+.B \-D
+Optimize directories in filesystem. This option causes e2fsck to
+try to optimize all directories, either by reindexing them if the
+filesystem supports directory indexing, or by sorting and compressing
+directories for smaller directories, or for filesystems using
+traditional linear directories.
+.IP
+Even without the
+.B \-D
+option,
+.B e2fsck
+may sometimes optimize a few directories --- for example, if
+directory indexing is enabled and a directory is not indexed and would
+benefit from being indexed, or if the index structures are corrupted
+and need to be rebuilt. The
+.B \-D
+option forces all directories in the filesystem to be optimized. This can
+sometimes make them a little smaller and slightly faster to search, but
+in practice, you should rarely need to use this option.
+.IP
+The
+.B \-D
+option will detect directory entries with duplicate names in a single
+directory, which e2fsck normally does not enforce for performance reasons.
+.TP
+.BI \-E " extended_options"
+Set e2fsck extended options. Extended options are comma
+separated, and may take an argument using the equals ('=') sign. The
+following options are supported:
+.RS 1.2i
+.TP
+.BI ea_ver= extended_attribute_version
+Set the version of the extended attribute blocks which
+.B e2fsck
+will require while checking the filesystem. The version number may
+be 1 or 2. The default extended attribute version format is 2.
+.TP
+.BI journal_only
+Only replay the journal if required, but do not perform any further checks
+or repairs.
+.TP
+.BI fragcheck
+During pass 1, print a detailed report of any discontiguous blocks for
+files in the filesystem.
+.TP
+.BI discard
+Attempt to discard free blocks and unused inode blocks after the full
+filesystem check (discarding blocks is useful on solid state devices and sparse
+/ thin-provisioned storage). Note that discard is done in pass 5 AFTER the
+filesystem has been fully checked and only if it does not contain recognizable
+errors. However there might be cases where
+.B e2fsck
+does not fully recognize a problem and hence in this case this
+option may prevent you from further manual data recovery.
+.TP
+.BI nodiscard
+Do not attempt to discard free blocks and unused inode blocks. This option is
+exactly the opposite of discard option. This is set as default.
+.TP
+.BI no_optimize_extents
+Do not offer to optimize the extent tree by eliminating unnecessary
+width or depth.
+.TP
+.BI readahead_kb
+Use this many KiB of memory to pre-fetch metadata in the hopes of reducing
+e2fsck runtime. By default, this is set to the size of two block groups' inode
+tables (typically 4MiB on a regular ext4 filesystem); if this amount is more
+than 1/50th of total physical memory, readahead is disabled. Set this to zero
+to disable readahead entirely.
+.TP
+.BI bmap2extent
+Convert block-mapped files to extent-mapped files.
+.TP
+.BI fixes_only
+Only fix damaged metadata; do not optimize htree directories or compress
+extent trees. This option is incompatible with the -D and -E bmap2extent
+options.
+.RE
+.TP
+.B \-f