overlay: create the merged path only if it does not exist

follow-up for ccb70a7 more information here: #1827 (comment) Signed-off-by: Giuseppe Scrivano <[email protected]>
containers · Mar 11, 2024 · 0441674 · 0441674
1 parent 853cc6a
commit 0441674
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Showing 2 changed files with 9 additions and 4 deletions.
diff --git a/drivers/overlay/overlay.go b/drivers/overlay/overlay.go
@@ -1666,9 +1666,11 @@ func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountO
 	}
 
 	mergedDir := path.Join(dir, "merged")
-	// Create the driver merged dir
-	if err := idtools.MkdirAs(mergedDir, 0o700, rootUID, rootGID); err != nil && !os.IsExist(err) {
-		return "", err
+	// Attempt to create the merged dir only if it doesn't exist.
+	if _, err := os.Stat(mergedDir); err != nil && !os.IsExist(err) {
+		if err := idtools.MkdirAs(mergedDir, 0o700, rootUID, rootGID); err != nil {
+			return "", err
+		}
 	}
 	if count := d.ctr.Increment(mergedDir); count > 1 {
 		return mergedDir, nil

diff --git a/tests/overlay-recreate.bats b/tests/overlay-recreate.bats
@@ -18,7 +18,8 @@ load helpers
 	storage unmount "$lowerlayer"
 	storage mount "$midlayer"
 	storage unmount "$midlayer"
-	storage mount "$upperlayer"
+	run storage --debug=false mount "$upperlayer"
+	merged_dir="$output"
 	storage unmount "$upperlayer"
 	# okay, but how about this?
 	rm -v ${TESTDIR}/root/overlay/*/link
@@ -27,6 +28,8 @@ load helpers
 	storage unmount "$lowerlayer"
 	storage mount "$midlayer"
 	storage unmount "$midlayer"
+	# check it works if we delete the merged directory.
+	rmdir "$merged_dir"
 	storage mount "$upperlayer"
 	storage unmount "$upperlayer"
 	# okay, not bad, kid.