From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 28 Jul 2011 04:11:47 +0000 (+0200)
Subject: vfs: conditionally call inode_wb_list_del()
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=b12362bdb61a230a67daa77bcd2a11e59b2802e1;p=openwrt%2Fstaging%2Fblogic.git

vfs: conditionally call inode_wb_list_del()

Some inodes (pipes, sockets, ...) are not in bdi writeback list.

evict() can avoid calling inode_wb_list_del() and its expensive spinlock
by checking inode i_wb_list being empty or not.

At this point, no other cpu/user can concurrently manipulate this inode
i_wb_list

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/inode.c b/fs/inode.c
index d0c72ff6b30e..9dab13ae6ef7 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -454,7 +454,9 @@ static void evict(struct inode *inode)
 	BUG_ON(!(inode->i_state & I_FREEING));
 	BUG_ON(!list_empty(&inode->i_lru));
 
-	inode_wb_list_del(inode);
+	if (!list_empty(&inode->i_wb_list))
+		inode_wb_list_del(inode);
+
 	inode_sb_list_del(inode);
 
 	if (op->evict_inode) {