An ext4 file system can be mounted with no extra options, same as any other file system:

~]# mount block_device /mount/point

The default mount options are optimal for most users. Options, such as acl, noacl, data, quota, noquota, user_xattr, nouser_xattr,
and many others that were already used with the ext2 and ext3 file
systems, are backward compatible and have the same usage and
functionality. Also, with the ext4 file system, several new
ext4-specific mount options have been added, for example:

barrier / nobarrier

By default, ext4 uses write barriers to ensure file system
integrity even when power is lost to a device with write caches enabled.
For devices without write caches, or with battery-backed write caches,
you disable barriers using the nobarrier option:

~]# mount -o nobarrier block_device /mount/point

stripe=value

This option allows you to specify the number of file system blocks
allocated for a single file operation. For RAID5 this number should be
equal the RAID chunk size multiplied by the number of disks.

journal_ioprio=value

This option allows you to set priority of I/O operations submitted
during a commit operation. The option can have a value from 7 to 0 (0
is the highest priority), and is set to 3 by default, which is slightly
higher priority than the default I/O priority.

Default mount options can be also set in the file system superblock using the tune4fs utility. For example, the following command sets the file system on the /dev/mapper/VolGroup00-LogVol02
device to be mounted by default with debugging disabled and
user-specified extended attributes and Posix access control lists
enabled:

~]# tune4fs -o ^debug,user_xattr,acl /dev/mapper/VolGroup00-LogVol02

For more information on this topic, refer to the tune4fs(8) manual page.

An ext3 file system can also be mounted as ext4 without changing the
format, allowing it to be mounted as ext3 again in the future. To do so,
run the following command on a block device that contains an ext3 file
system:

~]# mount -t ext4 block_device /mount/point

Doing so will only allow the ext3 file system to use ext4-specific
features that do not require a file format conversion. These features
include delayed allocation and multi-block allocation, and exclude features such as extent mapping.

For more information on mount options for the ext4 file system, see Section 2.2.2, “Specifying the Mount Options” and the mount(8) manual page.