2 #include <linux/wait.h>
3 #include <linux/backing-dev.h>
5 #include <linux/pagemap.h>
6 #include <linux/sched.h>
7 #include <linux/module.h>
8 #include <linux/writeback.h>
9 #include <linux/device.h>
11 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
14 EXPORT_SYMBOL(default_unplug_io_fn);
16 struct backing_dev_info default_backing_dev_info = {
17 .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
19 .capabilities = BDI_CAP_MAP_COPY,
20 .unplug_io_fn = default_unplug_io_fn,
22 EXPORT_SYMBOL_GPL(default_backing_dev_info);
24 static struct class *bdi_class;
25 DEFINE_MUTEX(bdi_lock);
28 #ifdef CONFIG_DEBUG_FS
29 #include <linux/debugfs.h>
30 #include <linux/seq_file.h>
32 static struct dentry *bdi_debug_root;
34 static void bdi_debug_init(void)
36 bdi_debug_root = debugfs_create_dir("bdi", NULL);
39 static int bdi_debug_stats_show(struct seq_file *m, void *v)
41 struct backing_dev_info *bdi = m->private;
42 unsigned long background_thresh;
43 unsigned long dirty_thresh;
44 unsigned long bdi_thresh;
46 get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
48 #define K(x) ((x) << (PAGE_SHIFT - 10))
50 "BdiWriteback: %8lu kB\n"
51 "BdiReclaimable: %8lu kB\n"
52 "BdiDirtyThresh: %8lu kB\n"
53 "DirtyThresh: %8lu kB\n"
54 "BackgroundThresh: %8lu kB\n",
55 (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
56 (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
59 K(background_thresh));
65 static int bdi_debug_stats_open(struct inode *inode, struct file *file)
67 return single_open(file, bdi_debug_stats_show, inode->i_private);
70 static const struct file_operations bdi_debug_stats_fops = {
71 .open = bdi_debug_stats_open,
74 .release = single_release,
77 static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
79 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
80 bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
81 bdi, &bdi_debug_stats_fops);
84 static void bdi_debug_unregister(struct backing_dev_info *bdi)
86 debugfs_remove(bdi->debug_stats);
87 debugfs_remove(bdi->debug_dir);
90 static inline void bdi_debug_init(void)
93 static inline void bdi_debug_register(struct backing_dev_info *bdi,
97 static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
102 static ssize_t read_ahead_kb_store(struct device *dev,
103 struct device_attribute *attr,
104 const char *buf, size_t count)
106 struct backing_dev_info *bdi = dev_get_drvdata(dev);
108 unsigned long read_ahead_kb;
109 ssize_t ret = -EINVAL;
111 read_ahead_kb = simple_strtoul(buf, &end, 10);
112 if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
113 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
119 #define K(pages) ((pages) << (PAGE_SHIFT - 10))
121 #define BDI_SHOW(name, expr) \
122 static ssize_t name##_show(struct device *dev, \
123 struct device_attribute *attr, char *page) \
125 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
127 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
130 BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
132 static ssize_t min_ratio_store(struct device *dev,
133 struct device_attribute *attr, const char *buf, size_t count)
135 struct backing_dev_info *bdi = dev_get_drvdata(dev);
138 ssize_t ret = -EINVAL;
140 ratio = simple_strtoul(buf, &end, 10);
141 if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
142 ret = bdi_set_min_ratio(bdi, ratio);
148 BDI_SHOW(min_ratio, bdi->min_ratio)
150 static ssize_t max_ratio_store(struct device *dev,
151 struct device_attribute *attr, const char *buf, size_t count)
153 struct backing_dev_info *bdi = dev_get_drvdata(dev);
156 ssize_t ret = -EINVAL;
158 ratio = simple_strtoul(buf, &end, 10);
159 if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
160 ret = bdi_set_max_ratio(bdi, ratio);
166 BDI_SHOW(max_ratio, bdi->max_ratio)
168 #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
170 static struct device_attribute bdi_dev_attrs[] = {
171 __ATTR_RW(read_ahead_kb),
172 __ATTR_RW(min_ratio),
173 __ATTR_RW(max_ratio),
177 static __init int bdi_class_init(void)
179 bdi_class = class_create(THIS_MODULE, "bdi");
180 bdi_class->dev_attrs = bdi_dev_attrs;
184 postcore_initcall(bdi_class_init);
186 static int __init default_bdi_init(void)
190 err = bdi_init(&default_backing_dev_info);
192 bdi_register(&default_backing_dev_info, NULL, "default");
196 subsys_initcall(default_bdi_init);
198 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
199 const char *fmt, ...)
205 if (bdi->dev) /* The driver needs to use separate queues per device */
209 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
216 mutex_lock(&bdi_lock);
217 list_add_tail(&bdi->bdi_list, &bdi_list);
218 mutex_unlock(&bdi_lock);
221 bdi_debug_register(bdi, dev_name(dev));
226 EXPORT_SYMBOL(bdi_register);
228 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
230 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
232 EXPORT_SYMBOL(bdi_register_dev);
234 static void bdi_remove_from_list(struct backing_dev_info *bdi)
236 mutex_lock(&bdi_lock);
237 list_del(&bdi->bdi_list);
238 mutex_unlock(&bdi_lock);
241 void bdi_unregister(struct backing_dev_info *bdi)
244 bdi_remove_from_list(bdi);
245 bdi_debug_unregister(bdi);
246 device_unregister(bdi->dev);
250 EXPORT_SYMBOL(bdi_unregister);
252 int bdi_init(struct backing_dev_info *bdi)
260 bdi->max_ratio = 100;
261 bdi->max_prop_frac = PROP_FRAC_BASE;
262 INIT_LIST_HEAD(&bdi->bdi_list);
263 INIT_LIST_HEAD(&bdi->b_io);
264 INIT_LIST_HEAD(&bdi->b_dirty);
265 INIT_LIST_HEAD(&bdi->b_more_io);
267 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
268 err = percpu_counter_init(&bdi->bdi_stat[i], 0);
273 bdi->dirty_exceeded = 0;
274 err = prop_local_init_percpu(&bdi->completions);
279 percpu_counter_destroy(&bdi->bdi_stat[i]);
281 bdi_remove_from_list(bdi);
286 EXPORT_SYMBOL(bdi_init);
288 void bdi_destroy(struct backing_dev_info *bdi)
292 WARN_ON(!list_empty(&bdi->b_dirty));
293 WARN_ON(!list_empty(&bdi->b_io));
294 WARN_ON(!list_empty(&bdi->b_more_io));
298 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
299 percpu_counter_destroy(&bdi->bdi_stat[i]);
301 prop_local_destroy_percpu(&bdi->completions);
303 EXPORT_SYMBOL(bdi_destroy);
305 static wait_queue_head_t congestion_wqh[2] = {
306 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
307 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
310 void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
313 wait_queue_head_t *wqh = &congestion_wqh[sync];
315 bit = sync ? BDI_sync_congested : BDI_async_congested;
316 clear_bit(bit, &bdi->state);
317 smp_mb__after_clear_bit();
318 if (waitqueue_active(wqh))
321 EXPORT_SYMBOL(clear_bdi_congested);
323 void set_bdi_congested(struct backing_dev_info *bdi, int sync)
327 bit = sync ? BDI_sync_congested : BDI_async_congested;
328 set_bit(bit, &bdi->state);
330 EXPORT_SYMBOL(set_bdi_congested);
333 * congestion_wait - wait for a backing_dev to become uncongested
334 * @sync: SYNC or ASYNC IO
335 * @timeout: timeout in jiffies
337 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
338 * write congestion. If no backing_devs are congested then just wait for the
339 * next write to be completed.
341 long congestion_wait(int sync, long timeout)
345 wait_queue_head_t *wqh = &congestion_wqh[sync];
347 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
348 ret = io_schedule_timeout(timeout);
349 finish_wait(wqh, &wait);
352 EXPORT_SYMBOL(congestion_wait);