mm: bdi: move statistics to debugfs

Move BDI statistics to debugfs:

   /sys/kernel/debug/bdi/<bdi>/stats

Use postcore_initcall() to initialize the sysfs class and debugfs,
because debugfs is initialized in core_initcall().

Update descriptions in ABI documentation.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index ad3271d1e90a..c49a2d045e11 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -16,6 +16,7 @@
 
 struct page;
 struct device;
+struct dentry;
 
 /*
  * Bits in backing_dev_info.state
@@ -55,6 +56,11 @@ struct backing_dev_info {
         unsigned int max_ratio, max_prop_frac;
 
         struct device *dev;
+
+#ifdef CONFIG_DEBUG_FS
+        struct dentry *debug_dir;
+        struct dentry *debug_stats;
+#endif
 };
 
 int bdi_init(struct backing_dev_info *bdi);