Add Hardlink Compatibility with Separate Rebalance Script

zfs-hardlink-rebalancing.sh

@@ -0,0 +1,282 @@
+#!/usr/bin/env bash
+
+# exit script on error
+set -e
+# exit on undeclared variable
+set -u
+
+# file used to track processed files
+rebalance_db_file_name="rebalance_db.txt"
+
+# index used for progress
+current_index=0
+
+## Color Constants
+
+# Reset
+Color_Off='\033[0m'       # Text Reset
+
+# Regular Colors
+Red='\033[0;31m'          # Red
+Green='\033[0;32m'        # Green
+Yellow='\033[0;33m'       # Yellow
+Cyan='\033[0;36m'         # Cyan
+
+## Functions
+
+# print a help message
+function print_usage() {
+  echo "Usage: zfs-inplace-rebalancing --checksum true --passes 1 source dest"
+  echo "Note: hardlinks in the 'dest' path will be temporarily deleted during the rebalance."
+}
+
+# print a given text entirely in a given color
+function color_echo () {
+    color=$1
+    text=$2
+    echo -e "${color}${text}${Color_Off}"
+}
+
+
+function get_rebalance_count () {
+    file_path=$1
+
+    line_nr=$(grep -xF -n "${file_path}" "./${rebalance_db_file_name}" | head -n 1 | cut -d: -f1)
+    if [ -z "${line_nr}" ]; then
+        echo "0"
+        return
+    else
+        rebalance_count_line_nr="$((line_nr + 1))"
+        rebalance_count=$(awk "NR == ${rebalance_count_line_nr}" "./${rebalance_db_file_name}")
+        echo "${rebalance_count}"
+        return
+    fi
+}
+
+# rebalance a specific file
+function rebalance () {
+    file_path=$1
+    hardlink_dir=$2
+
+    # check if file has exactly 2 links
+    # this shouldn't be needed in the typical case of `find` only finding files with links == 2
+    # but this can run for a long time, so it's good to double check if something changed
+    if [[ "${OSTYPE,,}" == "linux-gnu"* ]]; then
+        # Linux
+        #
+        #  -c  --format=FORMAT
+        #      use the specified FORMAT instead of the default; output a
+        #      newline after each use of FORMAT
+        #  %h     number of hard links
+
+        hardlink_count=$(stat -c "%h" "${file_path}")
+    elif [[ "${OSTYPE,,}" == "darwin"* ]] || [[ "${OSTYPE,,}" == "freebsd"* ]]; then
+        # Mac OS
+        # FreeBSD
+        #  -f format
+        #  Display information using the specified format
+        #   l       Number of hard links to file (st_nlink)
+
+        hardlink_count=$(stat -f %l "${file_path}")
+    else
+    	echo "Unsupported OS type: $OSTYPE"
+    	exit 1
+    fi
+
+    if [ "${hardlink_count}" -ne 2 ]; then
+        echo "Skipping non hard-linked file: ${file_path}"
+        return
+    fi
+
+    current_index="$((current_index + 1))"
+    progress_percent=$(printf '%0.2f' "$((current_index*10000/file_count))e-2")
+    color_echo "${Cyan}" "Progress -- Files: ${current_index}/${file_count} (${progress_percent}%)" 
+
+    # skip if the source file is no longer there
+    if [[ ! -f "${file_path}" ]]; then
+        color_echo "${Yellow}" "File is missing, skipping: ${file_path}" 
+	return
+    fi
+
+    # skip if hardlink file is not found
+    inode_val=$(ls -i "${file_path}" | awk '{print $1}')
+    hardlink_path=$(find "${hardlink_dir}" -inum ${inode_val})
+    if [[ ! -f "${hardlink_path}" ]]; then
+        color_echo "${Yellow}" "Hardlink is missing, skipping: ${file_path}"
+	return
+    fi
+
+    # skip if target number of passes is reached
+    if [ "${passes_flag}" -ge 1 ]; then
+        # check if target rebalance count is reached
+        rebalance_count=$(get_rebalance_count "${file_path}")
+        if [ "${rebalance_count}" -ge "${passes_flag}" ]; then
+        color_echo "${Yellow}" "Rebalance count (${passes_flag}) reached, skipping: ${file_path}"
+        return
+        fi
+    fi
+
+    tmp_extension=".balance"
+    tmp_file_path="${file_path}${tmp_extension}"
+
+    # create copy of file with .balance suffix
+    echo "Copying '${file_path}' to '${tmp_file_path}'..."
+    if [[ "${OSTYPE,,}" == "linux-gnu"* ]]; then
+        # Linux
+
+        # --reflink=never -- force standard copy (see ZFS Block Cloning)
+        # -a -- keep attributes, includes -d -- keep symlinks (dont copy target) and 
+        #       -p -- preserve ACLs to
+        # -x -- stay on one system
+        cp --reflink=never -ax "${file_path}" "${tmp_file_path}"
+    elif [[ "${OSTYPE,,}" == "darwin"* ]] || [[ "${OSTYPE,,}" == "freebsd"* ]]; then
+        # Mac OS
+        # FreeBSD
+
+        # -a -- Archive mode.  Same as -RpP. Includes preservation of modification 
+        #       time, access time, file flags, file mode, ACL, user ID, and group 
+        #       ID, as allowed by permissions.
+        # -x -- File system mount points are not traversed.
+        cp -ax "${file_path}" "${tmp_file_path}"
+    else
+        echo "Unsupported OS type: $OSTYPE"
+        exit 1
+    fi
+
+    # compare copy against original to make sure nothing went wrong
+    if [[ "${checksum_flag,,}" == "true"* ]]; then
+        echo "Comparing copy against original..."
+        if [[ "${OSTYPE,,}" == "linux-gnu"* ]]; then
+            # Linux
+
+            # file attributes
+            original_md5=$(lsattr "${file_path}" | awk '{print $1}')
+            # file permissions, owner, group
+            # shellcheck disable=SC2012
+            original_md5="${original_md5} $(ls -lha "${file_path}" | awk '{print $1 " " $3 " " $4}')"
+            # file content
+            original_md5="${original_md5} $(md5sum -b "${file_path}" | awk '{print $1}')"
+
+            # file attributes
+            copy_md5=$(lsattr "${tmp_file_path}" | awk '{print $1}')
+            # file permissions, owner, group
+            # shellcheck disable=SC2012
+            copy_md5="${copy_md5} $(ls -lha "${tmp_file_path}" | awk '{print $1 " " $3 " " $4}')"
+            # file content
+            copy_md5="${copy_md5} $(md5sum -b "${tmp_file_path}" | awk '{print $1}')"
+        elif [[ "${OSTYPE,,}" == "darwin"* ]] || [[ "${OSTYPE,,}" == "freebsd"* ]]; then
+            # Mac OS
+            # FreeBSD
+
+            # file attributes
+            original_md5=$(lsattr "${file_path}" | awk '{print $1}')
+            # file permissions, owner, group
+            # shellcheck disable=SC2012
+            original_md5="${original_md5} $(ls -lha "${file_path}" | awk '{print $1 " " $3 " " $4}')"
+            # file content
+            original_md5="${original_md5} $(md5 -q "${file_path}")"
+
+            # file attributes
+            copy_md5=$(lsattr "${tmp_file_path}" | awk '{print $1}')
+            # file permissions, owner, group
+            # shellcheck disable=SC2012
+            copy_md5="${copy_md5} $(ls -lha "${tmp_file_path}" | awk '{print $1 " " $3 " " $4}')"
+            # file content
+            copy_md5="${copy_md5} $(md5 -q "${tmp_file_path}")"
+        else
+            echo "Unsupported OS type: $OSTYPE"
+            exit 1
+        fi
+
+        if [[ "${original_md5}" == "${copy_md5}"* ]]; then
+            color_echo "${Green}" "MD5 OK"
+        else
+            color_echo "${Red}" "MD5 FAILED: ${original_md5} != ${copy_md5}"
+            exit 1
+        fi
+    fi
+
+    echo "Removing hardlink '${hardlink_path}'..."
+    rm "${hardlink_path}"
+
+    echo "Removing original '${file_path}'..."
+    rm "${file_path}"
+
+    echo "Renaming temporary copy to original '${file_path}'..."
+    mv "${tmp_file_path}" "${file_path}"
+
+    echo "Recreating deleted hardlink '${hardlink_path}'..."
+    ln "$file_path" "$hardlink_path"
+
+    if [ "${passes_flag}" -ge 1 ]; then
+        # update rebalance "database"
+        line_nr=$(grep -xF -n "${file_path}" "./${rebalance_db_file_name}" | head -n 1 | cut -d: -f1)
+        if [ -z "${line_nr}" ]; then
+            rebalance_count=1
+            echo "${file_path}" >> "./${rebalance_db_file_name}"
+            echo "${rebalance_count}" >> "./${rebalance_db_file_name}"
+        else
+            rebalance_count_line_nr="$((line_nr + 1))"
+            rebalance_count="$((rebalance_count + 1))"
+            sed -i "${rebalance_count_line_nr}s/.*/${rebalance_count}/" "./${rebalance_db_file_name}"
+        fi
+    fi
+}
+
+checksum_flag='true'
+passes_flag='1'
+
+if [[ "$#" -eq 0 ]]; then
+    print_usage
+    exit 0
+fi
+
+while true ; do
+    case "$1" in
+        -h | --help )
+            print_usage
+            exit 0
+        ;;
+        -c | --checksum )
+            if [[ "$2" == 1 || "$2" =~ (on|true|yes) ]]; then
+                checksum_flag="true"
+            else
+                checksum_flag="false"
+            fi
+            shift 2
+        ;;
+        -p | --passes )
+            passes_flag=$2
+            shift 2
+        ;;
+        *)
+            break
+        ;;
+    esac 
+done;
+
+source_path=$1
+dest_path=$2
+
+color_echo "$Cyan" "Start rebalancing $(date):"
+color_echo "$Cyan" "  Rebalance Path: ${source_path}"
+color_echo "$Cyan" "  Hardlink Path: ${dest_path}"
+color_echo "$Cyan" "  Rebalancing Passes: ${passes_flag}"
+color_echo "$Cyan" "  Use Checksum: ${checksum_flag}"
+
+# count number of hardlinked files
+file_count=$(find "${source_path}" -type f -links 2 | wc -l)
+
+color_echo "$Cyan" "  File count: ${file_count}"
+
+# create db file
+if [ "${passes_flag}" -ge 1 ]; then
+    touch "./${rebalance_db_file_name}"
+fi
+
+# recursively scan through files and execute "rebalance" procedure if the file is a hardlink
+find "${source_path}" -type f -links 2 -print0 | while IFS= read -r -d '' file; do rebalance "${file}" "${dest_path}"; done
+
+echo ""
+echo ""
+color_echo "$Green" "Done!"