It resulted in random, hard to reproduce ENOSPC errors down the line without either data or metadata being anywhere close to full. Neither us nor the btrfs developers that took a look at it were able to figure out what exactly went wrong, but it was something about new blocks not fitting anywhere despite lots of free space.
Someone on #btrfs said that the filesystem layout is a lot different when using the conversion tool and all of the regression testing happens with regular filesystems, not converted ones.
We reinstalled all machines from scratch. Never happened again.
Someone on #btrfs said that the filesystem layout is a lot different when using the conversion tool and all of the regression testing happens with regular filesystems, not converted ones.
We reinstalled all machines from scratch. Never happened again.