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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2024, SUSE LLC
*
* Authors: Enzo Matsumiya <ematsumiya@suse.de>
*
* This file implements I/O compression support for SMB2 messages (SMB 3.1.1 only).
* See compress/ for implementation details of each algorithm.
*
* References:
* MS-SMB2 "3.1.4.4 Compressing the Message" - for compression details
* MS-SMB2 "3.1.5.3 Decompressing the Chained Message" - for decompression details
* MS-XCA - for details of the supported algorithms
*/
#ifndef _SMB_COMPRESS_H
#define _SMB_COMPRESS_H
#include <linux/uio.h>
#include <linux/kernel.h>
#include "../common/smb2pdu.h"
#include "cifsglob.h"
/* sizeof(smb2_compression_hdr) - sizeof(OriginalPayloadSize) */
#define SMB_COMPRESS_HDR_LEN 16
/* sizeof(smb2_compression_payload_hdr) - sizeof(OriginalPayloadSize) */
#define SMB_COMPRESS_PAYLOAD_HDR_LEN 8
#define SMB_COMPRESS_MIN_LEN PAGE_SIZE
#ifdef CONFIG_CIFS_COMPRESSION
typedef int (*compress_send_fn)(struct TCP_Server_Info *, int, struct smb_rqst *);
int smb_compress(struct TCP_Server_Info *server, struct smb_rqst *rq, compress_send_fn send_fn);
/**
* should_compress() - Determines if a request (write) or the response to a
* request (read) should be compressed.
* @tcon: tcon of the request is being sent to
* @rqst: request to evaluate
*
* Return: true iff:
* - compression was successfully negotiated with server
* - server has enabled compression for the share
* - it's a read or write request
* - (write only) request length is >= SMB_COMPRESS_MIN_LEN
* - (write only) is_compressible() returns 1
*
* Return false otherwise.
*/
bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq);
/**
* smb_compress_alg_valid() - Validate a compression algorithm.
* @alg: Compression algorithm to check.
* @valid_none: Conditional check whether NONE algorithm should be
* considered valid or not.
*
* If @alg is SMB3_COMPRESS_NONE, this function returns @valid_none.
*
* Note that 'NONE' (0) compressor type is considered invalid in protocol
* negotiation, as it's never requested to/returned from the server.
*
* Return: true if @alg is valid/supported, false otherwise.
*/
static __always_inline int smb_compress_alg_valid(__le16 alg, bool valid_none)
{
if (alg == SMB3_COMPRESS_NONE)
return valid_none;
if (alg == SMB3_COMPRESS_LZ77 || alg == SMB3_COMPRESS_PATTERN)
return true;
return false;
}
#else /* !CONFIG_CIFS_COMPRESSION */
static inline int smb_compress(void *unused1, void *unused2, void *unused3)
{
return -EOPNOTSUPP;
}
static inline bool should_compress(void *unused1, void *unused2)
{
return false;
}
static inline int smb_compress_alg_valid(__le16 unused1, bool unused2)
{
return -EOPNOTSUPP;
}
#endif /* !CONFIG_CIFS_COMPRESSION */
#endif /* _SMB_COMPRESS_H */
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