debugfs basic usage in Linux

First, list files with inodes in a target filesystem:

$ cd /mnt
$ ls -il

Use debugfs to open the filesystem in debug mode in Linux:

debugfs /dev/vgstriped/lvdata

That is a pretty dangerous mode that allows you to do a lot of things that you shouldn't never be doing on an open file system. Note that the filesystem shouldn't be used by processes and have open files.

So, with debugfs you can do advanced stuff on an ext4 filesystem such as:

• looking into an inode:

  debugfs: stat <14>

  14 - is the target inode to look to, and you will get a lot of information about this inode: permissions, flags, acls, extents and so on
• dumping contents of an inode

  debugfs: dump <22> dumped

  22 - is the target inode to be dumped
  dumped - is the file name where the contents will be stored