[patch 30/35] fs: icache lazy LRU avoid LRU locking after IO operation

[npiggin]

Now that inode LRU and writeback lists and locking are separated,
it makes sense to avoid LRU manipulation after completing a writeback,
and instead rely on lazy-LRU algorithm to do the work for us.

Signed-off-by: Nick Piggin <npiggin@xxxxxxxxx>

---
 fs/fs-writeback.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c	2010-10-19 14:19:00.000000000 +1100
+++ linux-2.6/fs/fs-writeback.c	2010-10-19 14:19:18.000000000 +1100
@@ -410,7 +410,11 @@
 			 * The inode is clean
 			 */
 			list_del_init(&inode->i_io);
-			if (list_empty(&inode->i_lru))
+
+			/*
+			 * Put it on the LRU if it is unused, otherwise lazy.
+			 */
+			if (!inode->i_count && list_empty(&inode->i_lru))
 				__inode_lru_list_add(inode);
 		}
 	}


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