret;
105}
106EXPORT_SYMBOL(bdi_register);
107
108int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
109{
110 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
111}
112EXPORT_SYMBOL(bdi_register_dev);
113
114void bdi_unregister(struct backing_dev_info *bdi)
115{
116 if (bdi->dev) {
117 device_unregister(bdi->dev);
118 bdi->dev = NULL;
119 }
120}
121EXPORT_SYMBOL(bdi_unregister);
3fcfab16 122
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123int bdi_init(struct backing_dev_info *bdi)
124{
4b01a0b1 125 int i;
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126 int err;
127
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128 bdi->dev = NULL;
129
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130 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
131 err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
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132 if (err)
133 goto err;
134 }
135
136 bdi->dirty_exceeded = 0;
137 err = prop_local_init_percpu(&bdi->completions);
138
139 if (err) {
140err:
4b01a0b1 141 while (i--)
04fbfdc1 142 percpu_counter_destroy(&bdi->bdi_stat[i]);
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143 }
144
145 return err;
146}
147EXPORT_SYMBOL(bdi_init);
148
149void bdi_destroy(struct backing_dev_info *bdi)
150{
151 int i;
152
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153 bdi_unregister(bdi);
154
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155 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
156 percpu_counter_destroy(&bdi->bdi_stat[i]);
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157
158 prop_local_destroy_percpu(&bdi->completions);
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159}
160EXPORT_SYMBOL(bdi_destroy);
161
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162static wait_queue_head_t congestion_wqh[2] = {
163 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
164 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
165 };
166
167
168void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
169{
170 enum bdi_state bit;
171 wait_queue_head_t *wqh = &congestion_wqh[rw];
172
173 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
174 clear_bit(bit, &bdi->state);
175 smp_mb__after_clear_bit();
176 if (waitqueue_active(wqh))
177 wake_up(wqh);
178}
179EXPORT_SYMBOL(clear_bdi_congested);
180
181void set_bdi_congested(struct backing_dev_info *bdi, int rw)
182{
183 enum bdi_state bit;
184
185 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
186 set_bit(bit, &bdi->state);
187}
188EXPORT_SYMBOL(set_bdi_congested);
189
190/**
191 * congestion_wait - wait for a backing_dev to become uncongested
192 * @rw: READ or WRITE
193 * @timeout: timeout in jiffies
194 *
195 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
196 * write congestion. If no backing_devs are congested then just wait for the
197 * next write to be completed.
198 */
199long congestion_wait(int rw, long timeout)
200{
201 long ret;
202 DEFINE_WAIT(wait);
203 wait_queue_head_t *wqh = &congestion_wqh[rw];
204
205 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
206 ret = io_schedule_timeout(timeout);
207 finish_wait(wqh, &wait);
208 return ret;
209}
210EXPORT_SYMBOL(congestion_wait);
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