Merge pull request #5047 from damoclark/patch-1

cache: fix race condition in cache cleanup or similar.

changelog/unreleased/pull-5047

@@ -0,0 +1,7 @@
+Bugfix: Fix possible error on concurrent cache cleanup
+
+Fix for multiple restic processes executing concurrently and racing to
+remove obsolete snapshots from the local backend cache.  Restic now suppresses the `no
+such file or directory` error.
+
+https://github.com/restic/restic/pull/5047

internal/backend/cache/file.go

@@ -210,6 +210,10 @@ func (c *Cache) list(t restic.FileType) (restic.IDSet, error) {
 	dir := filepath.Join(c.path, cacheLayoutPaths[t])
 	err := filepath.Walk(dir, func(name string, fi os.FileInfo, err error) error {
 		if err != nil {
+			// ignore ErrNotExist to gracefully handle multiple processes clearing the cache
+			if errors.Is(err, os.ErrNotExist) {
+				return nil
+			}
 			return errors.Wrap(err, "Walk")
 		}