[linux-lvm] Rebuilding physical volume metadata

[Sasha Z]

I have managed to restore the volume group, but I can't mount it as a
filesystem, I can't format the logical volume, I can't do anything
with lvextend, etc.

Here's a basic operation that fails:

[root at fileserver mapper]# lvextend -L+5G /dev/vg0/lv0
  Extending logical volume lv0 to 525.70 GB
  device-mapper ioctl cmd 9 failed: Invalid argument
  Couldn't load device 'vg0-lv0'.
  Problem reactivating lv0

After doing that, lvdisplay says the logical volume is suspended.
What's wrong? /dev/vg0/lv0 is a symlink to /dev/mapper/vg0-lv0