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/config/folderconfiguration.go

@@ -282,8 +282,19 @@ func (l FolderDeviceConfigurationList) Len() int {
 	return len(l)
 }
 
-func (f *FolderConfiguration) CheckFreeSpace() error {
-	return checkFreeSpace(f.MinDiskFree, f.Filesystem())
+func (f *FolderConfiguration) CheckAvailableSpace(req int64) error {
+	fs := f.Filesystem()
+	usage, err := fs.Usage(".")
+	if err != nil {
+		return nil
+	}
+	usage.Free -= req
+	if usage.Free > 0 {
+		if err := checkFreeSpace(f.MinDiskFree, usage); err == nil {
+			return nil
+		}
+	}
+	return fmt.Errorf("insufficient space in %v %v", fs.Type(), fs.URI())
 }
 
 type FolderConfigurationList []FolderConfiguration

lib/config/size.go

@@ -76,22 +76,19 @@ func (Size) ParseDefault(s string) (interface{}, error) {
 	return ParseSize(s)
 }
 
-func checkFreeSpace(req Size, fs fs.Filesystem) error {
+func checkFreeSpace(req Size, usage fs.Usage) error {
 	val := req.BaseValue()
 	if val <= 0 {
 		return nil
 	}
 
-	usage, err := fs.Usage(".")
 	if req.Percentage() {
 		freePct := (float64(usage.Free) / float64(usage.Total)) * 100
-		if err == nil && freePct < val {
-			return fmt.Errorf("insufficient space in %v %v: %f %% < %v", fs.Type(), fs.URI(), freePct, req)
-		}
-	} else {
-		if err == nil && float64(usage.Free) < val {
-			return fmt.Errorf("insufficient space in %v %v: %v < %v", fs.Type(), fs.URI(), usage.Free, req)
+		if freePct < val {
+			return fmt.Errorf("%f %% < %v", freePct, req)
 		}
+	} else if float64(usage.Free) < val {
+		return fmt.Errorf("%v < %v", usage.Free, req)
 	}
 
 	return nil

lib/config/wrapper.go

@@ -445,5 +445,8 @@ func (w *Wrapper) MyName() string {
 // CheckHomeFreeSpace returns nil if the home disk has the required amount of
 // free space, or if home disk free space checking is disabled.
 func (w *Wrapper) CheckHomeFreeSpace() error {
-	return checkFreeSpace(w.Options().MinHomeDiskFree, fs.NewFilesystem(fs.FilesystemTypeBasic, filepath.Dir(w.ConfigPath())))
+	if usage, err := fs.NewFilesystem(fs.FilesystemTypeBasic, filepath.Dir(w.ConfigPath())).Usage("."); err == nil {
+		return checkFreeSpace(w.Options().MinHomeDiskFree, usage)
+	}
+	return nil
 }