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Working-partition ext4 filesystem shuts down unclean

February 21, 2020 — BarryK

The previous post about a corrupted superblock has raised another interesting fact. Yesterday's post:

Feodor has been running filesystem checks on the working-partition of some EasyOS USB-sticks, and found that they all have faults in the filesystem. Whereas, Quirky does not. Yes, I have replied to Feodor by email, repeated here:

Actually, the problem with ext3 and ext4 filesystem being "unclean" has always been there, even with the puppies, from the old versions to ...I presume, current versions.

It is because of the aufs layered filesystem, the ext3/4 f.s. in one of the layers, usually the top layer, doesn't unmount properly before shutdown.

We never had a solution for it. The aufs layers are setup in the initrd, then there is a switch_root to the top of the layered filesystem, and the initrd is gone, erased. There is no way to get back to the initrd to unmount the aufs filesystem, not properly anyway.

Actually, the very early puppies used 'pivot_root', which retains the initrd, and it was possible to go back to it at shutdown, and unmount the aufs. That was when the initrd was on a /dev/ram devices, before initrd bacame a cpio and ran in devtmpfs in RAM.

Quirky, on the otherhand, is a full install only, so no aufs layers.

If someone can figure out how to shutdown EasyOS (and the pups) so that a filesystem-check reports no errors, then you will get a prize!

Note, these errors are "harmless", or rather, we have never seen any negative result from them. 

Tags: easy