From 0441674005fa75b0e97d68bd0d162d7f5470882e Mon Sep 17 00:00:00 2001
From: Giuseppe Scrivano <gscrivan@redhat.com>
Date: Mon, 11 Mar 2024 13:55:02 +0100
Subject: [PATCH] overlay: create the merged path only if it does not exist

follow-up for ccb70a79a69a1a5137ff24720520534bfbcc2316

more information here: https://github.com/containers/storage/issues/1827#issuecomment-1988332922

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
---
 drivers/overlay/overlay.go  | 8 +++++---
 tests/overlay-recreate.bats | 5 ++++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/overlay/overlay.go b/drivers/overlay/overlay.go
index f007aa9437..ac3edcfd33 100644
--- 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
index 038a48810a..c3ebbb3297 100644
--- 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.