overlay, composefs: use data-only lower layers

use the new overlay data-only feature to mount the composefs data directory so there is no need for upper layers to create whiteouts to hide payload files. The feature was added to Linux 6.5. Signed-off-by: Giuseppe Scrivano <[email protected]>
containers · Sep 13, 2023 · 19118f6 · 19118f6
1 parent f109925
commit 19118f6
Showing 1 changed file with 8 additions and 4 deletions.
diff --git a/drivers/overlay/overlay.go b/drivers/overlay/overlay.go
@@ -1657,8 +1657,6 @@ func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountO
 		optsList = append(optsList, "metacopy=on", "redirect_dir=on")
 	}
 
-	absLowers = append(absLowers, composeFsLayers...)
-
 	if len(absLowers) == 0 {
 		absLowers = append(absLowers, path.Join(dir, "empty"))
 	}
@@ -1752,11 +1750,17 @@ func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountO
 		absLowers = newAbsDir
 	}
 
+	lowerDirs := strings.Join(absLowers, ":")
+	if len(composeFsLayers) > 0 {
+		composeFsLayersLowerDirs := strings.Join(composeFsLayers, "::")
+		lowerDirs = lowerDirs + "::" + composeFsLayersLowerDirs
+	}
+
 	var opts string
 	if readWrite {
-		opts = fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", strings.Join(absLowers, ":"), diffDir, workdir)
+		opts = fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", lowerDirs, diffDir, workdir)
 	} else {
-		opts = fmt.Sprintf("lowerdir=%s:%s", diffDir, strings.Join(absLowers, ":"))
+		opts = fmt.Sprintf("lowerdir=%s:%s", diffDir, lowerDirs)
 	}
 	if len(optsList) > 0 {
 		opts = fmt.Sprintf("%s,%s", opts, strings.Join(optsList, ","))