[PATCH v4 1/9] lib: zstd: Add zstd compatibility wrapper

[Nick Terrell]

From: Nick Terrell <terrelln@xxxxxx>

Adds zstd_compat.h which provides the necessary functions from the
current zstd.h API. It is only active for zstd versions 1.4.6 and newer.
That means it is disabled currently, but will become active when a later
patch in this series updates the zstd library in the kernel to 1.4.6.

This header allows the zstd upgrade to 1.4.6 without changing any
callers, since they all include zstd through the compatibility wrapper.
Later patches in this series transition each caller away from the
compatibility wrapper. After all the callers have been transitioned away
from the compatibility wrapper, the final patch in this series deletes
it.

Signed-off-by: Nick Terrell <terrelln@xxxxxx>
---
 crypto/zstd.c               |   2 +-
 fs/btrfs/zstd.c             |   2 +-
 fs/f2fs/compress.c          |   2 +-
 fs/squashfs/zstd_wrapper.c  |   2 +-
 include/linux/zstd_compat.h | 116 ++++++++++++++++++++++++++++++++++++
 lib/decompress_unzstd.c     |   2 +-
 6 files changed, 121 insertions(+), 5 deletions(-)
 create mode 100644 include/linux/zstd_compat.h

diff --git a/crypto/zstd.c b/crypto/zstd.c
index 1a3309f066f7..dcda3cad3b5c 100644
--- a/crypto/zstd.c
+++ b/crypto/zstd.c
@@ -11,7 +11,7 @@
 #include <linux/module.h>
 #include <linux/net.h>
 #include <linux/vmalloc.h>
-#include <linux/zstd.h>
+#include <linux/zstd_compat.h>
 #include <crypto/internal/scompress.h>
 
 
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 9a4871636c6c..a7367ff573d4 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -16,7 +16,7 @@
 #include <linux/refcount.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
-#include <linux/zstd.h>
+#include <linux/zstd_compat.h>
 #include "misc.h"
 #include "compression.h"
 #include "ctree.h"
diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 1dfb126a0cb2..e056f3a2b404 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -11,7 +11,7 @@
 #include <linux/backing-dev.h>
 #include <linux/lzo.h>
 #include <linux/lz4.h>
-#include <linux/zstd.h>
+#include <linux/zstd_compat.h>
 
 #include "f2fs.h"
 #include "node.h"
diff --git a/fs/squashfs/zstd_wrapper.c b/fs/squashfs/zstd_wrapper.c
index b7cb1faa652d..f8c512a6204e 100644
--- a/fs/squashfs/zstd_wrapper.c
+++ b/fs/squashfs/zstd_wrapper.c
@@ -11,7 +11,7 @@
 #include <linux/mutex.h>
 #include <linux/bio.h>
 #include <linux/slab.h>
-#include <linux/zstd.h>
+#include <linux/zstd_compat.h>
 #include <linux/vmalloc.h>
 
 #include "squashfs_fs.h"
diff --git a/include/linux/zstd_compat.h b/include/linux/zstd_compat.h
new file mode 100644
index 000000000000..cda9208bf04a
--- /dev/null
+++ b/include/linux/zstd_compat.h
@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of https://github.com/facebook/zstd.
+ * An additional grant of patent rights can be found in the PATENTS file in the
+ * same directory.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ */
+
+#ifndef ZSTD_COMPAT_H
+#define ZSTD_COMPAT_H
+
+#include <linux/zstd.h>
+
+#if defined(ZSTD_VERSION_NUMBER) && (ZSTD_VERSION_NUMBER >= 10406)
+/*
+ * This header provides backwards compatibility for the zstd-1.4.6 library
+ * upgrade. This header allows us to upgrade the zstd library version without
+ * modifying any callers. Then we will migrate callers from the compatibility
+ * wrapper one at a time until none remain. At which point we will delete this
+ * header.
+ *
+ * It is temporary and will be deleted once the upgrade is complete.
+ */
+
+#include <linux/zstd_errors.h>
+
+static inline size_t ZSTD_CCtxWorkspaceBound(ZSTD_compressionParameters compression_params)
+{
+    return ZSTD_estimateCCtxSize_usingCParams(compression_params);
+}
+
+static inline size_t ZSTD_CStreamWorkspaceBound(ZSTD_compressionParameters compression_params)
+{
+    return ZSTD_estimateCStreamSize_usingCParams(compression_params);
+}
+
+static inline size_t ZSTD_DCtxWorkspaceBound(void)
+{
+    return ZSTD_estimateDCtxSize();
+}
+
+static inline size_t ZSTD_DStreamWorkspaceBound(unsigned long long window_size)
+{
+    return ZSTD_estimateDStreamSize(window_size);
+}
+
+static inline ZSTD_CCtx* ZSTD_initCCtx(void* wksp, size_t wksp_size)
+{
+    if (wksp == NULL)
+        return NULL;
+    return ZSTD_initStaticCCtx(wksp, wksp_size);
+}
+
+static inline ZSTD_CStream* ZSTD_initCStream_compat(ZSTD_parameters params, uint64_t pledged_src_size, void* wksp, size_t wksp_size)
+{
+    ZSTD_CStream* cstream;
+    size_t ret;
+
+    if (wksp == NULL)
+        return NULL;
+
+    cstream = ZSTD_initStaticCStream(wksp, wksp_size);
+    if (cstream == NULL)
+        return NULL;
+
+    /* 0 means unknown in old API but means 0 in new API */
+    if (pledged_src_size == 0)
+        pledged_src_size = ZSTD_CONTENTSIZE_UNKNOWN;
+
+    ret = ZSTD_initCStream_advanced(cstream, NULL, 0, params, pledged_src_size);
+    if (ZSTD_isError(ret))
+        return NULL;
+
+    return cstream;
+}
+#define ZSTD_initCStream ZSTD_initCStream_compat
+
+static inline ZSTD_DCtx* ZSTD_initDCtx(void* wksp, size_t wksp_size)
+{
+    if (wksp == NULL)
+        return NULL;
+    return ZSTD_initStaticDCtx(wksp, wksp_size);
+}
+
+static inline ZSTD_DStream* ZSTD_initDStream_compat(unsigned long long window_size, void* wksp, size_t wksp_size)
+{
+    if (wksp == NULL)
+        return NULL;
+    (void)window_size;
+    return ZSTD_initStaticDStream(wksp, wksp_size);
+}
+#define ZSTD_initDStream ZSTD_initDStream_compat
+
+typedef ZSTD_frameHeader ZSTD_frameParams;
+
+static inline size_t ZSTD_getFrameParams(ZSTD_frameParams* frame_params, const void* src, size_t src_size)
+{
+    return ZSTD_getFrameHeader(frame_params, src, src_size);
+}
+
+static inline size_t ZSTD_compressCCtx_compat(ZSTD_CCtx* cctx, void* dst, size_t dst_capacity, const void* src, size_t src_size, ZSTD_parameters params)
+{
+    return ZSTD_compress_advanced(cctx, dst, dst_capacity, src, src_size, NULL, 0, params);
+}
+#define ZSTD_compressCCtx ZSTD_compressCCtx_compat
+
+#endif /* ZSTD_VERSION_NUMBER >= 10406 */
+#endif /* ZSTD_COMPAT_H */
diff --git a/lib/decompress_unzstd.c b/lib/decompress_unzstd.c
index 0ad2c15479ed..dbc290af26b4 100644
--- a/lib/decompress_unzstd.c
+++ b/lib/decompress_unzstd.c
@@ -77,7 +77,7 @@
 
 #include <linux/decompress/mm.h>
 #include <linux/kernel.h>
-#include <linux/zstd.h>
+#include <linux/zstd_compat.h>
 
 /* 128MB is the maximum window size supported by zstd. */
 #define ZSTD_WINDOWSIZE_MAX	(1 << ZSTD_WINDOWLOG_MAX)
-- 
2.28.0