[PATCH v2 1/8] ntfs: introduce transparent compression codec interface

Introduce struct ntfs_codec_ops and enum ntfs_codec_id to provide a
unified interface for compression and decompression algorithms. This
interface supports WOF and LZNT1 decompression.

Signed-off-by: Hyunchul Lee <[email protected]>
---
 fs/ntfs/ntfs_codec.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/fs/ntfs/ntfs_codec.h b/fs/ntfs/ntfs_codec.h
new file mode 100644
index 000000000000..14a69d1e4d7f
--- /dev/null
+++ b/fs/ntfs/ntfs_codec.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Transparent compression codec interface.
+ *
+ * Copyright (c) 2026 LG Electronics Co., Ltd.
+ */
+
+#ifndef _NTFS_CODEC_H
+#define _NTFS_CODEC_H
+
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+
+struct compress_context;
+
+enum ntfs_codec_id {
+	NTFS_CODEC_LZNT1,
+#ifdef CONFIG_NTFS_FS_WOF_COMPRESSION
+	NTFS_CODEC_XPRESS4K,
+	NTFS_CODEC_XPRESS8K,
+	NTFS_CODEC_XPRESS16K,
+	NTFS_CODEC_LZX32K,
+#endif
+};
+
+struct ntfs_codec_ops {
+	enum ntfs_codec_id id;
+	const char *name;
+	size_t (*scratch_size)(u32 chunk_size);
+	int (*decompress_chunk)(void *scratch,
+				const void *src, size_t src_len,
+				void *dst, size_t dst_len,
+				u32 chunk_size);
+	int (*decompress_pages)(struct page *dest_pages[],
+				int completed_pages[],
+				int *dest_index, int *dest_ofs,
+				int dest_max_index, int dest_max_ofs,
+				int xpage, char *xpage_done,
+				u8 *cb_start, u32 cb_size,
+				loff_t i_size, s64 initialized_size);
+	int (*compress_subblock)(struct compress_context *pctx,
+				 const char *inbuf, int bufsize, char *outbuf);
+};
+
+#endif /* _NTFS_CODEC_H */

-- 
2.43.0