wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 7f60472..794fd15 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -2046,9 +2046,9 @@
 	int ret = 0;
 	unsigned int truncated_clusters;
 
-	mutex_lock(&osb->osb_tl_inode->i_mutex);
+	inode_lock(osb->osb_tl_inode);
 	truncated_clusters = osb->truncated_clusters;
-	mutex_unlock(&osb->osb_tl_inode->i_mutex);
+	inode_unlock(osb->osb_tl_inode);
 
 	/*
 	 * Check whether we can succeed in allocating if we free