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Merge pull request #34342 from coolljt0725/fallback_to_naive_diff

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Fallback to use naive diff driver if enable CONFIG_OVERLAY_FS_REDIRECT_DIR
This commit is contained in:
Yong Tang 2017-10-03 06:45:17 -07:00 committed by GitHub
commit 595b929c57
2 changed files with 29 additions and 6 deletions
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31
daemon/graphdriver/overlay2/check.go
View file

@ -8,6 +8,7 @@ import (
"os"
"path"
"path/filepath"
"syscall"
"github.com/docker/docker/pkg/system"
"github.com/pkg/errors"
@ -15,10 +16,11 @@ import (
"golang.org/x/sys/unix"
)
// hasOpaqueCopyUpBug checks whether the filesystem has a bug
// doesSupportNativeDiff checks whether the filesystem has a bug
// which copies up the opaque flag when copying up an opaque
// directory. When this bug exists naive diff should be used.
func hasOpaqueCopyUpBug(d string) error {
// directory or the kernel enable CONFIG_OVERLAY_FS_REDIRECT_DIR.
// When these exist naive diff should be used.
func doesSupportNativeDiff(d string) error {
td, err := ioutil.TempDir(d, "opaque-bug-check")
if err != nil {
return err
@ -29,10 +31,13 @@ func hasOpaqueCopyUpBug(d string) error {
}
}()
// Make directories l1/d, l2/d, l3, work, merged
// Make directories l1/d, l1/d1, l2/d, l3, work, merged
if err := os.MkdirAll(filepath.Join(td, "l1", "d"), 0755); err != nil {
return err
}
if err := os.MkdirAll(filepath.Join(td, "l1", "d1"), 0755); err != nil {
return err
}
if err := os.MkdirAll(filepath.Join(td, "l2", "d"), 0755); err != nil {
return err
}
@ -75,5 +80,23 @@ func hasOpaqueCopyUpBug(d string) error {
return errors.New("opaque flag erroneously copied up, consider update to kernel 4.8 or later to fix")
}
// rename "d1" to "d2"
if err := os.Rename(filepath.Join(td, "merged", "d1"), filepath.Join(td, "merged", "d2")); err != nil {
// if rename failed with syscall.EXDEV, the kernel doesn't have CONFIG_OVERLAY_FS_REDIRECT_DIR enabled
if err.(*os.LinkError).Err == syscall.EXDEV {
return nil
}
return errors.Wrap(err, "failed to rename dir in merged directory")
}
// get the xattr of "d2"
xattrRedirect, err := system.Lgetxattr(filepath.Join(td, "l3", "d2"), "trusted.overlay.redirect")
if err != nil {
return errors.Wrap(err, "failed to read redirect flag on upper layer")
}
if string(xattrRedirect) == "d1" {
return errors.New("kernel has CONFIG_OVERLAY_FS_REDIRECT_DIR enabled")
}
return nil
}

4
daemon/graphdriver/overlay2/overlay.go
View file

@ -267,8 +267,8 @@ func supportsOverlay() error {
func useNaiveDiff(home string) bool {
useNaiveDiffLock.Do(func() {
if err := hasOpaqueCopyUpBug(home); err != nil {
logrus.Warnf("Not using native diff for overlay2: %v", err)
if err := doesSupportNativeDiff(home); err != nil {
logrus.Warnf("Not using native diff for overlay2, this may cause degraded performance for building images: %v", err)
useNaiveDiffOnly = true
}
})