Make `weed-fuse` compatible with systemd-based mount (#6814)

* Make weed-fuse compatible with systemd-mount series

* fix: add missing type annotation on skipAutofs param in FreeBSD build

The parameter was declared without a type, causing a compile error on FreeBSD.

* fix: guard hasAutofs nil dereference and make FsName conditional on autofs mode

- Check option.hasAutofs for nil before dereferencing to prevent panic
  when RunMount is called without the flag initialized.
- Only set FsName to "fuse" when autofs mode is active; otherwise
  preserve the descriptive server:path name for mount/df output.
- Fix typo: recogize -> recognize.

* fix: consistent error handling for autofs option and log ignored _netdev

- Replace panic with fmt.Fprintf+return false for autofs parse errors,
  matching the pattern used by other fuse option parsers.
- Log when _netdev option is silently stripped to aid debugging.

---------

Co-authored-by: Chris Lu <chris.lu@gmail.com>

weed/command/fuse_std.go

@@ -12,6 +12,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/util"
 	util_http "github.com/seaweedfs/seaweedfs/weed/util/http"
 )
@@ -267,6 +268,19 @@ func runFuse(cmd *Command, args []string) bool {
 				fmt.Fprintf(os.Stderr, "failed to parse 'sys.novncache' value %q: %v\n", parameter.value, err)
 				return false
 			}
+		case "autofs":
+			if parsed, err := strconv.ParseBool(parameter.value); err == nil {
+				mountOptions.hasAutofs = &parsed
+			} else {
+				fmt.Fprintf(os.Stderr, "failed to parse 'autofs' value %q: %v\n", parameter.value, err)
+				return false
+			}
+		case "_netdev":
+			// _netdev is used for systemd/fstab parser to signify that this is a network mount but systemd
+			// mount sometimes can't strip them off. Meanwhile, fuse3 would refuse to run with _netdev, we
+			// strip them here if it fails to be stripped by the caller.
+			//(See https://github.com/seaweedfs/seaweedfs/wiki/fstab/948a70df5c0d9d2d27561b96de53bde07a29d2db)
+			glog.V(0).Infof("ignoring _netdev mount option")
 		default:
 			t := parameter.name
 			if parameter.value != "true" {

weed/command/mount.go

@@ -58,6 +58,11 @@ type MountOptions struct {
 
 	// macOS-specific FUSE options
 	novncache *bool
+
+	// if true, we assume autofs exists over current mount point. Autofs (the kernel one, used by systemd automount)
+	// is expected to be mounted as a shim between auto-mounted fs and original mount point to provide auto mount.
+	// with this option, we ignore autofs mounted on the same point.
+	hasAutofs *bool
 }
 
 var (
@@ -98,6 +103,7 @@ func init() {
 	mountOptions.debugPort = cmdMount.Flag.Int("debug.port", 6061, "http port for debugging")
 	mountOptions.localSocket = cmdMount.Flag.String("localSocket", "", "default to /tmp/seaweedfs-mount-<mount_dir_hash>.sock")
 	mountOptions.disableXAttr = cmdMount.Flag.Bool("disableXAttr", false, "disable xattr")
+	mountOptions.hasAutofs = cmdMount.Flag.Bool("autofs", false, "ignore autofs mounted on the same mountpoint (useful when systemd.automount and autofs is used)")
 	mountOptions.fuseCommandPid = 0
 
 	// Periodic metadata flush to protect against orphan chunk cleanup

weed/command/mount_darwin.go

@@ -1,5 +1,5 @@
 package command
 
-func checkMountPointAvailable(dir string) bool {
+func checkMountPointAvailable(dir string, skipAutofs bool) bool {
 	return true
 }

weed/command/mount_freebsd.go

@@ -1,5 +1,5 @@
 package command
 
-func checkMountPointAvailable(dir string) bool {
+func checkMountPointAvailable(dir string, skipAutofs bool) bool {
 	return true
 }

weed/command/mount_linux.go

@@ -69,7 +69,7 @@ type Info struct {
 
 // Mounted determines if a specified mountpoint has been mounted.
 // On Linux it looks at /proc/self/mountinfo and on Solaris at mnttab.
-func mounted(mountPoint string) (bool, error) {
+func mounted(mountPoint string, skipAutofs bool) (bool, error) {
 	entries, err := parseMountTable()
 	if err != nil {
 		return false, err
@@ -78,6 +78,10 @@ func mounted(mountPoint string) (bool, error) {
 	// Search the table for the mountPoint
 	for _, e := range entries {
 		if e.Mountpoint == mountPoint {
+			// Check if the mountpoint is autofs
+			if skipAutofs && e.Fstype == "autofs" {
+				continue
+			}
 			return true, nil
 		}
 	}
@@ -137,13 +141,13 @@ func parseInfoFile(r io.Reader) ([]*Info, error) {
 	return out, nil
 }
 
-func checkMountPointAvailable(dir string) bool {
+func checkMountPointAvailable(dir string, skipAutofs bool) bool {
 	mountPoint := dir
 	if mountPoint != "/" && strings.HasSuffix(mountPoint, "/") {
 		mountPoint = mountPoint[0 : len(mountPoint)-1]
 	}
 
-	if mounted, err := mounted(mountPoint); err != nil || mounted {
+	if mounted, err := mounted(mountPoint, skipAutofs); err != nil || mounted {
 		if err != nil {
 			glog.Errorf("check %s: %v", mountPoint, err)
 		}

weed/command/mount_std.go

@@ -223,13 +223,21 @@ func RunMount(option *MountOptions, umask os.FileMode) bool {
 	}
 
 	// Ensure target mount point availability
-	if isValid := checkMountPointAvailable(dir); !isValid {
+	skipAutofs := option.hasAutofs != nil && *option.hasAutofs
+	if isValid := checkMountPointAvailable(dir, skipAutofs); !isValid {
 		glog.Fatalf("Target mount point is not available: %s, please check!", dir)
 		return true
 	}
 
 	serverFriendlyName := strings.ReplaceAll(*option.filer, ",", "+")
 
+	// When autofs/systemd-mount is used, FsName must be "fuse" so util-linux/mount can recognize
+	// it as a pseudo filesystem. Otherwise, preserve the descriptive name for mount/df output.
+	fsName := serverFriendlyName + ":" + filerMountRootPath
+	if skipAutofs {
+		fsName = "fuse"
+	}
+
 	// mount fuse
 	fuseMountOptions := &fuse.MountOptions{
 		AllowOther:               *option.allowOthers,
@@ -239,7 +247,7 @@ func RunMount(option *MountOptions, umask os.FileMode) bool {
 		MaxReadAhead:             1024 * 1024 * 2,
 		IgnoreSecurityLabels:     false,
 		RememberInodes:           false,
-		FsName:                   serverFriendlyName + ":" + filerMountRootPath,
+		FsName:                   fsName,
 		Name:                     "seaweedfs",
 		SingleThreaded:           false,
 		DisableXAttrs:            *option.disableXAttr,