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Fix systemd-repart discard hanging on large disks #556

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Fix systemd-repart discard hanging on large disks #556

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33 changes: 32 additions & 1 deletion pkg/repart/disk_repart.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,9 +20,11 @@ package repart
import (
_ "embed"
"encoding/json"
"errors"
"fmt"
"io"
"os"
"os/exec"
"path/filepath"
"regexp"
"runtime"
Expand All @@ -45,6 +47,8 @@ const (
// Do not change these values as this could break backward compatibility on already installed systems (e.g. reseting a system)
configType = "2ecf8b13-6846-4e8a-9bc3-284ff5e2ac22"
recoveryType = "3265f37b-3105-4777-bd97-cfcd9cc7cf99"

blkdiscardNotSupported = 2 // blkdiscard exit code for devices that do not support discard requests
)

//go:embed templates/partition.conf.tpl
Expand Down Expand Up @@ -176,7 +180,34 @@ func repartDisk(s *sys.System, d *deployment.Disk, empty string) (err error) {
parts[i] = Partition{Partition: part}
}

return runSystemdRepart(s, d.Device, parts, fmt.Sprintf("--empty=%s", empty))
// systemd-repart trimming the disk could result in the entire disk waiting to be fully zero'd out. This could hang
// installs on large drives. Now, before systemd-repart is triggered, we manually discard the entire disk in one pass
// through blkdiscard. This results in a native TRIM being executed whenever the drive typically runs the TRIM engine.
if empty == "force" {
err = discardDevice(s, d.Device)
if err != nil {
return err
}
}

return runSystemdRepart(s, d.Device, parts, fmt.Sprintf("--empty=%s", empty), "--discard=no")
}

// discardDevice discards the given device in a single pass. Devices not
// supporting discard requests fail silently, unexpected failures, such as "device in us" exit immediately.
// Runs without '--force' on to prevent accidentally trimming an in-use disk.
func discardDevice(s *sys.System, device string) error {
_, err := s.Runner().Run("blkdiscard", device)
if err == nil {
return nil
}

var exitErr *exec.ExitError
if errors.As(err, &exitErr) && exitErr.ExitCode() == blkdiscardNotSupported {
s.Logger().Warn("Device '%s' does not support discard, continuing without trimming it", device)
return nil
}
return fmt.Errorf("failed discarding device '%s': %w", device, err)
}

// runSystemdRepart runs systemd-repart for the given partitions and target device. It appends to the generated command the
Expand Down