1 2 #include <linux/wait.h> 3 #include <linux/backing-dev.h> 4 #include <linux/fs.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> 10 11 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) 12 { 13 } 14 EXPORT_SYMBOL(default_unplug_io_fn); 15 16 struct backing_dev_info default_backing_dev_info = { 17 .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE, 18 .state = 0, 19 .capabilities = BDI_CAP_MAP_COPY, 20 .unplug_io_fn = default_unplug_io_fn, 21 }; 22 EXPORT_SYMBOL_GPL(default_backing_dev_info); 23 24 static struct class *bdi_class; 25 26 #ifdef CONFIG_DEBUG_FS 27 #include <linux/debugfs.h> 28 #include <linux/seq_file.h> 29 30 static struct dentry *bdi_debug_root; 31 32 static void bdi_debug_init(void) 33 { 34 bdi_debug_root = debugfs_create_dir("bdi", NULL); 35 } 36 37 static int bdi_debug_stats_show(struct seq_file *m, void *v) 38 { 39 struct backing_dev_info *bdi = m->private; 40 unsigned long background_thresh; 41 unsigned long dirty_thresh; 42 unsigned long bdi_thresh; 43 44 get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi); 45 46 #define K(x) ((x) << (PAGE_SHIFT - 10)) 47 seq_printf(m, 48 "BdiWriteback: %8lu kB\n" 49 "BdiReclaimable: %8lu kB\n" 50 "BdiDirtyThresh: %8lu kB\n" 51 "DirtyThresh: %8lu kB\n" 52 "BackgroundThresh: %8lu kB\n", 53 (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), 54 (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), 55 K(bdi_thresh), 56 K(dirty_thresh), 57 K(background_thresh)); 58 #undef K 59 60 return 0; 61 } 62 63 static int bdi_debug_stats_open(struct inode *inode, struct file *file) 64 { 65 return single_open(file, bdi_debug_stats_show, inode->i_private); 66 } 67 68 static const struct file_operations bdi_debug_stats_fops = { 69 .open = bdi_debug_stats_open, 70 .read = seq_read, 71 .llseek = seq_lseek, 72 .release = single_release, 73 }; 74 75 static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) 76 { 77 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); 78 bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, 79 bdi, &bdi_debug_stats_fops); 80 } 81 82 static void bdi_debug_unregister(struct backing_dev_info *bdi) 83 { 84 debugfs_remove(bdi->debug_stats); 85 debugfs_remove(bdi->debug_dir); 86 } 87 #else 88 static inline void bdi_debug_init(void) 89 { 90 } 91 static inline void bdi_debug_register(struct backing_dev_info *bdi, 92 const char *name) 93 { 94 } 95 static inline void bdi_debug_unregister(struct backing_dev_info *bdi) 96 { 97 } 98 #endif 99 100 static ssize_t read_ahead_kb_store(struct device *dev, 101 struct device_attribute *attr, 102 const char *buf, size_t count) 103 { 104 struct backing_dev_info *bdi = dev_get_drvdata(dev); 105 char *end; 106 unsigned long read_ahead_kb; 107 ssize_t ret = -EINVAL; 108 109 read_ahead_kb = simple_strtoul(buf, &end, 10); 110 if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { 111 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); 112 ret = count; 113 } 114 return ret; 115 } 116 117 #define K(pages) ((pages) << (PAGE_SHIFT - 10)) 118 119 #define BDI_SHOW(name, expr) \ 120 static ssize_t name##_show(struct device *dev, \ 121 struct device_attribute *attr, char *page) \ 122 { \ 123 struct backing_dev_info *bdi = dev_get_drvdata(dev); \ 124 \ 125 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ 126 } 127 128 BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) 129 130 static ssize_t min_ratio_store(struct device *dev, 131 struct device_attribute *attr, const char *buf, size_t count) 132 { 133 struct backing_dev_info *bdi = dev_get_drvdata(dev); 134 char *end; 135 unsigned int ratio; 136 ssize_t ret = -EINVAL; 137 138 ratio = simple_strtoul(buf, &end, 10); 139 if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { 140 ret = bdi_set_min_ratio(bdi, ratio); 141 if (!ret) 142 ret = count; 143 } 144 return ret; 145 } 146 BDI_SHOW(min_ratio, bdi->min_ratio) 147 148 static ssize_t max_ratio_store(struct device *dev, 149 struct device_attribute *attr, const char *buf, size_t count) 150 { 151 struct backing_dev_info *bdi = dev_get_drvdata(dev); 152 char *end; 153 unsigned int ratio; 154 ssize_t ret = -EINVAL; 155 156 ratio = simple_strtoul(buf, &end, 10); 157 if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { 158 ret = bdi_set_max_ratio(bdi, ratio); 159 if (!ret) 160 ret = count; 161 } 162 return ret; 163 } 164 BDI_SHOW(max_ratio, bdi->max_ratio) 165 166 #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) 167 168 static struct device_attribute bdi_dev_attrs[] = { 169 __ATTR_RW(read_ahead_kb), 170 __ATTR_RW(min_ratio), 171 __ATTR_RW(max_ratio), 172 __ATTR_NULL, 173 }; 174 175 static __init int bdi_class_init(void) 176 { 177 bdi_class = class_create(THIS_MODULE, "bdi"); 178 bdi_class->dev_attrs = bdi_dev_attrs; 179 bdi_debug_init(); 180 return 0; 181 } 182 postcore_initcall(bdi_class_init); 183 184 static int __init default_bdi_init(void) 185 { 186 int err; 187 188 err = bdi_init(&default_backing_dev_info); 189 if (!err) 190 bdi_register(&default_backing_dev_info, NULL, "default"); 191 192 return err; 193 } 194 subsys_initcall(default_bdi_init); 195 196 int bdi_register(struct backing_dev_info *bdi, struct device *parent, 197 const char *fmt, ...) 198 { 199 va_list args; 200 int ret = 0; 201 struct device *dev; 202 203 if (bdi->dev) /* The driver needs to use separate queues per device */ 204 goto exit; 205 206 va_start(args, fmt); 207 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); 208 va_end(args); 209 if (IS_ERR(dev)) { 210 ret = PTR_ERR(dev); 211 goto exit; 212 } 213 214 bdi->dev = dev; 215 bdi_debug_register(bdi, dev_name(dev)); 216 217 exit: 218 return ret; 219 } 220 EXPORT_SYMBOL(bdi_register); 221 222 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) 223 { 224 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); 225 } 226 EXPORT_SYMBOL(bdi_register_dev); 227 228 void bdi_unregister(struct backing_dev_info *bdi) 229 { 230 if (bdi->dev) { 231 bdi_debug_unregister(bdi); 232 device_unregister(bdi->dev); 233 bdi->dev = NULL; 234 } 235 } 236 EXPORT_SYMBOL(bdi_unregister); 237 238 int bdi_init(struct backing_dev_info *bdi) 239 { 240 int i; 241 int err; 242 243 bdi->dev = NULL; 244 245 bdi->min_ratio = 0; 246 bdi->max_ratio = 100; 247 bdi->max_prop_frac = PROP_FRAC_BASE; 248 249 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { 250 err = percpu_counter_init(&bdi->bdi_stat[i], 0); 251 if (err) 252 goto err; 253 } 254 255 bdi->dirty_exceeded = 0; 256 err = prop_local_init_percpu(&bdi->completions); 257 258 if (err) { 259 err: 260 while (i--) 261 percpu_counter_destroy(&bdi->bdi_stat[i]); 262 } 263 264 return err; 265 } 266 EXPORT_SYMBOL(bdi_init); 267 268 void bdi_destroy(struct backing_dev_info *bdi) 269 { 270 int i; 271 272 bdi_unregister(bdi); 273 274 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) 275 percpu_counter_destroy(&bdi->bdi_stat[i]); 276 277 prop_local_destroy_percpu(&bdi->completions); 278 } 279 EXPORT_SYMBOL(bdi_destroy); 280 281 static wait_queue_head_t congestion_wqh[2] = { 282 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), 283 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) 284 }; 285 286 287 void clear_bdi_congested(struct backing_dev_info *bdi, int rw) 288 { 289 enum bdi_state bit; 290 wait_queue_head_t *wqh = &congestion_wqh[rw]; 291 292 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; 293 clear_bit(bit, &bdi->state); 294 smp_mb__after_clear_bit(); 295 if (waitqueue_active(wqh)) 296 wake_up(wqh); 297 } 298 EXPORT_SYMBOL(clear_bdi_congested); 299 300 void set_bdi_congested(struct backing_dev_info *bdi, int rw) 301 { 302 enum bdi_state bit; 303 304 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; 305 set_bit(bit, &bdi->state); 306 } 307 EXPORT_SYMBOL(set_bdi_congested); 308 309 /** 310 * congestion_wait - wait for a backing_dev to become uncongested 311 * @rw: READ or WRITE 312 * @timeout: timeout in jiffies 313 * 314 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit 315 * write congestion. If no backing_devs are congested then just wait for the 316 * next write to be completed. 317 */ 318 long congestion_wait(int rw, long timeout) 319 { 320 long ret; 321 DEFINE_WAIT(wait); 322 wait_queue_head_t *wqh = &congestion_wqh[rw]; 323 324 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); 325 ret = io_schedule_timeout(timeout); 326 finish_wait(wqh, &wait); 327 return ret; 328 } 329 EXPORT_SYMBOL(congestion_wait); 330 331