| // +build linux |
| |
| package overlayutils // import "github.com/docker/docker/daemon/graphdriver/overlayutils" |
| |
| import ( |
| "fmt" |
| "io/ioutil" |
| "os" |
| "path" |
| "path/filepath" |
| |
| "github.com/docker/docker/daemon/graphdriver" |
| "github.com/pkg/errors" |
| "github.com/sirupsen/logrus" |
| "golang.org/x/sys/unix" |
| ) |
| |
| // ErrDTypeNotSupported denotes that the backing filesystem doesn't support d_type. |
| func ErrDTypeNotSupported(driver, backingFs string) error { |
| msg := fmt.Sprintf("%s: the backing %s filesystem is formatted without d_type support, which leads to incorrect behavior.", driver, backingFs) |
| if backingFs == "xfs" { |
| msg += " Reformat the filesystem with ftype=1 to enable d_type support." |
| } |
| |
| if backingFs == "extfs" { |
| msg += " Reformat the filesystem (or use tune2fs) with -O filetype flag to enable d_type support." |
| } |
| |
| msg += " Backing filesystems without d_type support are not supported." |
| |
| return graphdriver.NotSupportedError(msg) |
| } |
| |
| // SupportsOverlay checks if the system supports overlay filesystem |
| // by performing an actual overlay mount. |
| // |
| // checkMultipleLowers parameter enables check for multiple lowerdirs, |
| // which is required for the overlay2 driver. |
| func SupportsOverlay(d string, checkMultipleLowers bool) error { |
| td, err := ioutil.TempDir(d, "check-overlayfs-support") |
| if err != nil { |
| return err |
| } |
| defer func() { |
| if err := os.RemoveAll(td); err != nil { |
| logrus.Warnf("Failed to remove check directory %v: %v", td, err) |
| } |
| }() |
| |
| for _, dir := range []string{"lower1", "lower2", "upper", "work", "merged"} { |
| if err := os.Mkdir(filepath.Join(td, dir), 0755); err != nil { |
| return err |
| } |
| } |
| |
| mnt := filepath.Join(td, "merged") |
| lowerDir := path.Join(td, "lower2") |
| if checkMultipleLowers { |
| lowerDir += ":" + path.Join(td, "lower1") |
| } |
| opts := fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", lowerDir, path.Join(td, "upper"), path.Join(td, "work")) |
| if err := unix.Mount("overlay", mnt, "overlay", 0, opts); err != nil { |
| return errors.Wrap(err, "failed to mount overlay") |
| } |
| if err := unix.Unmount(mnt, 0); err != nil { |
| logrus.Warnf("Failed to unmount check directory %v: %v", mnt, err) |
| } |
| return nil |
| } |