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https://github.com/etcd-io/bbolt.git
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b05bec2fe3
This commit is to add go-binding for go-dmflakey. It's used to simulate powerfailure with common filesystems. Signed-off-by: Wei Fu <fuweid89@gmail.com>
106 lines
3.0 KiB
Go
106 lines
3.0 KiB
Go
//go:build linux
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package dmflakey
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import (
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"fmt"
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"os"
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"os/exec"
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"time"
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"unsafe"
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"golang.org/x/sys/unix"
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)
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// newFlakeyDevice creates flakey device.
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//
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// REF: https://docs.kernel.org/admin-guide/device-mapper/dm-flakey.html
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func newFlakeyDevice(flakeyDevice, loopDevice string, interval time.Duration) error {
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loopSize, err := getBlkSize(loopDevice)
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if err != nil {
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return fmt.Errorf("failed to get the size of the loop device %s: %w", loopDevice, err)
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}
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// The flakey device will be available in interval.Seconds().
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table := fmt.Sprintf("0 %d flakey %s 0 %d 0",
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loopSize, loopDevice, int(interval.Seconds()))
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args := []string{"create", flakeyDevice, "--table", table}
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output, err := exec.Command("dmsetup", args...).CombinedOutput()
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if err != nil {
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return fmt.Errorf("failed to create flakey device %s with table %s (out: %s): %w",
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flakeyDevice, table, string(output), err)
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}
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return nil
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}
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// reloadFlakeyDevice reloads the flakey device with feature table.
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func reloadFlakeyDevice(flakeyDevice string, syncFS bool, table string) (retErr error) {
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args := []string{"suspend", "--nolockfs", flakeyDevice}
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if syncFS {
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args[1] = flakeyDevice
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args = args[:len(args)-1]
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}
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output, err := exec.Command("dmsetup", args...).CombinedOutput()
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if err != nil {
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return fmt.Errorf("failed to suspend flakey device %s (out: %s): %w",
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flakeyDevice, string(output), err)
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}
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defer func() {
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output, derr := exec.Command("dmsetup", "resume", flakeyDevice).CombinedOutput()
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if derr != nil {
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derr = fmt.Errorf("failed to resume flakey device %s (out: %s): %w",
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flakeyDevice, string(output), derr)
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}
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if retErr == nil {
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retErr = derr
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}
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}()
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output, err = exec.Command("dmsetup", "load", flakeyDevice, "--table", table).CombinedOutput()
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if err != nil {
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return fmt.Errorf("failed to reload flakey device %s with table (%s) (out: %s): %w",
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flakeyDevice, table, string(output), err)
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}
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return nil
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}
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// removeFlakeyDevice removes flakey device.
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func deleteFlakeyDevice(flakeyDevice string) error {
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output, err := exec.Command("dmsetup", "remove", flakeyDevice).CombinedOutput()
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if err != nil {
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return fmt.Errorf("failed to remove flakey device %s (out: %s): %w",
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flakeyDevice, string(output), err)
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}
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return nil
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}
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// getBlkSize64 gets device size in bytes (BLKGETSIZE64).
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//
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// REF: https://man7.org/linux/man-pages/man8/blockdev.8.html
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func getBlkSize64(device string) (int64, error) {
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deviceFd, err := os.Open(device)
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if err != nil {
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return 0, fmt.Errorf("failed to open device %s: %w", device, err)
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}
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defer deviceFd.Close()
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var size int64
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if _, _, err := unix.Syscall(unix.SYS_IOCTL, deviceFd.Fd(), unix.BLKGETSIZE64, uintptr(unsafe.Pointer(&size))); err != 0 {
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return 0, fmt.Errorf("failed to get block size: %w", err)
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}
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return size, nil
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}
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// getBlkSize gets size in 512-byte sectors (BLKGETSIZE64 / 512).
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//
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// REF: https://man7.org/linux/man-pages/man8/blockdev.8.html
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func getBlkSize(device string) (int64, error) {
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size, err := getBlkSize64(device)
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return size / 512, err
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}
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