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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> | |
cf0ca9fe PZ |
7 | #include <linux/writeback.h> |
8 | #include <linux/device.h> | |
9 | ||
10 | ||
11 | static struct class *bdi_class; | |
12 | ||
76f1418b MS |
13 | #ifdef CONFIG_DEBUG_FS |
14 | #include <linux/debugfs.h> | |
15 | #include <linux/seq_file.h> | |
16 | ||
17 | static struct dentry *bdi_debug_root; | |
18 | ||
19 | static void bdi_debug_init(void) | |
20 | { | |
21 | bdi_debug_root = debugfs_create_dir("bdi", NULL); | |
22 | } | |
23 | ||
24 | static int bdi_debug_stats_show(struct seq_file *m, void *v) | |
25 | { | |
26 | struct backing_dev_info *bdi = m->private; | |
27 | long background_thresh; | |
28 | long dirty_thresh; | |
29 | long bdi_thresh; | |
30 | ||
31 | get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi); | |
32 | ||
33 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
34 | seq_printf(m, | |
35 | "BdiWriteback: %8lu kB\n" | |
36 | "BdiReclaimable: %8lu kB\n" | |
37 | "BdiDirtyThresh: %8lu kB\n" | |
38 | "DirtyThresh: %8lu kB\n" | |
39 | "BackgroundThresh: %8lu kB\n", | |
40 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), | |
41 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), | |
42 | K(bdi_thresh), | |
43 | K(dirty_thresh), | |
44 | K(background_thresh)); | |
45 | #undef K | |
46 | ||
47 | return 0; | |
48 | } | |
49 | ||
50 | static int bdi_debug_stats_open(struct inode *inode, struct file *file) | |
51 | { | |
52 | return single_open(file, bdi_debug_stats_show, inode->i_private); | |
53 | } | |
54 | ||
55 | static const struct file_operations bdi_debug_stats_fops = { | |
56 | .open = bdi_debug_stats_open, | |
57 | .read = seq_read, | |
58 | .llseek = seq_lseek, | |
59 | .release = single_release, | |
60 | }; | |
61 | ||
62 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) | |
63 | { | |
64 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
65 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, | |
66 | bdi, &bdi_debug_stats_fops); | |
67 | } | |
68 | ||
69 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
70 | { | |
71 | debugfs_remove(bdi->debug_stats); | |
72 | debugfs_remove(bdi->debug_dir); | |
73 | } | |
74 | #else | |
75 | static inline void bdi_debug_init(void) | |
76 | { | |
77 | } | |
78 | static inline void bdi_debug_register(struct backing_dev_info *bdi, | |
79 | const char *name) | |
80 | { | |
81 | } | |
82 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
83 | { | |
84 | } | |
85 | #endif | |
86 | ||
cf0ca9fe PZ |
87 | static ssize_t read_ahead_kb_store(struct device *dev, |
88 | struct device_attribute *attr, | |
89 | const char *buf, size_t count) | |
90 | { | |
91 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
92 | char *end; | |
93 | unsigned long read_ahead_kb; | |
94 | ssize_t ret = -EINVAL; | |
95 | ||
96 | read_ahead_kb = simple_strtoul(buf, &end, 10); | |
97 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
98 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
99 | ret = count; | |
100 | } | |
101 | return ret; | |
102 | } | |
103 | ||
104 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
105 | ||
106 | #define BDI_SHOW(name, expr) \ | |
107 | static ssize_t name##_show(struct device *dev, \ | |
108 | struct device_attribute *attr, char *page) \ | |
109 | { \ | |
110 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
111 | \ | |
112 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
113 | } | |
114 | ||
115 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
116 | ||
189d3c4a PZ |
117 | static ssize_t min_ratio_store(struct device *dev, |
118 | struct device_attribute *attr, const char *buf, size_t count) | |
119 | { | |
120 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
121 | char *end; | |
122 | unsigned int ratio; | |
123 | ssize_t ret = -EINVAL; | |
124 | ||
125 | ratio = simple_strtoul(buf, &end, 10); | |
126 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
127 | ret = bdi_set_min_ratio(bdi, ratio); | |
128 | if (!ret) | |
129 | ret = count; | |
130 | } | |
131 | return ret; | |
132 | } | |
133 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
134 | ||
a42dde04 PZ |
135 | static ssize_t max_ratio_store(struct device *dev, |
136 | struct device_attribute *attr, const char *buf, size_t count) | |
137 | { | |
138 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
139 | char *end; | |
140 | unsigned int ratio; | |
141 | ssize_t ret = -EINVAL; | |
142 | ||
143 | ratio = simple_strtoul(buf, &end, 10); | |
144 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
145 | ret = bdi_set_max_ratio(bdi, ratio); | |
146 | if (!ret) | |
147 | ret = count; | |
148 | } | |
149 | return ret; | |
150 | } | |
151 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
152 | ||
cf0ca9fe PZ |
153 | #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) |
154 | ||
155 | static struct device_attribute bdi_dev_attrs[] = { | |
156 | __ATTR_RW(read_ahead_kb), | |
189d3c4a | 157 | __ATTR_RW(min_ratio), |
a42dde04 | 158 | __ATTR_RW(max_ratio), |
cf0ca9fe PZ |
159 | __ATTR_NULL, |
160 | }; | |
161 | ||
162 | static __init int bdi_class_init(void) | |
163 | { | |
164 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
165 | bdi_class->dev_attrs = bdi_dev_attrs; | |
76f1418b | 166 | bdi_debug_init(); |
cf0ca9fe PZ |
167 | return 0; |
168 | } | |
169 | ||
76f1418b | 170 | postcore_initcall(bdi_class_init); |
cf0ca9fe PZ |
171 | |
172 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, | |
173 | const char *fmt, ...) | |
174 | { | |
cf0ca9fe PZ |
175 | va_list args; |
176 | int ret = 0; | |
177 | struct device *dev; | |
178 | ||
179 | va_start(args, fmt); | |
19051c50 | 180 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 181 | va_end(args); |
cf0ca9fe PZ |
182 | if (IS_ERR(dev)) { |
183 | ret = PTR_ERR(dev); | |
184 | goto exit; | |
185 | } | |
186 | ||
187 | bdi->dev = dev; | |
19051c50 | 188 | bdi_debug_register(bdi, dev_name(dev)); |
cf0ca9fe PZ |
189 | |
190 | exit: | |
cf0ca9fe PZ |
191 | return ret; |
192 | } | |
193 | EXPORT_SYMBOL(bdi_register); | |
194 | ||
195 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) | |
196 | { | |
197 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); | |
198 | } | |
199 | EXPORT_SYMBOL(bdi_register_dev); | |
200 | ||
201 | void bdi_unregister(struct backing_dev_info *bdi) | |
202 | { | |
203 | if (bdi->dev) { | |
76f1418b | 204 | bdi_debug_unregister(bdi); |
cf0ca9fe PZ |
205 | device_unregister(bdi->dev); |
206 | bdi->dev = NULL; | |
207 | } | |
208 | } | |
209 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 210 | |
b2e8fb6e PZ |
211 | int bdi_init(struct backing_dev_info *bdi) |
212 | { | |
4b01a0b1 | 213 | int i; |
b2e8fb6e PZ |
214 | int err; |
215 | ||
cf0ca9fe PZ |
216 | bdi->dev = NULL; |
217 | ||
189d3c4a | 218 | bdi->min_ratio = 0; |
a42dde04 PZ |
219 | bdi->max_ratio = 100; |
220 | bdi->max_prop_frac = PROP_FRAC_BASE; | |
189d3c4a | 221 | |
b2e8fb6e PZ |
222 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
223 | err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0); | |
04fbfdc1 PZ |
224 | if (err) |
225 | goto err; | |
226 | } | |
227 | ||
228 | bdi->dirty_exceeded = 0; | |
229 | err = prop_local_init_percpu(&bdi->completions); | |
230 | ||
231 | if (err) { | |
232 | err: | |
4b01a0b1 | 233 | while (i--) |
04fbfdc1 | 234 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
235 | } |
236 | ||
237 | return err; | |
238 | } | |
239 | EXPORT_SYMBOL(bdi_init); | |
240 | ||
241 | void bdi_destroy(struct backing_dev_info *bdi) | |
242 | { | |
243 | int i; | |
244 | ||
cf0ca9fe PZ |
245 | bdi_unregister(bdi); |
246 | ||
b2e8fb6e PZ |
247 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
248 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
04fbfdc1 PZ |
249 | |
250 | prop_local_destroy_percpu(&bdi->completions); | |
b2e8fb6e PZ |
251 | } |
252 | EXPORT_SYMBOL(bdi_destroy); | |
253 | ||
3fcfab16 AM |
254 | static wait_queue_head_t congestion_wqh[2] = { |
255 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
256 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
257 | }; | |
258 | ||
259 | ||
260 | void clear_bdi_congested(struct backing_dev_info *bdi, int rw) | |
261 | { | |
262 | enum bdi_state bit; | |
263 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
264 | ||
265 | bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; | |
266 | clear_bit(bit, &bdi->state); | |
267 | smp_mb__after_clear_bit(); | |
268 | if (waitqueue_active(wqh)) | |
269 | wake_up(wqh); | |
270 | } | |
271 | EXPORT_SYMBOL(clear_bdi_congested); | |
272 | ||
273 | void set_bdi_congested(struct backing_dev_info *bdi, int rw) | |
274 | { | |
275 | enum bdi_state bit; | |
276 | ||
277 | bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; | |
278 | set_bit(bit, &bdi->state); | |
279 | } | |
280 | EXPORT_SYMBOL(set_bdi_congested); | |
281 | ||
282 | /** | |
283 | * congestion_wait - wait for a backing_dev to become uncongested | |
284 | * @rw: READ or WRITE | |
285 | * @timeout: timeout in jiffies | |
286 | * | |
287 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
288 | * write congestion. If no backing_devs are congested then just wait for the | |
289 | * next write to be completed. | |
290 | */ | |
291 | long congestion_wait(int rw, long timeout) | |
292 | { | |
293 | long ret; | |
294 | DEFINE_WAIT(wait); | |
295 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
296 | ||
297 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
298 | ret = io_schedule_timeout(timeout); | |
299 | finish_wait(wqh, &wait); | |
300 | return ret; | |
301 | } | |
302 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 303 |