mm: bdi: allow setting a maximum for the bdi dirty limit

[linux-2.6] / mm / backing-dev.c

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index b0ceb29da4c7a9b8c230e1956e324b62b1905727..08361b6aad5044f5f37a18e6eb162b034848578b 100644 (file)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -4,12 +4,171 @@
 #include <linux/fs.h>
 #include <linux/sched.h>
 #include <linux/module.h>
+#include <linux/writeback.h>
+#include <linux/device.h>
+
+
+static struct class *bdi_class;
+
+static ssize_t read_ahead_kb_store(struct device *dev,
+                                 struct device_attribute *attr,
+                                 const char *buf, size_t count)
+{
+       struct backing_dev_info *bdi = dev_get_drvdata(dev);
+       char *end;
+       unsigned long read_ahead_kb;
+       ssize_t ret = -EINVAL;
+
+       read_ahead_kb = simple_strtoul(buf, &end, 10);
+       if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
+               bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
+               ret = count;
+       }
+       return ret;
+}
+
+#define K(pages) ((pages) << (PAGE_SHIFT - 10))
+
+#define BDI_SHOW(name, expr)                                           \
+static ssize_t name##_show(struct device *dev,                         \
+                          struct device_attribute *attr, char *page)   \
+{                                                                      \
+       struct backing_dev_info *bdi = dev_get_drvdata(dev);            \
+                                                                       \
+       return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr);  \
+}
+
+BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
+
+BDI_SHOW(reclaimable_kb, K(bdi_stat(bdi, BDI_RECLAIMABLE)))
+BDI_SHOW(writeback_kb, K(bdi_stat(bdi, BDI_WRITEBACK)))
+
+static inline unsigned long get_dirty(struct backing_dev_info *bdi, int i)
+{
+       unsigned long thresh[3];
+
+       get_dirty_limits(&thresh[0], &thresh[1], &thresh[2], bdi);
+
+       return thresh[i];
+}
+
+BDI_SHOW(dirty_kb, K(get_dirty(bdi, 1)))
+BDI_SHOW(bdi_dirty_kb, K(get_dirty(bdi, 2)))
+
+static ssize_t min_ratio_store(struct device *dev,
+               struct device_attribute *attr, const char *buf, size_t count)
+{
+       struct backing_dev_info *bdi = dev_get_drvdata(dev);
+       char *end;
+       unsigned int ratio;
+       ssize_t ret = -EINVAL;
+
+       ratio = simple_strtoul(buf, &end, 10);
+       if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
+               ret = bdi_set_min_ratio(bdi, ratio);
+               if (!ret)
+                       ret = count;
+       }
+       return ret;
+}
+BDI_SHOW(min_ratio, bdi->min_ratio)
+
+static ssize_t max_ratio_store(struct device *dev,
+               struct device_attribute *attr, const char *buf, size_t count)
+{
+       struct backing_dev_info *bdi = dev_get_drvdata(dev);
+       char *end;
+       unsigned int ratio;
+       ssize_t ret = -EINVAL;
+
+       ratio = simple_strtoul(buf, &end, 10);
+       if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
+               ret = bdi_set_max_ratio(bdi, ratio);
+               if (!ret)
+                       ret = count;
+       }
+       return ret;
+}
+BDI_SHOW(max_ratio, bdi->max_ratio)
+
+#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
+
+static struct device_attribute bdi_dev_attrs[] = {
+       __ATTR_RW(read_ahead_kb),
+       __ATTR_RO(reclaimable_kb),
+       __ATTR_RO(writeback_kb),
+       __ATTR_RO(dirty_kb),
+       __ATTR_RO(bdi_dirty_kb),
+       __ATTR_RW(min_ratio),
+       __ATTR_RW(max_ratio),
+       __ATTR_NULL,
+};
+
+static __init int bdi_class_init(void)
+{
+       bdi_class = class_create(THIS_MODULE, "bdi");
+       bdi_class->dev_attrs = bdi_dev_attrs;
+       return 0;
+}
+
+core_initcall(bdi_class_init);
+
+int bdi_register(struct backing_dev_info *bdi, struct device *parent,
+               const char *fmt, ...)
+{
+       char *name;
+       va_list args;
+       int ret = 0;
+       struct device *dev;
+
+       va_start(args, fmt);
+       name = kvasprintf(GFP_KERNEL, fmt, args);
+       va_end(args);
+
+       if (!name)
+               return -ENOMEM;
+
+       dev = device_create(bdi_class, parent, MKDEV(0, 0), name);
+       if (IS_ERR(dev)) {
+               ret = PTR_ERR(dev);
+               goto exit;
+       }
+
+       bdi->dev = dev;
+       dev_set_drvdata(bdi->dev, bdi);
+
+exit:
+       kfree(name);
+       return ret;
+}
+EXPORT_SYMBOL(bdi_register);
+
+int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
+{
+       return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
+}
+EXPORT_SYMBOL(bdi_register_dev);
+
+void bdi_unregister(struct backing_dev_info *bdi)
+{
+       if (bdi->dev) {
+               device_unregister(bdi->dev);
+               bdi->dev = NULL;
+       }
+}
+EXPORT_SYMBOL(bdi_unregister);
 
 int bdi_init(struct backing_dev_info *bdi)
 {
-       int i, j;
+       int i;
        int err;
 
+       bdi->dev = NULL;
+
+       bdi->min_ratio = 0;
+       bdi->max_ratio = 100;
+       bdi->max_prop_frac = PROP_FRAC_BASE;
+
        for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
                err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
                if (err)
@@ -21,7 +180,7 @@ int bdi_init(struct backing_dev_info *bdi)
 
        if (err) {
 err:
-               for (j = 0; j < i; j++)
+               while (i--)
                        percpu_counter_destroy(&bdi->bdi_stat[i]);
        }
 
@@ -33,6 +192,8 @@ void bdi_destroy(struct backing_dev_info *bdi)
 {
        int i;
 
+       bdi_unregister(bdi);
+
        for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
                percpu_counter_destroy(&bdi->bdi_stat[i]);