SAFE public projects git trees. - safe/jmp/linux-2.6/blob - mm/backing-dev.c

   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 static ssize_t read_ahead_kb_store(struct device *dev,
  14                                   struct device_attribute *attr,
  15                                   const char *buf, size_t count)
  16 {
  17         struct backing_dev_info *bdi = dev_get_drvdata(dev);
  18         char *end;
  19         unsigned long read_ahead_kb;
  20         ssize_t ret = -EINVAL;
  21
  22         read_ahead_kb = simple_strtoul(buf, &end, 10);
  23         if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
  24                 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
  25                 ret = count;
  26         }
  27         return ret;
  28 }
  29
  30 #define K(pages) ((pages) << (PAGE_SHIFT - 10))
  31
  32 #define BDI_SHOW(name, expr)                                            \
  33 static ssize_t name##_show(struct device *dev,                          \
  34                            struct device_attribute *attr, char *page)   \
  35 {                                                                       \
  36         struct backing_dev_info *bdi = dev_get_drvdata(dev);            \
  37                                                                         \
  38         return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr);  \
  39 }
  40
  41 BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
  42
  43 BDI_SHOW(reclaimable_kb, K(bdi_stat(bdi, BDI_RECLAIMABLE)))
  44 BDI_SHOW(writeback_kb, K(bdi_stat(bdi, BDI_WRITEBACK)))
  45
  46 static inline unsigned long get_dirty(struct backing_dev_info *bdi, int i)
  47 {
  48         unsigned long thresh[3];
  49
  50         get_dirty_limits(&thresh[0], &thresh[1], &thresh[2], bdi);
  51
  52         return thresh[i];
  53 }
  54
  55 BDI_SHOW(dirty_kb, K(get_dirty(bdi, 1)))
  56 BDI_SHOW(bdi_dirty_kb, K(get_dirty(bdi, 2)))
  57
  58 static ssize_t min_ratio_store(struct device *dev,
  59                 struct device_attribute *attr, const char *buf, size_t count)
  60 {
  61         struct backing_dev_info *bdi = dev_get_drvdata(dev);
  62         char *end;
  63         unsigned int ratio;
  64         ssize_t ret = -EINVAL;
  65
  66         ratio = simple_strtoul(buf, &end, 10);
  67         if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
  68                 ret = bdi_set_min_ratio(bdi, ratio);
  69                 if (!ret)
  70                         ret = count;
  71         }
  72         return ret;
  73 }
  74 BDI_SHOW(min_ratio, bdi->min_ratio)
  75
  76 static ssize_t max_ratio_store(struct device *dev,
  77                 struct device_attribute *attr, const char *buf, size_t count)
  78 {
  79         struct backing_dev_info *bdi = dev_get_drvdata(dev);
  80         char *end;
  81         unsigned int ratio;
  82         ssize_t ret = -EINVAL;
  83
  84         ratio = simple_strtoul(buf, &end, 10);
  85         if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
  86                 ret = bdi_set_max_ratio(bdi, ratio);
  87                 if (!ret)
  88                         ret = count;
  89         }
  90         return ret;
  91 }
  92 BDI_SHOW(max_ratio, bdi->max_ratio)
  93
  94 #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
  95
  96 static struct device_attribute bdi_dev_attrs[] = {
  97         __ATTR_RW(read_ahead_kb),
  98         __ATTR_RO(reclaimable_kb),
  99         __ATTR_RO(writeback_kb),
 100         __ATTR_RO(dirty_kb),
 101         __ATTR_RO(bdi_dirty_kb),
 102         __ATTR_RW(min_ratio),
 103         __ATTR_RW(max_ratio),
 104         __ATTR_NULL,
 105 };
 106
 107 static __init int bdi_class_init(void)
 108 {
 109         bdi_class = class_create(THIS_MODULE, "bdi");
 110         bdi_class->dev_attrs = bdi_dev_attrs;
 111         return 0;
 112 }
 113
 114 core_initcall(bdi_class_init);
 115
 116 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
 117                 const char *fmt, ...)
 118 {
 119         char *name;
 120         va_list args;
 121         int ret = 0;
 122         struct device *dev;
 123
 124         va_start(args, fmt);
 125         name = kvasprintf(GFP_KERNEL, fmt, args);
 126         va_end(args);
 127
 128         if (!name)
 129                 return -ENOMEM;
 130
 131         dev = device_create(bdi_class, parent, MKDEV(0, 0), name);
 132         if (IS_ERR(dev)) {
 133                 ret = PTR_ERR(dev);
 134                 goto exit;
 135         }
 136
 137         bdi->dev = dev;
 138         dev_set_drvdata(bdi->dev, bdi);
 139
 140 exit:
 141         kfree(name);
 142         return ret;
 143 }
 144 EXPORT_SYMBOL(bdi_register);
 145
 146 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
 147 {
 148         return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
 149 }
 150 EXPORT_SYMBOL(bdi_register_dev);
 151
 152 void bdi_unregister(struct backing_dev_info *bdi)
 153 {
 154         if (bdi->dev) {
 155                 device_unregister(bdi->dev);
 156                 bdi->dev = NULL;
 157         }
 158 }
 159 EXPORT_SYMBOL(bdi_unregister);
 160
 161 int bdi_init(struct backing_dev_info *bdi)
 162 {
 163         int i;
 164         int err;
 165
 166         bdi->dev = NULL;
 167
 168         bdi->min_ratio = 0;
 169         bdi->max_ratio = 100;
 170         bdi->max_prop_frac = PROP_FRAC_BASE;
 171
 172         for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
 173                 err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
 174                 if (err)
 175                         goto err;
 176         }
 177
 178         bdi->dirty_exceeded = 0;
 179         err = prop_local_init_percpu(&bdi->completions);
 180
 181         if (err) {
 182 err:
 183                 while (i--)
 184                         percpu_counter_destroy(&bdi->bdi_stat[i]);
 185         }
 186
 187         return err;
 188 }
 189 EXPORT_SYMBOL(bdi_init);
 190
 191 void bdi_destroy(struct backing_dev_info *bdi)
 192 {
 193         int i;
 194
 195         bdi_unregister(bdi);
 196
 197         for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
 198                 percpu_counter_destroy(&bdi->bdi_stat[i]);
 199
 200         prop_local_destroy_percpu(&bdi->completions);
 201 }
 202 EXPORT_SYMBOL(bdi_destroy);
 203
 204 static wait_queue_head_t congestion_wqh[2] = {
 205                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
 206                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
 207         };
 208
 209
 210 void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
 211 {
 212         enum bdi_state bit;
 213         wait_queue_head_t *wqh = &congestion_wqh[rw];
 214
 215         bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
 216         clear_bit(bit, &bdi->state);
 217         smp_mb__after_clear_bit();
 218         if (waitqueue_active(wqh))
 219                 wake_up(wqh);
 220 }
 221 EXPORT_SYMBOL(clear_bdi_congested);
 222
 223 void set_bdi_congested(struct backing_dev_info *bdi, int rw)
 224 {
 225         enum bdi_state bit;
 226
 227         bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
 228         set_bit(bit, &bdi->state);
 229 }
 230 EXPORT_SYMBOL(set_bdi_congested);
 231
 232 /**
 233  * congestion_wait - wait for a backing_dev to become uncongested
 234  * @rw: READ or WRITE
 235  * @timeout: timeout in jiffies
 236  *
 237  * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
 238  * write congestion.  If no backing_devs are congested then just wait for the
 239  * next write to be completed.
 240  */
 241 long congestion_wait(int rw, long timeout)
 242 {
 243         long ret;
 244         DEFINE_WAIT(wait);
 245         wait_queue_head_t *wqh = &congestion_wqh[rw];
 246
 247         prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
 248         ret = io_schedule_timeout(timeout);
 249         finish_wait(wqh, &wait);
 250         return ret;
 251 }
 252 EXPORT_SYMBOL(congestion_wait);
 253