Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
11static struct class *bdi_class;
12
13#ifdef CONFIG_DEBUG_FS
14#include <linux/debugfs.h>
15#include <linux/seq_file.h>
16
17static struct dentry *bdi_debug_root;
18
19static void bdi_debug_init(void)
20{
21 bdi_debug_root = debugfs_create_dir("bdi", NULL);
22}
23
24static 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
50static 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
55static 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
62static 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
69static 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
75static inline void bdi_debug_init(void)
76{
77}
78static inline void bdi_debug_register(struct backing_dev_info *bdi,
79 const char *name)
80{
81}
82static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
83{
84}
85#endif
86
87static 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) \
107static 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
115BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
116
117static 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}
133BDI_SHOW(min_ratio, bdi->min_ratio)
134
135static 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}
151BDI_SHOW(max_ratio, bdi->max_ratio)
152
153#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
154
155static 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
162static __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
170postcore_initcall(bdi_class_init);
171
172int 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 va_start(args, fmt);
180 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
181 va_end(args);
182 if (IS_ERR(dev)) {
183 ret = PTR_ERR(dev);
184 goto exit;
185 }
186
187 bdi->dev = dev;
188 bdi_debug_register(bdi, dev_name(dev));
189
190exit:
191 return ret;
192}
193EXPORT_SYMBOL(bdi_register);
194
195int 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}
199EXPORT_SYMBOL(bdi_register_dev);
200
201void bdi_unregister(struct backing_dev_info *bdi)
202{
203 if (bdi->dev) {
204 bdi_debug_unregister(bdi);
205 device_unregister(bdi->dev);
206 bdi->dev = NULL;
207 }
208}
209EXPORT_SYMBOL(bdi_unregister);
210
211int bdi_init(struct backing_dev_info *bdi)
212{
213 int i;
214 int err;
215
216 bdi->dev = NULL;
217
218 bdi->min_ratio = 0;
219 bdi->max_ratio = 100;
220 bdi->max_prop_frac = PROP_FRAC_BASE;
221
222 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
223 err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
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) {
232err:
233 while (i--)
234 percpu_counter_destroy(&bdi->bdi_stat[i]);
235 }
236
237 return err;
238}
239EXPORT_SYMBOL(bdi_init);
240
241void bdi_destroy(struct backing_dev_info *bdi)
242{
243 int i;
244
245 bdi_unregister(bdi);
246
247 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
248 percpu_counter_destroy(&bdi->bdi_stat[i]);
249
250 prop_local_destroy_percpu(&bdi->completions);
251}
252EXPORT_SYMBOL(bdi_destroy);
253
254static 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
260void 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}
271EXPORT_SYMBOL(clear_bdi_congested);
272
273void 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}
280EXPORT_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 */
291long 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}
302EXPORT_SYMBOL(congestion_wait);
303