lib/model: Don't stop folder if out of disk space (fixes #2370) (#5099)

This removes the out of disk space check from CheckHealth. The disk space is now
only checked if there are files to pull, in which case pulling those files is
stopped, but everything else (dirs, links, deletes) keeps running -> can recover
disk space through pulling.

lib/model/folder.go

@@ -254,10 +254,6 @@ func (f *folder) getHealthError() error {
 		return err
 	}
 
-	if err := f.CheckFreeSpace(); err != nil {
-		return err
-	}
-
 	if err := f.model.cfg.CheckHomeFreeSpace(); err != nil {
 		return err
 	}

lib/model/folder_sendrecv.go

@@ -839,9 +839,12 @@ func (f *sendReceiveFolder) renameFile(source, target protocol.FileInfo, dbUpdat
 	l.Debugln(f, "taking rename shortcut", source.Name, "->", target.Name)
 
 	if f.versioner != nil {
-		err = osutil.Copy(f.fs, source.Name, target.Name)
+		err = f.CheckAvailableSpace(source.Size)
 		if err == nil {
-			err = osutil.InWritableDir(f.versioner.Archive, f.fs, source.Name)
+			err = osutil.Copy(f.fs, source.Name, target.Name)
+			if err == nil {
+				err = osutil.InWritableDir(f.versioner.Archive, f.fs, source.Name)
+			}
 		}
 	} else {
 		err = osutil.TryRename(f.fs, source.Name, target.Name)
@@ -1003,12 +1006,9 @@ func (f *sendReceiveFolder) handleFile(file protocol.FileInfo, copyChan chan<- c
 		blocksSize = file.Size
 	}
 
-	if f.MinDiskFree.BaseValue() > 0 {
-		if usage, err := f.fs.Usage("."); err == nil && usage.Free < blocksSize {
-			l.Warnf(`Folder "%s": insufficient disk space in %s for %s: have %.2f MiB, need %.2f MiB`, f.folderID, f.fs.URI(), file.Name, float64(usage.Free)/1024/1024, float64(blocksSize)/1024/1024)
-			f.newError("disk space", file.Name, errors.New("insufficient space"))
-			return
-		}
+	if err := f.CheckAvailableSpace(blocksSize); err != nil {
+		f.newError("pulling file", file.Name, err)
+		return
 	}
 
 	// Shuffle the blocks

lib/model/folder_sendrecv_test.go

@@ -91,15 +91,17 @@ func setUpSendReceiveFolder(model *Model) *sendReceiveFolder {
 			initialScanFinished: make(chan struct{}),
 			ctx:                 context.TODO(),
 			FolderConfiguration: config.FolderConfiguration{
+				FilesystemType:      fs.FilesystemTypeBasic,
+				Path:                "testdata",
 				PullerMaxPendingKiB: defaultPullerPendingKiB,
 			},
 		},
 
-		fs:        fs.NewMtimeFS(fs.NewFilesystem(fs.FilesystemTypeBasic, "testdata"), db.NewNamespacedKV(model.db, "mtime")),
 		queue:     newJobQueue(),
 		errors:    make(map[string]string),
 		errorsMut: sync.NewMutex(),
 	}
+	f.fs = fs.NewMtimeFS(f.Filesystem(), db.NewNamespacedKV(model.db, "mtime"))
 
 	// Folders are never actually started, so no initial scan will be done
 	close(f.initialScanFinished)