It is actually wise to shrink a btrfs filesystem on its partition by a few megabytes, so some expansion room is available in an emergency. There are very few f

It is actually wise to shrink a btrfs filesystem on its partition by a few megabytes, so some expansion room is available in an emergency. There are very few filesystems that can shrink like this: btrfs filesystem resize -1G /mount If the "btrfs fi df" command shows any of the data/system/metadata elements close to limits, it is time to take action. They can all push you into read-only mode.