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649e4c8889
Before this commit, overlay check was performed by looking for `overlay` in /proc/filesystem. This obviously might not work for rootless Docker (fs is there, but one can't use it as non-root). This commit changes the check to perform the actual mount, by reusing the code previously written to check for multiple lower dirs support. The old check is removed from both drivers, as well as the additional check for the multiple lower dirs support in overlay2 since it's now a part of the main check. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
69 lines
2.1 KiB
Go
69 lines
2.1 KiB
Go
// +build linux
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package overlayutils // import "github.com/docker/docker/daemon/graphdriver/overlayutils"
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import (
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"fmt"
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"io/ioutil"
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"os"
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"path"
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"path/filepath"
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"github.com/docker/docker/daemon/graphdriver"
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"github.com/pkg/errors"
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"github.com/sirupsen/logrus"
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"golang.org/x/sys/unix"
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)
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// ErrDTypeNotSupported denotes that the backing filesystem doesn't support d_type.
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func ErrDTypeNotSupported(driver, backingFs string) error {
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msg := fmt.Sprintf("%s: the backing %s filesystem is formatted without d_type support, which leads to incorrect behavior.", driver, backingFs)
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if backingFs == "xfs" {
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msg += " Reformat the filesystem with ftype=1 to enable d_type support."
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}
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if backingFs == "extfs" {
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msg += " Reformat the filesystem (or use tune2fs) with -O filetype flag to enable d_type support."
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}
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msg += " Backing filesystems without d_type support are not supported."
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return graphdriver.NotSupportedError(msg)
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}
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// SupportsOverlay checks if the system supports overlay filesystem
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// by performing an actual overlay mount.
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//
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// checkMultipleLowers parameter enables check for multiple lowerdirs,
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// which is required for the overlay2 driver.
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func SupportsOverlay(d string, checkMultipleLowers bool) error {
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td, err := ioutil.TempDir(d, "check-overlayfs-support")
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if err != nil {
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return err
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}
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defer func() {
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if err := os.RemoveAll(td); err != nil {
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logrus.Warnf("Failed to remove check directory %v: %v", td, err)
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}
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}()
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for _, dir := range []string{"lower1", "lower2", "upper", "work", "merged"} {
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if err := os.Mkdir(filepath.Join(td, dir), 0755); err != nil {
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return err
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}
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}
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mnt := filepath.Join(td, "merged")
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lowerDir := path.Join(td, "lower2")
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if checkMultipleLowers {
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lowerDir += ":" + path.Join(td, "lower1")
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}
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opts := fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", lowerDir, path.Join(td, "upper"), path.Join(td, "work"))
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if err := unix.Mount("overlay", mnt, "overlay", 0, opts); err != nil {
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return errors.Wrap(err, "failed to mount overlay")
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}
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if err := unix.Unmount(mnt, 0); err != nil {
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logrus.Warnf("Failed to unmount check directory %v: %v", mnt, err)
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}
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return nil
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}
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