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>

fs/configfs/inode.c

@@ -255,7 +255,7 @@ void configfs_hash_and_remove(struct dentry * dir, const char * name)
 		/* no inode means this hasn't been made visible yet */
 		return;
 
-	mutex_lock(&d_inode(dir)->i_mutex);
+	inode_lock(d_inode(dir));
 	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 		if (!sd->s_element)
 			continue;
@@ -268,5 +268,5 @@ void configfs_hash_and_remove(struct dentry * dir, const char * name)
 			break;
 		}
 	}
-	mutex_unlock(&d_inode(dir)->i_mutex);
+	inode_unlock(d_inode(dir));
 }