Installer partitioning step lets users resize a live Windows NTFS partition with cfdisk, resulting in unbootable Windows

[alkevintan]

Bug description

During install alongside existing Windows 11 on the same drive, the guided partitioning step launches cfdisk. I selected the existing Windows C: partition and used [ Resize ] to shrink it from 237.5G to 202.5G, then wrote.

cfdisk only rewrites the GPT entry — the NTFS filesystem inside still reported its original size. On next boot into Windows:

STOP CODE: UNMOUNTABLE_BOOT_VOLUME

Windows validates that the boot sector's declared volume size matches the partition and refuses to mount otherwise.

Evidence

From /var/log/omarchy-install.log: cfdisk session showing /dev/sdb3 resized 498059264 → 424673280 sectors ("Partition 3 resized"), followed by table write. No ntfsresize was ever run.

Expected behavior

Either

• warn/block when resizing a partition containing an in-use NTFS filesystem, pointing users to shrink from Windows Disk Management first, or
• run ntfsresize after the cfdisk resize when the target filesystem is NTFS (ntfsprogs available), or
• document this prominently in the dual-boot install docs.

Notes

Recoverable after the fact (patch NTFS boot sector size field to match the partition + ntfsfix + chkdsk), but data extents beyond the new boundary are already lost — this trap can cause silent data loss for dual-booters.

Omarchy version: 4.0.0. Full install logs available on request.

[alkevintan]

Follow-up: the other half of this dual-boot experience is also broken — limine-scan (the documented way to re-add Windows to the boot menu) generates a non-bootable entry because it copies the uppercase path from efibootmgr verbatim, while Limine's FAT lookup is case-sensitive. Details and fix suggestion in #7906.

[rastermanden]

This is a data-loss bug in the ISO configurator’s cfdisk path, not a suggestion.

cfdisk Resize only rewrites the GPT and does not shrink NTFS/ext4/btrfs/LUKS. The patch against omacom-io/omarchy-iso warns that Resize is table-only, snapshots the GPT, and restores it if an existing partition shrank. Deleting unused partitions to make free space still works.

PR: omacom/omarchy-iso#122