1 files changed, 228 insertions, 0 deletions
diff --git a/libbcachefs/lz4_compress.c b/libbcachefs/lz4_compress.c
new file mode 100644
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+++ b/libbcachefs/lz4_compress.c
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+/*
+ * LZ4 - Fast LZ compression algorithm
+ * Copyright (C) 2011-2012, Yann Collet.
+ * 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://fastcompression.blogspot.com/p/lz4.html
+ * - LZ4 source repository : http://code.google.com/p/lz4/
+ *
+ *  Changed for kernel use by:
+ *  Chanho Min <chanho.min@lge.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <asm/unaligned.h>
+#include "lz4.h"
+#include "lz4defs.h"
+
+#define LZ4_HASH_VALUE(p, _table)				\
+	__HASH_VALUE(p, MEMORY_USAGE - ilog2(sizeof(_table[0])))
+
+struct lz4_hash_table {
+	const u8	*(*add)(const struct lz4_hash_table, const u8 *);
+	void		*ctx;
+	const u8	*base;
+};
+
+#if __SIZEOF_POINTER__ == 4
+static inline const u8 *hash_table_add32(const struct lz4_hash_table hash,
+					 const u8 *ip)
+{
+	const u8 **table = hash.ctx;
+
+	swap(table[LZ4_HASH_VALUE(ip, table)], ip);
+	return ip;
+}
+#else
+static inline const u8 *hash_table_add32(const struct lz4_hash_table hash,
+					 const u8 *ip)
+{
+	u32 *table = hash.ctx;
+	size_t offset = ip - hash.base;
+
+	swap(table[LZ4_HASH_VALUE(ip, table)], offset);
+	return hash.base + offset;
+}
+#endif
+
+static inline const u8 *hash_table_add16(const struct lz4_hash_table hash,
+					 const u8 *ip)
+{
+	u16 *table = hash.ctx;
+	size_t offset = ip - hash.base;
+
+	swap(table[LZ4_HASH_VALUE(ip, table)], offset);
+	return hash.base + offset;
+}
+
+static inline const u8 *find_match(const struct lz4_hash_table hash,
+				   const u8 **ip, const u8 *anchor,
+				   const u8 *start, const u8 *mflimit)
+{
+	int findmatchattempts = (1U << SKIPSTRENGTH) + 3;
+
+	while (*ip <= mflimit) {
+		const u8 *ref = hash.add(hash, *ip);
+
+		if (ref >= *ip - MAX_DISTANCE && A32(ref) == A32(*ip)) {
+			/* found match: */
+			while (*ip > anchor &&
+			       ref > start &&
+			       unlikely((*ip)[-1] == ref[-1])) {
+				(*ip)--;
+				ref--;
+			}
+
+			return ref;
+		}
+
+		*ip += findmatchattempts++ >> SKIPSTRENGTH;
+	}
+
+	return NULL;
+}
+
+static inline int length_len(unsigned length)
+{
+	return length / 255 + 1;
+}
+
+/*
+ * LZ4_compressCtx :
+ * -----------------
+ * Compress 'isize' bytes from 'source' into an output buffer 'dest' of
+ * maximum size 'maxOutputSize'.  * If it cannot achieve it, compression
+ * will stop, and result of the function will be zero.
+ * return : the number of bytes written in buffer 'dest', or 0 if the
+ * compression fails
+ */
+static inline int lz4_compressctx(const struct lz4_hash_table hash,
+				  const u8 *src, size_t src_len,
+				  u8 *dst, size_t *dst_len)
+{
+	const u8 *ip = src, *anchor = ip, *ref;
+	const u8 *const iend = ip + src_len;
+	const u8 *const mflimit = iend - MFLIMIT;
+	const u8 *const matchlimit = iend - LASTLITERALS;
+	u8 *op = dst, *token;
+	u8 *const oend = op + *dst_len;
+	size_t literal_len, match_len, match_offset;
+
+	/* Init */
+	memset(hash.ctx, 0, LZ4_MEM_COMPRESS);
+	hash.add(hash, ip);
+
+	/* Always start with a literal: */
+	ip++;
+
+	while ((ref = find_match(hash, &ip, anchor, src, mflimit))) {
+		/*
+		 * We found a match; @ip now points to the match and @ref points
+		 * to the prior part of the input we matched with. Everything up
+		 * to @anchor has been encoded; the range from @anchor to @ip
+		 * didn't match and now has to be encoded as a literal:
+		 */
+		literal_len = ip - anchor;
+		match_offset = ip - ref;
+
+		/* MINMATCH bytes already matched from find_match(): */
+		ip += MINMATCH;
+		ref += MINMATCH;
+		match_len = common_length(ip, ref, matchlimit);
+		ip += match_len;
+
+		/* check output limit */
+		if (unlikely(op +
+			     1 + /* token */
+			     2 + /* match ofset */
+			     literal_len +
+			     length_len(literal_len) +
+			     length_len(match_len) +
+			     LASTLITERALS > oend))
+			break;
+
+		token = op++;
+		*token = encode_length(&op, literal_len) << ML_BITS;
+		MEMCPY_ADVANCE_CHUNKED(op, anchor, literal_len);
+		PUT_LE16_ADVANCE(op, match_offset);
+		*token += encode_length(&op, match_len);
+
+		anchor = ip;
+	}
+
+	/* Encode remaining input as literal: */
+	literal_len = iend - anchor;
+	if (unlikely(op +
+		     1 +
+		     literal_len +
+		     length_len(literal_len) > oend)) {
+		/* Return how much would be able to fit: */
+		ssize_t remaining = oend - op;
+		ssize_t encoded = anchor - src;
+
+		remaining -= length_len(remaining) + 1;
+
+		return -max(encoded + remaining, 1L);
+	}
+
+	token = op++;
+	*token = encode_length(&op, literal_len) << ML_BITS;
+	MEMCPY_ADVANCE(op, anchor, literal_len);
+
+	/* End */
+	BUG_ON(op > oend);
+	*dst_len = op - dst;
+	return 0;
+}
+
+__attribute__((flatten))
+int lz4_compress(const unsigned char *src, size_t src_len,
+		 unsigned char *dst, size_t *dst_len, void *wrkmem)
+{
+	if (src_len < LZ4_64KLIMIT) {
+		const struct lz4_hash_table hash = {
+			.add	= hash_table_add16,
+			.ctx	= wrkmem,
+			.base	= src,
+		};
+
+		return lz4_compressctx(hash, src, src_len, dst, dst_len);
+	} else {
+		const struct lz4_hash_table hash = {
+			.add	= hash_table_add32,
+			.ctx	= wrkmem,
+			.base	= src,
+		};
+
+		return lz4_compressctx(hash, src, src_len, dst, dst_len);
+	}
+}
+EXPORT_SYMBOL(lz4_compress);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_DESCRIPTION("LZ4 compressor");