[PATCH v2] include/linux/lz4.h: add some missing macros

[Gao Xiang <hsiangkao@linux.alibaba.com>]

Currently, LZ4_DISTANCE_MAX and LZ4_DECOMPRESS_INPLACE_MARGIN are
defined in the erofs subsystem for LZ4 in-place decompression, which is
somewhat unsuitable since they should belong to the LZ4 itself and
may change with future LZ4 codebase updates.

Move them to include/linux/lz4.h to match the upstream LZ4 library [1].
No logic changes.

[1] https://github.com/lz4/lz4/blob/v1.10.0/lib/lz4.h#L670

Cc: Yann Collet <yann.collet.73@gmail.com>
Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
change since v1:
 - should be `#define MAX_DISTANCE LZ4_DISTANCE_MAX` reported in
   https://lore.kernel.org/r/202501142005.DqdNQGKc-lkp@intel.com

 fs/erofs/decompressor.c  | 7 -------
 include/linux/lz4.h      | 6 ++++++
 lib/lz4/lz4_compress.c   | 1 -
 lib/lz4/lz4_decompress.c | 1 -
 lib/lz4/lz4defs.h        | 4 ++--
 lib/lz4/lz4hc_compress.c | 1 -
 6 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index eb318c7ddd80..2b123b070a42 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -7,14 +7,7 @@
 #include "compress.h"
 #include <linux/lz4.h>
 
-#ifndef LZ4_DISTANCE_MAX	/* history window size */
-#define LZ4_DISTANCE_MAX 65535	/* set to maximum value by default */
-#endif
-
 #define LZ4_MAX_DISTANCE_PAGES	(DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
-#ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
-#define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize)  (((srcsize) >> 8) + 32)
-#endif
 
 struct z_erofs_lz4_decompress_ctx {
 	struct z_erofs_decompress_req *rq;
diff --git a/include/linux/lz4.h b/include/linux/lz4.h
index b16e15b9587a..ad6042a718b5 100644
--- a/include/linux/lz4.h
+++ b/include/linux/lz4.h
@@ -645,4 +645,10 @@ int LZ4_decompress_safe_usingDict(const char *source, char *dest,
 int LZ4_decompress_fast_usingDict(const char *source, char *dest,
 	int originalSize, const char *dictStart, int dictSize);
 
+#define LZ4_DECOMPRESS_INPLACE_MARGIN(compressedSize)          (((compressedSize) >> 8) + 32)
+
+#ifndef LZ4_DISTANCE_MAX	/* history window size; can be user-defined at compile time */
+#define LZ4_DISTANCE_MAX 65535	/* set to maximum value by default */
+#endif
+
 #endif
diff --git a/lib/lz4/lz4_compress.c b/lib/lz4/lz4_compress.c
index b0bbeeb74b9e..2a397bb2c661 100644
--- a/lib/lz4/lz4_compress.c
+++ b/lib/lz4/lz4_compress.c
@@ -33,7 +33,6 @@
 /*-************************************
  *	Dependencies
  **************************************/
-#include <linux/lz4.h>
 #include "lz4defs.h"
 #include <linux/module.h>
 #include <linux/kernel.h>
diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
index 0e31e6da5ce7..3a2cd9acada4 100644
--- a/lib/lz4/lz4_decompress.c
+++ b/lib/lz4/lz4_decompress.c
@@ -33,7 +33,6 @@
 /*-************************************
  *	Dependencies
  **************************************/
-#include <linux/lz4.h>
 #include "lz4defs.h"
 #include <linux/init.h>
 #include <linux/module.h>
diff --git a/lib/lz4/lz4defs.h b/lib/lz4/lz4defs.h
index cb358d6bde5a..17277ec16919 100644
--- a/lib/lz4/lz4defs.h
+++ b/lib/lz4/lz4defs.h
@@ -39,6 +39,7 @@
 
 #include <linux/bitops.h>
 #include <linux/string.h>	 /* memset, memcpy */
+#include <linux/lz4.h>
 
 #define FORCE_INLINE __always_inline
 
@@ -92,8 +93,7 @@ typedef uintptr_t uptrval;
 #define MB (1 << 20)
 #define GB (1U << 30)
 
-#define MAXD_LOG 16
-#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
+#define MAX_DISTANCE LZ4_DISTANCE_MAX
 #define STEPSIZE sizeof(size_t)
 
 #define ML_BITS	4
diff --git a/lib/lz4/lz4hc_compress.c b/lib/lz4/lz4hc_compress.c
index bc45594ad2a8..91936dc3d14b 100644
--- a/lib/lz4/lz4hc_compress.c
+++ b/lib/lz4/lz4hc_compress.c
@@ -34,7 +34,6 @@
 /*-************************************
  *	Dependencies
  **************************************/
-#include <linux/lz4.h>
 #include "lz4defs.h"
 #include <linux/module.h>
 #include <linux/kernel.h>
-- 
2.43.5