Fail to start server if detected cross-device mounts. (#4807)

Fixes #4764

cmd/endpoint.go

@@ -21,11 +21,13 @@ import (
 	"net"
 	"net/url"
 	"path"
+	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
 
 	"github.com/minio/minio-go/pkg/set"
+	"github.com/minio/minio/pkg/mountinfo"
 )
 
 // EndpointType - enum for endpoint type.
@@ -99,7 +101,8 @@ func NewEndpoint(arg string) (ep Endpoint, e error) {
 			return ep, fmt.Errorf("invalid URL endpoint format")
 		}
 
-		host, port, err := net.SplitHostPort(u.Host)
+		var host, port string
+		host, port, err = net.SplitHostPort(u.Host)
 		if err != nil {
 			if !strings.Contains(err.Error(), "missing port in address") {
 				return ep, fmt.Errorf("invalid URL endpoint format: %s", err)
@@ -226,6 +229,22 @@ func NewEndpointList(args ...string) (endpoints EndpointList, err error) {
 	return endpoints, nil
 }
 
+// Checks if there are any cross device mounts.
+func checkCrossDeviceMounts(endpoints EndpointList) (err error) {
+	var absPaths []string
+	for _, endpoint := range endpoints {
+		if endpoint.IsLocal {
+			var absPath string
+			absPath, err = filepath.Abs(endpoint.Path)
+			if err != nil {
+				return err
+			}
+			absPaths = append(absPaths, absPath)
+		}
+	}
+	return mountinfo.CheckCrossDevice(absPaths)
+}
+
 // CreateEndpoints - validates and creates new endpoints for given args.
 func CreateEndpoints(serverAddr string, args ...string) (string, EndpointList, SetupType, error) {
 	var endpoints EndpointList
@@ -246,13 +265,16 @@ func CreateEndpoints(serverAddr string, args ...string) (string, EndpointList, S
 		if err != nil {
 			return serverAddr, endpoints, setupType, err
 		}
-
 		if endpoint.Type() != PathEndpointType {
 			return serverAddr, endpoints, setupType, fmt.Errorf("use path style endpoint for FS setup")
 		}
-
 		endpoints = append(endpoints, endpoint)
 		setupType = FSSetupType
+
+		// Check for cross device mounts if any.
+		if err = checkCrossDeviceMounts(endpoints); err != nil {
+			return serverAddr, endpoints, setupType, err
+		}
 		return serverAddr, endpoints, setupType, nil
 	}
 
@@ -261,6 +283,11 @@ func CreateEndpoints(serverAddr string, args ...string) (string, EndpointList, S
 		return serverAddr, endpoints, setupType, err
 	}
 
+	// Check for cross device mounts if any.
+	if err = checkCrossDeviceMounts(endpoints); err != nil {
+		return serverAddr, endpoints, setupType, err
+	}
+
 	// Return XL setup when all endpoints are path style.
 	if endpoints[0].Type() == PathEndpointType {
 		setupType = XLSetupType

cmd/fs-v1-helpers.go

@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"fmt"
 	"io"
 	"os"
 	pathutil "path"
@@ -360,6 +361,9 @@ func fsRenameFile(sourcePath, destPath string) error {
 		return traceError(err)
 	}
 	if err := os.Rename((sourcePath), (destPath)); err != nil {
+		if isSysErrCrossDevice(err) {
+			return traceError(fmt.Errorf("%s (%s)->(%s)", errCrossDeviceLink, sourcePath, destPath))
+		}
 		return traceError(err)
 	}
 	return nil

cmd/posix-errors.go

@@ -118,3 +118,10 @@ func isSysErrHandleInvalid(err error) bool {
 	}
 	return false
 }
+
+func isSysErrCrossDevice(err error) bool {
+	if e, ok := err.(*os.LinkError); ok {
+		return e.Err == syscall.EXDEV
+	}
+	return false
+}

cmd/posix.go

@@ -102,6 +102,7 @@ func newPosix(path string) (StorageAPI, error) {
 	if err != nil {
 		return nil, err
 	}
+
 	st := &posix{
 		diskPath: diskPath,
 		// 1MiB buffer pool for posix internal operations.

cmd/server-main.go

@@ -91,6 +91,7 @@ func serverHandleCmdArgs(ctx *cli.Context) {
 
 	var setupType SetupType
 	var err error
+
 	globalMinioAddr, globalEndpoints, setupType, err = CreateEndpoints(serverAddr, ctx.Args()...)
 	fatalIf(err, "Invalid command line arguments server=‘%s’, args=%s", serverAddr, ctx.Args())
 	globalMinioHost, globalMinioPort = mustSplitHostPort(globalMinioAddr)

cmd/storage-errors.go

@@ -83,6 +83,9 @@ var errFileAccessDenied = errors.New("file access denied")
 // verification is empty or invalid.
 var errBitrotHashAlgoInvalid = errors.New("bit-rot hash algorithm is invalid")
 
+// errCrossDeviceLink - rename across devices not allowed.
+var errCrossDeviceLink = errors.New("Rename across devices not allowed, please fix your backend configuration")
+
 // hashMisMatchError - represents a bit-rot hash verification failure
 // error.
 type hashMismatchError struct {