VirtioFS reports incorrect filesystem capacity for an APFS external volume #2713

Describe the bug

OrbStack reports an incorrect filesystem capacity for a bind-mounted APFS external volume.

The host volume is approximately 2 TB, with about 106 GB free. However, inside a container using an OrbStack VirtioFS bind mount, statfs() reports approximately 465 TiB total capacity and 439 TiB used.

This causes applications such as Immich to display incorrect storage information.

Environment

• macOS: 15.4.1 (24E263)
• OrbStack: 2.2.3
• Docker Engine: 29.4.0
• Host filesystem: APFS
• External volume: /Volumes/KIOKA
• Volume size: 2.0 TB
• Mount type inside container: VirtioFS

To Reproduce

1. Create a directory on an external APFS volume:

   mkdir -p /Volumes/KIOKA/test-volume

2. Start a container with a bind mount:

   docker run --rm \
     -v /Volumes/KIOKA/test-volume:/data \
     alpine:latest \
     df -h /data

3. Compare the result with the host:

   df -h /Volumes/KIOKA

4. Read the filesystem statistics from a Node.js container:

   docker run --rm \
     -v /Volumes/KIOKA/test-volume:/data \
     node:22-alpine \
     node -e '
       const fs = require("node:fs");
       const s = fs.statfsSync("/data", { bigint: true });
       console.log({
         blocks: s.blocks.toString(),
         bfree: s.bfree.toString(),
         bavail: s.bavail.toString(),
         bsize: s.bsize.toString()
       });
     '

Actual behavior

On the host:

/dev/disk7s1   1.8Ti   1.7Ti   106Gi   95%   /Volumes/KIOKA

Inside the container, /data reports:

Filesystem      Size  Used Avail Use%
mac             1.9T  1.8T  107G  95%  /data

However, Node.js calculates the following from statfs():

total: 465.75 TiB
used:  439.22 TiB
free:   26.53 TiB

The relevant values are:

blocks: 488374545
bfree:  27817877
bavail: 27817877
bsize:  1048576

Expected behavior

The container should receive filesystem statistics matching the host volume:

total: approximately 1.8 TiB
used:  approximately 1.7 TiB
free:  approximately 106 GiB

Diagnostic report (REQUIRED)

OrbStack info:
Version: 2.2.3
Commit: c83556b0ef8f1ba9a33abbb194622b6b7a1c0307 (v2.2.3)

System info:
macOS: 15.4.1 (24E263)
CPU: arm64, 10 cores
CPU model: Apple M4
Model: Mac16,10
Memory: 16 GiB

Full report: https://orbstack.dev/_admin/diag/orbstack-diagreport_2026-09-25T12-09-46.644794Z.zip

Screenshots and additional context (optional)

No response

This may be related to #2532, but it appears to be a different manifestation. In this case, the block count is approximately correct for the 2 TB volume, while f_bsize is reported as 1 MiB instead of approximately 4 KiB. This produces a 256x capacity inflation.