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94ae8c3fee
- Check data compressibility with some heuristics (copied from
btrfs):
- should_compress() final decision is is_compressible(data)
- Cleanup compress/lz77.h leaving only lz77_compress() exposed:
- Move parts to compress/lz77.c, while removing the rest of it
because they were either unused, used only once, were
implemented wrong (thanks to David Howells for the help)
- Updated the compression parameters (still compatible with
Windows implementation) trading off ~20% compression ratio
for ~40% performance:
- min match len: 3 -> 4
- max distance: 8KiB -> 1KiB
- hash table type: u32 * -> u64 *
Known bugs:
This implementation currently works fine in general, but breaks with
some payloads used during testing. Investigation ongoing, to be
fixed in a next commit.
Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
Co-developed-by: David Howells <dhowells@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
91 lines
2.8 KiB
C
91 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2024, SUSE LLC
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*
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* Authors: Enzo Matsumiya <ematsumiya@suse.de>
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*
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* This file implements I/O compression support for SMB2 messages (SMB 3.1.1 only).
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* See compress/ for implementation details of each algorithm.
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*
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* References:
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* MS-SMB2 "3.1.4.4 Compressing the Message" - for compression details
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* MS-SMB2 "3.1.5.3 Decompressing the Chained Message" - for decompression details
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* MS-XCA - for details of the supported algorithms
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*/
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#ifndef _SMB_COMPRESS_H
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#define _SMB_COMPRESS_H
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#include <linux/uio.h>
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#include <linux/kernel.h>
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#include "../common/smb2pdu.h"
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#include "cifsglob.h"
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/* sizeof(smb2_compression_hdr) - sizeof(OriginalPayloadSize) */
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#define SMB_COMPRESS_HDR_LEN 16
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/* sizeof(smb2_compression_payload_hdr) - sizeof(OriginalPayloadSize) */
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#define SMB_COMPRESS_PAYLOAD_HDR_LEN 8
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#define SMB_COMPRESS_MIN_LEN PAGE_SIZE
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#ifdef CONFIG_CIFS_COMPRESSION
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typedef int (*compress_send_fn)(struct TCP_Server_Info *, int, struct smb_rqst *);
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int smb_compress(struct TCP_Server_Info *server, struct smb_rqst *rq, compress_send_fn send_fn);
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/**
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* should_compress() - Determines if a request (write) or the response to a
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* request (read) should be compressed.
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* @tcon: tcon of the request is being sent to
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* @rqst: request to evaluate
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*
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* Return: true iff:
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* - compression was successfully negotiated with server
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* - server has enabled compression for the share
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* - it's a read or write request
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* - (write only) request length is >= SMB_COMPRESS_MIN_LEN
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* - (write only) is_compressible() returns 1
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*
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* Return false otherwise.
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*/
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bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq);
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/**
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* smb_compress_alg_valid() - Validate a compression algorithm.
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* @alg: Compression algorithm to check.
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* @valid_none: Conditional check whether NONE algorithm should be
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* considered valid or not.
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*
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* If @alg is SMB3_COMPRESS_NONE, this function returns @valid_none.
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*
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* Note that 'NONE' (0) compressor type is considered invalid in protocol
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* negotiation, as it's never requested to/returned from the server.
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*
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* Return: true if @alg is valid/supported, false otherwise.
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*/
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static __always_inline int smb_compress_alg_valid(__le16 alg, bool valid_none)
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{
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if (alg == SMB3_COMPRESS_NONE)
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return valid_none;
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if (alg == SMB3_COMPRESS_LZ77 || alg == SMB3_COMPRESS_PATTERN)
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return true;
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return false;
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}
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#else /* !CONFIG_CIFS_COMPRESSION */
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static inline int smb_compress(void *unused1, void *unused2, void *unused3)
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{
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return -EOPNOTSUPP;
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}
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static inline bool should_compress(void *unused1, void *unused2)
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{
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return false;
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}
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static inline int smb_compress_alg_valid(__le16 unused1, bool unused2)
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{
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return -EOPNOTSUPP;
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}
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#endif /* !CONFIG_CIFS_COMPRESSION */
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#endif /* _SMB_COMPRESS_H */
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