1 files changed, 219 insertions, 0 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index e8644b1e5527..7c4f9e097095 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -4,12 +4,229 @@
 #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;
+
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+static struct dentry *bdi_debug_root;
+
+static void bdi_debug_init(void)
+{
+        bdi_debug_root = debugfs_create_dir("bdi", NULL);
+}
+
+static int bdi_debug_stats_show(struct seq_file *m, void *v)
+{
+        struct backing_dev_info *bdi = m->private;
+        long background_thresh;
+        long dirty_thresh;
+        long bdi_thresh;
+
+        get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
+
+#define K(x) ((x) << (PAGE_SHIFT - 10))
+        seq_printf(m,
+                   "BdiWriteback:     %8lu kB\n"
+                   "BdiReclaimable:   %8lu kB\n"
+                   "BdiDirtyThresh:   %8lu kB\n"
+                   "DirtyThresh:      %8lu kB\n"
+                   "BackgroundThresh: %8lu kB\n",
+                   (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
+                   (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
+                   K(bdi_thresh),
+                   K(dirty_thresh),
+                   K(background_thresh));
+#undef K
+
+        return 0;
+}
+
+static int bdi_debug_stats_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, bdi_debug_stats_show, inode->i_private);
+}
+
+static const struct file_operations bdi_debug_stats_fops = {
+        .open           = bdi_debug_stats_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
+{
+        bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
+        bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
+                                               bdi, &bdi_debug_stats_fops);
+}
+
+static void bdi_debug_unregister(struct backing_dev_info *bdi)
+{
+        debugfs_remove(bdi->debug_stats);
+        debugfs_remove(bdi->debug_dir);
+}
+#else
+static inline void bdi_debug_init(void)
+{
+}
+static inline void bdi_debug_register(struct backing_dev_info *bdi,
+                                      const char *name)
+{
+}
+static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
+{
+}
+#endif
+
+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))
+
+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_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;
+        bdi_debug_init();
+        return 0;
+}
+
+postcore_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);
+        bdi_debug_register(bdi, name);
+
+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) {
+                bdi_debug_unregister(bdi);
+                device_unregister(bdi->dev);
+                bdi->dev = NULL;
+        }
+}
+EXPORT_SYMBOL(bdi_unregister);
 
 int bdi_init(struct backing_dev_info *bdi)
 {
         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)
@@ -33,6 +250,8 @@ 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]);