debugfs:  ?
Available debugfs requests:

show_debugfs_params, params
                         Show debugfs parameters
open_filesys, open       Open a filesystem
close_filesys, close     Close the filesystem
freefrag, e2freefrag     Report free space fragmentation
feature, features        Set/print superblock features
dirty_filesys, dirty     Mark the filesystem as dirty
init_filesys             Initialize a filesystem (DESTROYS DATA)
show_super_stats, stats  Show superblock statistics
ncheck                   Do inode->name translation
icheck                   Do block->inode translation
change_root_directory, chroot
                         Change root directory
change_working_directory, cd
                         Change working directory
list_directory, ls       List directory
show_inode_info, stat    Show inode information 
dump_extents, extents, ex
                         Dump extents information 
blocks                   Dump blocks used by an inode 
filefrag                 Report fragmentation information for an inode
link, ln                 Create directory link
unlink                   Delete a directory link
mkdir                    Create a directory
rmdir                    Remove a directory
rm                       Remove a file (unlink and kill_file, if appropriate)
kill_file                Deallocate an inode and its blocks
clri                     Clear an inode‘s contents
freei                    Clear an inode‘s in-use flag
seti                     Set an inode‘s in-use flag
testi                    Test an inode‘s in-use flag
freeb                    Clear a block‘s in-use flag
setb                     Set a block‘s in-use flag
testb                    Test a block‘s in-use flag
modify_inode, mi         Modify an inode by structure
find_free_block, ffb     Find free block(s)
find_free_inode, ffi     Find free inode(s)
print_working_directory, pwd
                         Print current working directory
expand_dir, expand       Expand directory
mknod                    Create a special file
list_deleted_inodes, lsdel
                         List deleted inodes
undelete, undel          Undelete file
write                    Copy a file from your native filesystem
dump_inode, dump         Dump an inode out to a file
cat                      Dump an inode out to stdout
lcd                      Change the current directory on your native filesystem
rdump                    Recursively dump a directory to the native filesystem
set_super_value, ssv     Set superblock value
set_inode_field, sif     Set inode field
set_block_group, set_bg  Set block group descriptor field
logdump                  Dump the contents of the journal
htree_dump, htree        Dump a hash-indexed directory
dx_hash, hash            Calculate the directory hash of a filename
dirsearch                Search a directory for a particular filename
bmap                     Calculate the logical->physical block mapping for an inode
punch, truncate          Punch (or truncate) blocks from an inode by deallocating them
symlink                  Create a symbolic link
imap                     Calculate the location of an inode
dump_unused              Dump unused blocks
set_current_time         Set current time to use when setting filesystem fields
supported_features       Print features supported by this version of e2fsprogs
dump_mmp                 Dump MMP information
set_mmp_value, smmp      Set MMP value
extent_open, eo          Open inode for extent manipulation
zap_block, zap           Zap block: fill with 0, pattern, flip bits etc.
block_dump, bd           Dump contents of a block
help                     Display info on command or topic.
list_requests, lr, ?     List available commands.
quit, q                  Leave the subsystem.
debugfs:  
debugfs:  
debugfs:  
debugfs:  
debugfs:  q