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>

drivers/mtd/ubi/cdev.c

@@ -174,9 +174,9 @@ static int vol_cdev_fsync(struct file *file, loff_t start, loff_t end,
 	struct ubi_device *ubi = desc->vol->ubi;
 	struct inode *inode = file_inode(file);
 	int err;
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	err = ubi_sync(ubi->ubi_num);
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	return err;
 }