initramfs-tools-core: fsck hook does not honor <pass> field from /etc/fstab

[andrea biardi]

In Ubuntu 24 LTS, update-initramfs calls its fsck hook to determine which fsck binaries, if any, need to be installed in the initramfs.

Unfortunately, it does honor the <pass> field correctly; when set to zero, the intended behavior is not to run any fsck at boot.

This is useful, for example, when the root filesystem is on zfs, and the entry in /etc/fstab typically reads:

tank/root / zfs defaults 0 0

(or, equally, lacks the last two fields - as documented in "man fstab")

Currently, update-initramfs produces this warning:

W: Couldn't identify type of root file system for fsck hook

Note that there are other filesystem types for which the administrator might want to set <pass> to zero; I am attaching a patch that corrects the behavior of the fsck hook to respect the setting configured by them.