xl: StatVol and ListVols should handle cases when disks are missing. (#1703)

Remove unnecessary code, handle cases of missing disk.

xl-erasure-v1.go

@@ -188,8 +188,6 @@ func (xl XL) DeleteVol(volume string) error {
 
 // ListVols - list volumes.
 func (xl XL) ListVols() (volsInfo []VolInfo, err error) {
-	emptyCount := 0
-
 	// Initialize sync waitgroup.
 	var wg = &sync.WaitGroup{}
 
@@ -202,45 +200,37 @@ func (xl XL) ListVols() (volsInfo []VolInfo, err error) {
 			defer wg.Done()
 
 			// Initiate listing.
-			vlsInfo, lErr := disk.ListVols()
-			if lErr == nil {
-				if len(vlsInfo) == 0 {
-					emptyCount++ // Calculate empty count specially.
-				} else {
+			vlsInfo, _ := disk.ListVols()
 			successVols[index] = vlsInfo
-				}
-			}
 		}(index, disk)
 	}
+
 	// For all the list volumes running in parallel to finish.
 	wg.Wait()
 
-	// If all list operations resulted in an empty count which is same
-	// as your total storage disks, then it is a valid case return
-	// success with empty vols.
-	if emptyCount == len(xl.storageDisks) {
-		return []VolInfo{}, nil
-	} else if len(successVols) < xl.readQuorum {
-		// If there is data and not empty, then we attempt quorum verification.
-		// Verify if we have enough quorum to list vols.
-		return nil, errReadQuorum
-	}
-
-	var total, free int64
 	// Loop through success vols and get aggregated usage values.
-	for _, vlsInfo := range successVols {
-		if len(vlsInfo) == 0 {
+	var vlsInfo []VolInfo
+	var total, free int64
+	for _, vlsInfo = range successVols {
+		if len(vlsInfo) <= 1 {
+			continue
+		}
+		var vlInfo VolInfo
+		for _, vlInfo = range vlsInfo {
+			if vlInfo.Name == "" {
 				continue
 			}
-		free += vlsInfo[0].Free
-		total += vlsInfo[0].Total
+			break
+		}
+		free += vlInfo.Free
+		total += vlInfo.Total
 	}
 
 	// Save the updated usage values back into the vols.
-	for _, volInfo := range successVols[0] {
-		volInfo.Free = free
-		volInfo.Total = total
-		volsInfo = append(volsInfo, volInfo)
+	for _, vlInfo := range vlsInfo {
+		vlInfo.Free = free
+		vlInfo.Total = total
+		volsInfo = append(volsInfo, vlInfo)
 	}
 
 	// NOTE: The assumption here is that volumes across all disks in
@@ -252,10 +242,10 @@ func (xl XL) ListVols() (volsInfo []VolInfo, err error) {
 
 // getAllVolInfo - list bucket volume info from all disks.
 // Returns error slice indicating the failed volume stat operations.
-func (xl XL) getAllVolInfo(volume string) (volsInfo []VolInfo, errs []error) {
+func (xl XL) getAllVolInfo(volume string) ([]VolInfo, []error) {
 	// Create errs and volInfo slices of storageDisks size.
-	errs = make([]error, len(xl.storageDisks))
-	volsInfo = make([]VolInfo, len(xl.storageDisks))
+	var errs = make([]error, len(xl.storageDisks))
+	var volsInfo = make([]VolInfo, len(xl.storageDisks))
 
 	// Allocate a new waitgroup.
 	var wg = &sync.WaitGroup{}
@@ -287,7 +277,6 @@ func (xl XL) getAllVolInfo(volume string) (volsInfo []VolInfo, errs []error) {
 // - error if any.
 func (xl XL) listAllVolInfo(volume string) ([]VolInfo, bool, error) {
 	volsInfo, errs := xl.getAllVolInfo(volume)
-	volsInfo = removeDuplicateVols(volsInfo)
 	notFoundCount := 0
 	for _, err := range errs {
 		if err == errVolumeNotFound {
@@ -327,75 +316,42 @@ func (xl XL) listAllVolInfo(volume string) ([]VolInfo, bool, error) {
 	return volsInfo, heal, nil
 }
 
-// healVolume - heals any missing volumes.
-func (xl XL) healVolume(volume string) error {
-	// Lists volume info for all online disks.
-	volsInfo, heal, err := xl.listAllVolInfo(volume)
-	if err != nil {
-		return err
-	}
-	if !heal {
-		return nil
-	}
-	// Create volume if missing on online disks.
-	for index, volInfo := range volsInfo {
-		if volInfo.Name != "" {
-			continue
-		}
-		// Volinfo name would be an empty string, create it.
-		if err = xl.storageDisks[index].MakeVol(volume); err != nil {
-			continue
-		}
-	}
-	return nil
-}
-
-// Removes any duplicate vols.
-func removeDuplicateVols(volsInfo []VolInfo) []VolInfo {
-	// Use map to record duplicates as we find them.
-	result := []VolInfo{}
-
-	m := make(map[string]VolInfo)
-	for _, v := range volsInfo {
-		if _, found := m[v.Name]; !found {
-			m[v.Name] = v
-		}
-	}
-
-	result = make([]VolInfo, 0, len(m))
-	for _, v := range m {
-		result = append(result, v)
-	}
-	// Return the new slice.
-	return result
-}
-
 // StatVol - get volume stat info.
 func (xl XL) StatVol(volume string) (volInfo VolInfo, err error) {
 	if !isValidVolname(volume) {
 		return VolInfo{}, errInvalidArgument
 	}
 
+	// List and figured out if we need healing.
 	volsInfo, heal, err := xl.listAllVolInfo(volume)
 	if err != nil {
 		return VolInfo{}, err
 	}
 
+	// Heal for missing entries.
 	if heal {
 		go func() {
-			hErr := xl.healVolume(volume)
-			errorIf(hErr, "Unable to heal volume "+volume+".")
+			// Create volume if missing on disks.
+			for index, volInfo := range volsInfo {
+				if volInfo.Name != "" {
+					continue
+				}
+				// Volinfo name would be an empty string, create it.
+				xl.storageDisks[index].MakeVol(volume)
+			}
 		}()
 	}
 
 	// Loop through all statVols, calculate the actual usage values.
 	var total, free int64
-	for _, volInfo := range volsInfo {
+	for _, volInfo = range volsInfo {
+		if volInfo.Name == "" {
+			continue
+		}
 		free += volInfo.Free
 		total += volInfo.Total
 	}
-	// Filter volsInfo and update the volInfo.
-	volInfo = volsInfo[0]
+	// Update the aggregated values.
 	volInfo.Free = free
 	volInfo.Total = total
 	return volInfo, nil