From c4ae0c65455c1bb30d1b71c6dd9a1a62aadde8ef Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 28 Jul 2011 06:55:13 +0200
Subject: [PATCH] vfs: avoid call to inode_lru_list_del() if possible

inode_lru_list_del() is expensive because of per superblock lru locking,
while some inodes are not in lru list.

Adding a check in iput_final() can speedup pipe/sockets workloads on
SMP.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/inode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/inode.c b/fs/inode.c
index e445be2a18f9..5aab80dc008c 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1330,7 +1330,8 @@ static void iput_final(struct inode *inode)
 	}
 
 	inode->i_state |= I_FREEING;
-	inode_lru_list_del(inode);
+	if (!list_empty(&inode->i_lru))
+		inode_lru_list_del(inode);
 	spin_unlock(&inode->i_lock);
 
 	evict(inode);