I have 2 data sources. One is btrfs (raid) and one is a simple ext4 partition. Those should be transparently displayed as one. This is a simple read only example, but the lower/upper/workdir version produces the same problem, with btrfs as upper and ext4 as lower.
mount -t overlay overlay -o lowerdir=/mnt/raid/folder1/:/mnt/ext4/folder1 -o comment=merge -o nfs_export=on /data/merged
overlay /data/merged overlay defaults,lowerdir=/mnt/raid/folder1/:/mnt/ext4/folder1,comment=merge,nfs_export=on 0 0
this is my nfs export:
exportfs -ra produces:
exportfs: /data/merged does not support NFS export
My configuration: Ubuntu 18.04 LTS with HWE kernel 4.18.0-13-generic This is my main source for the config: https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt
Maybe I am missing some NFSv4 stuff (which is needed for nfs exporting an overlayfs) ?
I am in a chicken-egg situation for my secondary harddrive (non boot):
- My BTRFS mount has gone readonly because no space left.
btrfs filesystem resize only works on mounted volumes.
- I needed to umount this ro mount in force mode (because of device busy).
- If I try to mount rw it fails because of errors (most likely caused by no space left)
- If I try to run
btrfs check --repair it gives device busy
What to do to find out what keeps
/dev/sda busy? My hdd is listed in
/etc/fstab, does that matter (
UUID=262a8d86-279a-4f6b-8968-32e200c32255 /mnt/hdd btrfs defaults,compress=zlib 0 1)???
lsof | grep /dev/s -> nothing
lsof | grep /mnt/hdd-> nothing
- The same for
fuser -> nothing
mount -o recovery /dev/sda /mnt/hdd
[63035.539792] BTRFS error (device sda): Remounting read-write after error is not allowed
If I try to run:
root@myhost:/mnt# btrfs check --repair /dev/sda enabling repair mode ERROR: cannot open device '/dev/sda': Device or resource busy ERROR: cannot open file system