fs: Update object modtime when metadata is updated (#12818)

Follow S3 behavior of updating object modtime when object metadata is
updated.

cmd/fs-v1-helpers.go

@@ -24,6 +24,7 @@ import (
 	pathutil "path"
 	"runtime"
 	"strings"
+	"time"
 
 	"github.com/minio/minio/internal/lock"
 	"github.com/minio/minio/internal/logger"
@@ -168,6 +169,25 @@ func fsStat(ctx context.Context, statLoc string) (os.FileInfo, error) {
 	return fi, nil
 }
 
+// fsTouch updates a file access & modtime with current time
+func fsTouch(ctx context.Context, statLoc string) error {
+	if statLoc == "" {
+		logger.LogIf(ctx, errInvalidArgument)
+		return errInvalidArgument
+	}
+	if err := checkPathLength(statLoc); err != nil {
+		logger.LogIf(ctx, err)
+		return err
+	}
+	now := time.Now()
+	if err := os.Chtimes(statLoc, now, now); err != nil {
+		logger.LogIf(ctx, err)
+		return err
+	}
+
+	return nil
+}
+
 // Lookup if volume exists, returns volume attributes upon success.
 func fsStatVolume(ctx context.Context, volume string) (os.FileInfo, error) {
 	fi, err := fsStat(ctx, volume)

cmd/fs-v1.go

@@ -682,8 +682,15 @@ func (fs *FSObjects) CopyObject(ctx context.Context, srcBucket, srcObject, dstBu
 			return oi, toObjectErr(err, srcBucket, srcObject)
 		}
 
-		// Stat the file to get file size.
+		fsObjectPath := pathJoin(fs.fsPath, srcBucket, srcObject)
-		fi, err := fsStatFile(ctx, pathJoin(fs.fsPath, srcBucket, srcObject))
+
+		// Update object modtime
+		err = fsTouch(ctx, fsObjectPath)
+		if err != nil {
+			return oi, toObjectErr(err, srcBucket, srcObject)
+		}
+		// Stat the file to get object info
+		fi, err := fsStatFile(ctx, fsObjectPath)
 		if err != nil {
 			return oi, toObjectErr(err, srcBucket, srcObject)
 		}