Report correct error when O_DIRECT is not supported (#9545)

fixes #9537

cmd/config/errors.go

@@ -169,6 +169,12 @@ Example 1:
    $ minio server /data/minio/`,
 	)
 
+	ErrUnsupportedBackend = newErrFn(
+		"Unable to write to the backend",
+		"Please ensure your disk supports O_DIRECT",
+		"",
+	)
+
 	ErrUnableToWriteInBackend = newErrFn(
 		"Unable to write to the backend",
 		"Please ensure MinIO binary has write permissions for the backend",

cmd/fs-v1.go

@@ -131,8 +131,12 @@ func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {
 	var err error
 	if fsPath, err = getValidPath(fsPath); err != nil {
 		if err == errMinDiskSize {
-			return nil, err
+			return nil, config.ErrUnableToWriteInBackend(err).Hint(err.Error())
+		} else if err == errUnsupportedDisk {
+			hint := fmt.Sprintf("'%s' does not support O_DIRECT flags, refusing to use", fsPath)
+			return nil, config.ErrUnsupportedBackend(err).Hint(hint)
 		}
+
 		// Show a descriptive error with a hint about how to fix it.
 		var username string
 		if u, err := user.Current(); err == nil {

cmd/posix-errors.go

@@ -38,6 +38,11 @@ func isSysErrNoSpace(err error) bool {
 	return errors.Is(err, syscall.ENOSPC)
 }
 
+// Invalid argument, unsupported flags such as O_DIRECT
+func isSysErrInvalidArg(err error) bool {
+	return errors.Is(err, syscall.EINVAL)
+}
+
 // Input/output error
 func isSysErrIO(err error) bool {
 	return errors.Is(err, syscall.EIO)

cmd/posix.go

@@ -177,13 +177,20 @@ func getValidPath(path string) (string, error) {
 	// check if backend is writable.
 	var rnd [8]byte
 	_, _ = rand.Read(rnd[:])
+
 	fn := pathJoin(path, ".writable-check-"+hex.EncodeToString(rnd[:])+".tmp")
-	file, err := disk.OpenFileDirectIO(fn, os.O_CREATE, 0600)
+	defer os.Remove(fn)
+
+	// open file in direct I/O and use default umask, this also verifies
+	// if direct i/o failed.
+	file, err := disk.OpenFileDirectIO(fn, os.O_CREATE|os.O_EXCL, 0666)
 	if err != nil {
+		if isSysErrInvalidArg(err) {
+			return path, errUnsupportedDisk
+		}
 		return path, err
 	}
 	file.Close()
-	os.Remove(fn)
 
 	return path, nil
 }
@@ -1279,6 +1286,8 @@ func (s *posix) CreateFile(volume, path string, fileSize int64, r io.Reader) (er
 			return errFileAccessDenied
 		case isSysErrIO(err):
 			return errFaultyDisk
+		case isSysErrInvalidArg(err):
+			return errUnsupportedDisk
 		default:
 			return err
 		}

cmd/server-main.go

@@ -215,7 +215,11 @@ func initSafeMode() (err error) {
 			logger.Info("Waiting for all MinIO sub-systems to be initialized.. trying to acquire lock")
 			continue
 		}
+
+		// These messages only meant primarily for distributed setup, so only log during distributed setup.
+		if globalIsDistXL {
 			logger.Info("Waiting for all MinIO sub-systems to be initialized.. lock acquired")
+		}
 
 		// Migrate all backend configs to encrypted backend configs, optionally
 		// handles rotating keys for encryption, if there is any retriable failure
@@ -225,6 +229,10 @@ func initSafeMode() (err error) {
 			// if all sub-systems initialized successfully return right away
 			if err = initAllSubsystems(newObject); err == nil {
 				// All successful return.
+				if globalIsDistXL {
+					// These messages only meant primarily for distributed setup, so only log during distributed setup.
+					logger.Info("All MinIO sub-systems initialized successfully")
+				}
 				return nil
 			}
 		}

cmd/storage-errors.go

@@ -25,6 +25,9 @@ var errCorruptedFormat = StorageErr("corrupted backend format, please join https
 // errUnformattedDisk - unformatted disk found.
 var errUnformattedDisk = StorageErr("unformatted disk found")
 
+// errUnsupporteDisk - when disk does not support O_DIRECT flag.
+var errUnsupportedDisk = StorageErr("disk does not support O_DIRECT")
+
 // errDiskFull - cannot create volume or files when disk is full.
 var errDiskFull = StorageErr("disk path full")
 
@@ -81,7 +84,7 @@ var errBitrotHashAlgoInvalid = StorageErr("bit-rot hash algorithm is invalid")
 var errCrossDeviceLink = StorageErr("Rename across devices not allowed, please fix your backend configuration")
 
 // errMinDiskSize - cannot create volume or files when disk size is less than threshold.
-var errMinDiskSize = StorageErr("The disk size is less than the minimum threshold")
+var errMinDiskSize = StorageErr("The disk size is less than 900MiB threshold")
 
 // errLessData - returned when less data available than what was requested.
 var errLessData = StorageErr("less data available than what was requested")

cmd/storage-rest-server.go

@@ -738,6 +738,12 @@ func registerStorageRESTHandlers(router *mux.Router, endpointZones EndpointZones
 			}
 			storage, err := newPosix(endpoint.Path)
 			if err != nil {
+				if err == errMinDiskSize {
+					logger.Fatal(config.ErrUnableToWriteInBackend(err).Hint(err.Error()), "Unable to initialize backend")
+				} else if err == errUnsupportedDisk {
+					hint := fmt.Sprintf("'%s' does not support O_DIRECT flags, refusing to use", endpoint.Path)
+					logger.Fatal(config.ErrUnsupportedBackend(err).Hint(hint), "Unable to initialize backend")
+				}
 				// Show a descriptive error with a hint about how to fix it.
 				var username string
 				if u, err := user.Current(); err == nil {
@@ -747,7 +753,7 @@ func registerStorageRESTHandlers(router *mux.Router, endpointZones EndpointZones
 				}
 				hint := fmt.Sprintf("Run the following command to add the convenient permissions: `sudo chown %s %s && sudo chmod u+rxw %s`",
 					username, endpoint.Path, endpoint.Path)
-				logger.Fatal(config.ErrUnableToWriteInBackend(err).Msg(err.Error()).Hint(hint),
+				logger.Fatal(config.ErrUnableToWriteInBackend(err).Hint(hint),
 					"Unable to initialize posix backend")
 			}