| #!/bin/sh |
| |
| dir="$1" |
| dev="$2" |
| |
| if [ "$1" = "--help" ] || [ ! -d "${dir}" ]; then |
| echo "Usage: $0 dir [mke2fs args] dev" |
| exit 1 |
| fi |
| |
| shift |
| |
| # Goal: Put all the files at the beginning (which mke2fs does) and minimize |
| # the number of free inodes given the minimum number of blocks required. |
| # Hence all this math to get the inode ratio just right. |
| |
| bytes="$(du -ks "${dir}" | awk '{print $1}')" |
| bytes="$((bytes * 1024))" |
| inodes="$(find "${dir}" -print0 | xargs -0 stat -c '%i' | sort -g | uniq | wc -l)" |
| block_sz=4096 |
| inode_sz=256 |
| sb_overhead=4096 |
| blocks_per_group="$((block_sz * 8))" |
| bytes_per_group="$((blocks_per_group * block_sz))" |
| inode_bytes="$((inodes * inode_sz))" |
| |
| # Estimate overhead with the minimum number of groups... |
| nr_groups="$(( (bytes + inode_bytes + bytes_per_group - 1) / bytes_per_group))" |
| inode_bytes_per_group="$((inode_bytes / nr_groups))" |
| inode_blocks_per_group="$(( (inode_bytes_per_group + (block_sz - 1)) / block_sz ))" |
| per_grp_overhead="$(( ((3 + inode_blocks_per_group) * block_sz) + 64 ))" |
| overhead="$(( sb_overhead + (per_grp_overhead * nr_groups) ))" |
| used_bytes="$((bytes + overhead))" |
| |
| # Then do it again with the real number of groups. |
| nr_groups="$(( (used_bytes + (bytes_per_group - 1)) / bytes_per_group))" |
| tot_blocks="$((nr_groups * blocks_per_group))" |
| tot_bytes="$((tot_blocks * block_sz))" |
| |
| ratio="$((bytes / inodes))" |
| mkfs_blocks="$((tot_blocks * 4 / 3))" |
| |
| mke2fs -i "${ratio}" -T ext4 -d "${dir}" -O ^resize_inode,sparse_super2,metadata_csum,64bit,^has_journal -E packed_meta_blocks=1,num_backup_sb=0 -b "${block_sz}" -I "${inodesz}" -F "${dev}" "${mkfs_blocks}" || exit |
| |
| e2fsck -fyD "${dev}" |
| |
| blocks="$(dumpe2fs -h "${dev}" 2>&1 | grep 'Block count:' | awk '{print $3}')" |
| while resize2fs -f -M "${dev}"; do |
| new_blocks="$(dumpe2fs -h "${dev}" 2>&1 | grep 'Block count:' | awk '{print $3}')" |
| if [ "${new_blocks}" -eq "${blocks}" ]; then |
| break; |
| fi |
| blocks="${new_blocks}" |
| done |
| |
| if [ ! -b "${dev}" ]; then |
| truncate -s "$((blocks * block_sz))" "${dev}" || (e2image -ar "${dev}" "${dev}.min"; mv "${dev}.min" "${dev}") |
| fi |
| |
| e2fsck -fy "${dev}" |
| |
| dir_blocks="$((bytes / block_sz))" |
| overhead="$((blocks - dir_blocks))" |
| echo "Minimized image overhead: $((100 * overhead / dir_blocks))%" |
| |
| exit 0 |