fix: pick valid FileInfo additionally based on dataDir (#12116)

* fix: pick valid FileInfo additionally based on dataDir

historically we have always relied on modTime
to be consistent and same, we can now add additional
reference to look for the same dataDir value.

A dataDir is the same for an object at a given point in
time for a given version, let's say a `null` version
is overwritten in quorum we do not by mistake pick
up the fileInfo's incorrectly.

* make sure to not preserve fi.Data

Signed-off-by: Harshavardhana <harsha@minio.io>

cmd/erasure-healing-common.go

@@ -25,9 +25,11 @@ import (
 )
 
 // commonTime returns a maximally occurring time from a list of time.
-func commonTime(modTimes []time.Time) (modTime time.Time, count int) {
+func commonTime(modTimes []time.Time, dataDirs []string) (modTime time.Time, dataDir string) {
 	var maxima int // Counter for remembering max occurrence of elements.
-	timeOccurenceMap := make(map[int64]int)
+
+	timeOccurenceMap := make(map[int64]int, len(modTimes))
+	dataDirOccurenceMap := make(map[string]int, len(dataDirs))
 	// Ignore the uuid sentinel and count the rest.
 	for _, time := range modTimes {
 		if time.Equal(timeSentinel) {
@@ -36,6 +38,13 @@ func commonTime(modTimes []time.Time) (modTime time.Time, count int) {
 		timeOccurenceMap[time.UnixNano()]++
 	}
 
+	for _, dataDir := range dataDirs {
+		if dataDir == "" {
+			continue
+		}
+		dataDirOccurenceMap[dataDir]++
+	}
+
 	// Find the common cardinality from previously collected
 	// occurrences of elements.
 	for nano, count := range timeOccurenceMap {
@@ -46,8 +55,18 @@ func commonTime(modTimes []time.Time) (modTime time.Time, count int) {
 		}
 	}
 
+	// Find the common cardinality from the previously collected
+	// occurrences of elements.
+	var dmaxima int
+	for ddataDir, count := range dataDirOccurenceMap {
+		if count > dmaxima {
+			dmaxima = count
+			dataDir = ddataDir
+		}
+	}
+
 	// Return the collected common uuid.
-	return modTime, maxima
+	return modTime, dataDir
 }
 
 // Beginning of unix time is treated as sentinel value here.
@@ -101,24 +120,33 @@ func listObjectModtimes(partsMetadata []FileInfo, errs []error) (modTimes []time
 // - a slice of disks where disk having 'older' xl.meta (or nothing)
 // are set to nil.
 // - latest (in time) of the maximally occurring modTime(s).
-func listOnlineDisks(disks []StorageAPI, partsMetadata []FileInfo, errs []error) (onlineDisks []StorageAPI, modTime time.Time) {
+func listOnlineDisks(disks []StorageAPI, partsMetadata []FileInfo, errs []error) (onlineDisks []StorageAPI, modTime time.Time, dataDir string) {
 	onlineDisks = make([]StorageAPI, len(disks))
 
 	// List all the file commit ids from parts metadata.
 	modTimes := listObjectModtimes(partsMetadata, errs)
 
+	dataDirs := make([]string, len(partsMetadata))
+	for idx, fi := range partsMetadata {
+		if errs[idx] != nil {
+			continue
+		}
+		dataDirs[idx] = fi.DataDir
+	}
+
 	// Reduce list of UUIDs to a single common value.
-	modTime, _ = commonTime(modTimes)
+	modTime, dataDir = commonTime(modTimes, dataDirs)
 
 	// Create a new online disks slice, which have common uuid.
 	for index, t := range modTimes {
-		if t.Equal(modTime) {
+		if partsMetadata[index].IsValid() && t.Equal(modTime) && partsMetadata[index].DataDir == dataDir {
 			onlineDisks[index] = disks[index]
 		} else {
 			onlineDisks[index] = nil
 		}
 	}
-	return onlineDisks, modTime
+
+	return onlineDisks, modTime, dataDir
 }
 
 // Returns the latest updated FileInfo files and error in case of failure.
@@ -131,16 +159,24 @@ func getLatestFileInfo(ctx context.Context, partsMetadata []FileInfo, errs []err
 	// List all the file commit ids from parts metadata.
 	modTimes := listObjectModtimes(partsMetadata, errs)
 
+	dataDirs := make([]string, len(partsMetadata))
+	for idx, fi := range partsMetadata {
+		if errs[idx] != nil {
+			continue
+		}
+		dataDirs[idx] = fi.DataDir
+	}
+
 	// Count all latest updated FileInfo values
 	var count int
 	var latestFileInfo FileInfo
 
 	// Reduce list of UUIDs to a single common value - i.e. the last updated Time
-	modTime, _ := commonTime(modTimes)
+	modTime, dataDir := commonTime(modTimes, dataDirs)
 
 	// Interate through all the modTimes and count the FileInfo(s) with latest time.
 	for index, t := range modTimes {
-		if t.Equal(modTime) && partsMetadata[index].IsValid() {
+		if partsMetadata[index].IsValid() && t.Equal(modTime) && dataDir == partsMetadata[index].DataDir {
 			latestFileInfo = partsMetadata[index]
 			count++
 		}