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fix: upgrade snapshot epoch bump to hard error #470

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Merged
ejc3 merged 2 commits into from
Feb 23, 2026
Merged

fix: upgrade snapshot epoch bump to hard error #470

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bffc6fc
fix: upgrade patch_mmds to hard error after snapshot creation
ejc3 Feb 23, 2026
2134b7f
fix: clean up temp snapshot dir on MMDS epoch bump failure
ejc3 Feb 23, 2026
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8 changes: 6 additions & 2 deletions src/commands/common.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1436,7 +1436,10 @@ pub async fn create_snapshot_core(

// Firecracker resets all vsock connections during snapshot creation
// (VIRTIO_VSOCK_EVENT_TRANSPORT_RESET). Bump restore-epoch in MMDS so fc-agent's
// background watcher detects this and remounts FUSE volumes.
// background watcher detects this and triggers handle_clone_restore() which
// re-registers the exec server's AsyncFd (stale after transport reset) and
// reconnects the output vsock. This MUST succeed — if the epoch isn't bumped,
// the exec server stays stale and health checks hang for ~60s.
let restore_epoch = std::time::SystemTime::now()
.duration_since(std::time::UNIX_EPOCH)
.map(|d| d.as_secs())
Expand All @@ -1449,7 +1452,8 @@ pub async fn create_snapshot_core(
}))
.await
{
warn!(error = %e, "failed to bump restore-epoch after snapshot (FUSE remount may be delayed)");
let _ = tokio::fs::remove_dir_all(&temp_snapshot_dir).await;
return Err(e).context("bumping restore-epoch in MMDS after snapshot");
}

if has_base {
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