Partition Move & Resize Engine

Moving or resizing a partition requires careful coordination between filesystem dimensions and low-level partition table boundaries. fparted enforces mathematical sequencing for all geometry transitions.

---

🔄 Shrink vs Grow Execution Ordering

To prevent data corruption, operations follow opposite ordering depending on whether the partition is shrinking or growing:

flowchart TD
    subgraph Shrink Flow
        S1[1. Unmount Target] --> S2[2. Check Filesystem: e2fsck]
        S2 --> S3[3. Shrink Filesystem: resize2fs]
        S3 --> S4[4. Shrink Partition Boundary: parted resizepart]
    end

    subgraph Grow Flow
        G1[1. Grow Partition Boundary: parted resizepart] --> G2[2. Grow Filesystem: resize2fs / resize.f2fs]
        G2 --> G3[3. Verify Filesystem Integrity]
    end

[!IMPORTANT] If a partition boundary were shrunk before the filesystem inside it, the filesystem's metadata and trailing data blocks would be instantly truncated and lost. fparted guarantees that resize2fs always precedes parted resizepart during shrink operations.

---

🔀 Three-Case Move Algorithm

Moving a partition involves one of three geometric cases:

Case 1: Non-Overlapping Move

When new boundaries do not intersect old boundaries: 1. Create a temporary target partition at the new location (mkpart). 2. Smart copy filesystem data (e2image -ra -p for ext4, or dd conv=fsync for raw blocks). 3. Remove the old partition entry (rm).

Case 2: Overlapping Left Move (newStart < oldStart)

When shifting a partition toward the beginning of the disk: 1. Expand the partition rightwards/leftwards to encompass both ranges (resizepart). 2. Copy blocks in forward direction (skip=oldStart seek=newStart conv=notrunc). 3. Truncate trailing sectors to match the final size.

Case 3: Overlapping Right Move (newStart > oldStart)

When shifting a partition toward the end of the disk: 1. Expand the partition boundary rightwards (resizepart). 2. Copy blocks in reverse order to prevent source data overwrite. 3. Adjust final start/end boundaries and verify with e2fsck.