Why do I have "errors=remount-ro" option in my ext4 partition in my Linux?

Question

In mount man page errors=remount-ro is an option for mounting fat but this option doesn't appear in ext4 options catalog. I know what this option means: In case of mistake remounting the partition like readonly but I don't know if it's a correct option or only a bug.

Answer 1

It is perfectly valid for ext4, and is defined in the ext4 manpage:

errors={continue|remount-ro|panic}

Define the behavior when an error is encountered. (Either ignore errors and just mark the filesystem erroneous and continue, or remount the filesystem read-only, or panic and halt the system.) The default is set in the filesystem superblock, and can be changed using tune2fs(8).

Some versions of the mount manpage do list this option for ext4; others refer to the manpage linked above:

Mount options for ext2, ext3 and ext4

See the options section of the ext2(5), ext3(5) or ext4(5) man page (the e2fsprogs package must be installed).