Fix BTRFS 'no space left' errors on Ubuntu when df shows available space

btrfs_fix_ubuntu_no_space.sh

#!/bin/bash
#
# BTRFS "No Space Left" Fix for Ubuntu
# Fixes ENOSPC errors when df shows available space
# https://gist.github.com/your-username/gist-id
#
# Usage: 
#   chmod +x btrfs_fix_ubuntu_no_space.sh
#   ./btrfs_fix_ubuntu_no_space.sh
#

set -e

echo "=== BTRFS No Space Left Fix ==="
echo ""

# Check if running on BTRFS
echo "1. Checking filesystem type..."
if ! command -v btrfs &> /dev/null; then
    echo "ERROR: btrfs command not found. This script is for BTRFS filesystems only."
    exit 1
fi

echo ""
echo "2. Current BTRFS filesystem usage:"
sudo btrfs filesystem usage /

echo ""
echo "3. Running BTRFS balance to reclaim metadata space..."
echo "   This may take 2-5 minutes..."

# Balance data chunks with low usage
sudo btrfs balance start -dusage=5 /

# Balance metadata chunks with low usage
sudo btrfs balance start -musage=5 /

echo ""
echo "4. Balance complete. Checking disk space:"
df -h /

echo ""
echo "=== Fix Complete ==="
echo "If you still get ENOSPC errors, run with higher usage values:"
echo "  sudo btrfs balance start -dusage=20 /"
echo "  sudo btrfs balance start -musage=20 /"