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 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 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)) 116 117 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) 134 135 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 }; 161 162 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); 171 172 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 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)); 189 190 exit: 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) { 204 bdi_debug_unregister(bdi); 205 device_unregister(bdi->dev); 206 bdi->dev = NULL; 207 } 208 } 209 EXPORT_SYMBOL(bdi_unregister); 210 211 int 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) { 232 err: 233 while (i--) 234 percpu_counter_destroy(&bdi->bdi_stat[i]); 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; 244 245 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 } 252 EXPORT_SYMBOL(bdi_destroy); 253 254 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); 303 304