lib: Return error from db.FileSet.Snapshot (fixes #7419, ref #5907) (#7424)

2021-03-07 13:43:22 +01:00 · 2021-03-07 13:43:22 +01:00 · 310fba4c12
parent c1d06d9501
commit 310fba4c12
25 changed files with 601 additions and 344 deletions
--- a/go.mod
+++ b/go.mod
@ -28,6 +28,7 @@ require (
 	github.com/lucas-clemente/quic-go v0.19.3
 	github.com/maruel/panicparse v1.5.1
 	github.com/mattn/go-isatty v0.0.12
 	github.com/maxbrunsfeld/counterfeiter/v6 v6.3.0 // indirect
 	github.com/minio/sha256-simd v0.1.1
 	github.com/miscreant/miscreant.go v0.0.0-20200214223636-26d376326b75
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
@ -49,6 +50,7 @@ require (
 	golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4
 	golang.org/x/text v0.3.4
 	golang.org/x/time v0.0.0-20200630173020-3af7569d3a1e
 	golang.org/x/tools v0.1.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b // indirect
 )
--- a/go.sum
+++ b/go.sum
@ -261,6 +261,8 @@ github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Ky
 github.com/mattn/go-runewidth v0.0.2/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
 github.com/matttproud/golang_protobuf_extensions v1.0.1 h1:4hp9jkHxhMHkqkrB3Ix0jegS5sx/RkqARlsWZ6pIwiU=
 github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
 github.com/maxbrunsfeld/counterfeiter/v6 v6.3.0 h1:8E6DrFvII6QR4eJ3PkFvV+lc03P+2qwqTPLm1ax7694=
 github.com/maxbrunsfeld/counterfeiter/v6 v6.3.0/go.mod h1:fcEyUyXZXoV4Abw8DX0t7wyL8mCDxXyU4iAFZfT3IHw=
 github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b/go.mod h1:01TrycV0kFyexm33Z7vhZRXopbI8J3TDReVlkTgMUxE=
 github.com/microcosm-cc/bluemonday v1.0.1/go.mod h1:hsXNsILzKxV+sX77C5b8FSuKF00vh2OMYv+xgHpAMF4=
 github.com/miekg/dns v1.0.14/go.mod h1:W1PPwlIAgtquWBMBEV9nkV9Cazfe8ScdGz/Lj7v3Nrg=
@ -380,6 +382,7 @@ github.com/ryanuber/columnize v0.0.0-20160712163229-9b3edd62028f/go.mod h1:sm1tb
 github.com/samuel/go-zookeeper v0.0.0-20190923202752-2cc03de413da/go.mod h1:gi+0XIa01GRL2eRQVjQkKGqKF3SF9vZR/HnPullcV2E=
 github.com/sasha-s/go-deadlock v0.2.0 h1:lMqc+fUb7RrFS3gQLtoQsJ7/6TV/pAIFvBsqX73DK8Y=
 github.com/sasha-s/go-deadlock v0.2.0/go.mod h1:StQn567HiB1fF2yJ44N9au7wOhrPS3iZqiDbRupzT10=
 github.com/sclevine/spec v1.4.0/go.mod h1:LvpgJaFyvQzRvc1kaDs0bulYwzC70PbiYjC4QnFHkOM=
 github.com/sean-/seed v0.0.0-20170313163322-e2103e2c3529/go.mod h1:DxrIzT+xaE7yg65j358z/aeFdxmN0P9QXhEzd20vsDc=
 github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
 github.com/shirou/gopsutil/v3 v3.20.11 h1:NeVf1K0cgxsWz+N3671ojRptdgzvp7BXL3KV21R0JnA=
@ -446,6 +449,7 @@ github.com/viant/toolbox v0.24.0/go.mod h1:OxMCG57V0PXuIP2HNQrtJf2CjqdmbrOx5EkMI
 github.com/vitrun/qart v0.0.0-20160531060029-bf64b92db6b0 h1:okhMind4q9H1OxF44gNegWkiP4H/gsTFLalHFa4OOUI=
 github.com/vitrun/qart v0.0.0-20160531060029-bf64b92db6b0/go.mod h1:TTbGUfE+cXXceWtbTHq6lqcTvYPBKLNejBEbnUsQJtU=
 github.com/xiang90/probing v0.0.0-20190116061207-43a291ad63a2/go.mod h1:UETIi67q53MR2AWcXfiuqkDkRtnGDLqkBTpCHuJHxtU=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 go.etcd.io/bbolt v1.3.3/go.mod h1:IbVyRI1SCnLcuJnV2u8VeU0CEYM7e686BmAb1XKL+uU=
 go.etcd.io/etcd v0.0.0-20191023171146-3cf2f69b5738/go.mod h1:dnLIgRNXwCJa5e+c6mIZCrds/GIG4ncV9HhK5PX7jPg=
 go.opencensus.io v0.18.0/go.mod h1:vKdFvxhtzZ9onBp9VKHK8z/sRpBMnKAsufL7wlDrCOA=
@ -483,6 +487,8 @@ golang.org/x/lint v0.0.0-20190313153728-d0100b6bd8b3/go.mod h1:6SW0HCj/g11FgYtHl
 golang.org/x/lint v0.0.0-20190930215403-16217165b5de/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
 golang.org/x/mod v0.0.0-20190513183733-4bf6d317e70e/go.mod h1:mXi4GBBbnImb6dmsKGUJ2LatrhH/nqhxcFungHvyanc=
 golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
 golang.org/x/mod v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@ -507,6 +513,8 @@ golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81R
 golang.org/x/net v0.0.0-20200707034311-ab3426394381/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20200813134508-3edf25e44fcc/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20201006153459-a7d1128ccaa0/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20201026091529-146b70c837a4/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20201031054903-ff519b6c9102 h1:42cLlJJdEh+ySyeUUbEQ5bsTiq8voBeTuweGVkY6Puw=
 golang.org/x/net v0.0.0-20201031054903-ff519b6c9102/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
@ -520,6 +528,7 @@ golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180823144017-11551d06cbcc/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@ -582,7 +591,11 @@ golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135/go.mod h1:RgjU9mgBXZiqYHBn
 golang.org/x/tools v0.0.0-20190621195816-6e04913cbbac/go.mod h1:/rFqwRUd4F7ZHNgwSSTFct+R/Kf4OFW1sUzUTQQTgfc=
 golang.org/x/tools v0.0.0-20191029041327-9cc4af7d6b2c/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191029190741-b9c20aec41a5/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20200103221440-774c71fcf114/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/tools v0.0.0-20201023174141-c8cfbd0f21e6/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
 golang.org/x/tools v0.1.0 h1:po9/4sTYwZU9lPhi1tOrb4hCv3qrhiQ77LZfGa2OjwY=
 golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
--- a/gui/default/syncthing/core/syncthingController.js
+++ b/gui/default/syncthing/core/syncthingController.js
@ -600,7 +600,13 @@ angular.module('syncthing.core')
                }
                $scope.completion[device][folder] = data;
                recalcCompletion(device);
-            }).error($scope.emitHTTPError);
+            }).error(function(data, status, headers, config) {
                if (status === 404) {
                    console.log("refreshCompletion:", data);
                } else {
                    $scope.emitHTTPError(data, status, headers, config);
                }
            });
        }
        function refreshConnectionStats() {
--- a/gui/default/untrusted/syncthing/core/syncthingController.js
+++ b/gui/default/untrusted/syncthing/core/syncthingController.js
@ -600,7 +600,13 @@ angular.module('syncthing.core')
                }
                $scope.completion[device][folder] = data;
                recalcCompletion(device);
-            }).error($scope.emitHTTPError);
+            }).error(function(data, status, headers, config) {
                if (status === 404) {
                    console.log("refreshCompletion:", data);
                } else {
                    $scope.emitHTTPError(data, status, headers, config);
                }
            })
        }
        function refreshConnectionStats() {
--- a/lib/api/api.go
+++ b/lib/api/api.go
@ -746,7 +746,15 @@ func (s *service) getDBCompletion(w http.ResponseWriter, r *http.Request) {
 		}
 	}
-	sendJSON(w, s.model.Completion(device, folder).Map())
+	if comp, err := s.model.Completion(device, folder); err != nil {
 		status := http.StatusInternalServerError
 		if isFolderNotFound(err) {
 			status = http.StatusNotFound
 		}
 		http.Error(w, err.Error(), status)
 	} else {
 		sendJSON(w, comp.Map())
 	}
 }
 func (s *service) getDBStatus(w http.ResponseWriter, r *http.Request) {
@ -878,8 +886,25 @@ func (s *service) getDBFile(w http.ResponseWriter, r *http.Request) {
 	qs := r.URL.Query()
 	folder := qs.Get("folder")
 	file := qs.Get("file")
-	gf, gfOk := s.model.CurrentGlobalFile(folder, file)
+
-	lf, lfOk := s.model.CurrentFolderFile(folder, file)
+	errStatus := http.StatusInternalServerError
 	gf, gfOk, err := s.model.CurrentGlobalFile(folder, file)
 	if err != nil {
 		if isFolderNotFound(err) {
 			errStatus = http.StatusNotFound
 		}
 		http.Error(w, err.Error(), errStatus)
 		return
 	}
 	lf, lfOk, err := s.model.CurrentFolderFile(folder, file)
 	if err != nil {
 		if isFolderNotFound(err) {
 			errStatus = http.StatusNotFound
 		}
 		http.Error(w, err.Error(), errStatus)
 		return
 	}
 	if !(gfOk || lfOk) {
 		// This file for sure does not exist.
@ -887,7 +912,11 @@ func (s *service) getDBFile(w http.ResponseWriter, r *http.Request) {
 		return
 	}
-	av := s.model.Availability(folder, gf, protocol.BlockInfo{})
+	av, err := s.model.Availability(folder, gf, protocol.BlockInfo{})
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 	}
 	sendJSON(w, map[string]interface{}{
 		"global":       jsonFileInfo(gf),
 		"local":        jsonFileInfo(lf),
@ -1498,7 +1527,12 @@ func (s *service) getPeerCompletion(w http.ResponseWriter, r *http.Request) {
 		for _, device := range folder.DeviceIDs() {
 			deviceStr := device.String()
 			if _, ok := s.model.Connection(device); ok {
-				tot[deviceStr] += s.model.Completion(device, folder.ID).CompletionPct
+				comp, err := s.model.Completion(device, folder.ID)
 				if err != nil {
 					http.Error(w, err.Error(), http.StatusInternalServerError)
 					return
 				}
 				tot[deviceStr] += comp.CompletionPct
 			} else {
 				tot[deviceStr] = 0
 			}
@ -1860,3 +1894,16 @@ func errorString(err error) *string {
 	}
 	return nil
 }
 func isFolderNotFound(err error) bool {
 	for _, target := range []error{
 		model.ErrFolderMissing,
 		model.ErrFolderPaused,
 		model.ErrFolderNotRunning,
 	} {
 		if errors.Is(err, target) {
 			return true
 		}
 	}
 	return false
 }
--- a/lib/db/benchmark_test.go
+++ b/lib/db/benchmark_test.go
@ -185,7 +185,7 @@ func BenchmarkNeedHalf(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		count := 0
-		snap := benchS.Snapshot()
+		snap := snapshot(b, benchS)
 		snap.WithNeed(protocol.LocalDeviceID, func(fi protocol.FileIntf) bool {
 			count++
 			return true
@ -209,7 +209,7 @@ func BenchmarkNeedHalfRemote(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		count := 0
-		snap := fset.Snapshot()
+		snap := snapshot(b, fset)
 		snap.WithNeed(remoteDevice0, func(fi protocol.FileIntf) bool {
 			count++
 			return true
@ -230,7 +230,7 @@ func BenchmarkHave(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		count := 0
-		snap := benchS.Snapshot()
+		snap := snapshot(b, benchS)
 		snap.WithHave(protocol.LocalDeviceID, func(fi protocol.FileIntf) bool {
 			count++
 			return true
@ -251,7 +251,7 @@ func BenchmarkGlobal(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		count := 0
-		snap := benchS.Snapshot()
+		snap := snapshot(b, benchS)
 		snap.WithGlobal(func(fi protocol.FileIntf) bool {
 			count++
 			return true
@ -272,7 +272,7 @@ func BenchmarkNeedHalfTruncated(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		count := 0
-		snap := benchS.Snapshot()
+		snap := snapshot(b, benchS)
 		snap.WithNeedTruncated(protocol.LocalDeviceID, func(fi protocol.FileIntf) bool {
 			count++
 			return true
@ -293,7 +293,7 @@ func BenchmarkHaveTruncated(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		count := 0
-		snap := benchS.Snapshot()
+		snap := snapshot(b, benchS)
 		snap.WithHaveTruncated(protocol.LocalDeviceID, func(fi protocol.FileIntf) bool {
 			count++
 			return true
@ -314,7 +314,7 @@ func BenchmarkGlobalTruncated(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		count := 0
-		snap := benchS.Snapshot()
+		snap := snapshot(b, benchS)
 		snap.WithGlobalTruncated(func(fi protocol.FileIntf) bool {
 			count++
 			return true
@ -336,7 +336,7 @@ func BenchmarkNeedCount(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		snap := benchS.Snapshot()
+		snap := snapshot(b, benchS)
 		_ = snap.NeedSize(protocol.LocalDeviceID)
 		snap.Release()
 	}
--- a/lib/db/db_test.go
+++ b/lib/db/db_test.go
@ -77,7 +77,7 @@ func TestIgnoredFiles(t *testing.T) {
 	// Local files should have the "ignored" bit in addition to just being
 	// generally invalid if we want to look at the simulation of that bit.
-	snap := fs.Snapshot()
+	snap := snapshot(t, fs)
 	defer snap.Release()
 	fi, ok := snap.Get(protocol.LocalDeviceID, "foo")
 	if !ok {
@ -866,7 +866,7 @@ func TestCheckLocalNeed(t *testing.T) {
 	fs.Update(remoteDevice0, files)
 	checkNeed := func() {
-		snap := fs.Snapshot()
+		snap := snapshot(t, fs)
 		defer snap.Release()
 		c := snap.NeedSize(protocol.LocalDeviceID)
 		if c.Files != 2 {
@ -974,7 +974,7 @@ func TestNeedAfterDropGlobal(t *testing.T) {
 	fs.Update(remoteDevice1, files[1:])
 	// remoteDevice1 needs one file: test
-	snap := fs.Snapshot()
+	snap := snapshot(t, fs)
 	c := snap.NeedSize(remoteDevice1)
 	if c.Files != 1 {
 		t.Errorf("Expected 1 needed files initially, got %v", c.Files)
@ -986,7 +986,7 @@ func TestNeedAfterDropGlobal(t *testing.T) {
 	fs.Drop(remoteDevice0)
 	// remoteDevice1 still needs test.
-	snap = fs.Snapshot()
+	snap = snapshot(t, fs)
 	c = snap.NeedSize(remoteDevice1)
 	if c.Files != 1 {
 		t.Errorf("Expected still 1 needed files, got %v", c.Files)
--- a/lib/db/meta_test.go
+++ b/lib/db/meta_test.go
@ -117,7 +117,7 @@ func TestRecalcMeta(t *testing.T) {
 	s1.Update(protocol.LocalDeviceID, files)
 	// Verify local/global size
-	snap := s1.Snapshot()
+	snap := snapshot(t, s1)
 	ls := snap.LocalSize()
 	gs := snap.GlobalSize()
 	snap.Release()
@ -149,7 +149,7 @@ func TestRecalcMeta(t *testing.T) {
 	}
 	// Verify that our bad data "took"
-	snap = s1.Snapshot()
+	snap = snapshot(t, s1)
 	ls = snap.LocalSize()
 	gs = snap.GlobalSize()
 	snap.Release()
@ -164,7 +164,7 @@ func TestRecalcMeta(t *testing.T) {
 	s2 := newFileSet(t, "test", fs.NewFilesystem(fs.FilesystemTypeFake, "fake"), ldb)
 	// Verify local/global size
-	snap = s2.Snapshot()
+	snap = snapshot(t, s2)
 	ls = snap.LocalSize()
 	gs = snap.GlobalSize()
 	snap.Release()
--- a/lib/db/set.go
+++ b/lib/db/set.go
@ -151,12 +151,13 @@ type Snapshot struct {
 	fatalError func(error, string)
 }
-func (s *FileSet) Snapshot() *Snapshot {
+func (s *FileSet) Snapshot() (*Snapshot, error) {
 	opStr := fmt.Sprintf("%s Snapshot()", s.folder)
 	l.Debugf(opStr)
 	t, err := s.db.newReadOnlyTransaction()
 	if err != nil {
-		fatalError(err, opStr, s.db)
+		s.db.handleFailure(err)
 		return nil, err
 	}
 	return &Snapshot{
 		folder: s.folder,
@ -165,7 +166,7 @@ func (s *FileSet) Snapshot() *Snapshot {
 		fatalError: func(err error, opStr string) {
 			fatalError(err, opStr, s.db)
 		},
-	}
+	}, nil
 }
 func (s *Snapshot) Release() {
--- a/lib/db/set_test.go
+++ b/lib/db/set_test.go
@ -45,9 +45,9 @@ func genBlocks(n int) []protocol.BlockInfo {
 	return b
 }
-func globalList(s *db.FileSet) []protocol.FileInfo {
+func globalList(t testing.TB, s *db.FileSet) []protocol.FileInfo {
 	var fs []protocol.FileInfo
-	snap := s.Snapshot()
+	snap := snapshot(t, s)
 	defer snap.Release()
 	snap.WithGlobal(func(fi protocol.FileIntf) bool {
 		f := fi.(protocol.FileInfo)
@ -56,9 +56,9 @@ func globalList(s *db.FileSet) []protocol.FileInfo {
 	})
 	return fs
 }
-func globalListPrefixed(s *db.FileSet, prefix string) []db.FileInfoTruncated {
+func globalListPrefixed(t testing.TB, s *db.FileSet, prefix string) []db.FileInfoTruncated {
 	var fs []db.FileInfoTruncated
-	snap := s.Snapshot()
+	snap := snapshot(t, s)
 	defer snap.Release()
 	snap.WithPrefixedGlobalTruncated(prefix, func(fi protocol.FileIntf) bool {
 		f := fi.(db.FileInfoTruncated)
@ -68,9 +68,9 @@ func globalListPrefixed(s *db.FileSet, prefix string) []db.FileInfoTruncated {
 	return fs
 }
-func haveList(s *db.FileSet, n protocol.DeviceID) []protocol.FileInfo {
+func haveList(t testing.TB, s *db.FileSet, n protocol.DeviceID) []protocol.FileInfo {
 	var fs []protocol.FileInfo
-	snap := s.Snapshot()
+	snap := snapshot(t, s)
 	defer snap.Release()
 	snap.WithHave(n, func(fi protocol.FileIntf) bool {
 		f := fi.(protocol.FileInfo)
@ -80,9 +80,9 @@ func haveList(s *db.FileSet, n protocol.DeviceID) []protocol.FileInfo {
 	return fs
 }
-func haveListPrefixed(s *db.FileSet, n protocol.DeviceID, prefix string) []db.FileInfoTruncated {
+func haveListPrefixed(t testing.TB, s *db.FileSet, n protocol.DeviceID, prefix string) []db.FileInfoTruncated {
 	var fs []db.FileInfoTruncated
-	snap := s.Snapshot()
+	snap := snapshot(t, s)
 	defer snap.Release()
 	snap.WithPrefixedHaveTruncated(n, prefix, func(fi protocol.FileIntf) bool {
 		f := fi.(db.FileInfoTruncated)
@ -92,9 +92,9 @@ func haveListPrefixed(s *db.FileSet, n protocol.DeviceID, prefix string) []db.Fi
 	return fs
 }
-func needList(s *db.FileSet, n protocol.DeviceID) []protocol.FileInfo {
+func needList(t testing.TB, s *db.FileSet, n protocol.DeviceID) []protocol.FileInfo {
 	var fs []protocol.FileInfo
-	snap := s.Snapshot()
+	snap := snapshot(t, s)
 	defer snap.Release()
 	snap.WithNeed(n, func(fi protocol.FileIntf) bool {
 		f := fi.(protocol.FileInfo)
@ -221,7 +221,7 @@ func TestGlobalSet(t *testing.T) {
 	check := func() {
 		t.Helper()
-		g := fileList(globalList(m))
+		g := fileList(globalList(t, m))
 		sort.Sort(g)
 		if fmt.Sprint(g) != fmt.Sprint(expectedGlobal) {
@ -244,7 +244,7 @@ func TestGlobalSet(t *testing.T) {
 			}
 			globalBytes += f.FileSize()
 		}
-		gs := globalSize(m)
+		gs := globalSize(t, m)
 		if gs.Files != globalFiles {
 			t.Errorf("Incorrect GlobalSize files; %d != %d", gs.Files, globalFiles)
 		}
@ -258,7 +258,7 @@ func TestGlobalSet(t *testing.T) {
 			t.Errorf("Incorrect GlobalSize bytes; %d != %d", gs.Bytes, globalBytes)
 		}
-		h := fileList(haveList(m, protocol.LocalDeviceID))
+		h := fileList(haveList(t, m, protocol.LocalDeviceID))
 		sort.Sort(h)
 		if fmt.Sprint(h) != fmt.Sprint(localTot) {
@ -281,7 +281,7 @@ func TestGlobalSet(t *testing.T) {
 			}
 			haveBytes += f.FileSize()
 		}
-		ls := localSize(m)
+		ls := localSize(t, m)
 		if ls.Files != haveFiles {
 			t.Errorf("Incorrect LocalSize files; %d != %d", ls.Files, haveFiles)
 		}
@ -295,14 +295,14 @@ func TestGlobalSet(t *testing.T) {
 			t.Errorf("Incorrect LocalSize bytes; %d != %d", ls.Bytes, haveBytes)
 		}
-		h = fileList(haveList(m, remoteDevice0))
+		h = fileList(haveList(t, m, remoteDevice0))
 		sort.Sort(h)
 		if fmt.Sprint(h) != fmt.Sprint(remoteTot) {
 			t.Errorf("Have incorrect (remote);\n A: %v !=\n E: %v", h, remoteTot)
 		}
-		n := fileList(needList(m, protocol.LocalDeviceID))
+		n := fileList(needList(t, m, protocol.LocalDeviceID))
 		sort.Sort(n)
 		if fmt.Sprint(n) != fmt.Sprint(expectedLocalNeed) {
@ -311,7 +311,7 @@ func TestGlobalSet(t *testing.T) {
 		checkNeed(t, m, protocol.LocalDeviceID, expectedLocalNeed)
-		n = fileList(needList(m, remoteDevice0))
+		n = fileList(needList(t, m, remoteDevice0))
 		sort.Sort(n)
 		if fmt.Sprint(n) != fmt.Sprint(expectedRemoteNeed) {
@ -320,7 +320,7 @@ func TestGlobalSet(t *testing.T) {
 		checkNeed(t, m, remoteDevice0, expectedRemoteNeed)
-		snap := m.Snapshot()
+		snap := snapshot(t, m)
 		defer snap.Release()
 		f, ok := snap.Get(protocol.LocalDeviceID, "b")
 		if !ok {
@ -365,7 +365,7 @@ func TestGlobalSet(t *testing.T) {
 	check()
-	snap := m.Snapshot()
+	snap := snapshot(t, m)
 	av := []protocol.DeviceID{protocol.LocalDeviceID, remoteDevice0}
 	a := snap.Availability("a")
@ -431,14 +431,14 @@ func TestGlobalSet(t *testing.T) {
 	check()
-	h := fileList(haveList(m, remoteDevice1))
+	h := fileList(haveList(t, m, remoteDevice1))
 	sort.Sort(h)
 	if fmt.Sprint(h) != fmt.Sprint(secRemote) {
 		t.Errorf("Have incorrect (secRemote);\n A: %v !=\n E: %v", h, secRemote)
 	}
-	n := fileList(needList(m, remoteDevice1))
+	n := fileList(needList(t, m, remoteDevice1))
 	sort.Sort(n)
 	if fmt.Sprint(n) != fmt.Sprint(expectedSecRemoteNeed) {
@ -478,7 +478,7 @@ func TestNeedWithInvalid(t *testing.T) {
 	replace(s, remoteDevice0, remote0Have)
 	replace(s, remoteDevice1, remote1Have)
-	need := fileList(needList(s, protocol.LocalDeviceID))
+	need := fileList(needList(t, s, protocol.LocalDeviceID))
 	sort.Sort(need)
 	if fmt.Sprint(need) != fmt.Sprint(expectedNeed) {
@ -506,7 +506,7 @@ func TestUpdateToInvalid(t *testing.T) {
 	replace(s, protocol.LocalDeviceID, localHave)
-	have := fileList(haveList(s, protocol.LocalDeviceID))
+	have := fileList(haveList(t, s, protocol.LocalDeviceID))
 	sort.Sort(have)
 	if fmt.Sprint(have) != fmt.Sprint(localHave) {
@ -523,7 +523,7 @@ func TestUpdateToInvalid(t *testing.T) {
 	s.Update(protocol.LocalDeviceID, append(fileList{}, localHave[1], localHave[4]))
-	have = fileList(haveList(s, protocol.LocalDeviceID))
+	have = fileList(haveList(t, s, protocol.LocalDeviceID))
 	sort.Sort(have)
 	if fmt.Sprint(have) != fmt.Sprint(localHave) {
@ -567,7 +567,7 @@ func TestInvalidAvailability(t *testing.T) {
 	replace(s, remoteDevice0, remote0Have)
 	replace(s, remoteDevice1, remote1Have)
-	snap := s.Snapshot()
+	snap := snapshot(t, s)
 	defer snap.Release()
 	if av := snap.Availability("both"); len(av) != 2 {
@ -608,7 +608,7 @@ func TestGlobalReset(t *testing.T) {
 	}
 	replace(m, protocol.LocalDeviceID, local)
-	g := globalList(m)
+	g := globalList(t, m)
 	sort.Sort(fileList(g))
 	if diff, equal := messagediff.PrettyDiff(local, g); !equal {
@ -618,7 +618,7 @@ func TestGlobalReset(t *testing.T) {
 	replace(m, remoteDevice0, remote)
 	replace(m, remoteDevice0, nil)
-	g = globalList(m)
+	g = globalList(t, m)
 	sort.Sort(fileList(g))
 	if diff, equal := messagediff.PrettyDiff(local, g); !equal {
@ -655,7 +655,7 @@ func TestNeed(t *testing.T) {
 	replace(m, protocol.LocalDeviceID, local)
 	replace(m, remoteDevice0, remote)
-	need := needList(m, protocol.LocalDeviceID)
+	need := needList(t, m, protocol.LocalDeviceID)
 	sort.Sort(fileList(need))
 	sort.Sort(fileList(shouldNeed))
@ -725,10 +725,10 @@ func TestListDropFolder(t *testing.T) {
 	if diff, equal := messagediff.PrettyDiff(expectedFolderList, actualFolderList); !equal {
 		t.Fatalf("FolderList mismatch. Diff:\n%s", diff)
 	}
-	if l := len(globalList(s0)); l != 3 {
+	if l := len(globalList(t, s0)); l != 3 {
 		t.Errorf("Incorrect global length %d != 3 for s0", l)
 	}
-	if l := len(globalList(s1)); l != 3 {
+	if l := len(globalList(t, s1)); l != 3 {
 		t.Errorf("Incorrect global length %d != 3 for s1", l)
 	}
@ -741,10 +741,10 @@ func TestListDropFolder(t *testing.T) {
 	if diff, equal := messagediff.PrettyDiff(expectedFolderList, actualFolderList); !equal {
 		t.Fatalf("FolderList mismatch. Diff:\n%s", diff)
 	}
-	if l := len(globalList(s0)); l != 3 {
+	if l := len(globalList(t, s0)); l != 3 {
 		t.Errorf("Incorrect global length %d != 3 for s0", l)
 	}
-	if l := len(globalList(s1)); l != 0 {
+	if l := len(globalList(t, s1)); l != 0 {
 		t.Errorf("Incorrect global length %d != 0 for s1", l)
 	}
 }
@ -780,13 +780,13 @@ func TestGlobalNeedWithInvalid(t *testing.T) {
 		protocol.FileInfo{Name: "d", Version: protocol.Vector{Counters: []protocol.Counter{{ID: remoteDevice0.Short(), Value: 1002}}}},
 	}
-	need := fileList(needList(s, protocol.LocalDeviceID))
+	need := fileList(needList(t, s, protocol.LocalDeviceID))
 	if fmt.Sprint(need) != fmt.Sprint(total) {
 		t.Errorf("Need incorrect;\n A: %v !=\n E: %v", need, total)
 	}
 	checkNeed(t, s, protocol.LocalDeviceID, total)
-	global := fileList(globalList(s))
+	global := fileList(globalList(t, s))
 	if fmt.Sprint(global) != fmt.Sprint(total) {
 		t.Errorf("Global incorrect;\n A: %v !=\n E: %v", global, total)
 	}
@ -810,7 +810,7 @@ func TestLongPath(t *testing.T) {
 	replace(s, protocol.LocalDeviceID, local)
-	gf := globalList(s)
+	gf := globalList(t, s)
 	if l := len(gf); l != 1 {
 		t.Fatalf("Incorrect len %d != 1 for global list", l)
 	}
@ -911,17 +911,17 @@ func TestDropFiles(t *testing.T) {
 	// Check that they're there
-	h := haveList(m, protocol.LocalDeviceID)
+	h := haveList(t, m, protocol.LocalDeviceID)
 	if len(h) != len(local0) {
 		t.Errorf("Incorrect number of files after update, %d != %d", len(h), len(local0))
 	}
-	h = haveList(m, remoteDevice0)
+	h = haveList(t, m, remoteDevice0)
 	if len(h) != len(remote0) {
 		t.Errorf("Incorrect number of files after update, %d != %d", len(h), len(local0))
 	}
-	g := globalList(m)
+	g := globalList(t, m)
 	if len(g) != len(local0) {
 		// local0 covers all files
 		t.Errorf("Incorrect global files after update, %d != %d", len(g), len(local0))
@ -931,17 +931,17 @@ func TestDropFiles(t *testing.T) {
 	m.Drop(protocol.LocalDeviceID)
-	h = haveList(m, protocol.LocalDeviceID)
+	h = haveList(t, m, protocol.LocalDeviceID)
 	if len(h) != 0 {
 		t.Errorf("Incorrect number of files after drop, %d != %d", len(h), 0)
 	}
-	h = haveList(m, remoteDevice0)
+	h = haveList(t, m, remoteDevice0)
 	if len(h) != len(remote0) {
 		t.Errorf("Incorrect number of files after update, %d != %d", len(h), len(local0))
 	}
-	g = globalList(m)
+	g = globalList(t, m)
 	if len(g) != len(remote0) {
 		// the ones in remote0 remain
 		t.Errorf("Incorrect global files after update, %d != %d", len(g), len(remote0))
@ -961,20 +961,20 @@ func TestIssue4701(t *testing.T) {
 	s.Update(protocol.LocalDeviceID, localHave)
-	if c := localSize(s); c.Files != 1 {
+	if c := localSize(t, s); c.Files != 1 {
 		t.Errorf("Expected 1 local file, got %v", c.Files)
 	}
-	if c := globalSize(s); c.Files != 1 {
+	if c := globalSize(t, s); c.Files != 1 {
 		t.Errorf("Expected 1 global file, got %v", c.Files)
 	}
 	localHave[1].LocalFlags = 0
 	s.Update(protocol.LocalDeviceID, localHave)
-	if c := localSize(s); c.Files != 2 {
+	if c := localSize(t, s); c.Files != 2 {
 		t.Errorf("Expected 2 local files, got %v", c.Files)
 	}
-	if c := globalSize(s); c.Files != 2 {
+	if c := globalSize(t, s); c.Files != 2 {
 		t.Errorf("Expected 2 global files, got %v", c.Files)
 	}
@ -982,10 +982,10 @@ func TestIssue4701(t *testing.T) {
 	localHave[1].LocalFlags = protocol.FlagLocalIgnored
 	s.Update(protocol.LocalDeviceID, localHave)
-	if c := localSize(s); c.Files != 0 {
+	if c := localSize(t, s); c.Files != 0 {
 		t.Errorf("Expected 0 local files, got %v", c.Files)
 	}
-	if c := globalSize(s); c.Files != 0 {
+	if c := globalSize(t, s); c.Files != 0 {
 		t.Errorf("Expected 0 global files, got %v", c.Files)
 	}
 }
@ -1009,7 +1009,7 @@ func TestWithHaveSequence(t *testing.T) {
 	replace(s, protocol.LocalDeviceID, localHave)
 	i := 2
-	snap := s.Snapshot()
+	snap := snapshot(t, s)
 	defer snap.Release()
 	snap.WithHaveSequence(int64(i), func(fi protocol.FileIntf) bool {
 		if f := fi.(protocol.FileInfo); !f.IsEquivalent(localHave[i-1], 0) {
@ -1061,7 +1061,7 @@ loop:
 			break loop
 		default:
 		}
-		snap := s.Snapshot()
+		snap := snapshot(t, s)
 		snap.WithHaveSequence(prevSeq+1, func(fi protocol.FileIntf) bool {
 			if fi.SequenceNo() < prevSeq+1 {
 				t.Fatal("Skipped ", prevSeq+1, fi.SequenceNo())
@ -1089,11 +1089,11 @@ func TestIssue4925(t *testing.T) {
 	replace(s, protocol.LocalDeviceID, localHave)
 	for _, prefix := range []string{"dir", "dir/"} {
-		pl := haveListPrefixed(s, protocol.LocalDeviceID, prefix)
+		pl := haveListPrefixed(t, s, protocol.LocalDeviceID, prefix)
 		if l := len(pl); l != 2 {
 			t.Errorf("Expected 2, got %v local items below %v", l, prefix)
 		}
-		pl = globalListPrefixed(s, prefix)
+		pl = globalListPrefixed(t, s, prefix)
 		if l := len(pl); l != 2 {
 			t.Errorf("Expected 2, got %v global items below %v", l, prefix)
 		}
@ -1114,24 +1114,24 @@ func TestMoveGlobalBack(t *testing.T) {
 	s.Update(protocol.LocalDeviceID, localHave)
 	s.Update(remoteDevice0, remote0Have)
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 1 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 1 {
 		t.Error("Expected 1 local need, got", need)
 	} else if !need[0].IsEquivalent(remote0Have[0], 0) {
 		t.Errorf("Local need incorrect;\n A: %v !=\n E: %v", need[0], remote0Have[0])
 	}
 	checkNeed(t, s, protocol.LocalDeviceID, remote0Have[:1])
-	if need := needList(s, remoteDevice0); len(need) != 0 {
+	if need := needList(t, s, remoteDevice0); len(need) != 0 {
 		t.Error("Expected no need for remote 0, got", need)
 	}
 	checkNeed(t, s, remoteDevice0, nil)
-	ls := localSize(s)
+	ls := localSize(t, s)
 	if haveBytes := localHave[0].Size; ls.Bytes != haveBytes {
 		t.Errorf("Incorrect LocalSize bytes; %d != %d", ls.Bytes, haveBytes)
 	}
-	gs := globalSize(s)
+	gs := globalSize(t, s)
 	if globalBytes := remote0Have[0].Size; gs.Bytes != globalBytes {
 		t.Errorf("Incorrect GlobalSize bytes; %d != %d", gs.Bytes, globalBytes)
 	}
@ -1142,24 +1142,24 @@ func TestMoveGlobalBack(t *testing.T) {
 	remote0Have[0].Version = remote0Have[0].Version.Update(remoteDevice0.Short()).DropOthers(remoteDevice0.Short())
 	s.Update(remoteDevice0, remote0Have)
-	if need := needList(s, remoteDevice0); len(need) != 1 {
+	if need := needList(t, s, remoteDevice0); len(need) != 1 {
 		t.Error("Expected 1 need for remote 0, got", need)
 	} else if !need[0].IsEquivalent(localHave[0], 0) {
 		t.Errorf("Need for remote 0 incorrect;\n A: %v !=\n E: %v", need[0], localHave[0])
 	}
 	checkNeed(t, s, remoteDevice0, localHave[:1])
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 0 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 0 {
 		t.Error("Expected no local need, got", need)
 	}
 	checkNeed(t, s, protocol.LocalDeviceID, nil)
-	ls = localSize(s)
+	ls = localSize(t, s)
 	if haveBytes := localHave[0].Size; ls.Bytes != haveBytes {
 		t.Errorf("Incorrect LocalSize bytes; %d != %d", ls.Bytes, haveBytes)
 	}
-	gs = globalSize(s)
+	gs = globalSize(t, s)
 	if globalBytes := localHave[0].Size; gs.Bytes != globalBytes {
 		t.Errorf("Incorrect GlobalSize bytes; %d != %d", gs.Bytes, globalBytes)
 	}
@ -1181,7 +1181,7 @@ func TestIssue5007(t *testing.T) {
 	s.Update(remoteDevice0, fs)
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 1 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 1 {
 		t.Fatal("Expected 1 local need, got", need)
 	} else if !need[0].IsEquivalent(fs[0], 0) {
 		t.Fatalf("Local need incorrect;\n A: %v !=\n E: %v", need[0], fs[0])
@ -1191,7 +1191,7 @@ func TestIssue5007(t *testing.T) {
 	fs[0].LocalFlags = protocol.FlagLocalIgnored
 	s.Update(protocol.LocalDeviceID, fs)
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 0 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 0 {
 		t.Fatal("Expected no local need, got", need)
 	}
 	checkNeed(t, s, protocol.LocalDeviceID, nil)
@ -1211,7 +1211,7 @@ func TestNeedDeleted(t *testing.T) {
 	s.Update(remoteDevice0, fs)
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 0 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 0 {
 		t.Fatal("Expected no local need, got", need)
 	}
 	checkNeed(t, s, protocol.LocalDeviceID, nil)
@ -1220,7 +1220,7 @@ func TestNeedDeleted(t *testing.T) {
 	fs[0].Version = fs[0].Version.Update(remoteDevice0.Short())
 	s.Update(remoteDevice0, fs)
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 1 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 1 {
 		t.Fatal("Expected 1 local need, got", need)
 	} else if !need[0].IsEquivalent(fs[0], 0) {
 		t.Fatalf("Local need incorrect;\n A: %v !=\n E: %v", need[0], fs[0])
@ -1231,7 +1231,7 @@ func TestNeedDeleted(t *testing.T) {
 	fs[0].Version = fs[0].Version.Update(remoteDevice0.Short())
 	s.Update(remoteDevice0, fs)
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 0 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 0 {
 		t.Fatal("Expected no local need, got", need)
 	}
 	checkNeed(t, s, protocol.LocalDeviceID, nil)
@ -1261,22 +1261,22 @@ func TestReceiveOnlyAccounting(t *testing.T) {
 	replace(s, protocol.LocalDeviceID, files)
 	replace(s, remote, files)
-	if n := localSize(s).Files; n != 3 {
+	if n := localSize(t, s).Files; n != 3 {
 		t.Fatal("expected 3 local files initially, not", n)
 	}
-	if n := localSize(s).Bytes; n != 30 {
+	if n := localSize(t, s).Bytes; n != 30 {
 		t.Fatal("expected 30 local bytes initially, not", n)
 	}
-	if n := globalSize(s).Files; n != 3 {
+	if n := globalSize(t, s).Files; n != 3 {
 		t.Fatal("expected 3 global files initially, not", n)
 	}
-	if n := globalSize(s).Bytes; n != 30 {
+	if n := globalSize(t, s).Bytes; n != 30 {
 		t.Fatal("expected 30 global bytes initially, not", n)
 	}
-	if n := receiveOnlyChangedSize(s).Files; n != 0 {
+	if n := receiveOnlyChangedSize(t, s).Files; n != 0 {
 		t.Fatal("expected 0 receive only changed files initially, not", n)
 	}
-	if n := receiveOnlyChangedSize(s).Bytes; n != 0 {
+	if n := receiveOnlyChangedSize(t, s).Bytes; n != 0 {
 		t.Fatal("expected 0 receive only changed bytes initially, not", n)
 	}
@ -1291,22 +1291,22 @@ func TestReceiveOnlyAccounting(t *testing.T) {
 	// Check that we see the files
-	if n := localSize(s).Files; n != 3 {
+	if n := localSize(t, s).Files; n != 3 {
 		t.Fatal("expected 3 local files after local change, not", n)
 	}
-	if n := localSize(s).Bytes; n != 120 {
+	if n := localSize(t, s).Bytes; n != 120 {
 		t.Fatal("expected 120 local bytes after local change, not", n)
 	}
-	if n := globalSize(s).Files; n != 3 {
+	if n := globalSize(t, s).Files; n != 3 {
 		t.Fatal("expected 3 global files after local change, not", n)
 	}
-	if n := globalSize(s).Bytes; n != 30 {
+	if n := globalSize(t, s).Bytes; n != 30 {
 		t.Fatal("expected 30 global files after local change, not", n)
 	}
-	if n := receiveOnlyChangedSize(s).Files; n != 1 {
+	if n := receiveOnlyChangedSize(t, s).Files; n != 1 {
 		t.Fatal("expected 1 receive only changed file after local change, not", n)
 	}
-	if n := receiveOnlyChangedSize(s).Bytes; n != 100 {
+	if n := receiveOnlyChangedSize(t, s).Bytes; n != 100 {
 		t.Fatal("expected 100 receive only changed btyes after local change, not", n)
 	}
@ -1322,22 +1322,22 @@ func TestReceiveOnlyAccounting(t *testing.T) {
 	// Check that we see the files, same data as initially
-	if n := localSize(s).Files; n != 3 {
+	if n := localSize(t, s).Files; n != 3 {
 		t.Fatal("expected 3 local files after revert, not", n)
 	}
-	if n := localSize(s).Bytes; n != 30 {
+	if n := localSize(t, s).Bytes; n != 30 {
 		t.Fatal("expected 30 local bytes after revert, not", n)
 	}
-	if n := globalSize(s).Files; n != 3 {
+	if n := globalSize(t, s).Files; n != 3 {
 		t.Fatal("expected 3 global files after revert, not", n)
 	}
-	if n := globalSize(s).Bytes; n != 30 {
+	if n := globalSize(t, s).Bytes; n != 30 {
 		t.Fatal("expected 30 global bytes after revert, not", n)
 	}
-	if n := receiveOnlyChangedSize(s).Files; n != 0 {
+	if n := receiveOnlyChangedSize(t, s).Files; n != 0 {
 		t.Fatal("expected 0 receive only changed files after revert, not", n)
 	}
-	if n := receiveOnlyChangedSize(s).Bytes; n != 0 {
+	if n := receiveOnlyChangedSize(t, s).Bytes; n != 0 {
 		t.Fatal("expected 0 receive only changed bytes after revert, not", n)
 	}
 }
@ -1366,7 +1366,7 @@ func TestNeedAfterUnignore(t *testing.T) {
 	local.ModifiedS = 0
 	s.Update(protocol.LocalDeviceID, fileList{local})
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 1 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 1 {
 		t.Fatal("Expected one local need, got", need)
 	} else if !need[0].IsEquivalent(remote, 0) {
 		t.Fatalf("Got %v, expected %v", need[0], remote)
@ -1387,7 +1387,7 @@ func TestRemoteInvalidNotAccounted(t *testing.T) {
 	}
 	s.Update(remoteDevice0, files)
-	global := globalSize(s)
+	global := globalSize(t, s)
 	if global.Files != 1 {
 		t.Error("Expected one file in global size, not", global.Files)
 	}
@ -1411,7 +1411,7 @@ func TestNeedWithNewerInvalid(t *testing.T) {
 	s.Update(remoteDevice0, fileList{file})
 	s.Update(remoteDevice1, fileList{file})
-	need := needList(s, protocol.LocalDeviceID)
+	need := needList(t, s, protocol.LocalDeviceID)
 	if len(need) != 1 {
 		t.Fatal("Locally missing file should be needed")
 	}
@ -1427,7 +1427,7 @@ func TestNeedWithNewerInvalid(t *testing.T) {
 	s.Update(remoteDevice1, fileList{inv})
 	// We still have an old file, we need the newest valid file
-	need = needList(s, protocol.LocalDeviceID)
+	need = needList(t, s, protocol.LocalDeviceID)
 	if len(need) != 1 {
 		t.Fatal("Locally missing file should be needed regardless of invalid files")
 	}
@ -1452,13 +1452,13 @@ func TestNeedAfterDeviceRemove(t *testing.T) {
 	s.Update(remoteDevice0, fs)
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 1 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 1 {
 		t.Fatal("Expected one local need, got", need)
 	}
 	s.Drop(remoteDevice0)
-	if need := needList(s, protocol.LocalDeviceID); len(need) != 0 {
+	if need := needList(t, s, protocol.LocalDeviceID); len(need) != 0 {
 		t.Fatal("Expected no local need, got", need)
 	}
 	checkNeed(t, s, protocol.LocalDeviceID, nil)
@ -1481,7 +1481,7 @@ func TestCaseSensitive(t *testing.T) {
 	replace(s, protocol.LocalDeviceID, local)
-	gf := globalList(s)
+	gf := globalList(t, s)
 	if l := len(gf); l != len(local) {
 		t.Fatalf("Incorrect len %d != %d for global list", l, len(local))
 	}
@ -1551,7 +1551,7 @@ func TestSequenceIndex(t *testing.T) {
 		// a subset of those files if we manage to run before a complete
 		// update has happened since our last iteration.
 		latest = latest[:0]
-		snap := s.Snapshot()
+		snap := snapshot(t, s)
 		snap.WithHaveSequence(seq+1, func(f protocol.FileIntf) bool {
 			seen[f.FileName()] = f
 			latest = append(latest, f)
@ -1617,7 +1617,7 @@ func TestIgnoreAfterReceiveOnly(t *testing.T) {
 	s.Update(protocol.LocalDeviceID, fs)
-	snap := s.Snapshot()
+	snap := snapshot(t, s)
 	defer snap.Release()
 	if f, ok := snap.Get(protocol.LocalDeviceID, file); !ok {
 		t.Error("File missing in db")
@ -1654,7 +1654,7 @@ func TestUpdateWithOneFileTwice(t *testing.T) {
 	s.Update(protocol.LocalDeviceID, fs)
-	snap := s.Snapshot()
+	snap := snapshot(t, s)
 	defer snap.Release()
 	count := 0
 	snap.WithHaveSequence(0, func(f protocol.FileIntf) bool {
@ -1678,7 +1678,7 @@ func TestNeedRemoteOnly(t *testing.T) {
 	}
 	s.Update(remoteDevice0, remote0Have)
-	need := needSize(s, remoteDevice0)
+	need := needSize(t, s, remoteDevice0)
 	if !need.Equal(db.Counts{}) {
 		t.Error("Expected nothing needed, got", need)
 	}
@ -1697,14 +1697,14 @@ func TestNeedRemoteAfterReset(t *testing.T) {
 	s.Update(protocol.LocalDeviceID, files)
 	s.Update(remoteDevice0, files)
-	need := needSize(s, remoteDevice0)
+	need := needSize(t, s, remoteDevice0)
 	if !need.Equal(db.Counts{}) {
 		t.Error("Expected nothing needed, got", need)
 	}
 	s.Drop(remoteDevice0)
-	need = needSize(s, remoteDevice0)
+	need = needSize(t, s, remoteDevice0)
 	if exp := (db.Counts{Files: 1}); !need.Equal(exp) {
 		t.Errorf("Expected %v, got %v", exp, need)
 	}
@ -1723,10 +1723,10 @@ func TestIgnoreLocalChanged(t *testing.T) {
 	}
 	s.Update(protocol.LocalDeviceID, files)
-	if c := globalSize(s).Files; c != 0 {
+	if c := globalSize(t, s).Files; c != 0 {
 		t.Error("Expected no global file, got", c)
 	}
-	if c := localSize(s).Files; c != 1 {
+	if c := localSize(t, s).Files; c != 1 {
 		t.Error("Expected one local file, got", c)
 	}
@ -1734,10 +1734,10 @@ func TestIgnoreLocalChanged(t *testing.T) {
 	files[0].LocalFlags = protocol.FlagLocalIgnored
 	s.Update(protocol.LocalDeviceID, files)
-	if c := globalSize(s).Files; c != 0 {
+	if c := globalSize(t, s).Files; c != 0 {
 		t.Error("Expected no global file, got", c)
 	}
-	if c := localSize(s).Files; c != 0 {
+	if c := localSize(t, s).Files; c != 0 {
 		t.Error("Expected no local file, got", c)
 	}
 }
@ -1789,26 +1789,26 @@ func replace(fs *db.FileSet, device protocol.DeviceID, files []protocol.FileInfo
 	fs.Update(device, files)
 }
-func localSize(fs *db.FileSet) db.Counts {
+func localSize(t testing.TB, fs *db.FileSet) db.Counts {
-	snap := fs.Snapshot()
+	snap := snapshot(t, fs)
 	defer snap.Release()
 	return snap.LocalSize()
 }
-func globalSize(fs *db.FileSet) db.Counts {
+func globalSize(t testing.TB, fs *db.FileSet) db.Counts {
-	snap := fs.Snapshot()
+	snap := snapshot(t, fs)
 	defer snap.Release()
 	return snap.GlobalSize()
 }
-func needSize(fs *db.FileSet, id protocol.DeviceID) db.Counts {
+func needSize(t testing.TB, fs *db.FileSet, id protocol.DeviceID) db.Counts {
-	snap := fs.Snapshot()
+	snap := snapshot(t, fs)
 	defer snap.Release()
 	return snap.NeedSize(id)
 }
-func receiveOnlyChangedSize(fs *db.FileSet) db.Counts {
+func receiveOnlyChangedSize(t testing.TB, fs *db.FileSet) db.Counts {
-	snap := fs.Snapshot()
+	snap := snapshot(t, fs)
 	defer snap.Release()
 	return snap.ReceiveOnlyChangedSize()
 }
@ -1833,7 +1833,7 @@ func filesToCounts(files []protocol.FileInfo) db.Counts {
 func checkNeed(t testing.TB, s *db.FileSet, dev protocol.DeviceID, expected []protocol.FileInfo) {
 	t.Helper()
-	counts := needSize(s, dev)
+	counts := needSize(t, s, dev)
 	if exp := filesToCounts(expected); !exp.Equal(counts) {
 		t.Errorf("Count incorrect (%v): expected %v, got %v", dev, exp, counts)
 	}
@ -1860,3 +1860,12 @@ func newFileSet(t testing.TB, folder string, fs fs.Filesystem, ll *db.Lowlevel)
 	}
 	return fset
 }
 func snapshot(t testing.TB, fset *db.FileSet) *db.Snapshot {
 	t.Helper()
 	snap, err := fset.Snapshot()
 	if err != nil {
 		t.Fatal(err)
 	}
 	return snap
 }
--- a/lib/db/util_test.go
+++ b/lib/db/util_test.go
@ -92,6 +92,15 @@ func newFileSet(t testing.TB, folder string, fs fs.Filesystem, db *Lowlevel) *Fi
 	return fset
 }
 func snapshot(t testing.TB, fset *FileSet) *Snapshot {
 	t.Helper()
 	snap, err := fset.Snapshot()
 	if err != nil {
 		t.Fatal(err)
 	}
 	return snap
 }
 // The following commented tests were used to generate jsons files to stdout for
 // future tests and are kept here for reference (reuse).
--- a/lib/model/folder.go
+++ b/lib/model/folder.go
@ -27,6 +27,7 @@ import (
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/scanner"
 	"github.com/syncthing/syncthing/lib/stats"
 	"github.com/syncthing/syncthing/lib/svcutil"
 	"github.com/syncthing/syncthing/lib/sync"
 	"github.com/syncthing/syncthing/lib/util"
 	"github.com/syncthing/syncthing/lib/versioner"
@ -87,7 +88,7 @@ type syncRequest struct {
 }
 type puller interface {
-	pull() bool // true when successful and should not be retried
+	pull() (bool, error) // true when successful and should not be retried
 }
 func newFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, evLogger events.Logger, ioLimiter *byteSemaphore, ver versioner.Versioner) folder {
@ -164,16 +165,20 @@ func (f *folder) Serve(ctx context.Context) error {
 	initialCompleted := f.initialScanFinished
 	for {
 		var err error
 		select {
 		case <-f.ctx.Done():
 			close(f.done)
 			return nil
 		case <-f.pullScheduled:
-			f.pull()
+			_, err = f.pull()
 		case <-f.pullFailTimer.C:
-			if !f.pull() && f.pullPause < 60*f.pullBasePause() {
+			var success bool
 			success, err = f.pull()
 			if (err != nil || !success) && f.pullPause < 60*f.pullBasePause() {
 				// Back off from retrying to pull
 				f.pullPause *= 2
 			}
@ -181,18 +186,19 @@ func (f *folder) Serve(ctx context.Context) error {
 		case <-initialCompleted:
 			// Initial scan has completed, we should do a pull
 			initialCompleted = nil // never hit this case again
-			f.pull()
+			_, err = f.pull()
 		case <-f.forcedRescanRequested:
-			f.handleForcedRescans()
+			err = f.handleForcedRescans()
 		case <-f.scanTimer.C:
 			l.Debugln(f, "Scanning due to timer")
-			f.scanTimerFired()
+			err = f.scanTimerFired()
 		case req := <-f.doInSyncChan:
 			l.Debugln(f, "Running something due to request")
-			req.err <- req.fn()
+			err = req.fn()
 			req.err <- err
 		case next := <-f.scanDelay:
 			l.Debugln(f, "Delaying scan")
@ -200,16 +206,23 @@ func (f *folder) Serve(ctx context.Context) error {
 		case fsEvents := <-f.watchChan:
 			l.Debugln(f, "Scan due to watcher")
-			f.scanSubdirs(fsEvents)
+			err = f.scanSubdirs(fsEvents)
 		case <-f.restartWatchChan:
 			l.Debugln(f, "Restart watcher")
-			f.restartWatch()
+			err = f.restartWatch()
 		case <-f.versionCleanupTimer.C:
 			l.Debugln(f, "Doing version cleanup")
 			f.versionCleanupTimerFired()
 		}
 		if err != nil {
 			if svcutil.IsFatal(err) {
 				return err
 			}
 			f.setError(err)
 		}
 	}
 }
@ -307,7 +320,7 @@ func (f *folder) getHealthErrorWithoutIgnores() error {
 	return nil
 }
-func (f *folder) pull() (success bool) {
+func (f *folder) pull() (success bool, err error) {
 	f.pullFailTimer.Stop()
 	select {
 	case <-f.pullFailTimer.C:
@ -318,7 +331,7 @@ func (f *folder) pull() (success bool) {
 	case <-f.initialScanFinished:
 	default:
 		// Once the initial scan finished, a pull will be scheduled
-		return true
+		return true, nil
 	}
 	defer func() {
@ -330,7 +343,10 @@ func (f *folder) pull() (success bool) {
 	// If there is nothing to do, don't even enter sync-waiting state.
 	abort := true
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return false, err
 	}
 	snap.WithNeed(protocol.LocalDeviceID, func(intf protocol.FileIntf) bool {
 		abort = false
 		return false
@ -341,16 +357,16 @@ func (f *folder) pull() (success bool) {
 		f.errorsMut.Lock()
 		f.pullErrors = nil
 		f.errorsMut.Unlock()
-		return true
+		return true, nil
 	}
 	// Abort early (before acquiring a token) if there's a folder error
-	err := f.getHealthErrorWithoutIgnores()
+	err = f.getHealthErrorWithoutIgnores()
 	f.setError(err)
 	if err != nil {
 		l.Debugln("Skipping pull of", f.Description(), "due to folder error:", err)
-		return false
+		return false, err
 	}
 	f.setError(nil)
 	// Send only folder doesn't do any io, it only checks for out-of-sync
 	// items that differ in metadata and updates those.
@ -358,8 +374,7 @@ func (f *folder) pull() (success bool) {
 		f.setState(FolderSyncWaiting)
 		if err := f.ioLimiter.takeWithContext(f.ctx, 1); err != nil {
-			f.setError(err)
+			return true, err
 			return true
 		}
 		defer f.ioLimiter.give(1)
 	}
@ -374,23 +389,23 @@ func (f *folder) pull() (success bool) {
 		}
 	}()
 	err = f.getHealthErrorAndLoadIgnores()
 	f.setError(err)
 	if err != nil {
 		l.Debugln("Skipping pull of", f.Description(), "due to folder error:", err)
-		return false
+		return false, err
 	}
-	success = f.puller.pull()
+	success, err = f.puller.pull()
-	if success {
+	if success && err == nil {
-		return true
+		return true, nil
 	}
 	// Pulling failed, try again later.
 	delay := f.pullPause + time.Since(startTime)
 	l.Infof("Folder %v isn't making sync progress - retrying in %v.", f.Description(), util.NiceDurationString(delay))
 	f.pullFailTimer.Reset(delay)
-	return false
+
 	return false, err
 }
 func (f *folder) scanSubdirs(subDirs []string) error {
@ -399,7 +414,6 @@ func (f *folder) scanSubdirs(subDirs []string) error {
 	oldHash := f.ignores.Hash()
 	err := f.getHealthErrorAndLoadIgnores()
 	f.setError(err)
 	if err != nil {
 		// If there is a health error we set it as the folder error. We do not
 		// clear the folder error if there is no health error, as there might be
@ -407,6 +421,7 @@ func (f *folder) scanSubdirs(subDirs []string) error {
 		// we do not use the CheckHealth() convenience function here.
 		return err
 	}
 	f.setError(nil)
 	// Check on the way out if the ignore patterns changed as part of scanning
 	// this folder. If they did we should schedule a pull of the folder so that
@ -443,7 +458,10 @@ func (f *folder) scanSubdirs(subDirs []string) error {
 	// Clean the list of subitems to ensure that we start at a known
 	// directory, and don't scan subdirectories of things we've already
 	// scanned.
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return err
 	}
 	subDirs = unifySubs(subDirs, func(file string) bool {
 		_, ok := snap.Get(protocol.LocalDeviceID, file)
 		return ok
@ -560,7 +578,10 @@ func (f *folder) scanSubdirsBatchAppendFunc(batch *fileInfoBatch) batchAppendFun
 func (f *folder) scanSubdirsChangedAndNew(subDirs []string, batch *fileInfoBatch, batchAppend batchAppendFunc) (int, error) {
 	changes := 0
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return changes, err
 	}
 	defer snap.Release()
 	// If we return early e.g. due to a folder health error, the scan needs
@ -629,7 +650,10 @@ func (f *folder) scanSubdirsDeletedAndIgnored(subDirs []string, batch *fileInfoB
 	var toIgnore []db.FileInfoTruncated
 	ignoredParent := ""
 	changes := 0
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return 0, err
 	}
 	defer snap.Release()
 	for _, sub := range subDirs {
@ -821,7 +845,7 @@ func (f *folder) findRename(snap *db.Snapshot, file protocol.FileInfo, alreadyUs
 	return nf, found
 }
-func (f *folder) scanTimerFired() {
+func (f *folder) scanTimerFired() error {
 	err := f.scanSubdirs(nil)
 	select {
@ -836,6 +860,8 @@ func (f *folder) scanTimerFired() {
 	}
 	f.Reschedule()
 	return err
 }
 func (f *folder) versionCleanupTimerFired() {
@ -884,10 +910,10 @@ func (f *folder) scheduleWatchRestart() {
 // restartWatch should only ever be called synchronously. If you want to use
 // this asynchronously, you should probably use scheduleWatchRestart instead.
-func (f *folder) restartWatch() {
+func (f *folder) restartWatch() error {
 	f.stopWatch()
 	f.startWatch()
-	f.scanSubdirs(nil)
+	return f.scanSubdirs(nil)
 }
 // startWatch should only ever be called synchronously. If you want to use
@ -1166,7 +1192,7 @@ func (f *folder) emitDiskChangeEvents(fs []protocol.FileInfo, typeOfEvent events
 	}
 }
-func (f *folder) handleForcedRescans() {
+func (f *folder) handleForcedRescans() error {
 	f.forcedRescanPathsMut.Lock()
 	paths := make([]string, 0, len(f.forcedRescanPaths))
 	for path := range f.forcedRescanPaths {
@ -1175,7 +1201,7 @@ func (f *folder) handleForcedRescans() {
 	f.forcedRescanPaths = make(map[string]struct{})
 	f.forcedRescanPathsMut.Unlock()
 	if len(paths) == 0 {
-		return
+		return nil
 	}
 	batch := newFileInfoBatch(func(fs []protocol.FileInfo) error {
@ -1183,10 +1209,16 @@ func (f *folder) handleForcedRescans() {
 		return nil
 	})
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return err
 	}
 	defer snap.Release()
 	for _, path := range paths {
-		_ = batch.flushIfFull()
+		if err := batch.flushIfFull(); err != nil {
 			return err
 		}
 		fi, ok := snap.Get(protocol.LocalDeviceID, path)
 		if !ok {
@ -1196,11 +1228,21 @@ func (f *folder) handleForcedRescans() {
 		batch.append(fi)
 	}
-	snap.Release()
+	if err = batch.flush(); err != nil {
 		return err
 	}
-	_ = batch.flush()
+	return f.scanSubdirs(paths)
 }
-	_ = f.scanSubdirs(paths)
+// dbSnapshots gets a snapshot from the fileset, and wraps any error
 // in a svcutil.FatalErr.
 func (f *folder) dbSnapshot() (*db.Snapshot, error) {
 	snap, err := f.fset.Snapshot()
 	if err != nil {
 		return nil, svcutil.AsFatalErr(err, svcutil.ExitError)
 	}
 	return snap, nil
 }
 // The exists function is expected to return true for all known paths
--- a/lib/model/folder_recvenc.go
+++ b/lib/model/folder_recvenc.go
@ -32,10 +32,10 @@ func newReceiveEncryptedFolder(model *model, fset *db.FileSet, ignores *ignore.M
 }
 func (f *receiveEncryptedFolder) Revert() {
-	f.doInSync(func() error { f.revert(); return nil })
+	f.doInSync(f.revert)
 }
-func (f *receiveEncryptedFolder) revert() {
+func (f *receiveEncryptedFolder) revert() error {
 	l.Infof("Reverting unexpected items in folder %v (receive-encrypted)", f.Description())
 	f.setState(FolderScanning)
@ -46,7 +46,10 @@ func (f *receiveEncryptedFolder) revert() {
 		return nil
 	})
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return err
 	}
 	defer snap.Release()
 	var iterErr error
 	var dirs []string
@ -85,12 +88,10 @@ func (f *receiveEncryptedFolder) revert() {
 	f.revertHandleDirs(dirs, snap)
 	if iterErr == nil {
 		iterErr = batch.flush()
 	}
 	if iterErr != nil {
-		l.Infoln("Failed to delete unexpected items:", iterErr)
+		return iterErr
 	}
 	return batch.flush()
 }
 func (f *receiveEncryptedFolder) revertHandleDirs(dirs []string, snap *db.Snapshot) {
--- a/lib/model/folder_recvonly.go
+++ b/lib/model/folder_recvonly.go
@ -63,10 +63,10 @@ func newReceiveOnlyFolder(model *model, fset *db.FileSet, ignores *ignore.Matche
 }
 func (f *receiveOnlyFolder) Revert() {
-	f.doInSync(func() error { f.revert(); return nil })
+	f.doInSync(f.revert)
 }
-func (f *receiveOnlyFolder) revert() {
+func (f *receiveOnlyFolder) revert() error {
 	l.Infof("Reverting folder %v", f.Description)
 	f.setState(FolderScanning)
@ -84,7 +84,10 @@ func (f *receiveOnlyFolder) revert() {
 	batch := make([]protocol.FileInfo, 0, maxBatchSizeFiles)
 	batchSizeBytes := 0
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return err
 	}
 	defer snap.Release()
 	snap.WithHave(protocol.LocalDeviceID, func(intf protocol.FileIntf) bool {
 		fi := intf.(protocol.FileInfo)
@ -161,6 +164,8 @@ func (f *receiveOnlyFolder) revert() {
 	// pull by itself. Make sure we schedule one so that we start
 	// downloading files.
 	f.SchedulePull()
 	return nil
 }
 // deleteQueue handles deletes by delegating to a handler and queuing
--- a/lib/model/folder_recvonly_test.go
+++ b/lib/model/folder_recvonly_test.go
@ -384,7 +384,7 @@ func TestRecvOnlyRemoteUndoChanges(t *testing.T) {
 	// Do the same changes on the remote
 	files := make([]protocol.FileInfo, 0, 2)
-	snap := f.fset.Snapshot()
+	snap := fsetSnapshot(t, f.fset)
 	snap.WithHave(protocol.LocalDeviceID, func(fi protocol.FileIntf) bool {
 		if n := fi.FileName(); n != file && n != knownFile {
 			return true
--- a/lib/model/folder_sendonly.go
+++ b/lib/model/folder_sendonly.go
@ -36,11 +36,14 @@ func (f *sendOnlyFolder) PullErrors() []FileError {
 }
 // pull checks need for files that only differ by metadata (no changes on disk)
-func (f *sendOnlyFolder) pull() bool {
+func (f *sendOnlyFolder) pull() (bool, error) {
 	batch := make([]protocol.FileInfo, 0, maxBatchSizeFiles)
 	batchSizeBytes := 0
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return false, err
 	}
 	defer snap.Release()
 	snap.WithNeed(protocol.LocalDeviceID, func(intf protocol.FileIntf) bool {
 		if len(batch) == maxBatchSizeFiles || batchSizeBytes > maxBatchSizeBytes {
@ -83,14 +86,14 @@ func (f *sendOnlyFolder) pull() bool {
 		f.updateLocalsFromPulling(batch)
 	}
-	return true
+	return true, nil
 }
 func (f *sendOnlyFolder) Override() {
-	f.doInSync(func() error { f.override(); return nil })
+	f.doInSync(f.override)
 }
-func (f *sendOnlyFolder) override() {
+func (f *sendOnlyFolder) override() error {
 	l.Infoln("Overriding global state on folder", f.Description())
 	f.setState(FolderScanning)
@ -98,7 +101,10 @@ func (f *sendOnlyFolder) override() {
 	batch := make([]protocol.FileInfo, 0, maxBatchSizeFiles)
 	batchSizeBytes := 0
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return err
 	}
 	defer snap.Release()
 	snap.WithNeed(protocol.LocalDeviceID, func(fi protocol.FileIntf) bool {
 		need := fi.(protocol.FileInfo)
@ -130,4 +136,5 @@ func (f *sendOnlyFolder) override() {
 	if len(batch) > 0 {
 		f.updateLocalsFromScanning(batch)
 	}
 	return nil
 }
--- a/lib/model/folder_sendrecv.go
+++ b/lib/model/folder_sendrecv.go
@ -156,7 +156,7 @@ func newSendReceiveFolder(model *model, fset *db.FileSet, ignores *ignore.Matche
 // pull returns true if it manages to get all needed items from peers, i.e. get
 // the device in sync with the global state.
-func (f *sendReceiveFolder) pull() bool {
+func (f *sendReceiveFolder) pull() (bool, error) {
 	l.Debugf("%v pulling", f)
 	scanChan := make(chan string)
@ -173,10 +173,11 @@ func (f *sendReceiveFolder) pull() bool {
 	f.pullErrors = nil
 	f.errorsMut.Unlock()
 	var err error
 	for tries := 0; tries < maxPullerIterations; tries++ {
 		select {
 		case <-f.ctx.Done():
-			return false
+			return false, f.ctx.Err()
 		default:
 		}
@ -184,7 +185,10 @@ func (f *sendReceiveFolder) pull() bool {
 		// it to FolderSyncing during the last iteration.
 		f.setState(FolderSyncPreparing)
-		changed = f.pullerIteration(scanChan)
+		changed, err = f.pullerIteration(scanChan)
 		if err != nil {
 			return false, err
 		}
 		l.Debugln(f, "changed", changed, "on try", tries+1)
@ -219,19 +223,22 @@ func (f *sendReceiveFolder) pull() bool {
 		})
 	}
-	return changed == 0
+	return changed == 0, nil
 }
 // pullerIteration runs a single puller iteration for the given folder and
 // returns the number items that should have been synced (even those that
 // might have failed). One puller iteration handles all files currently
 // flagged as needed in the folder.
-func (f *sendReceiveFolder) pullerIteration(scanChan chan<- string) int {
+func (f *sendReceiveFolder) pullerIteration(scanChan chan<- string) (int, error) {
 	f.errorsMut.Lock()
 	f.tempPullErrors = make(map[string]string)
 	f.errorsMut.Unlock()
-	snap := f.fset.Snapshot()
+	snap, err := f.dbSnapshot()
 	if err != nil {
 		return 0, err
 	}
 	defer snap.Release()
 	pullChan := make(chan pullBlockState)
@ -265,7 +272,7 @@ func (f *sendReceiveFolder) pullerIteration(scanChan chan<- string) int {
 	pullWg.Add(1)
 	go func() {
 		// pullerRoutine finishes when pullChan is closed
-		f.pullerRoutine(pullChan, finisherChan)
+		f.pullerRoutine(snap, pullChan, finisherChan)
 		pullWg.Done()
 	}()
@ -300,7 +307,7 @@ func (f *sendReceiveFolder) pullerIteration(scanChan chan<- string) int {
 	f.queue.Reset()
-	return changed
+	return changed, nil
 }
 func (f *sendReceiveFolder) processNeeded(snap *db.Snapshot, dbUpdateChan chan<- dbUpdateJob, copyChan chan<- copyBlocksState, scanChan chan<- string) (int, map[string]protocol.FileInfo, []protocol.FileInfo, error) {
@ -582,7 +589,7 @@ func (f *sendReceiveFolder) handleDir(file protocol.FileInfo, snap *db.Snapshot,
 	// that don't result in a conflict.
 	case err == nil && !info.IsDir():
 		// Check that it is what we have in the database.
-		curFile, hasCurFile := f.model.CurrentFolderFile(f.folderID, file.Name)
+		curFile, hasCurFile := snap.Get(protocol.LocalDeviceID, file.Name)
 		if err := f.scanIfItemChanged(file.Name, info, curFile, hasCurFile, scanChan); err != nil {
 			err = errors.Wrap(err, "handling dir")
 			f.newPullError(file.Name, err)
@ -766,7 +773,7 @@ func (f *sendReceiveFolder) handleSymlinkCheckExisting(file protocol.FileInfo, s
 		return err
 	}
 	// Check that it is what we have in the database.
-	curFile, hasCurFile := f.model.CurrentFolderFile(f.folderID, file.Name)
+	curFile, hasCurFile := snap.Get(protocol.LocalDeviceID, file.Name)
 	if err := f.scanIfItemChanged(file.Name, info, curFile, hasCurFile, scanChan); err != nil {
 		return err
 	}
@ -1427,7 +1434,7 @@ func (f *sendReceiveFolder) verifyBuffer(buf []byte, block protocol.BlockInfo) e
 	return nil
 }
-func (f *sendReceiveFolder) pullerRoutine(in <-chan pullBlockState, out chan<- *sharedPullerState) {
+func (f *sendReceiveFolder) pullerRoutine(snap *db.Snapshot, in <-chan pullBlockState, out chan<- *sharedPullerState) {
 	requestLimiter := newByteSemaphore(f.PullerMaxPendingKiB * 1024)
 	wg := sync.NewWaitGroup()
@ -1458,13 +1465,13 @@ func (f *sendReceiveFolder) pullerRoutine(in <-chan pullBlockState, out chan<- *
 			defer wg.Done()
 			defer requestLimiter.give(bytes)
-			f.pullBlock(state, out)
+			f.pullBlock(state, snap, out)
 		}()
 	}
 	wg.Wait()
 }
-func (f *sendReceiveFolder) pullBlock(state pullBlockState, out chan<- *sharedPullerState) {
+func (f *sendReceiveFolder) pullBlock(state pullBlockState, snap *db.Snapshot, out chan<- *sharedPullerState) {
 	// Get an fd to the temporary file. Technically we don't need it until
 	// after fetching the block, but if we run into an error here there is
 	// no point in issuing the request to the network.
@ -1483,7 +1490,7 @@ func (f *sendReceiveFolder) pullBlock(state pullBlockState, out chan<- *sharedPu
 	}
 	var lastError error
-	candidates := f.model.Availability(f.folderID, state.file, state.block)
+	candidates := f.model.availabilityInSnapshot(f.FolderConfiguration, snap, state.file, state.block)
 	for {
 		select {
 		case <-f.ctx.Done():
--- a/lib/model/folder_sendrecv_test.go
+++ b/lib/model/folder_sendrecv_test.go
@ -135,7 +135,7 @@ func TestHandleFile(t *testing.T) {
 	copyChan := make(chan copyBlocksState, 1)
-	f.handleFile(requiredFile, f.fset.Snapshot(), copyChan)
+	f.handleFile(requiredFile, fsetSnapshot(t, f.fset), copyChan)
 	// Receive the results
 	toCopy := <-copyChan
@ -181,7 +181,7 @@ func TestHandleFileWithTemp(t *testing.T) {
 	copyChan := make(chan copyBlocksState, 1)
-	f.handleFile(requiredFile, f.fset.Snapshot(), copyChan)
+	f.handleFile(requiredFile, fsetSnapshot(t, f.fset), copyChan)
 	// Receive the results
 	toCopy := <-copyChan
@ -245,7 +245,7 @@ func TestCopierFinder(t *testing.T) {
 			go f.copierRoutine(copyChan, pullChan, finisherChan)
 			defer close(copyChan)
-			f.handleFile(requiredFile, f.fset.Snapshot(), copyChan)
+			f.handleFile(requiredFile, fsetSnapshot(t, f.fset), copyChan)
 			timeout := time.After(10 * time.Second)
 			pulls := make([]pullBlockState, 4)
@ -379,7 +379,7 @@ func TestWeakHash(t *testing.T) {
 	// Test 1 - no weak hashing, file gets fully repulled (`expectBlocks` pulls).
 	fo.WeakHashThresholdPct = 101
-	fo.handleFile(desiredFile, fo.fset.Snapshot(), copyChan)
+	fo.handleFile(desiredFile, fsetSnapshot(t, fo.fset), copyChan)
 	var pulls []pullBlockState
 	timeout := time.After(10 * time.Second)
@ -408,7 +408,7 @@ func TestWeakHash(t *testing.T) {
 	// Test 2 - using weak hash, expectPulls blocks pulled.
 	fo.WeakHashThresholdPct = -1
-	fo.handleFile(desiredFile, fo.fset.Snapshot(), copyChan)
+	fo.handleFile(desiredFile, fsetSnapshot(t, fo.fset), copyChan)
 	pulls = pulls[:0]
 	for len(pulls) < expectPulls {
@ -489,7 +489,7 @@ func TestDeregisterOnFailInCopy(t *testing.T) {
 	finisherBufferChan := make(chan *sharedPullerState, 1)
 	finisherChan := make(chan *sharedPullerState)
 	dbUpdateChan := make(chan dbUpdateJob, 1)
-	snap := f.fset.Snapshot()
+	snap := fsetSnapshot(t, f.fset)
 	copyChan, copyWg := startCopier(f, pullChan, finisherBufferChan)
 	go f.finisherRoutine(snap, finisherChan, dbUpdateChan, make(chan string))
@ -589,13 +589,13 @@ func TestDeregisterOnFailInPull(t *testing.T) {
 	finisherBufferChan := make(chan *sharedPullerState)
 	finisherChan := make(chan *sharedPullerState)
 	dbUpdateChan := make(chan dbUpdateJob, 1)
-	snap := f.fset.Snapshot()
+	snap := fsetSnapshot(t, f.fset)
 	copyChan, copyWg := startCopier(f, pullChan, finisherBufferChan)
 	pullWg := sync.NewWaitGroup()
 	pullWg.Add(1)
 	go func() {
-		f.pullerRoutine(pullChan, finisherBufferChan)
+		f.pullerRoutine(snap, pullChan, finisherBufferChan)
 		pullWg.Done()
 	}()
 	go f.finisherRoutine(snap, finisherChan, dbUpdateChan, make(chan string))
@ -696,7 +696,7 @@ func TestIssue3164(t *testing.T) {
 	dbUpdateChan := make(chan dbUpdateJob, 1)
-	f.deleteDir(file, f.fset.Snapshot(), dbUpdateChan, make(chan string))
+	f.deleteDir(file, fsetSnapshot(t, f.fset), dbUpdateChan, make(chan string))
 	if _, err := ffs.Stat("issue3164"); !fs.IsNotExist(err) {
 		t.Fatal(err)
@ -828,7 +828,7 @@ func TestCopyOwner(t *testing.T) {
 	dbUpdateChan := make(chan dbUpdateJob, 1)
 	scanChan := make(chan string)
 	defer close(dbUpdateChan)
-	f.handleDir(dir, f.fset.Snapshot(), dbUpdateChan, scanChan)
+	f.handleDir(dir, fsetSnapshot(t, f.fset), dbUpdateChan, scanChan)
 	select {
 	case <-dbUpdateChan: // empty the channel for later
 	case toScan := <-scanChan:
@ -858,7 +858,7 @@ func TestCopyOwner(t *testing.T) {
 	// but it's the way data is passed around. When the database update
 	// comes the finisher is done.
-	snap := f.fset.Snapshot()
+	snap := fsetSnapshot(t, f.fset)
 	finisherChan := make(chan *sharedPullerState)
 	copierChan, copyWg := startCopier(f, nil, finisherChan)
 	go f.finisherRoutine(snap, finisherChan, dbUpdateChan, nil)
@ -926,7 +926,7 @@ func TestSRConflictReplaceFileByDir(t *testing.T) {
 	dbUpdateChan := make(chan dbUpdateJob, 1)
 	scanChan := make(chan string, 1)
-	f.handleDir(file, f.fset.Snapshot(), dbUpdateChan, scanChan)
+	f.handleDir(file, fsetSnapshot(t, f.fset), dbUpdateChan, scanChan)
 	if confls := existingConflicts(name, ffs); len(confls) != 1 {
 		t.Fatal("Expected one conflict, got", len(confls))
@ -959,7 +959,7 @@ func TestSRConflictReplaceFileByLink(t *testing.T) {
 	dbUpdateChan := make(chan dbUpdateJob, 1)
 	scanChan := make(chan string, 1)
-	f.handleSymlink(file, f.fset.Snapshot(), dbUpdateChan, scanChan)
+	f.handleSymlink(file, fsetSnapshot(t, f.fset), dbUpdateChan, scanChan)
 	if confls := existingConflicts(name, ffs); len(confls) != 1 {
 		t.Fatal("Expected one conflict, got", len(confls))
@ -1001,7 +1001,7 @@ func TestDeleteBehindSymlink(t *testing.T) {
 	fi.Version = fi.Version.Update(device1.Short())
 	scanChan := make(chan string, 1)
 	dbUpdateChan := make(chan dbUpdateJob, 1)
-	f.deleteFile(fi, f.fset.Snapshot(), dbUpdateChan, scanChan)
+	f.deleteFile(fi, fsetSnapshot(t, f.fset), dbUpdateChan, scanChan)
 	select {
 	case f := <-scanChan:
 		t.Fatalf("Received %v on scanChan", f)
@ -1031,7 +1031,7 @@ func TestPullCtxCancel(t *testing.T) {
 	var cancel context.CancelFunc
 	f.ctx, cancel = context.WithCancel(context.Background())
-	go f.pullerRoutine(pullChan, finisherChan)
+	go f.pullerRoutine(fsetSnapshot(t, f.fset), pullChan, finisherChan)
 	defer close(pullChan)
 	emptyState := func() pullBlockState {
@ -1077,7 +1077,7 @@ func TestPullDeleteUnscannedDir(t *testing.T) {
 	scanChan := make(chan string, 1)
 	dbUpdateChan := make(chan dbUpdateJob, 1)
-	f.deleteDir(fi, f.fset.Snapshot(), dbUpdateChan, scanChan)
+	f.deleteDir(fi, fsetSnapshot(t, f.fset), dbUpdateChan, scanChan)
 	if _, err := ffs.Stat(dir); fs.IsNotExist(err) {
 		t.Error("directory has been deleted")
@ -1226,7 +1226,7 @@ func TestPullTempFileCaseConflict(t *testing.T) {
 		fd.Close()
 	}
-	f.handleFile(file, f.fset.Snapshot(), copyChan)
+	f.handleFile(file, fsetSnapshot(t, f.fset), copyChan)
 	cs := <-copyChan
 	if _, err := cs.tempFile(); err != nil {
@ -1252,7 +1252,7 @@ func TestPullCaseOnlyRename(t *testing.T) {
 	must(t, f.scanSubdirs(nil))
-	cur, ok := m.CurrentFolderFile(f.ID, name)
+	cur, ok := m.testCurrentFolderFile(f.ID, name)
 	if !ok {
 		t.Fatal("file missing")
 	}
@ -1266,7 +1266,7 @@ func TestPullCaseOnlyRename(t *testing.T) {
 	dbUpdateChan := make(chan dbUpdateJob, 2)
 	scanChan := make(chan string, 2)
-	snap := f.fset.Snapshot()
+	snap := fsetSnapshot(t, f.fset)
 	defer snap.Release()
 	if err := f.renameFile(cur, deleted, confl, snap, dbUpdateChan, scanChan); err != nil {
 		t.Error(err)
@ -1293,7 +1293,7 @@ func TestPullSymlinkOverExistingWindows(t *testing.T) {
 	must(t, f.scanSubdirs(nil))
-	file, ok := m.CurrentFolderFile(f.ID, name)
+	file, ok := m.testCurrentFolderFile(f.ID, name)
 	if !ok {
 		t.Fatal("file missing")
 	}
@ -1301,11 +1301,12 @@ func TestPullSymlinkOverExistingWindows(t *testing.T) {
 	scanChan := make(chan string)
-	changed := f.pullerIteration(scanChan)
+	changed, err := f.pullerIteration(scanChan)
 	must(t, err)
 	if changed != 1 {
 		t.Error("Expected one change in pull, got", changed)
 	}
-	if file, ok := m.CurrentFolderFile(f.ID, name); !ok {
+	if file, ok := m.testCurrentFolderFile(f.ID, name); !ok {
 		t.Error("symlink entry missing")
 	} else if !file.IsUnsupported() {
 		t.Error("symlink entry isn't marked as unsupported")
@ -1341,7 +1342,7 @@ func TestPullDeleteCaseConflict(t *testing.T) {
 		t.Error("Missing db update for file")
 	}
-	snap := f.fset.Snapshot()
+	snap := fsetSnapshot(t, f.fset)
 	defer snap.Release()
 	f.deleteDir(fi, snap, dbUpdateChan, scanChan)
 	select {
@ -1371,7 +1372,7 @@ func TestPullDeleteIgnoreChildDir(t *testing.T) {
 	scanChan := make(chan string, 2)
-	err := f.deleteDirOnDisk(parent, f.fset.Snapshot(), scanChan)
+	err := f.deleteDirOnDisk(parent, fsetSnapshot(t, f.fset), scanChan)
 	if err == nil {
 		t.Error("no error")
 	}
--- a/lib/model/folder_summary.go
+++ b/lib/model/folder_summary.go
@ -96,7 +96,7 @@ func (c *folderSummaryService) Summary(folder string) (map[string]interface{}, e
 	// For API backwards compatibility (SyncTrayzor needs it) an empty folder
 	// summary is returned for not running folders, an error might actually be
 	// more appropriate
-	if err != nil && err != ErrFolderPaused && err != errFolderNotRunning {
+	if err != nil && err != ErrFolderPaused && err != ErrFolderNotRunning {
 		return nil, err
 	}
@ -348,9 +348,14 @@ func (c *folderSummaryService) sendSummary(ctx context.Context, folder string) {
 		// Get completion percentage of this folder for the
 		// remote device.
-		comp := c.model.Completion(devCfg.DeviceID, folder).Map()
+		comp, err := c.model.Completion(devCfg.DeviceID, folder)
-		comp["folder"] = folder
+		if err != nil {
-		comp["device"] = devCfg.DeviceID.String()
+			l.Debugf("Error getting completion for folder %v, device %v: %v", folder, devCfg.DeviceID, err)
-		c.evLogger.Log(events.FolderCompletion, comp)
+			continue
 		}
 		ev := comp.Map()
 		ev["folder"] = folder
 		ev["device"] = devCfg.DeviceID.String()
 		c.evLogger.Log(events.FolderCompletion, ev)
 	}
 }
--- a/lib/model/indexsender.go
+++ b/lib/model/indexsender.go
@ -131,7 +131,10 @@ func (s *indexSender) sendIndexTo(ctx context.Context) error {
 	var err error
 	var f protocol.FileInfo
-	snap := s.fset.Snapshot()
+	snap, err := s.fset.Snapshot()
 	if err != nil {
 		return svcutil.AsFatalErr(err, svcutil.ExitError)
 	}
 	defer snap.Release()
 	previousWasDelete := false
 	snap.WithHaveSequence(s.prevSequence+1, func(fi protocol.FileIntf) bool {
--- a/lib/model/mocks/model.go
+++ b/lib/model/mocks/model.go
@ -22,7 +22,7 @@ type Model struct {
 		arg1 protocol.Connection
 		arg2 protocol.Hello
 	}
-	AvailabilityStub        func(string, protocol.FileInfo, protocol.BlockInfo) []model.Availability
+	AvailabilityStub        func(string, protocol.FileInfo, protocol.BlockInfo) ([]model.Availability, error)
 	availabilityMutex       sync.RWMutex
 	availabilityArgsForCall []struct {
 		arg1 string
@ -31,9 +31,11 @@ type Model struct {
 	}
 	availabilityReturns struct {
 		result1 []model.Availability
 		result2 error
 	}
 	availabilityReturnsOnCall map[int]struct {
 		result1 []model.Availability
 		result2 error
 	}
 	BringToFrontStub        func(string, string)
 	bringToFrontMutex       sync.RWMutex
@ -59,7 +61,7 @@ type Model struct {
 	clusterConfigReturnsOnCall map[int]struct {
 		result1 error
 	}
-	CompletionStub        func(protocol.DeviceID, string) model.FolderCompletion
+	CompletionStub        func(protocol.DeviceID, string) (model.FolderCompletion, error)
 	completionMutex       sync.RWMutex
 	completionArgsForCall []struct {
 		arg1 protocol.DeviceID
@ -67,9 +69,11 @@ type Model struct {
 	}
 	completionReturns struct {
 		result1 model.FolderCompletion
 		result2 error
 	}
 	completionReturnsOnCall map[int]struct {
 		result1 model.FolderCompletion
 		result2 error
 	}
 	ConnectionStub        func(protocol.DeviceID) (protocol.Connection, bool)
 	connectionMutex       sync.RWMutex
@ -94,7 +98,7 @@ type Model struct {
 	connectionStatsReturnsOnCall map[int]struct {
 		result1 map[string]interface{}
 	}
-	CurrentFolderFileStub        func(string, string) (protocol.FileInfo, bool)
+	CurrentFolderFileStub        func(string, string) (protocol.FileInfo, bool, error)
 	currentFolderFileMutex       sync.RWMutex
 	currentFolderFileArgsForCall []struct {
 		arg1 string
@ -103,12 +107,14 @@ type Model struct {
 	currentFolderFileReturns struct {
 		result1 protocol.FileInfo
 		result2 bool
 		result3 error
 	}
 	currentFolderFileReturnsOnCall map[int]struct {
 		result1 protocol.FileInfo
 		result2 bool
 		result3 error
 	}
-	CurrentGlobalFileStub        func(string, string) (protocol.FileInfo, bool)
+	CurrentGlobalFileStub        func(string, string) (protocol.FileInfo, bool, error)
 	currentGlobalFileMutex       sync.RWMutex
 	currentGlobalFileArgsForCall []struct {
 		arg1 string
@ -117,10 +123,12 @@ type Model struct {
 	currentGlobalFileReturns struct {
 		result1 protocol.FileInfo
 		result2 bool
 		result3 error
 	}
 	currentGlobalFileReturnsOnCall map[int]struct {
 		result1 protocol.FileInfo
 		result2 bool
 		result3 error
 	}
 	CurrentIgnoresStub        func(string) ([]string, []string, error)
 	currentIgnoresMutex       sync.RWMutex
@ -577,7 +585,7 @@ func (fake *Model) AddConnectionArgsForCall(i int) (protocol.Connection, protoco
 	return argsForCall.arg1, argsForCall.arg2
 }
-func (fake *Model) Availability(arg1 string, arg2 protocol.FileInfo, arg3 protocol.BlockInfo) []model.Availability {
+func (fake *Model) Availability(arg1 string, arg2 protocol.FileInfo, arg3 protocol.BlockInfo) ([]model.Availability, error) {
 	fake.availabilityMutex.Lock()
 	ret, specificReturn := fake.availabilityReturnsOnCall[len(fake.availabilityArgsForCall)]
 	fake.availabilityArgsForCall = append(fake.availabilityArgsForCall, struct {
@ -593,9 +601,9 @@ func (fake *Model) Availability(arg1 string, arg2 protocol.FileInfo, arg3 protoc
 		return stub(arg1, arg2, arg3)
 	}
 	if specificReturn {
-		return ret.result1
+		return ret.result1, ret.result2
 	}
-	return fakeReturns.result1
+	return fakeReturns.result1, fakeReturns.result2
 }
 func (fake *Model) AvailabilityCallCount() int {
@ -604,7 +612,7 @@ func (fake *Model) AvailabilityCallCount() int {
 	return len(fake.availabilityArgsForCall)
 }
-func (fake *Model) AvailabilityCalls(stub func(string, protocol.FileInfo, protocol.BlockInfo) []model.Availability) {
+func (fake *Model) AvailabilityCalls(stub func(string, protocol.FileInfo, protocol.BlockInfo) ([]model.Availability, error)) {
 	fake.availabilityMutex.Lock()
 	defer fake.availabilityMutex.Unlock()
 	fake.AvailabilityStub = stub
@ -617,27 +625,30 @@ func (fake *Model) AvailabilityArgsForCall(i int) (string, protocol.FileInfo, pr
 	return argsForCall.arg1, argsForCall.arg2, argsForCall.arg3
 }
-func (fake *Model) AvailabilityReturns(result1 []model.Availability) {
+func (fake *Model) AvailabilityReturns(result1 []model.Availability, result2 error) {
 	fake.availabilityMutex.Lock()
 	defer fake.availabilityMutex.Unlock()
 	fake.AvailabilityStub = nil
 	fake.availabilityReturns = struct {
 		result1 []model.Availability
-	}{result1}
+		result2 error
 	}{result1, result2}
 }
-func (fake *Model) AvailabilityReturnsOnCall(i int, result1 []model.Availability) {
+func (fake *Model) AvailabilityReturnsOnCall(i int, result1 []model.Availability, result2 error) {
 	fake.availabilityMutex.Lock()
 	defer fake.availabilityMutex.Unlock()
 	fake.AvailabilityStub = nil
 	if fake.availabilityReturnsOnCall == nil {
 		fake.availabilityReturnsOnCall = make(map[int]struct {
 			result1 []model.Availability
 			result2 error
 		})
 	}
 	fake.availabilityReturnsOnCall[i] = struct {
 		result1 []model.Availability
-	}{result1}
+		result2 error
 	}{result1, result2}
 }
 func (fake *Model) BringToFront(arg1 string, arg2 string) {
@ -768,7 +779,7 @@ func (fake *Model) ClusterConfigReturnsOnCall(i int, result1 error) {
 	}{result1}
 }
-func (fake *Model) Completion(arg1 protocol.DeviceID, arg2 string) model.FolderCompletion {
+func (fake *Model) Completion(arg1 protocol.DeviceID, arg2 string) (model.FolderCompletion, error) {
 	fake.completionMutex.Lock()
 	ret, specificReturn := fake.completionReturnsOnCall[len(fake.completionArgsForCall)]
 	fake.completionArgsForCall = append(fake.completionArgsForCall, struct {
@ -783,9 +794,9 @@ func (fake *Model) Completion(arg1 protocol.DeviceID, arg2 string) model.FolderC
 		return stub(arg1, arg2)
 	}
 	if specificReturn {
-		return ret.result1
+		return ret.result1, ret.result2
 	}
-	return fakeReturns.result1
+	return fakeReturns.result1, fakeReturns.result2
 }
 func (fake *Model) CompletionCallCount() int {
@ -794,7 +805,7 @@ func (fake *Model) CompletionCallCount() int {
 	return len(fake.completionArgsForCall)
 }
-func (fake *Model) CompletionCalls(stub func(protocol.DeviceID, string) model.FolderCompletion) {
+func (fake *Model) CompletionCalls(stub func(protocol.DeviceID, string) (model.FolderCompletion, error)) {
 	fake.completionMutex.Lock()
 	defer fake.completionMutex.Unlock()
 	fake.CompletionStub = stub
@ -807,27 +818,30 @@ func (fake *Model) CompletionArgsForCall(i int) (protocol.DeviceID, string) {
 	return argsForCall.arg1, argsForCall.arg2
 }
-func (fake *Model) CompletionReturns(result1 model.FolderCompletion) {
+func (fake *Model) CompletionReturns(result1 model.FolderCompletion, result2 error) {
 	fake.completionMutex.Lock()
 	defer fake.completionMutex.Unlock()
 	fake.CompletionStub = nil
 	fake.completionReturns = struct {
 		result1 model.FolderCompletion
-	}{result1}
+		result2 error
 	}{result1, result2}
 }
-func (fake *Model) CompletionReturnsOnCall(i int, result1 model.FolderCompletion) {
+func (fake *Model) CompletionReturnsOnCall(i int, result1 model.FolderCompletion, result2 error) {
 	fake.completionMutex.Lock()
 	defer fake.completionMutex.Unlock()
 	fake.CompletionStub = nil
 	if fake.completionReturnsOnCall == nil {
 		fake.completionReturnsOnCall = make(map[int]struct {
 			result1 model.FolderCompletion
 			result2 error
 		})
 	}
 	fake.completionReturnsOnCall[i] = struct {
 		result1 model.FolderCompletion
-	}{result1}
+		result2 error
 	}{result1, result2}
 }
 func (fake *Model) Connection(arg1 protocol.DeviceID) (protocol.Connection, bool) {
@ -947,7 +961,7 @@ func (fake *Model) ConnectionStatsReturnsOnCall(i int, result1 map[string]interf
 	}{result1}
 }
-func (fake *Model) CurrentFolderFile(arg1 string, arg2 string) (protocol.FileInfo, bool) {
+func (fake *Model) CurrentFolderFile(arg1 string, arg2 string) (protocol.FileInfo, bool, error) {
 	fake.currentFolderFileMutex.Lock()
 	ret, specificReturn := fake.currentFolderFileReturnsOnCall[len(fake.currentFolderFileArgsForCall)]
 	fake.currentFolderFileArgsForCall = append(fake.currentFolderFileArgsForCall, struct {
@ -962,9 +976,9 @@ func (fake *Model) CurrentFolderFile(arg1 string, arg2 string) (protocol.FileInf
 		return stub(arg1, arg2)
 	}
 	if specificReturn {
-		return ret.result1, ret.result2
+		return ret.result1, ret.result2, ret.result3
 	}
-	return fakeReturns.result1, fakeReturns.result2
+	return fakeReturns.result1, fakeReturns.result2, fakeReturns.result3
 }
 func (fake *Model) CurrentFolderFileCallCount() int {
@ -973,7 +987,7 @@ func (fake *Model) CurrentFolderFileCallCount() int {
 	return len(fake.currentFolderFileArgsForCall)
 }
-func (fake *Model) CurrentFolderFileCalls(stub func(string, string) (protocol.FileInfo, bool)) {
+func (fake *Model) CurrentFolderFileCalls(stub func(string, string) (protocol.FileInfo, bool, error)) {
 	fake.currentFolderFileMutex.Lock()
 	defer fake.currentFolderFileMutex.Unlock()
 	fake.CurrentFolderFileStub = stub
@ -986,17 +1000,18 @@ func (fake *Model) CurrentFolderFileArgsForCall(i int) (string, string) {
 	return argsForCall.arg1, argsForCall.arg2
 }
-func (fake *Model) CurrentFolderFileReturns(result1 protocol.FileInfo, result2 bool) {
+func (fake *Model) CurrentFolderFileReturns(result1 protocol.FileInfo, result2 bool, result3 error) {
 	fake.currentFolderFileMutex.Lock()
 	defer fake.currentFolderFileMutex.Unlock()
 	fake.CurrentFolderFileStub = nil
 	fake.currentFolderFileReturns = struct {
 		result1 protocol.FileInfo
 		result2 bool
-	}{result1, result2}
+		result3 error
 	}{result1, result2, result3}
 }
-func (fake *Model) CurrentFolderFileReturnsOnCall(i int, result1 protocol.FileInfo, result2 bool) {
+func (fake *Model) CurrentFolderFileReturnsOnCall(i int, result1 protocol.FileInfo, result2 bool, result3 error) {
 	fake.currentFolderFileMutex.Lock()
 	defer fake.currentFolderFileMutex.Unlock()
 	fake.CurrentFolderFileStub = nil
@ -1004,15 +1019,17 @@ func (fake *Model) CurrentFolderFileReturnsOnCall(i int, result1 protocol.FileIn
 		fake.currentFolderFileReturnsOnCall = make(map[int]struct {
 			result1 protocol.FileInfo
 			result2 bool
 			result3 error
 		})
 	}
 	fake.currentFolderFileReturnsOnCall[i] = struct {
 		result1 protocol.FileInfo
 		result2 bool
-	}{result1, result2}
+		result3 error
 	}{result1, result2, result3}
 }
-func (fake *Model) CurrentGlobalFile(arg1 string, arg2 string) (protocol.FileInfo, bool) {
+func (fake *Model) CurrentGlobalFile(arg1 string, arg2 string) (protocol.FileInfo, bool, error) {
 	fake.currentGlobalFileMutex.Lock()
 	ret, specificReturn := fake.currentGlobalFileReturnsOnCall[len(fake.currentGlobalFileArgsForCall)]
 	fake.currentGlobalFileArgsForCall = append(fake.currentGlobalFileArgsForCall, struct {
@ -1027,9 +1044,9 @@ func (fake *Model) CurrentGlobalFile(arg1 string, arg2 string) (protocol.FileInf
 		return stub(arg1, arg2)
 	}
 	if specificReturn {
-		return ret.result1, ret.result2
+		return ret.result1, ret.result2, ret.result3
 	}
-	return fakeReturns.result1, fakeReturns.result2
+	return fakeReturns.result1, fakeReturns.result2, fakeReturns.result3
 }
 func (fake *Model) CurrentGlobalFileCallCount() int {
@ -1038,7 +1055,7 @@ func (fake *Model) CurrentGlobalFileCallCount() int {
 	return len(fake.currentGlobalFileArgsForCall)
 }
-func (fake *Model) CurrentGlobalFileCalls(stub func(string, string) (protocol.FileInfo, bool)) {
+func (fake *Model) CurrentGlobalFileCalls(stub func(string, string) (protocol.FileInfo, bool, error)) {
 	fake.currentGlobalFileMutex.Lock()
 	defer fake.currentGlobalFileMutex.Unlock()
 	fake.CurrentGlobalFileStub = stub
@ -1051,17 +1068,18 @@ func (fake *Model) CurrentGlobalFileArgsForCall(i int) (string, string) {
 	return argsForCall.arg1, argsForCall.arg2
 }
-func (fake *Model) CurrentGlobalFileReturns(result1 protocol.FileInfo, result2 bool) {
+func (fake *Model) CurrentGlobalFileReturns(result1 protocol.FileInfo, result2 bool, result3 error) {
 	fake.currentGlobalFileMutex.Lock()
 	defer fake.currentGlobalFileMutex.Unlock()
 	fake.CurrentGlobalFileStub = nil
 	fake.currentGlobalFileReturns = struct {
 		result1 protocol.FileInfo
 		result2 bool
-	}{result1, result2}
+		result3 error
 	}{result1, result2, result3}
 }
-func (fake *Model) CurrentGlobalFileReturnsOnCall(i int, result1 protocol.FileInfo, result2 bool) {
+func (fake *Model) CurrentGlobalFileReturnsOnCall(i int, result1 protocol.FileInfo, result2 bool, result3 error) {
 	fake.currentGlobalFileMutex.Lock()
 	defer fake.currentGlobalFileMutex.Unlock()
 	fake.CurrentGlobalFileStub = nil
@ -1069,12 +1087,14 @@ func (fake *Model) CurrentGlobalFileReturnsOnCall(i int, result1 protocol.FileIn
 		fake.currentGlobalFileReturnsOnCall = make(map[int]struct {
 			result1 protocol.FileInfo
 			result2 bool
 			result3 error
 		})
 	}
 	fake.currentGlobalFileReturnsOnCall[i] = struct {
 		result1 protocol.FileInfo
 		result2 bool
-	}{result1, result2}
+		result3 error
 	}{result1, result2, result3}
 }
 func (fake *Model) CurrentIgnores(arg1 string) ([]string, []string, error) {
--- a/lib/model/model.go
+++ b/lib/model/model.go
@ -98,11 +98,11 @@ type Model interface {
 	LocalChangedFolderFiles(folder string, page, perpage int) ([]db.FileInfoTruncated, error)
 	FolderProgressBytesCompleted(folder string) int64
-	CurrentFolderFile(folder string, file string) (protocol.FileInfo, bool)
+	CurrentFolderFile(folder string, file string) (protocol.FileInfo, bool, error)
-	CurrentGlobalFile(folder string, file string) (protocol.FileInfo, bool)
+	CurrentGlobalFile(folder string, file string) (protocol.FileInfo, bool, error)
-	Availability(folder string, file protocol.FileInfo, block protocol.BlockInfo) []Availability
+	Availability(folder string, file protocol.FileInfo, block protocol.BlockInfo) ([]Availability, error)
-	Completion(device protocol.DeviceID, folder string) FolderCompletion
+	Completion(device protocol.DeviceID, folder string) (FolderCompletion, error)
 	ConnectionStats() map[string]interface{}
 	DeviceStatistics() (map[protocol.DeviceID]stats.DeviceStatistics, error)
 	FolderStatistics() (map[string]stats.FolderStatistics, error)
@ -179,8 +179,8 @@ var (
 	errDeviceIgnored     = errors.New("device is ignored")
 	errDeviceRemoved     = errors.New("device has been removed")
 	ErrFolderPaused      = errors.New("folder is paused")
-	errFolderNotRunning  = errors.New("folder is not running")
+	ErrFolderNotRunning  = errors.New("folder is not running")
-	errFolderMissing     = errors.New("no such folder")
+	ErrFolderMissing     = errors.New("no such folder")
 	errNetworkNotAllowed = errors.New("network not allowed")
 	errNoVersioner       = errors.New("folder has no versioner")
 	// errors about why a connection is closed
@ -875,7 +875,7 @@ func (comp FolderCompletion) Map() map[string]interface{} {
 // (including the local device) or explicitly protocol.LocalDeviceID. An
 // empty folder string means the aggregate of all folders shared with the
 // given device.
-func (m *model) Completion(device protocol.DeviceID, folder string) FolderCompletion {
+func (m *model) Completion(device protocol.DeviceID, folder string) (FolderCompletion, error) {
 	// The user specifically asked for our own device ID. Internally that is
 	// known as protocol.LocalDeviceID so translate.
 	if device == m.id {
@ -891,21 +891,29 @@ func (m *model) Completion(device protocol.DeviceID, folder string) FolderComple
 	var comp FolderCompletion
 	for _, fcfg := range m.cfg.FolderList() {
 		if device == protocol.LocalDeviceID || fcfg.SharedWith(device) {
-			comp.add(m.folderCompletion(device, fcfg.ID))
+			folderComp, err := m.folderCompletion(device, fcfg.ID)
 			if err != nil {
 				return FolderCompletion{}, err
 			}
 			comp.add(folderComp)
 		}
 	}
-	return comp
+	return comp, nil
 }
-func (m *model) folderCompletion(device protocol.DeviceID, folder string) FolderCompletion {
+func (m *model) folderCompletion(device protocol.DeviceID, folder string) (FolderCompletion, error) {
 	m.fmut.RLock()
-	rf, ok := m.folderFiles[folder]
+	err := m.checkFolderRunningLocked(folder)
 	rf := m.folderFiles[folder]
 	m.fmut.RUnlock()
-	if !ok {
+	if err != nil {
-		return FolderCompletion{} // Folder doesn't exist, so we hardly have any of it
+		return FolderCompletion{}, err
 	}
-	snap := rf.Snapshot()
+	snap, err := rf.Snapshot()
 	if err != nil {
 		return FolderCompletion{}, err
 	}
 	defer snap.Release()
 	m.pmut.RLock()
@ -922,7 +930,7 @@ func (m *model) folderCompletion(device protocol.DeviceID, folder string) Folder
 	comp := newFolderCompletion(snap.GlobalSize(), need, snap.Sequence(device))
 	l.Debugf("%v Completion(%s, %q): %v", m, device, folder, comp.Map())
-	return comp
+	return comp, nil
 }
 // DBSnapshot returns a snapshot of the database content relevant to the given folder.
@ -934,7 +942,7 @@ func (m *model) DBSnapshot(folder string) (*db.Snapshot, error) {
 	if err != nil {
 		return nil, err
 	}
-	return rf.Snapshot(), nil
+	return rf.Snapshot()
 }
 func (m *model) FolderProgressBytesCompleted(folder string) int64 {
@ -951,10 +959,13 @@ func (m *model) NeedFolderFiles(folder string, page, perpage int) ([]db.FileInfo
 	m.fmut.RUnlock()
 	if !rfOk {
-		return nil, nil, nil, errFolderMissing
+		return nil, nil, nil, ErrFolderMissing
 	}
-	snap := rf.Snapshot()
+	snap, err := rf.Snapshot()
 	if err != nil {
 		return nil, nil, nil, err
 	}
 	defer snap.Release()
 	var progress, queued, rest []db.FileInfoTruncated
 	var seen map[string]struct{}
@ -1018,10 +1029,13 @@ func (m *model) RemoteNeedFolderFiles(folder string, device protocol.DeviceID, p
 	m.fmut.RUnlock()
 	if !ok {
-		return nil, errFolderMissing
+		return nil, ErrFolderMissing
 	}
-	snap := rf.Snapshot()
+	snap, err := rf.Snapshot()
 	if err != nil {
 		return nil, err
 	}
 	defer snap.Release()
 	files := make([]db.FileInfoTruncated, 0, perpage)
@ -1043,10 +1057,13 @@ func (m *model) LocalChangedFolderFiles(folder string, page, perpage int) ([]db.
 	m.fmut.RUnlock()
 	if !ok {
-		return nil, errFolderMissing
+		return nil, ErrFolderMissing
 	}
-	snap := rf.Snapshot()
+	snap, err := rf.Snapshot()
 	if err != nil {
 		return nil, err
 	}
 	defer snap.Release()
 	if snap.ReceiveOnlyChangedSize().TotalItems() == 0 {
@ -1120,7 +1137,7 @@ func (m *model) handleIndex(deviceID protocol.DeviceID, folder string, fs []prot
 	if cfg, ok := m.cfg.Folder(folder); !ok || !cfg.SharedWith(deviceID) {
 		l.Infof("%v for unexpected folder ID %q sent from device %q; ensure that the folder exists and that this device is selected under \"Share With\" in the folder configuration.", op, folder, deviceID)
-		return errors.Wrap(errFolderMissing, folder)
+		return errors.Wrap(ErrFolderMissing, folder)
 	} else if cfg.Paused {
 		l.Debugf("%v for paused folder (ID %q) sent from device %q.", op, folder, deviceID)
 		return errors.Wrap(ErrFolderPaused, folder)
@ -1133,7 +1150,7 @@ func (m *model) handleIndex(deviceID protocol.DeviceID, folder string, fs []prot
 	if !existing {
 		l.Infof("%v for nonexistent folder %q", op, folder)
-		return errors.Wrap(errFolderMissing, folder)
+		return errors.Wrap(ErrFolderMissing, folder)
 	}
 	if running {
@ -1930,7 +1947,11 @@ func newLimitedRequestResponse(size int, limiters ...*byteSemaphore) *requestRes
 }
 func (m *model) recheckFile(deviceID protocol.DeviceID, folder, name string, offset int64, hash []byte, weakHash uint32) {
-	cf, ok := m.CurrentFolderFile(folder, name)
+	cf, ok, err := m.CurrentFolderFile(folder, name)
 	if err != nil {
 		l.Debugf("%v recheckFile: %s: %q / %q: current file error: %v", m, deviceID, folder, name, err)
 		return
 	}
 	if !ok {
 		l.Debugf("%v recheckFile: %s: %q / %q: no current file", m, deviceID, folder, name)
 		return
@ -1976,28 +1997,36 @@ func (m *model) recheckFile(deviceID protocol.DeviceID, folder, name string, off
 	l.Debugf("%v recheckFile: %s: %q / %q", m, deviceID, folder, name)
 }
-func (m *model) CurrentFolderFile(folder string, file string) (protocol.FileInfo, bool) {
+func (m *model) CurrentFolderFile(folder string, file string) (protocol.FileInfo, bool, error) {
 	m.fmut.RLock()
 	fs, ok := m.folderFiles[folder]
 	m.fmut.RUnlock()
 	if !ok {
-		return protocol.FileInfo{}, false
+		return protocol.FileInfo{}, false, ErrFolderMissing
 	}
-	snap := fs.Snapshot()
+	snap, err := fs.Snapshot()
-	defer snap.Release()
+	if err != nil {
-	return snap.Get(protocol.LocalDeviceID, file)
+		return protocol.FileInfo{}, false, err
 	}
 	f, ok := snap.Get(protocol.LocalDeviceID, file)
 	snap.Release()
 	return f, ok, nil
 }
-func (m *model) CurrentGlobalFile(folder string, file string) (protocol.FileInfo, bool) {
+func (m *model) CurrentGlobalFile(folder string, file string) (protocol.FileInfo, bool, error) {
 	m.fmut.RLock()
 	fs, ok := m.folderFiles[folder]
 	m.fmut.RUnlock()
 	if !ok {
-		return protocol.FileInfo{}, false
+		return protocol.FileInfo{}, false, ErrFolderMissing
 	}
-	snap := fs.Snapshot()
+	snap, err := fs.Snapshot()
-	defer snap.Release()
+	if err != nil {
-	return snap.GetGlobal(file)
+		return protocol.FileInfo{}, false, err
 	}
 	f, ok := snap.GetGlobal(file)
 	snap.Release()
 	return f, ok, nil
 }
 // Connection returns the current connection for device, and a boolean whether a connection was found.
@ -2552,7 +2581,7 @@ func (m *model) GlobalDirectoryTree(folder, prefix string, levels int, dirsOnly
 	files, ok := m.folderFiles[folder]
 	m.fmut.RUnlock()
 	if !ok {
-		return nil, errFolderMissing
+		return nil, ErrFolderMissing
 	}
 	root := &TreeEntry{
@ -2565,9 +2594,11 @@ func (m *model) GlobalDirectoryTree(folder, prefix string, levels int, dirsOnly
 		prefix = prefix + sep
 	}
-	snap := files.Snapshot()
+	snap, err := files.Snapshot()
 	if err != nil {
 		return nil, err
 	}
 	defer snap.Release()
 	var err error
 	snap.WithPrefixedGlobalTruncated(prefix, func(fi protocol.FileIntf) bool {
 		f := fi.(db.FileInfoTruncated)
@ -2661,7 +2692,7 @@ func (m *model) RestoreFolderVersions(folder string, versions map[string]time.Ti
 	return restoreErrors, nil
 }
-func (m *model) Availability(folder string, file protocol.FileInfo, block protocol.BlockInfo) []Availability {
+func (m *model) Availability(folder string, file protocol.FileInfo, block protocol.BlockInfo) ([]Availability, error) {
 	// The slightly unusual locking sequence here is because we need to hold
 	// pmut for the duration (as the value returned from foldersFiles can
 	// get heavily modified on Close()), but also must acquire fmut before
@ -2675,17 +2706,25 @@ func (m *model) Availability(folder string, file protocol.FileInfo, block protoc
 	m.fmut.RUnlock()
 	if !ok {
-		return nil
+		return nil, ErrFolderMissing
 	}
-	var availabilities []Availability
+	snap, err := fs.Snapshot()
-	snap := fs.Snapshot()
+	if err != nil {
 		return nil, err
 	}
 	defer snap.Release()
 	return m.availabilityInSnapshot(cfg, snap, file, block), nil
 }
 func (m *model) availabilityInSnapshot(cfg config.FolderConfiguration, snap *db.Snapshot, file protocol.FileInfo, block protocol.BlockInfo) []Availability {
 	var availabilities []Availability
 	for _, device := range snap.Availability(file.Name) {
 		if _, ok := m.remotePausedFolders[device]; !ok {
 			continue
 		}
-		if _, ok := m.remotePausedFolders[device][folder]; ok {
+		if _, ok := m.remotePausedFolders[device][cfg.ID]; ok {
 			continue
 		}
 		_, ok := m.conn[device]
@ -2695,7 +2734,7 @@ func (m *model) Availability(folder string, file protocol.FileInfo, block protoc
 	}
 	for _, device := range cfg.Devices {
-		if m.deviceDownloads[device.DeviceID].Has(folder, file.Name, file.Version, int(block.Offset/int64(file.BlockSize()))) {
+		if m.deviceDownloads[device.DeviceID].Has(cfg.ID, file.Name, file.Version, int(block.Offset/int64(file.BlockSize()))) {
 			availabilities = append(availabilities, Availability{ID: device.DeviceID, FromTemporary: true})
 		}
 	}
@ -2960,12 +2999,12 @@ func (m *model) checkFolderRunningLocked(folder string) error {
 	}
 	if cfg, ok := m.cfg.Folder(folder); !ok {
-		return errFolderMissing
+		return ErrFolderMissing
 	} else if cfg.Paused {
 		return ErrFolderPaused
 	}
-	return errFolderNotRunning
+	return ErrFolderNotRunning
 }
 // PendingDevices lists unknown devices that tried to connect.
--- a/lib/model/model_test.go
+++ b/lib/model/model_test.go
@ -2300,7 +2300,7 @@ func TestIssue3496(t *testing.T) {
 	fs := m.folderFiles["default"]
 	m.fmut.RUnlock()
 	var localFiles []protocol.FileInfo
-	snap := fs.Snapshot()
+	snap := fsetSnapshot(t, fs)
 	snap.WithHave(protocol.LocalDeviceID, func(i protocol.FileIntf) bool {
 		localFiles = append(localFiles, i.(protocol.FileInfo))
 		return true
@ -2329,7 +2329,7 @@ func TestIssue3496(t *testing.T) {
 	// Check that the completion percentage for us makes sense
-	comp := m.Completion(protocol.LocalDeviceID, "default")
+	comp := m.testCompletion(protocol.LocalDeviceID, "default")
 	if comp.NeedBytes > comp.GlobalBytes {
 		t.Errorf("Need more bytes than exist, not possible: %d > %d", comp.NeedBytes, comp.GlobalBytes)
 	}
@ -2393,7 +2393,7 @@ func TestNoRequestsFromPausedDevices(t *testing.T) {
 	files.Update(device1, []protocol.FileInfo{file})
 	files.Update(device2, []protocol.FileInfo{file})
-	avail := m.Availability("default", file, file.Blocks[0])
+	avail := m.testAvailability("default", file, file.Blocks[0])
 	if len(avail) != 0 {
 		t.Errorf("should not be available, no connections")
 	}
@ -2403,7 +2403,7 @@ func TestNoRequestsFromPausedDevices(t *testing.T) {
 	// !!! This is not what I'd expect to happen, as we don't even know if the peer has the original index !!!
-	avail = m.Availability("default", file, file.Blocks[0])
+	avail = m.testAvailability("default", file, file.Blocks[0])
 	if len(avail) != 2 {
 		t.Errorf("should have two available")
 	}
@ -2423,7 +2423,7 @@ func TestNoRequestsFromPausedDevices(t *testing.T) {
 	m.ClusterConfig(device1, cc)
 	m.ClusterConfig(device2, cc)
-	avail = m.Availability("default", file, file.Blocks[0])
+	avail = m.testAvailability("default", file, file.Blocks[0])
 	if len(avail) != 2 {
 		t.Errorf("should have two available")
 	}
@ -2431,7 +2431,7 @@ func TestNoRequestsFromPausedDevices(t *testing.T) {
 	m.Closed(newFakeConnection(device1, m), errDeviceUnknown)
 	m.Closed(newFakeConnection(device2, m), errDeviceUnknown)
-	avail = m.Availability("default", file, file.Blocks[0])
+	avail = m.testAvailability("default", file, file.Blocks[0])
 	if len(avail) != 0 {
 		t.Errorf("should have no available")
 	}
@ -2446,7 +2446,7 @@ func TestNoRequestsFromPausedDevices(t *testing.T) {
 	ccp.Folders[0].Paused = true
 	m.ClusterConfig(device1, ccp)
-	avail = m.Availability("default", file, file.Blocks[0])
+	avail = m.testAvailability("default", file, file.Blocks[0])
 	if len(avail) != 1 {
 		t.Errorf("should have one available")
 	}
@ -2479,12 +2479,12 @@ func TestIssue2571(t *testing.T) {
 	m.ScanFolder("default")
-	if dir, ok := m.CurrentFolderFile("default", "toLink"); !ok {
+	if dir, ok := m.testCurrentFolderFile("default", "toLink"); !ok {
 		t.Fatalf("Dir missing in db")
 	} else if !dir.IsSymlink() {
 		t.Errorf("Dir wasn't changed to symlink")
 	}
-	if file, ok := m.CurrentFolderFile("default", filepath.Join("toLink", "a")); !ok {
+	if file, ok := m.testCurrentFolderFile("default", filepath.Join("toLink", "a")); !ok {
 		t.Fatalf("File missing in db")
 	} else if !file.Deleted {
 		t.Errorf("File below symlink has not been marked as deleted")
@ -2517,7 +2517,7 @@ func TestIssue4573(t *testing.T) {
 	m.ScanFolder("default")
-	if file, ok := m.CurrentFolderFile("default", file); !ok {
+	if file, ok := m.testCurrentFolderFile("default", file); !ok {
 		t.Fatalf("File missing in db")
 	} else if file.Deleted {
 		t.Errorf("Inaccessible file has been marked as deleted.")
@ -2577,7 +2577,7 @@ func TestInternalScan(t *testing.T) {
 	m.ScanFolder("default")
 	for path, cond := range testCases {
-		if f, ok := m.CurrentFolderFile("default", path); !ok {
+		if f, ok := m.testCurrentFolderFile("default", path); !ok {
 			t.Fatalf("%v missing in db", path)
 		} else if cond(f) {
 			t.Errorf("Incorrect db entry for %v", path)
@ -2638,14 +2638,14 @@ func TestRemoveDirWithContent(t *testing.T) {
 	m := setupModel(t, defaultCfgWrapper)
 	defer cleanupModel(m)
-	dir, ok := m.CurrentFolderFile("default", "dirwith")
+	dir, ok := m.testCurrentFolderFile("default", "dirwith")
 	if !ok {
 		t.Fatalf("Can't get dir \"dirwith\" after initial scan")
 	}
 	dir.Deleted = true
 	dir.Version = dir.Version.Update(device1.Short()).Update(device1.Short())
-	file, ok := m.CurrentFolderFile("default", content)
+	file, ok := m.testCurrentFolderFile("default", content)
 	if !ok {
 		t.Fatalf("Can't get file \"%v\" after initial scan", content)
 	}
@ -2657,11 +2657,11 @@ func TestRemoveDirWithContent(t *testing.T) {
 	// Is there something we could trigger on instead of just waiting?
 	timeout := time.NewTimer(5 * time.Second)
 	for {
-		dir, ok := m.CurrentFolderFile("default", "dirwith")
+		dir, ok := m.testCurrentFolderFile("default", "dirwith")
 		if !ok {
 			t.Fatalf("Can't get dir \"dirwith\" after index update")
 		}
-		file, ok := m.CurrentFolderFile("default", content)
+		file, ok := m.testCurrentFolderFile("default", content)
 		if !ok {
 			t.Fatalf("Can't get file \"%v\" after index update", content)
 		}
@ -2713,11 +2713,11 @@ func TestIssue4475(t *testing.T) {
 	created := false
 	for {
 		if !created {
-			if _, ok := m.CurrentFolderFile("default", fileName); ok {
+			if _, ok := m.testCurrentFolderFile("default", fileName); ok {
 				created = true
 			}
 		} else {
-			dir, ok := m.CurrentFolderFile("default", "delDir")
+			dir, ok := m.testCurrentFolderFile("default", "delDir")
 			if !ok {
 				t.Fatalf("can't get dir from db")
 			}
@ -2954,7 +2954,7 @@ func TestPausedFolders(t *testing.T) {
 		t.Errorf("Expected folder paused error, received: %v", err)
 	}
-	if err := m.ScanFolder("nonexistent"); err != errFolderMissing {
+	if err := m.ScanFolder("nonexistent"); err != ErrFolderMissing {
 		t.Errorf("Expected missing folder error, received: %v", err)
 	}
 }
@ -3035,7 +3035,7 @@ func TestIssue5002(t *testing.T) {
 		t.Error(err)
 	}
-	file, ok := m.CurrentFolderFile("default", "foo")
+	file, ok := m.testCurrentFolderFile("default", "foo")
 	if !ok {
 		t.Fatal("test file should exist")
 	}
@ -3054,7 +3054,7 @@ func TestParentOfUnignored(t *testing.T) {
 	m.SetIgnores("default", []string{"!quux", "*"})
-	if parent, ok := m.CurrentFolderFile("default", "baz"); !ok {
+	if parent, ok := m.testCurrentFolderFile("default", "baz"); !ok {
 		t.Errorf(`Directory "baz" missing in db`)
 	} else if parent.IsIgnored() {
 		t.Errorf(`Directory "baz" is ignored`)
@ -3222,7 +3222,7 @@ func TestModTimeWindow(t *testing.T) {
 	// Get current version
-	fi, ok := m.CurrentFolderFile("default", name)
+	fi, ok := m.testCurrentFolderFile("default", name)
 	if !ok {
 		t.Fatal("File missing")
 	}
@ -3237,7 +3237,7 @@ func TestModTimeWindow(t *testing.T) {
 	// No change due to within window
-	fi, _ = m.CurrentFolderFile("default", name)
+	fi, _ = m.testCurrentFolderFile("default", name)
 	if !fi.Version.Equal(v) {
 		t.Fatalf("Got version %v, expected %v", fi.Version, v)
 	}
@ -3251,7 +3251,7 @@ func TestModTimeWindow(t *testing.T) {
 	// Version should have updated
-	fi, _ = m.CurrentFolderFile("default", name)
+	fi, _ = m.testCurrentFolderFile("default", name)
 	if fi.Version.Compare(v) != protocol.Greater {
 		t.Fatalf("Got result %v, expected %v", fi.Version.Compare(v), protocol.Greater)
 	}
@ -3368,8 +3368,8 @@ func TestFolderAPIErrors(t *testing.T) {
 		if err := method(fcfg.ID); err != ErrFolderPaused {
 			t.Errorf(`Expected "%v", got "%v" (method no %v)`, ErrFolderPaused, err, i)
 		}
-		if err := method("notexisting"); err != errFolderMissing {
+		if err := method("notexisting"); err != ErrFolderMissing {
-			t.Errorf(`Expected "%v", got "%v" (method no %v)`, errFolderMissing, err, i)
+			t.Errorf(`Expected "%v", got "%v" (method no %v)`, ErrFolderMissing, err, i)
 		}
 	}
 }
@ -3776,7 +3776,7 @@ func TestScanDeletedROChangedOnSR(t *testing.T) {
 	must(t, writeFile(ffs, name, []byte(name), 0644))
 	m.ScanFolders()
-	file, ok := m.CurrentFolderFile(fcfg.ID, name)
+	file, ok := m.testCurrentFolderFile(fcfg.ID, name)
 	if !ok {
 		t.Fatal("file missing in db")
 	}
@ -3927,7 +3927,7 @@ func TestIssue6961(t *testing.T) {
 	pauseFolder(t, wcfg, fcfg.ID, true)
 	pauseFolder(t, wcfg, fcfg.ID, false)
-	if comp := m.Completion(device2, fcfg.ID); comp.NeedDeletes != 0 {
+	if comp := m.testCompletion(device2, fcfg.ID); comp.NeedDeletes != 0 {
 		t.Error("Expected 0 needed deletes, got", comp.NeedDeletes)
 	} else {
 		t.Log(comp)
@ -3946,7 +3946,7 @@ func TestCompletionEmptyGlobal(t *testing.T) {
 	files[0].Deleted = true
 	files[0].Version = files[0].Version.Update(device1.Short())
 	m.IndexUpdate(device1, fcfg.ID, files)
-	comp := m.Completion(protocol.LocalDeviceID, fcfg.ID)
+	comp := m.testCompletion(protocol.LocalDeviceID, fcfg.ID)
 	if comp.CompletionPct != 95 {
 		t.Error("Expected completion of 95%, got", comp.CompletionPct)
 	}
@ -3978,13 +3978,13 @@ func TestNeedMetaAfterIndexReset(t *testing.T) {
 	files[0].Sequence = seq
 	m.IndexUpdate(device1, fcfg.ID, files)
-	if comp := m.Completion(device2, fcfg.ID); comp.NeedItems != 1 {
+	if comp := m.testCompletion(device2, fcfg.ID); comp.NeedItems != 1 {
 		t.Error("Expected one needed item for device2, got", comp.NeedItems)
 	}
 	// Pretend we had an index reset on device 1
 	m.Index(device1, fcfg.ID, files)
-	if comp := m.Completion(device2, fcfg.ID); comp.NeedItems != 1 {
+	if comp := m.testCompletion(device2, fcfg.ID); comp.NeedItems != 1 {
 		t.Error("Expected one needed item for device2, got", comp.NeedItems)
 	}
 }
--- a/lib/model/testutils_test.go
+++ b/lib/model/testutils_test.go
@ -152,6 +152,7 @@ func setupModel(t testing.TB, w config.Wrapper) *testModel {
 type testModel struct {
 	*model
 	t        testing.TB
 	cancel   context.CancelFunc
 	evCancel context.CancelFunc
 	stopped  chan struct{}
@ -171,6 +172,7 @@ func newModel(t testing.TB, cfg config.Wrapper, id protocol.DeviceID, clientName
 		model:    m,
 		evCancel: cancel,
 		stopped:  make(chan struct{}),
 		t:        t,
 	}
 }
@ -184,6 +186,24 @@ func (m *testModel) ServeBackground() {
 	<-m.started
 }
 func (m *testModel) testAvailability(folder string, file protocol.FileInfo, block protocol.BlockInfo) []Availability {
 	av, err := m.model.Availability(folder, file, block)
 	must(m.t, err)
 	return av
 }
 func (m *testModel) testCurrentFolderFile(folder string, file string) (protocol.FileInfo, bool) {
 	f, ok, err := m.model.CurrentFolderFile(folder, file)
 	must(m.t, err)
 	return f, ok
 }
 func (m *testModel) testCompletion(device protocol.DeviceID, folder string) FolderCompletion {
 	comp, err := m.Completion(protocol.LocalDeviceID, "default")
 	must(m.t, err)
 	return comp
 }
 func cleanupModel(m *testModel) {
 	if m.cancel != nil {
 		m.cancel()
@ -277,6 +297,15 @@ func dbSnapshot(t *testing.T, m Model, folder string) *db.Snapshot {
 	return snap
 }
 func fsetSnapshot(t *testing.T, fset *db.FileSet) *db.Snapshot {
 	t.Helper()
 	snap, err := fset.Snapshot()
 	if err != nil {
 		t.Fatal(err)
 	}
 	return snap
 }
 // Reach in and update the ignore matcher to one that always does
 // reloads when asked to, instead of checking file mtimes. This is
 // because we will be changing the files on disk often enough that the
--- a/lib/svcutil/svcutil.go
+++ b/lib/svcutil/svcutil.go
@ -38,6 +38,11 @@ func AsFatalErr(err error, status ExitStatus) *FatalErr {
 	}
 }
 func IsFatal(err error) bool {
 	ferr := &FatalErr{}
 	return errors.As(err, &ferr)
 }
 func (e *FatalErr) Error() string {
 	return e.Err.Error()
 }