2 #include <linux/wait.h>
3 #include <linux/backing-dev.h>
5 #include <linux/sched.h>
6 #include <linux/module.h>
7 #include <linux/writeback.h>
8 #include <linux/device.h>
11 static struct class *bdi_class;
13 #ifdef CONFIG_DEBUG_FS
14 #include <linux/debugfs.h>
15 #include <linux/seq_file.h>
17 static struct dentry *bdi_debug_root;
19 static void bdi_debug_init(void)
21 bdi_debug_root = debugfs_create_dir("bdi", NULL);
24 static int bdi_debug_stats_show(struct seq_file *m, void *v)
26 struct backing_dev_info *bdi = m->private;
27 unsigned long background_thresh;
28 unsigned long dirty_thresh;
29 unsigned long bdi_thresh;
31 get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
33 #define K(x) ((x) << (PAGE_SHIFT - 10))
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)),
44 K(background_thresh));
50 static int bdi_debug_stats_open(struct inode *inode, struct file *file)
52 return single_open(file, bdi_debug_stats_show, inode->i_private);
55 static const struct file_operations bdi_debug_stats_fops = {
56 .open = bdi_debug_stats_open,
59 .release = single_release,
62 static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
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);
69 static void bdi_debug_unregister(struct backing_dev_info *bdi)
71 debugfs_remove(bdi->debug_stats);
72 debugfs_remove(bdi->debug_dir);
75 static inline void bdi_debug_init(void)
78 static inline void bdi_debug_register(struct backing_dev_info *bdi,
82 static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
87 static ssize_t read_ahead_kb_store(struct device *dev,
88 struct device_attribute *attr,
89 const char *buf, size_t count)
91 struct backing_dev_info *bdi = dev_get_drvdata(dev);
93 unsigned long read_ahead_kb;
94 ssize_t ret = -EINVAL;
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);
104 #define K(pages) ((pages) << (PAGE_SHIFT - 10))
106 #define BDI_SHOW(name, expr) \
107 static ssize_t name##_show(struct device *dev, \
108 struct device_attribute *attr, char *page) \
110 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
112 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
115 BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
117 static ssize_t min_ratio_store(struct device *dev,
118 struct device_attribute *attr, const char *buf, size_t count)
120 struct backing_dev_info *bdi = dev_get_drvdata(dev);
123 ssize_t ret = -EINVAL;
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);
133 BDI_SHOW(min_ratio, bdi->min_ratio)
135 static ssize_t max_ratio_store(struct device *dev,
136 struct device_attribute *attr, const char *buf, size_t count)
138 struct backing_dev_info *bdi = dev_get_drvdata(dev);
141 ssize_t ret = -EINVAL;
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);
151 BDI_SHOW(max_ratio, bdi->max_ratio)
153 #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
155 static struct device_attribute bdi_dev_attrs[] = {
156 __ATTR_RW(read_ahead_kb),
157 __ATTR_RW(min_ratio),
158 __ATTR_RW(max_ratio),
162 static __init int bdi_class_init(void)
164 bdi_class = class_create(THIS_MODULE, "bdi");
165 bdi_class->dev_attrs = bdi_dev_attrs;
170 postcore_initcall(bdi_class_init);
172 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
173 const char *fmt, ...)
179 if (bdi->dev) /* The driver needs to use separate queues per device */
183 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
191 bdi_debug_register(bdi, dev_name(dev));
196 EXPORT_SYMBOL(bdi_register);
198 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
200 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
202 EXPORT_SYMBOL(bdi_register_dev);
204 void bdi_unregister(struct backing_dev_info *bdi)
207 bdi_debug_unregister(bdi);
208 device_unregister(bdi->dev);
212 EXPORT_SYMBOL(bdi_unregister);
214 int bdi_init(struct backing_dev_info *bdi)
222 bdi->max_ratio = 100;
223 bdi->max_prop_frac = PROP_FRAC_BASE;
225 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
226 err = percpu_counter_init(&bdi->bdi_stat[i], 0);
231 bdi->dirty_exceeded = 0;
232 err = prop_local_init_percpu(&bdi->completions);
237 percpu_counter_destroy(&bdi->bdi_stat[i]);
242 EXPORT_SYMBOL(bdi_init);
244 void bdi_destroy(struct backing_dev_info *bdi)
250 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
251 percpu_counter_destroy(&bdi->bdi_stat[i]);
253 prop_local_destroy_percpu(&bdi->completions);
255 EXPORT_SYMBOL(bdi_destroy);
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])
263 void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
266 wait_queue_head_t *wqh = &congestion_wqh[rw];
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))
274 EXPORT_SYMBOL(clear_bdi_congested);
276 void set_bdi_congested(struct backing_dev_info *bdi, int rw)
280 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
281 set_bit(bit, &bdi->state);
283 EXPORT_SYMBOL(set_bdi_congested);
286 * congestion_wait - wait for a backing_dev to become uncongested
288 * @timeout: timeout in jiffies
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.
294 long congestion_wait(int rw, long timeout)
298 wait_queue_head_t *wqh = &congestion_wqh[rw];
300 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
301 ret = io_schedule_timeout(timeout);
302 finish_wait(wqh, &wait);
305 EXPORT_SYMBOL(congestion_wait);