Overlayfs: restore removed or changed file from "lower"

Question

OpenWrt uses overlayfs

# mount | grep overlay
/dev/ubi0_2 on /overlay type ubifs (rw,noatime)
overlayfs:/overlay on / type overlay (rw,noatime,lowerdir=/,upperdir=/overlay/upper,workdir=/overlay/work)

Somehow real lowerdir is /rom

# mount | grep rom
mtd:ubi_rootfs on /rom type squashfs (ro,relatime)

How to restore file to make it the as in /rom? Remove records from overlays: whiteouts and opaque dirs.

Workaround

cp /rom/path/to/file /overlay/upper/path/to/file

Similar question but about AUFS https://unix.stackexchange.com/questions/92287/aufs-whiteout-removal. — kyb, Sep 10 '19 at 10:33

score 9 · Accepted Answer · answered Sep 17 '19 at 06:20

9

Remove file from /overlay/upper, and then remount rootfs.

rm /overlay/upper/my/file
mount -o remount /

answered Sep 17 '19 at 06:20

kyb

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Thanks, works like a charm! I figured the first command myself then was going to reboot the router, but remount is enough apparently and much faster. – Thomas Guyot-Sionnest Dec 09 '21 at 19:53
It might be even enough just to remount the overlayfs instead of the full rootfs. – Martin H. Jan 18 '22 at 14:20

Overlayfs: restore removed or changed file from "lower"

1 Answers1