[PATCH RFC 6/9] lib/lz4: switch the HC compressor to the vendored sources
From: Michal Wilczynski
Date: Fri Sep 25 2026 - 07:37:44 EST
Replace the forked LZ4HC with thin entry points over the vendored
lz4hc.c.
The HC entry points clamp the level below LZ4HC_CLEVEL_OPT_MIN, since
upstream routes levels 10 and up to the optimal parser whose ~64K
workspace does not fit a kernel stack. Levels are clamped rather than
rejected so existing f2fs and zram settings keep working; they now
compress as level 9.
f2fs and zram both take user levels up to LZ4HC_MAX_CLEVEL, so
<linux/lz4.h> gains LZ4HC_CLAMP_CLEVEL and says what happens at or above
it. A later patch ties that constant to upstream's LZ4HC_CLEVEL_OPT_MIN
with a static_assert, once <linux/lz4.h> is in scope of these files.
Levels 1 and 2 change in the other direction. Upstream routes them
through its new lz4mid strategy: at a 4K block that is 26% faster for
10% and 19% worse ratio, and at 64K it is 83% and 90% faster for 14% and
26% worse. In the fork level 1 was only 10% faster than level 3 while
compressing 17% worse, so this is a better point on the curve rather
than a loss, but it is a change. f2fs rejects levels below
LZ4HC_MIN_CLEVEL, so only zram can select them; a caller that wants the
old ratio should ask for level 3.
As with LZ4_stream_t, LZ4_streamHC_t becomes an incomplete type, and the
macros that laid the forked structure out (LZ4HC_DICTIONARY_LOGSIZE,
LZ4HC_MAXD, LZ4HC_MAXD_MASK, LZ4HC_HASH_LOG, LZ4HC_HASHTABLESIZE,
LZ4HC_HASH_MASK, LZ4_STREAMHCSIZE, LZ4_STREAMHCSIZE_SIZET) go with it.
LZ4HC_MEM_COMPRESS grows from 262192 to upstream's LZ4_STREAMHC_MINSIZE,
262200: upstream's LZ4HC_CCtx_internal has fields the forked one does
not, most visibly the dictionary context pointer. It has to grow in the
same commit; an allocation eight bytes short of what the compressor
initialises would overrun zram's compress path. The size is
static_asserted against upstream's own LZ4_STREAMHC_MINSIZE, so a future
re-sync that changes it fails the build rather than the allocation.
lz4hc.c pulls in lz4.c for its common definitions, which include two
decoder tables used there only by the fast decode loop. On architectures
where that loop is off, W=1 reports them as unused. Silence that one
warning for this one object rather than edit the vendored file.
This retires one local patch:
commit b08918fb3f27 ("lz4: do not export static symbol")
Signed-off-by: Michal Wilczynski <m.wilczynski@xxxxxxxxxxx>
---
drivers/block/zram/backend_lz4hc.c | 2 +-
include/linux/lz4.h | 53 +--
lib/lz4/Makefile | 4 +
lib/lz4/lz4hc_compress.c | 785 +++----------------------------------
4 files changed, 76 insertions(+), 768 deletions(-)
diff --git a/drivers/block/zram/backend_lz4hc.c b/drivers/block/zram/backend_lz4hc.c
index d8aa01bb258fec760b597a88296dfaa4e0049693..894695753d99bf2fec7e191c4ec2fff489b5bddd 100644
--- a/drivers/block/zram/backend_lz4hc.c
+++ b/drivers/block/zram/backend_lz4hc.c
@@ -69,7 +69,7 @@ static int lz4hc_create(struct zcomp_params *params, struct zcomp_ctx *ctx)
if (!zctx->dstrm)
goto error;
- zctx->cstrm = kzalloc_obj(*zctx->cstrm);
+ zctx->cstrm = kzalloc(LZ4HC_MEM_COMPRESS, GFP_KERNEL);
if (!zctx->cstrm)
goto error;
}
diff --git a/include/linux/lz4.h b/include/linux/lz4.h
index e96353a67d617a4d734cecaf3764814df692428b..0e617c096653ba122f466b019c68a30661e04989 100644
--- a/include/linux/lz4.h
+++ b/include/linux/lz4.h
@@ -59,19 +59,15 @@
#define LZ4HC_DEFAULT_CLEVEL 9
#define LZ4HC_MAX_CLEVEL 16
-#define LZ4HC_DICTIONARY_LOGSIZE 16
-#define LZ4HC_MAXD (1<<LZ4HC_DICTIONARY_LOGSIZE)
-#define LZ4HC_MAXD_MASK (LZ4HC_MAXD - 1)
-#define LZ4HC_HASH_LOG (LZ4HC_DICTIONARY_LOGSIZE - 1)
-#define LZ4HC_HASHTABLESIZE (1 << LZ4HC_HASH_LOG)
-#define LZ4HC_HASH_MASK (LZ4HC_HASHTABLESIZE - 1)
+/* Levels from here up select the optimal parser, whose ~64K workspace does
+ * not fit a kernel stack; lib/lz4 clamps them to LZ4HC_CLAMP_CLEVEL - 1.
+ * Anything up to LZ4HC_MAX_CLEVEL is still accepted, just no harder.
+ */
+#define LZ4HC_CLAMP_CLEVEL 10
/*-************************************************************************
* STREAMING CONSTANTS AND STRUCTURES
**************************************************************************/
-#define LZ4_STREAMHCSIZE 262192
-#define LZ4_STREAMHCSIZE_SIZET (262192 / sizeof(size_t))
-
#define LZ4_STREAMDECODESIZE_U64 4
#define LZ4_STREAMDECODESIZE (LZ4_STREAMDECODESIZE_U64 * \
sizeof(unsigned long long))
@@ -83,29 +79,10 @@
typedef union LZ4_stream_u LZ4_stream_t;
/*
- * LZ4_streamHC_t - information structure to track an LZ4HC stream.
+ * LZ4_streamHC_t - an LZ4HC stream. Incomplete: lib/lz4 owns the layout.
+ * Allocate LZ4HC_MEM_COMPRESS bytes and cast, do not sizeof().
*/
-typedef struct {
- unsigned int hashTable[LZ4HC_HASHTABLESIZE];
- unsigned short chainTable[LZ4HC_MAXD];
- /* next block to continue on current prefix */
- const unsigned char *end;
- /* All index relative to this position */
- const unsigned char *base;
- /* alternate base for extDict */
- const unsigned char *dictBase;
- /* below that point, need extDict */
- unsigned int dictLimit;
- /* below that point, no more dict */
- unsigned int lowLimit;
- /* index from which to continue dict update */
- unsigned int nextToUpdate;
- unsigned int compressionLevel;
-} LZ4HC_CCtx_internal;
-typedef union {
- size_t table[LZ4_STREAMHCSIZE_SIZET];
- LZ4HC_CCtx_internal internal_donotuse;
-} LZ4_streamHC_t;
+typedef union LZ4_streamHC_u LZ4_streamHC_t;
/*
* LZ4_streamDecode_t - information structure to track an
@@ -133,7 +110,7 @@ typedef union {
* buffer is rejected, and the stateless entry points cannot report that.
*/
#define LZ4_MEM_COMPRESS 16416
-#define LZ4HC_MEM_COMPRESS LZ4_STREAMHCSIZE
+#define LZ4HC_MEM_COMPRESS 262200
/*-************************************************************************
* Compression Functions
@@ -310,9 +287,9 @@ int LZ4_decompress_safe_partial(const char *source, char *dest,
* @srcSize: size of the input data. Max supported value is LZ4_MAX_INPUT_SIZE
* @dstCapacity: full or partial size of buffer 'dst',
* which must be already allocated
- * @compressionLevel: Recommended values are between 4 and 9, although any
- * value between 1 and LZ4HC_MAX_CLEVEL will work.
- * Values >LZ4HC_MAX_CLEVEL behave the same as 16.
+ * @compressionLevel: Recommended values are between 4 and 9. Levels of
+ * LZ4HC_CLAMP_CLEVEL and above are clamped to LZ4HC_CLAMP_CLEVEL - 1;
+ * see that macro.
* @wrkmem: address of the working memory.
* This requires 'wrkmem' of size LZ4HC_MEM_COMPRESS, aligned to 8 bytes.
*
@@ -328,9 +305,9 @@ int LZ4_compress_HC(const char *src, char *dst, int srcSize, int dstCapacity,
/**
* LZ4_resetStreamHC() - Init an allocated 'LZ4_streamHC_t' structure
* @streamHCPtr: pointer to the 'LZ4_streamHC_t' structure
- * @compressionLevel: Recommended values are between 4 and 9, although any
- * value between 1 and LZ4HC_MAX_CLEVEL will work.
- * Values >LZ4HC_MAX_CLEVEL behave the same as 16.
+ * @compressionLevel: Recommended values are between 4 and 9. Levels of
+ * LZ4HC_CLAMP_CLEVEL and above are clamped to LZ4HC_CLAMP_CLEVEL - 1;
+ * see that macro.
*
* An LZ4_streamHC_t structure can be allocated once
* and re-used multiple times.
diff --git a/lib/lz4/Makefile b/lib/lz4/Makefile
index e9d83cff4ea4efe1097f54caba72e268cecb04af..9ac36ada805cc99d6db43d141394e51b4b1f7598 100644
--- a/lib/lz4/Makefile
+++ b/lib/lz4/Makefile
@@ -9,3 +9,7 @@ ccflags-y += -I $(src)/freestanding
obj-$(CONFIG_LZ4_COMPRESS) += lz4_compress.o
obj-$(CONFIG_LZ4HC_COMPRESS) += lz4hc_compress.o
obj-$(CONFIG_LZ4_DECOMPRESS) += lz4_decompress.o
+
+# lz4hc.c pulls in lz4.c's common definitions, which include two decoder
+# tables nothing here uses when LZ4_FAST_DEC_LOOP is off.
+CFLAGS_lz4hc_compress.o += $(call cc-disable-warning, unused-const-variable)
diff --git a/lib/lz4/lz4hc_compress.c b/lib/lz4/lz4hc_compress.c
index 91936dc3d14bca31752a361693380aad8eb3b98a..6070719bab54e90a8a163c08842a5531d7b2b4ac 100644
--- a/lib/lz4/lz4hc_compress.c
+++ b/lib/lz4/lz4hc_compress.c
@@ -1,766 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
/*
- * LZ4 HC - High Compression Mode of LZ4
- * Copyright (C) 2011-2015, Yann Collet.
+ * Copyright (C) 2011 - 2016, Yann Collet.
+ * Copyright (C) 2016, Sven Schmidt <4sschmid@xxxxxxxxxxxxxxxxxxxxxxxxx>
+ * Copyright (c) 2026 Samsung Electronics Co., Ltd.
+ * Author: Michal Wilczynski <m.wilczynski@xxxxxxxxxxx>
*
- * BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php)
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- * * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- * You can contact the author at :
- * - LZ4 homepage : http://www.lz4.org
- * - LZ4 source repository : https://github.com/lz4/lz4
+ * LZ4 HC compressor -- kernel entry points
*
- * Changed for kernel usage by:
- * Sven Schmidt <4sschmid@xxxxxxxxxxxxxxxxxxxxxxxxx>
+ * The compressor is upstream's, in the verbatim lz4hc.c included below.
+ * LZ4_compress_HC() takes the kernel's trailing wrkmem argument and forwards
+ * to LZ4_compress_HC_extStateHC(); the level-taking entry points clamp the
+ * level below LZ4HC_CLEVEL_OPT_MIN (see lz4hc_clamp_level()).
*/
-/*-************************************
- * Dependencies
- **************************************/
-#include "lz4defs.h"
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/string.h> /* memset */
-
-/* *************************************
- * Local Constants and types
- ***************************************/
-
-#define OPTIMAL_ML (int)((ML_MASK - 1) + MINMATCH)
-
-#define HASH_FUNCTION(i) (((i) * 2654435761U) \
- >> ((MINMATCH*8) - LZ4HC_HASH_LOG))
-#define DELTANEXTU16(p) chainTable[(U16)(p)] /* faster */
-
-static U32 LZ4HC_hashPtr(const void *ptr)
-{
- return HASH_FUNCTION(LZ4_read32(ptr));
-}
-
-/**************************************
- * HC Compression
- **************************************/
-static void LZ4HC_init(LZ4HC_CCtx_internal *hc4, const BYTE *start)
-{
- memset((void *)hc4->hashTable, 0, sizeof(hc4->hashTable));
- memset(hc4->chainTable, 0xFF, sizeof(hc4->chainTable));
- hc4->nextToUpdate = 64 * KB;
- hc4->base = start - 64 * KB;
- hc4->end = start;
- hc4->dictBase = start - 64 * KB;
- hc4->dictLimit = 64 * KB;
- hc4->lowLimit = 64 * KB;
-}
-
-/* Update chains up to ip (excluded) */
-static FORCE_INLINE void LZ4HC_Insert(LZ4HC_CCtx_internal *hc4,
- const BYTE *ip)
-{
- U16 * const chainTable = hc4->chainTable;
- U32 * const hashTable = hc4->hashTable;
- const BYTE * const base = hc4->base;
- U32 const target = (U32)(ip - base);
- U32 idx = hc4->nextToUpdate;
-
- while (idx < target) {
- U32 const h = LZ4HC_hashPtr(base + idx);
- size_t delta = idx - hashTable[h];
-
- if (delta > MAX_DISTANCE)
- delta = MAX_DISTANCE;
-
- DELTANEXTU16(idx) = (U16)delta;
+#include "lz4_deps.h"
- hashTable[h] = idx;
- idx++;
- }
-
- hc4->nextToUpdate = target;
-}
-
-static FORCE_INLINE int LZ4HC_InsertAndFindBestMatch(
- LZ4HC_CCtx_internal *hc4, /* Index table will be updated */
- const BYTE *ip,
- const BYTE * const iLimit,
- const BYTE **matchpos,
- const int maxNbAttempts)
+/* lz4hc.c includes lz4.c with LZ4_COMMONDEFS_ONLY, which stops short of
+ * LZ4_compressBound(). Supply it for lz4hc.c's internal use.
+ */
+static int LZ4_compressBound(int isize)
{
- U16 * const chainTable = hc4->chainTable;
- U32 * const HashTable = hc4->hashTable;
- const BYTE * const base = hc4->base;
- const BYTE * const dictBase = hc4->dictBase;
- const U32 dictLimit = hc4->dictLimit;
- const U32 lowLimit = (hc4->lowLimit + 64 * KB > (U32)(ip - base))
- ? hc4->lowLimit
- : (U32)(ip - base) - (64 * KB - 1);
- U32 matchIndex;
- int nbAttempts = maxNbAttempts;
- size_t ml = 0;
-
- /* HC4 match finder */
- LZ4HC_Insert(hc4, ip);
- matchIndex = HashTable[LZ4HC_hashPtr(ip)];
-
- while ((matchIndex >= lowLimit)
- && (nbAttempts)) {
- nbAttempts--;
- if (matchIndex >= dictLimit) {
- const BYTE * const match = base + matchIndex;
-
- if (*(match + ml) == *(ip + ml)
- && (LZ4_read32(match) == LZ4_read32(ip))) {
- size_t const mlt = LZ4_count(ip + MINMATCH,
- match + MINMATCH, iLimit) + MINMATCH;
-
- if (mlt > ml) {
- ml = mlt;
- *matchpos = match;
- }
- }
- } else {
- const BYTE * const match = dictBase + matchIndex;
-
- if (LZ4_read32(match) == LZ4_read32(ip)) {
- size_t mlt;
- const BYTE *vLimit = ip
- + (dictLimit - matchIndex);
-
- if (vLimit > iLimit)
- vLimit = iLimit;
- mlt = LZ4_count(ip + MINMATCH,
- match + MINMATCH, vLimit) + MINMATCH;
- if ((ip + mlt == vLimit)
- && (vLimit < iLimit))
- mlt += LZ4_count(ip + mlt,
- base + dictLimit,
- iLimit);
- if (mlt > ml) {
- /* virtual matchpos */
- ml = mlt;
- *matchpos = base + matchIndex;
- }
- }
- }
- matchIndex -= DELTANEXTU16(matchIndex);
- }
-
- return (int)ml;
+ return LZ4_COMPRESSBOUND(isize);
}
-static FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch(
- LZ4HC_CCtx_internal *hc4,
- const BYTE * const ip,
- const BYTE * const iLowLimit,
- const BYTE * const iHighLimit,
- int longest,
- const BYTE **matchpos,
- const BYTE **startpos,
- const int maxNbAttempts)
-{
- U16 * const chainTable = hc4->chainTable;
- U32 * const HashTable = hc4->hashTable;
- const BYTE * const base = hc4->base;
- const U32 dictLimit = hc4->dictLimit;
- const BYTE * const lowPrefixPtr = base + dictLimit;
- const U32 lowLimit = (hc4->lowLimit + 64 * KB > (U32)(ip - base))
- ? hc4->lowLimit
- : (U32)(ip - base) - (64 * KB - 1);
- const BYTE * const dictBase = hc4->dictBase;
- U32 matchIndex;
- int nbAttempts = maxNbAttempts;
- int delta = (int)(ip - iLowLimit);
-
- /* First Match */
- LZ4HC_Insert(hc4, ip);
- matchIndex = HashTable[LZ4HC_hashPtr(ip)];
-
- while ((matchIndex >= lowLimit)
- && (nbAttempts)) {
- nbAttempts--;
- if (matchIndex >= dictLimit) {
- const BYTE *matchPtr = base + matchIndex;
+#include "upstream/lz4hc.c"
- if (*(iLowLimit + longest)
- == *(matchPtr - delta + longest)) {
- if (LZ4_read32(matchPtr) == LZ4_read32(ip)) {
- int mlt = MINMATCH + LZ4_count(
- ip + MINMATCH,
- matchPtr + MINMATCH,
- iHighLimit);
- int back = 0;
-
- while ((ip + back > iLowLimit)
- && (matchPtr + back > lowPrefixPtr)
- && (ip[back - 1] == matchPtr[back - 1]))
- back--;
-
- mlt -= back;
-
- if (mlt > longest) {
- longest = (int)mlt;
- *matchpos = matchPtr + back;
- *startpos = ip + back;
- }
- }
- }
- } else {
- const BYTE * const matchPtr = dictBase + matchIndex;
-
- if (LZ4_read32(matchPtr) == LZ4_read32(ip)) {
- size_t mlt;
- int back = 0;
- const BYTE *vLimit = ip + (dictLimit - matchIndex);
-
- if (vLimit > iHighLimit)
- vLimit = iHighLimit;
-
- mlt = LZ4_count(ip + MINMATCH,
- matchPtr + MINMATCH, vLimit) + MINMATCH;
-
- if ((ip + mlt == vLimit) && (vLimit < iHighLimit))
- mlt += LZ4_count(ip + mlt, base + dictLimit,
- iHighLimit);
- while ((ip + back > iLowLimit)
- && (matchIndex + back > lowLimit)
- && (ip[back - 1] == matchPtr[back - 1]))
- back--;
-
- mlt -= back;
-
- if ((int)mlt > longest) {
- longest = (int)mlt;
- *matchpos = base + matchIndex + back;
- *startpos = ip + back;
- }
- }
- }
-
- matchIndex -= DELTANEXTU16(matchIndex);
- }
-
- return longest;
-}
-
-static FORCE_INLINE int LZ4HC_encodeSequence(
- const BYTE **ip,
- BYTE **op,
- const BYTE **anchor,
- int matchLength,
- const BYTE * const match,
- limitedOutput_directive limitedOutputBuffer,
- BYTE *oend)
-{
- int length;
- BYTE *token;
-
- /* Encode Literal length */
- length = (int)(*ip - *anchor);
- token = (*op)++;
-
- if ((limitedOutputBuffer)
- && ((*op + (length>>8)
- + length + (2 + 1 + LASTLITERALS)) > oend)) {
- /* Check output limit */
- return 1;
- }
- if (length >= (int)RUN_MASK) {
- int len;
-
- *token = (RUN_MASK<<ML_BITS);
- len = length - RUN_MASK;
- for (; len > 254 ; len -= 255)
- *(*op)++ = 255;
- *(*op)++ = (BYTE)len;
- } else
- *token = (BYTE)(length<<ML_BITS);
-
- /* Copy Literals */
- LZ4_wildCopy(*op, *anchor, (*op) + length);
- *op += length;
-
- /* Encode Offset */
- LZ4_writeLE16(*op, (U16)(*ip - match));
- *op += 2;
-
- /* Encode MatchLength */
- length = (int)(matchLength - MINMATCH);
-
- if ((limitedOutputBuffer)
- && (*op + (length>>8)
- + (1 + LASTLITERALS) > oend)) {
- /* Check output limit */
- return 1;
- }
-
- if (length >= (int)ML_MASK) {
- *token += ML_MASK;
- length -= ML_MASK;
-
- for (; length > 509 ; length -= 510) {
- *(*op)++ = 255;
- *(*op)++ = 255;
- }
-
- if (length > 254) {
- length -= 255;
- *(*op)++ = 255;
- }
-
- *(*op)++ = (BYTE)length;
- } else
- *token += (BYTE)(length);
-
- /* Prepare next loop */
- *ip += matchLength;
- *anchor = *ip;
-
- return 0;
-}
+/* Upstream's short names for these clash with <linux/minmax.h>. */
+#undef MIN
+#undef MAX
+#undef KB
+#undef MB
+#undef GB
-static int LZ4HC_compress_generic(
- LZ4HC_CCtx_internal *const ctx,
- const char * const source,
- char * const dest,
- int const inputSize,
- int const maxOutputSize,
- int compressionLevel,
- limitedOutput_directive limit
- )
-{
- const BYTE *ip = (const BYTE *) source;
- const BYTE *anchor = ip;
- const BYTE * const iend = ip + inputSize;
- const BYTE * const mflimit = iend - MFLIMIT;
- const BYTE * const matchlimit = (iend - LASTLITERALS);
-
- BYTE *op = (BYTE *) dest;
- BYTE * const oend = op + maxOutputSize;
-
- unsigned int maxNbAttempts;
- int ml, ml2, ml3, ml0;
- const BYTE *ref = NULL;
- const BYTE *start2 = NULL;
- const BYTE *ref2 = NULL;
- const BYTE *start3 = NULL;
- const BYTE *ref3 = NULL;
- const BYTE *start0;
- const BYTE *ref0;
-
- /* init */
- if (compressionLevel > LZ4HC_MAX_CLEVEL)
- compressionLevel = LZ4HC_MAX_CLEVEL;
- if (compressionLevel < 1)
- compressionLevel = LZ4HC_DEFAULT_CLEVEL;
- maxNbAttempts = 1 << (compressionLevel - 1);
- ctx->end += inputSize;
-
- ip++;
-
- /* Main Loop */
- while (ip < mflimit) {
- ml = LZ4HC_InsertAndFindBestMatch(ctx, ip,
- matchlimit, (&ref), maxNbAttempts);
- if (!ml) {
- ip++;
- continue;
- }
-
- /* saved, in case we would skip too much */
- start0 = ip;
- ref0 = ref;
- ml0 = ml;
-
-_Search2:
- if (ip + ml < mflimit)
- ml2 = LZ4HC_InsertAndGetWiderMatch(ctx,
- ip + ml - 2, ip + 0,
- matchlimit, ml, &ref2,
- &start2, maxNbAttempts);
- else
- ml2 = ml;
-
- if (ml2 == ml) {
- /* No better match */
- if (LZ4HC_encodeSequence(&ip, &op,
- &anchor, ml, ref, limit, oend))
- return 0;
- continue;
- }
-
- if (start0 < ip) {
- if (start2 < ip + ml0) {
- /* empirical */
- ip = start0;
- ref = ref0;
- ml = ml0;
- }
- }
-
- /* Here, start0 == ip */
- if ((start2 - ip) < 3) {
- /* First Match too small : removed */
- ml = ml2;
- ip = start2;
- ref = ref2;
- goto _Search2;
- }
-
-_Search3:
- /*
- * Currently we have :
- * ml2 > ml1, and
- * ip1 + 3 <= ip2 (usually < ip1 + ml1)
- */
- if ((start2 - ip) < OPTIMAL_ML) {
- int correction;
- int new_ml = ml;
-
- if (new_ml > OPTIMAL_ML)
- new_ml = OPTIMAL_ML;
- if (ip + new_ml > start2 + ml2 - MINMATCH)
- new_ml = (int)(start2 - ip) + ml2 - MINMATCH;
-
- correction = new_ml - (int)(start2 - ip);
-
- if (correction > 0) {
- start2 += correction;
- ref2 += correction;
- ml2 -= correction;
- }
- }
- /*
- * Now, we have start2 = ip + new_ml,
- * with new_ml = min(ml, OPTIMAL_ML = 18)
- */
-
- if (start2 + ml2 < mflimit)
- ml3 = LZ4HC_InsertAndGetWiderMatch(ctx,
- start2 + ml2 - 3, start2,
- matchlimit, ml2, &ref3, &start3,
- maxNbAttempts);
- else
- ml3 = ml2;
-
- if (ml3 == ml2) {
- /* No better match : 2 sequences to encode */
- /* ip & ref are known; Now for ml */
- if (start2 < ip + ml)
- ml = (int)(start2 - ip);
- /* Now, encode 2 sequences */
- if (LZ4HC_encodeSequence(&ip, &op, &anchor,
- ml, ref, limit, oend))
- return 0;
- ip = start2;
- if (LZ4HC_encodeSequence(&ip, &op, &anchor,
- ml2, ref2, limit, oend))
- return 0;
- continue;
- }
-
- if (start3 < ip + ml + 3) {
- /* Not enough space for match 2 : remove it */
- if (start3 >= (ip + ml)) {
- /* can write Seq1 immediately
- * ==> Seq2 is removed,
- * so Seq3 becomes Seq1
- */
- if (start2 < ip + ml) {
- int correction = (int)(ip + ml - start2);
-
- start2 += correction;
- ref2 += correction;
- ml2 -= correction;
- if (ml2 < MINMATCH) {
- start2 = start3;
- ref2 = ref3;
- ml2 = ml3;
- }
- }
-
- if (LZ4HC_encodeSequence(&ip, &op, &anchor,
- ml, ref, limit, oend))
- return 0;
- ip = start3;
- ref = ref3;
- ml = ml3;
-
- start0 = start2;
- ref0 = ref2;
- ml0 = ml2;
- goto _Search2;
- }
-
- start2 = start3;
- ref2 = ref3;
- ml2 = ml3;
- goto _Search3;
- }
-
- /*
- * OK, now we have 3 ascending matches;
- * let's write at least the first one
- * ip & ref are known; Now for ml
- */
- if (start2 < ip + ml) {
- if ((start2 - ip) < (int)ML_MASK) {
- int correction;
-
- if (ml > OPTIMAL_ML)
- ml = OPTIMAL_ML;
- if (ip + ml > start2 + ml2 - MINMATCH)
- ml = (int)(start2 - ip) + ml2 - MINMATCH;
- correction = ml - (int)(start2 - ip);
- if (correction > 0) {
- start2 += correction;
- ref2 += correction;
- ml2 -= correction;
- }
- } else
- ml = (int)(start2 - ip);
- }
- if (LZ4HC_encodeSequence(&ip, &op, &anchor, ml,
- ref, limit, oend))
- return 0;
-
- ip = start2;
- ref = ref2;
- ml = ml2;
-
- start2 = start3;
- ref2 = ref3;
- ml2 = ml3;
-
- goto _Search3;
- }
-
- /* Encode Last Literals */
- {
- int lastRun = (int)(iend - anchor);
-
- if ((limit)
- && (((char *)op - dest) + lastRun + 1
- + ((lastRun + 255 - RUN_MASK)/255)
- > (U32)maxOutputSize)) {
- /* Check output limit */
- return 0;
- }
- if (lastRun >= (int)RUN_MASK) {
- *op++ = (RUN_MASK<<ML_BITS);
- lastRun -= RUN_MASK;
- for (; lastRun > 254 ; lastRun -= 255)
- *op++ = 255;
- *op++ = (BYTE) lastRun;
- } else
- *op++ = (BYTE)(lastRun<<ML_BITS);
- LZ4_memcpy(op, anchor, iend - anchor);
- op += iend - anchor;
- }
+#include "lz4_kernel_api.h"
+#include <linux/export.h>
+#include <linux/module.h>
- /* End */
- return (int) (((char *)op) - dest);
-}
+/* Catch any divergence from upstream's layout at build time. */
+static_assert(sizeof(LZ4_streamHC_t) == LZ4_STREAMHC_MINSIZE);
+static_assert(LZ4_STREAMHC_MINSIZE == 262200); /* LZ4HC_MEM_COMPRESS */
-static int LZ4_compress_HC_extStateHC(
- void *state,
- const char *src,
- char *dst,
- int srcSize,
- int maxDstSize,
- int compressionLevel)
+/* Levels >= LZ4HC_CLEVEL_OPT_MIN (10) reach the optimal parser, whose ~64K
+ * opt[] does not fit a kernel stack, so clamp them to 9. Clamp rather than
+ * reject so existing f2fs and zram settings keep working. Levels 3..9 are
+ * untouched; 1 and 2 are upstream's lz4mid, faster and weaker than the
+ * shallow hash chain the fork used for them.
+ */
+static int lz4hc_clamp_level(int compressionLevel)
{
- LZ4HC_CCtx_internal *ctx = &((LZ4_streamHC_t *)state)->internal_donotuse;
+ if (compressionLevel >= LZ4HC_CLEVEL_OPT_MIN)
+ return LZ4HC_CLEVEL_OPT_MIN - 1;
- if (((size_t)(state)&(sizeof(void *) - 1)) != 0) {
- /* Error : state is not aligned
- * for pointers (32 or 64 bits)
- */
- return 0;
- }
-
- LZ4HC_init(ctx, (const BYTE *)src);
-
- if (maxDstSize < LZ4_compressBound(srcSize))
- return LZ4HC_compress_generic(ctx, src, dst,
- srcSize, maxDstSize, compressionLevel, limitedOutput);
- else
- return LZ4HC_compress_generic(ctx, src, dst,
- srcSize, maxDstSize, compressionLevel, noLimit);
+ return compressionLevel;
}
-int LZ4_compress_HC(const char *src, char *dst, int srcSize,
- int maxDstSize, int compressionLevel, void *wrkmem)
+int LZ4_compress_HC(const char *src, char *dst, int srcSize, int dstCapacity,
+ int compressionLevel, void *wrkmem)
{
- return LZ4_compress_HC_extStateHC(wrkmem, src, dst,
- srcSize, maxDstSize, compressionLevel);
+ return LZ4_compress_HC_extStateHC(wrkmem, src, dst, srcSize,
+ dstCapacity,
+ lz4hc_clamp_level(compressionLevel));
}
EXPORT_SYMBOL(LZ4_compress_HC);
-/**************************************
- * Streaming Functions
- **************************************/
-void LZ4_resetStreamHC(LZ4_streamHC_t *LZ4_streamHCPtr, int compressionLevel)
+void LZ4_resetStreamHC(LZ4_streamHC_t *streamHCPtr, int compressionLevel)
{
- LZ4_streamHCPtr->internal_donotuse.base = NULL;
- LZ4_streamHCPtr->internal_donotuse.compressionLevel = (unsigned int)compressionLevel;
+ __lz4_resetStreamHC(streamHCPtr, lz4hc_clamp_level(compressionLevel));
}
EXPORT_SYMBOL(LZ4_resetStreamHC);
-int LZ4_loadDictHC(LZ4_streamHC_t *LZ4_streamHCPtr,
- const char *dictionary,
- int dictSize)
+int LZ4_loadDictHC(LZ4_streamHC_t *streamHCPtr, const char *dictionary,
+ int dictSize)
{
- LZ4HC_CCtx_internal *ctxPtr = &LZ4_streamHCPtr->internal_donotuse;
-
- if (dictSize > 64 * KB) {
- dictionary += dictSize - 64 * KB;
- dictSize = 64 * KB;
- }
- LZ4HC_init(ctxPtr, (const BYTE *)dictionary);
- if (dictSize >= 4)
- LZ4HC_Insert(ctxPtr, (const BYTE *)dictionary + (dictSize - 3));
- ctxPtr->end = (const BYTE *)dictionary + dictSize;
- return dictSize;
+ return __lz4_loadDictHC(streamHCPtr, dictionary, dictSize);
}
EXPORT_SYMBOL(LZ4_loadDictHC);
-/* compression */
-
-static void LZ4HC_setExternalDict(
- LZ4HC_CCtx_internal *ctxPtr,
- const BYTE *newBlock)
-{
- if (ctxPtr->end >= ctxPtr->base + 4) {
- /* Referencing remaining dictionary content */
- LZ4HC_Insert(ctxPtr, ctxPtr->end - 3);
- }
-
- /*
- * Only one memory segment for extDict,
- * so any previous extDict is lost at this stage
- */
- ctxPtr->lowLimit = ctxPtr->dictLimit;
- ctxPtr->dictLimit = (U32)(ctxPtr->end - ctxPtr->base);
- ctxPtr->dictBase = ctxPtr->base;
- ctxPtr->base = newBlock - ctxPtr->dictLimit;
- ctxPtr->end = newBlock;
- /* match referencing will resume from there */
- ctxPtr->nextToUpdate = ctxPtr->dictLimit;
-}
-
-static int LZ4_compressHC_continue_generic(
- LZ4_streamHC_t *LZ4_streamHCPtr,
- const char *source,
- char *dest,
- int inputSize,
- int maxOutputSize,
- limitedOutput_directive limit)
-{
- LZ4HC_CCtx_internal *ctxPtr = &LZ4_streamHCPtr->internal_donotuse;
-
- /* auto - init if forgotten */
- if (ctxPtr->base == NULL)
- LZ4HC_init(ctxPtr, (const BYTE *) source);
-
- /* Check overflow */
- if ((size_t)(ctxPtr->end - ctxPtr->base) > 2 * GB) {
- size_t dictSize = (size_t)(ctxPtr->end - ctxPtr->base)
- - ctxPtr->dictLimit;
- if (dictSize > 64 * KB)
- dictSize = 64 * KB;
- LZ4_loadDictHC(LZ4_streamHCPtr,
- (const char *)(ctxPtr->end) - dictSize, (int)dictSize);
- }
-
- /* Check if blocks follow each other */
- if ((const BYTE *)source != ctxPtr->end)
- LZ4HC_setExternalDict(ctxPtr, (const BYTE *)source);
-
- /* Check overlapping input/dictionary space */
- {
- const BYTE *sourceEnd = (const BYTE *) source + inputSize;
- const BYTE * const dictBegin = ctxPtr->dictBase + ctxPtr->lowLimit;
- const BYTE * const dictEnd = ctxPtr->dictBase + ctxPtr->dictLimit;
-
- if ((sourceEnd > dictBegin)
- && ((const BYTE *)source < dictEnd)) {
- if (sourceEnd > dictEnd)
- sourceEnd = dictEnd;
- ctxPtr->lowLimit = (U32)(sourceEnd - ctxPtr->dictBase);
-
- if (ctxPtr->dictLimit - ctxPtr->lowLimit < 4)
- ctxPtr->lowLimit = ctxPtr->dictLimit;
- }
- }
-
- return LZ4HC_compress_generic(ctxPtr, source, dest,
- inputSize, maxOutputSize, ctxPtr->compressionLevel, limit);
-}
-
-int LZ4_compress_HC_continue(
- LZ4_streamHC_t *LZ4_streamHCPtr,
- const char *source,
- char *dest,
- int inputSize,
- int maxOutputSize)
+int LZ4_compress_HC_continue(LZ4_streamHC_t *streamHCPtr, const char *src,
+ char *dst, int srcSize, int maxDstSize)
{
- if (maxOutputSize < LZ4_compressBound(inputSize))
- return LZ4_compressHC_continue_generic(LZ4_streamHCPtr,
- source, dest, inputSize, maxOutputSize, limitedOutput);
- else
- return LZ4_compressHC_continue_generic(LZ4_streamHCPtr,
- source, dest, inputSize, maxOutputSize, noLimit);
+ return __lz4_compress_HC_continue(streamHCPtr, src, dst, srcSize,
+ maxDstSize);
}
EXPORT_SYMBOL(LZ4_compress_HC_continue);
-/* dictionary saving */
-
-int LZ4_saveDictHC(
- LZ4_streamHC_t *LZ4_streamHCPtr,
- char *safeBuffer,
- int dictSize)
+int LZ4_saveDictHC(LZ4_streamHC_t *streamHCPtr, char *safeBuffer,
+ int maxDictSize)
{
- LZ4HC_CCtx_internal *const streamPtr = &LZ4_streamHCPtr->internal_donotuse;
- int const prefixSize = (int)(streamPtr->end
- - (streamPtr->base + streamPtr->dictLimit));
-
- if (dictSize > 64 * KB)
- dictSize = 64 * KB;
- if (dictSize < 4)
- dictSize = 0;
- if (dictSize > prefixSize)
- dictSize = prefixSize;
-
- memmove(safeBuffer, streamPtr->end - dictSize, dictSize);
-
- {
- U32 const endIndex = (U32)(streamPtr->end - streamPtr->base);
-
- streamPtr->end = (const BYTE *)safeBuffer + dictSize;
- streamPtr->base = streamPtr->end - endIndex;
- streamPtr->dictLimit = endIndex - dictSize;
- streamPtr->lowLimit = endIndex - dictSize;
-
- if (streamPtr->nextToUpdate < streamPtr->dictLimit)
- streamPtr->nextToUpdate = streamPtr->dictLimit;
- }
- return dictSize;
+ return __lz4_saveDictHC(streamHCPtr, safeBuffer, maxDictSize);
}
EXPORT_SYMBOL(LZ4_saveDictHC);
--
2.34.1