From 572c1079a59c4cefff99fb49e4291fe25f0880a5 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Mon, 2 Dec 2019 16:02:38 +0000
Subject: [PATCH] fserrors: Make a new NoLowLevelRetry error and don't retry
 them #3777

---
 fs/fserrors/error.go | 52 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/fs/fserrors/error.go b/fs/fserrors/error.go
index c1aa31e89..aa3e6067f 100644
--- a/fs/fserrors/error.go
+++ b/fs/fserrors/error.go
@@ -178,6 +178,53 @@ func IsNoRetryError(err error) (isNoRetry bool) {
 	return
 }
 
+// NoLowLevelRetrier is an optional interface for error as to whether
+// the operation should not be retried at a low level.
+//
+// NoLowLevelRetry errors won't be retried by low level retry loops.
+type NoLowLevelRetrier interface {
+	error
+	NoLowLevelRetry() bool
+}
+
+// wrappedNoLowLevelRetryError is an error wrapped so it will satisfy the
+// NoLowLevelRetrier interface and return true
+type wrappedNoLowLevelRetryError struct {
+	error
+}
+
+// NoLowLevelRetry interface
+func (err wrappedNoLowLevelRetryError) NoLowLevelRetry() bool {
+	return true
+}
+
+// Check interface
+var _ NoLowLevelRetrier = wrappedNoLowLevelRetryError{error(nil)}
+
+// NoLowLevelRetryError makes an error which indicates the sync
+// shouldn't be low level retried.
+func NoLowLevelRetryError(err error) error {
+	return wrappedNoLowLevelRetryError{err}
+}
+
+// Cause returns the underlying error
+func (err wrappedNoLowLevelRetryError) Cause() error {
+	return err.error
+}
+
+// IsNoLowLevelRetryError returns true if err conforms to the NoLowLevelRetry
+// interface and calling the NoLowLevelRetry method returns true.
+func IsNoLowLevelRetryError(err error) (isNoLowLevelRetry bool) {
+	errors.Walk(err, func(err error) bool {
+		if r, ok := err.(NoLowLevelRetrier); ok {
+			isNoLowLevelRetry = r.NoLowLevelRetry()
+			return true
+		}
+		return false
+	})
+	return
+}
+
 // RetryAfter is an optional interface for error as to whether the
 // operation should be retried after a given delay
 //
@@ -345,6 +392,11 @@ func ShouldRetry(err error) bool {
 		return false
 	}
 
+	// If error has been marked to NoLowLevelRetry then don't retry
+	if IsNoLowLevelRetryError(err) {
+		return false
+	}
+
 	// Find root cause if available
 	retriable, err := Cause(err)
 	if retriable {