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 #include <linux/writeback.h>
8 #include <linux/device.h>
9
10
11 static struct class *bdi_class;
12
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
bdi_debug_init(void)19 static void bdi_debug_init(void)
20 {
21 bdi_debug_root = debugfs_create_dir("bdi", NULL);
22 }
23
bdi_debug_stats_show(struct seq_file * m,void * v)24 static int bdi_debug_stats_show(struct seq_file *m, void *v)
25 {
26 struct backing_dev_info *bdi = m->private;
27 unsigned long background_thresh;
28 unsigned long dirty_thresh;
29 unsigned 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
bdi_debug_stats_open(struct inode * inode,struct file * file)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
bdi_debug_register(struct backing_dev_info * bdi,const char * name)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
bdi_debug_unregister(struct backing_dev_info * bdi)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
bdi_debug_init(void)75 static inline void bdi_debug_init(void)
76 {
77 }
bdi_debug_register(struct backing_dev_info * bdi,const char * name)78 static inline void bdi_debug_register(struct backing_dev_info *bdi,
79 const char *name)
80 {
81 }
bdi_debug_unregister(struct backing_dev_info * bdi)82 static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
83 {
84 }
85 #endif
86
read_ahead_kb_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
min_ratio_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
max_ratio_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
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),
157 __ATTR_RW(min_ratio),
158 __ATTR_RW(max_ratio),
159 __ATTR_NULL,
160 };
161
bdi_class_init(void)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;
166 bdi_debug_init();
167 return 0;
168 }
169
170 postcore_initcall(bdi_class_init);
171
bdi_register(struct backing_dev_info * bdi,struct device * parent,const char * fmt,...)172 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
173 const char *fmt, ...)
174 {
175 va_list args;
176 int ret = 0;
177 struct device *dev;
178
179 if (bdi->dev) /* The driver needs to use separate queues per device */
180 goto exit;
181
182 va_start(args, fmt);
183 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
184 va_end(args);
185 if (IS_ERR(dev)) {
186 ret = PTR_ERR(dev);
187 goto exit;
188 }
189
190 bdi->dev = dev;
191 bdi_debug_register(bdi, dev_name(dev));
192
193 exit:
194 return ret;
195 }
196 EXPORT_SYMBOL(bdi_register);
197
bdi_register_dev(struct backing_dev_info * bdi,dev_t dev)198 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
199 {
200 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
201 }
202 EXPORT_SYMBOL(bdi_register_dev);
203
bdi_unregister(struct backing_dev_info * bdi)204 void bdi_unregister(struct backing_dev_info *bdi)
205 {
206 if (bdi->dev) {
207 bdi_debug_unregister(bdi);
208 device_unregister(bdi->dev);
209 bdi->dev = NULL;
210 }
211 }
212 EXPORT_SYMBOL(bdi_unregister);
213
bdi_init(struct backing_dev_info * bdi)214 int bdi_init(struct backing_dev_info *bdi)
215 {
216 int i;
217 int err;
218
219 bdi->dev = NULL;
220
221 bdi->min_ratio = 0;
222 bdi->max_ratio = 100;
223 bdi->max_prop_frac = PROP_FRAC_BASE;
224
225 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
226 err = percpu_counter_init(&bdi->bdi_stat[i], 0);
227 if (err)
228 goto err;
229 }
230
231 bdi->dirty_exceeded = 0;
232 err = prop_local_init_percpu(&bdi->completions);
233
234 if (err) {
235 err:
236 while (i--)
237 percpu_counter_destroy(&bdi->bdi_stat[i]);
238 }
239
240 return err;
241 }
242 EXPORT_SYMBOL(bdi_init);
243
bdi_destroy(struct backing_dev_info * bdi)244 void bdi_destroy(struct backing_dev_info *bdi)
245 {
246 int i;
247
248 bdi_unregister(bdi);
249
250 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
251 percpu_counter_destroy(&bdi->bdi_stat[i]);
252
253 prop_local_destroy_percpu(&bdi->completions);
254 }
255 EXPORT_SYMBOL(bdi_destroy);
256
257 static wait_queue_head_t congestion_wqh[2] = {
258 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
259 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
260 };
261
262
clear_bdi_congested(struct backing_dev_info * bdi,int rw)263 void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
264 {
265 enum bdi_state bit;
266 wait_queue_head_t *wqh = &congestion_wqh[rw];
267
268 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
269 clear_bit(bit, &bdi->state);
270 smp_mb__after_clear_bit();
271 if (waitqueue_active(wqh))
272 wake_up(wqh);
273 }
274 EXPORT_SYMBOL(clear_bdi_congested);
275
set_bdi_congested(struct backing_dev_info * bdi,int rw)276 void set_bdi_congested(struct backing_dev_info *bdi, int rw)
277 {
278 enum bdi_state bit;
279
280 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
281 set_bit(bit, &bdi->state);
282 }
283 EXPORT_SYMBOL(set_bdi_congested);
284
285 /**
286 * congestion_wait - wait for a backing_dev to become uncongested
287 * @rw: READ or WRITE
288 * @timeout: timeout in jiffies
289 *
290 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
291 * write congestion. If no backing_devs are congested then just wait for the
292 * next write to be completed.
293 */
congestion_wait(int rw,long timeout)294 long congestion_wait(int rw, long timeout)
295 {
296 long ret;
297 DEFINE_WAIT(wait);
298 wait_queue_head_t *wqh = &congestion_wqh[rw];
299
300 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
301 ret = io_schedule_timeout(timeout);
302 finish_wait(wqh, &wait);
303 return ret;
304 }
305 EXPORT_SYMBOL(congestion_wait);
306
307