[PATCH] writeback: remove the internal 5% low bound on dirty_ratio

[Wu Fengguang]

The dirty_ratio was silently limited to >= 5%. This is not a user
expected behavior. Let's rip it.

It's not likely the user space will depend on the old behavior.
So the risk of breaking user space is very low.

CC: Jan Kara <jack@xxxxxxx>
CC: Neil Brown <neilb@xxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
 mm/page-writeback.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- linux-next.orig/mm/page-writeback.c	2010-08-20 10:55:17.000000000 +0800
+++ linux-next/mm/page-writeback.c	2010-08-20 10:56:36.000000000 +0800
@@ -415,14 +415,8 @@ void global_dirty_limits(unsigned long *
 
 	if (vm_dirty_bytes)
 		dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
-	else {
-		int dirty_ratio;
-
-		dirty_ratio = vm_dirty_ratio;
-		if (dirty_ratio < 5)
-			dirty_ratio = 5;
-		dirty = (dirty_ratio * available_memory) / 100;
-	}
+	else
+		dirty = (vm_dirty_ratio * available_memory) / 100;
 
 	if (dirty_background_bytes)
 		background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE);
--
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