[PATCH 11/17] writeback: add bdi_dirty_limit() kernel-doc

[Wu Fengguang <fengguang.wu@intel.com>]

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Clarify the bdi_dirty_limit() comment.

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
 mm/page-writeback.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- linux-next.orig/mm/page-writeback.c	2011-05-05 23:30:22.000000000 +0800
+++ linux-next/mm/page-writeback.c	2011-05-05 23:30:31.000000000 +0800
@@ -437,10 +437,17 @@ void global_dirty_limits(unsigned long *
 	*pdirty = dirty;
 }
 
-/*
+/**
  * bdi_dirty_limit - @bdi's share of dirty throttling threshold
+ * @bdi: the backing_dev_info to query
+ * @dirty: global dirty limit in pages
+ *
+ * Returns @bdi's dirty limit in pages. The term "dirty" in the context of
+ * dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages.
+ * And the "limit" in the name is not seriously taken as hard limit in
+ * balance_dirty_pages().
  *
- * Allocate high/low dirty limits to fast/slow devices, in order to prevent
+ * It allocates high/low dirty limits to fast/slow devices, in order to prevent
  * - starving fast devices
  * - piling up dirty pages (that will take long time to sync) on slow devices
  *