fix(filer): apply default disk type after location-prefix resolution in gRPC AssignVolume (#8836)

* fix(filer): apply default disk type after location-prefix resolution in gRPC AssignVolume

The gRPC AssignVolume path was applying the filer's default DiskType to
the request before calling detectStorageOption. This caused the default
to shadow any disk type configured via a filer location-prefix rule,
diverging from the HTTP write path which applies the default only when
no rule matches.

Extract resolveAssignStorageOption to apply the filer default disk type
after detectStorageOption, so location-prefix rules take precedence.

* fix(filer): apply default disk type after location-prefix resolution in TUS upload path

Same class of bug as the gRPC AssignVolume fix: the TUS tusWriteData
handler called detectStorageOption0 but never applied the filer's
default DiskType when no location-prefix rule matched. This made TUS
uploads ignore the -disk flag entirely.

weed/server/filer_grpc_server_test.go

@@ -0,0 +1,68 @@
+package weed_server
+
+import (
+	"context"
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/filer"
+	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
+)
+
+func TestResolveAssignStorageOptionUsesBucketRuleBeforeFilerDiskDefault(t *testing.T) {
+	fc := filer.NewFilerConf()
+	if err := fc.SetLocationConf(&filer_pb.FilerConf_PathConf{
+		LocationPrefix: "/buckets/zot",
+		DiskType:       "disk",
+	}); err != nil {
+		t.Fatalf("set location conf: %v", err)
+	}
+
+	fs := &FilerServer{
+		option: &FilerOption{
+			DiskType: "hdd",
+		},
+		filer: &filer.Filer{
+			DirBucketsPath:    "/buckets",
+			FilerConf:         fc,
+			MaxFilenameLength: 255,
+		},
+	}
+
+	so, err := fs.resolveAssignStorageOption(context.Background(), &filer_pb.AssignVolumeRequest{
+		Path: "/buckets/zot/.uploads/upload-id/0001_part.part",
+	})
+	if err != nil {
+		t.Fatalf("resolve assign storage option: %v", err)
+	}
+
+	if got, want := so.Collection, "zot"; got != want {
+		t.Fatalf("collection = %q, want %q", got, want)
+	}
+	if got, want := so.DiskType, "disk"; got != want {
+		t.Fatalf("disk type = %q, want %q", got, want)
+	}
+}
+
+func TestResolveAssignStorageOptionFallsBackToFilerDiskDefault(t *testing.T) {
+	fs := &FilerServer{
+		option: &FilerOption{
+			DiskType: "hdd",
+		},
+		filer: &filer.Filer{
+			DirBucketsPath:    "/buckets",
+			FilerConf:         filer.NewFilerConf(),
+			MaxFilenameLength: 255,
+		},
+	}
+
+	so, err := fs.resolveAssignStorageOption(context.Background(), &filer_pb.AssignVolumeRequest{
+		Path: "/tmp/unmatched/file.bin",
+	})
+	if err != nil {
+		t.Fatalf("resolve assign storage option: %v", err)
+	}
+
+	if got, want := so.DiskType, "hdd"; got != want {
+		t.Fatalf("disk type = %q, want %q", got, want)
+	}
+}