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 #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
  77
  78 static struct device_attribute bdi_dev_attrs[] = {
  79         __ATTR_RW(read_ahead_kb),
  80         __ATTR_RO(reclaimable_kb),
  81         __ATTR_RO(writeback_kb),
  82         __ATTR_RO(dirty_kb),
  83         __ATTR_RO(bdi_dirty_kb),
  84         __ATTR_RW(min_ratio),
  85         __ATTR_NULL,
  86 };
  87
  88 static __init int bdi_class_init(void)
  89 {
  90         bdi_class = class_create(THIS_MODULE, "bdi");
  91         bdi_class->dev_attrs = bdi_dev_attrs;
  92         return 0;
  93 }
  94
  95 core_initcall(bdi_class_init);
  96
  97 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
  98                 const char *fmt, ...)
  99 {
 100         char *name;
 101         va_list args;
 102         int ret = 0;
 103         struct device *dev;
 104
 105         va_start(args, fmt);
 106         name = kvasprintf(GFP_KERNEL, fmt, args);
 107         va_end(args);
 108
 109         if (!name)
 110                 return -ENOMEM;
 111
 112         dev = device_create(bdi_class, parent, MKDEV(0, 0), name);
 113         if (IS_ERR(dev)) {
 114                 ret = PTR_ERR(dev);
 115                 goto exit;
 116         }
 117
 118         bdi->dev = dev;
 119         dev_set_drvdata(bdi->dev, bdi);
 120
 121 exit:
 122         kfree(name);
 123         return ret;
 124 }
 125 EXPORT_SYMBOL(bdi_register);
 126
 127 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
 128 {
 129         return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
 130 }
 131 EXPORT_SYMBOL(bdi_register_dev);
 132
 133 void bdi_unregister(struct backing_dev_info *bdi)
 134 {
 135         if (bdi->dev) {
 136                 device_unregister(bdi->dev);
 137                 bdi->dev = NULL;
 138         }
 139 }
 140 EXPORT_SYMBOL(bdi_unregister);
 141
 142 int bdi_init(struct backing_dev_info *bdi)
 143 {
 144         int i;
 145         int err;
 146
 147         bdi->dev = NULL;
 148
 149         bdi->min_ratio = 0;
 150
 151         for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
 152                 err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
 153                 if (err)
 154                         goto err;
 155         }
 156
 157         bdi->dirty_exceeded = 0;
 158         err = prop_local_init_percpu(&bdi->completions);
 159
 160         if (err) {
 161 err:
 162                 while (i--)
 163                         percpu_counter_destroy(&bdi->bdi_stat[i]);
 164         }
 165
 166         return err;
 167 }
 168 EXPORT_SYMBOL(bdi_init);
 169
 170 void bdi_destroy(struct backing_dev_info *bdi)
 171 {
 172         int i;
 173
 174         bdi_unregister(bdi);
 175
 176         for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
 177                 percpu_counter_destroy(&bdi->bdi_stat[i]);
 178
 179         prop_local_destroy_percpu(&bdi->completions);
 180 }
 181 EXPORT_SYMBOL(bdi_destroy);
 182
 183 static wait_queue_head_t congestion_wqh[2] = {
 184                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
 185                 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
 186         };
 187
 188
 189 void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
 190 {
 191         enum bdi_state bit;
 192         wait_queue_head_t *wqh = &congestion_wqh[rw];
 193
 194         bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
 195         clear_bit(bit, &bdi->state);
 196         smp_mb__after_clear_bit();
 197         if (waitqueue_active(wqh))
 198                 wake_up(wqh);
 199 }
 200 EXPORT_SYMBOL(clear_bdi_congested);
 201
 202 void set_bdi_congested(struct backing_dev_info *bdi, int rw)
 203 {
 204         enum bdi_state bit;
 205
 206         bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
 207         set_bit(bit, &bdi->state);
 208 }
 209 EXPORT_SYMBOL(set_bdi_congested);
 210
 211 /**
 212  * congestion_wait - wait for a backing_dev to become uncongested
 213  * @rw: READ or WRITE
 214  * @timeout: timeout in jiffies
 215  *
 216  * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
 217  * write congestion.  If no backing_devs are congested then just wait for the
 218  * next write to be completed.
 219  */
 220 long congestion_wait(int rw, long timeout)
 221 {
 222         long ret;
 223         DEFINE_WAIT(wait);
 224         wait_queue_head_t *wqh = &congestion_wqh[rw];
 225
 226         prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
 227         ret = io_schedule_timeout(timeout);
 228         finish_wait(wqh, &wait);
 229         return ret;
 230 }
 231 EXPORT_SYMBOL(congestion_wait);
 232