From 8452fd2ab4873801440d4d5a0460f8072da486c1 Mon Sep 17 00:00:00 2001
From: Simon Frei <freisim93@gmail.com>
Date: Fri, 25 Sep 2020 11:27:44 +0200
Subject: [PATCH] lib/model, lib/scanner: Prevent races aborting scans (fixes
 #6994) (#6997)

---
 lib/model/folder.go       | 5 +++++
 lib/scanner/blockqueue.go | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/lib/model/folder.go b/lib/model/folder.go
index ffd167ab1..e77726c3c 100644
--- a/lib/model/folder.go
+++ b/lib/model/folder.go
@@ -520,6 +520,11 @@ func (f *folder) scanSubdirs(subDirs []string) error {
 		}
 
 		if err := batch.flushIfFull(); err != nil {
+			// Prevent a race between the scan aborting due to context
+			// cancellation and releasing the snapshot in defer here.
+			scanCancel()
+			for range fchan {
+			}
 			return err
 		}
 
diff --git a/lib/scanner/blockqueue.go b/lib/scanner/blockqueue.go
index 6c22714c2..a56187535 100644
--- a/lib/scanner/blockqueue.go
+++ b/lib/scanner/blockqueue.go
@@ -136,6 +136,10 @@ func (ph *parallelHasher) hashFiles(ctx context.Context) {
 
 func (ph *parallelHasher) closeWhenDone() {
 	ph.wg.Wait()
+	// In case the hasher aborted on context, wait for filesystem
+	// walking/progress routine to finish.
+	for range ph.inbox {
+	}
 	if ph.done != nil {
 		close(ph.done)
 	}