Explanation of errors found by fsck on ext4 filesystem

Solution 1:

These are not errors. They are standard info messages.

You say that fsck fixed them, so there's nothing to worry about. It is not necessarily because you used shutdown -r. It could be due to a lot of different reasons.

As long as fsck was successful, there's no reason to be alarmed.

Solution 2:

To properly check your file system...

• boot to a Ubuntu Live DVD/USB in “Try Ubuntu” mode
• open a terminal window by pressing Ctrl+Alt+T
• type sudo fdisk -l
• identify the /dev/sdXX device name for your "Linux Filesystem"
• type sudo fsck -f /dev/sdXX, replacing sdXX with the number you found earlier
• repeat the fsck command if there were errors
• type reboot