+.BI \-E " extended-options"
+Set extended options for the file system. Extended options are comma
+separated, and may take an argument using the equals ('=') sign.
+The following extended options are supported:
+.RS 1.2i
+.TP
+.B clear_mmp
+Reset the MMP block (if any) back to the clean state. Use only if
+absolutely certain the device is not currently mounted or being
+fscked, or major file system corruption can result. Needs '-f'.
+.TP
+.BI mmp_update_interval= interval
+Adjust the initial MMP update interval to
+.I interval
+seconds. Specifying an
+.I interval
+of 0 means to use the default interval. The specified interval must
+be less than 300 seconds. Requires that the
+.B mmp
+feature be enabled.
+.TP
+.BI stride= stride-size
+Configure the file system for a RAID array with
+.I stride-size
+file system blocks. This is the number of blocks read or written to disk
+before moving to next disk. This mostly affects placement of file system
+metadata like bitmaps at
+.BR mke2fs (2)
+time to avoid placing them on a single disk, which can hurt the performance.
+It may also be used by block allocator.
+.TP
+.BI stripe_width= stripe-width
+Configure the file system for a RAID array with
+.I stripe-width
+file system blocks per stripe. This is typically be stride-size * N, where
+N is the number of data disks in the RAID (e.g. RAID 5 N+1, RAID 6 N+2).
+This allows the block allocator to prevent read-modify-write of the
+parity in a RAID stripe if possible when the data is written.
+.TP
+.BI hash_alg= hash-alg
+Set the default hash algorithm used for file systems with hashed b-tree
+directories. Valid algorithms accepted are:
+.IR legacy ,
+.IR half_md4 ,
+and
+.IR tea .
+.TP
+.BI encoding= encoding-name
+Enable the
+.I casefold
+feature in the super block and set
+.I encoding-name
+as the encoding to be used. If
+.I encoding-name
+is not specified, utf8 is used. The encoding cannot be altered if casefold
+was previously enabled.
+.TP
+.BI encoding_flags= encoding-flags
+Define parameters for file name character encoding operations. If a
+flag is not changed using this parameter, its default value is used.
+.I encoding-flags
+should be a comma-separated lists of flags to be enabled. The flags cannot be
+altered if casefold was previously enabled.
+
+The only flag that can be set right now is
+.I strict
+which means that invalid strings should be rejected by the file system.
+In the default configuration, the
+.I strict
+flag is disabled.
+.TP
+.BI mount_opts= mount_option_string
+Set a set of default mount options which will be used when the file
+system is mounted. Unlike the bitmask-based default mount options which
+can be specified with the
+.B -o
+option,
+.I mount_option_string
+is an arbitrary string with a maximum length of 63 bytes, which is
+stored in the superblock.
+.IP
+The ext4 file system driver will first apply
+the bitmask-based default options, and then parse the
+.IR mount_option_string ,
+before parsing the mount options passed from the
+.BR mount (8)
+program.
+.IP
+This superblock setting is only honored in 2.6.35+ kernels;
+and not at all by the ext2 and ext3 file system drivers.
+.TP
+.B force_fsck
+Set a flag in the file system superblock indicating that errors have been found.
+This will force fsck to run at the next mount.
+.TP
+.B test_fs
+Set a flag in the file system superblock indicating that it may be
+mounted using experimental kernel code, such as the ext4dev file system.
+.TP
+.B ^test_fs
+Clear the test_fs flag, indicating the file system should only be mounted
+using production-level file system code.
+.RE
+.TP