Skip parent directory creation in mount (#4310)

A POSIX filesystem does not implicitly create parent directories when
they do not exist. Directories must be explicitly created and
permissions be set.

This also fixes a bug where asynchronous operations would create a
file in the filer before the parent directory was created. If the
file was a symlink or another special type of file the directory
would inherit that type and become unusable in the mounted FS.

weed/mount/weedfs_symlink.go

@@ -3,13 +3,15 @@ package mount
 import (
 	"context"
 	"fmt"
-	"github.com/hanwen/go-fuse/v2/fuse"
-	"github.com/seaweedfs/seaweedfs/weed/filer"
-	"github.com/seaweedfs/seaweedfs/weed/glog"
-	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
 	"os"
 	"syscall"
 	"time"
+
+	"github.com/hanwen/go-fuse/v2/fuse"
+
+	"github.com/seaweedfs/seaweedfs/weed/filer"
+	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
 )
 
 /** Create a symbolic link */
@@ -42,7 +44,8 @@ func (wfs *WFS) Symlink(cancel <-chan struct{}, header *fuse.InHeader, target st
 				SymlinkTarget: target,
 			},
 		},
-		Signatures: []int32{wfs.signature},
+		Signatures:               []int32{wfs.signature},
+		SkipCheckParentDirectory: true,
 	}
 
 	err := wfs.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {