Merge pull request #34342 from coolljt0725/fallback_to_naive_diff
Fallback to use naive diff driver if enable CONFIG_OVERLAY_FS_REDIRECT_DIR
diff --git a/daemon/graphdriver/overlay2/check.go b/daemon/graphdriver/overlay2/check.go
index 851c409..f29630b 100644
--- a/daemon/graphdriver/overlay2/check.go
+++ b/daemon/graphdriver/overlay2/check.go
@@ -8,6 +8,7 @@
"os"
"path"
"path/filepath"
+ "syscall"
"github.com/docker/docker/pkg/system"
"github.com/pkg/errors"
@@ -15,10 +16,11 @@
"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 @@
}
}()
- // 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 @@
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
}
diff --git a/daemon/graphdriver/overlay2/overlay.go b/daemon/graphdriver/overlay2/overlay.go
index f350ca9..0f252e6 100644
--- a/daemon/graphdriver/overlay2/overlay.go
+++ b/daemon/graphdriver/overlay2/overlay.go
@@ -267,8 +267,8 @@
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
}
})
