pstore: add zstd compression support

This patch added the 6th compression algorithm support for pstore: zstd.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>

fs/pstore/Kconfig

@@ -50,12 +50,19 @@ config PSTORE_842_COMPRESS
 	help
 	  This option enables 842 compression algorithm support.
 
+config PSTORE_ZSTD_COMPRESS
+	bool "zstd compression"
+	depends on PSTORE
+	select CRYPTO_ZSTD
+	help
+	  This option enables zstd compression algorithm support.
+
 config PSTORE_COMPRESS
 	def_bool y
 	depends on PSTORE
 	depends on PSTORE_DEFLATE_COMPRESS || PSTORE_LZO_COMPRESS ||	\
 		   PSTORE_LZ4_COMPRESS || PSTORE_LZ4HC_COMPRESS ||	\
-		   PSTORE_842_COMPRESS
+		   PSTORE_842_COMPRESS || PSTORE_ZSTD_COMPRESS
 
 choice
 	prompt "Default pstore compression algorithm"
@@ -65,8 +72,8 @@ choice
 	  This change be changed at boot with "pstore.compress=..." on
 	  the kernel command line.
 
-	  Currently, pstore has support for 5 compression algorithms:
-	  deflate, lzo, lz4, lz4hc and 842.
+	  Currently, pstore has support for 6 compression algorithms:
+	  deflate, lzo, lz4, lz4hc, 842 and zstd.
 
 	  The default compression algorithm is deflate.
 
@@ -85,6 +92,9 @@ choice
 	config PSTORE_842_COMPRESS_DEFAULT
 		bool "842" if PSTORE_842_COMPRESS
 
+	config PSTORE_ZSTD_COMPRESS_DEFAULT
+		bool "zstd" if PSTORE_ZSTD_COMPRESS
+
 endchoice
 
 config PSTORE_COMPRESS_DEFAULT
@@ -95,6 +105,7 @@ config PSTORE_COMPRESS_DEFAULT
 	default "lz4" if PSTORE_LZ4_COMPRESS_DEFAULT
 	default "lz4hc" if PSTORE_LZ4HC_COMPRESS_DEFAULT
 	default "842" if PSTORE_842_COMPRESS_DEFAULT
+	default "zstd" if PSTORE_ZSTD_COMPRESS_DEFAULT
 
 config PSTORE_CONSOLE
 	bool "Log kernel console messages"

fs/pstore/platform.c

@@ -34,6 +34,9 @@
 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
 #include <linux/lz4.h>
 #endif
+#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
+#include <linux/zstd.h>
+#endif
 #include <linux/crypto.h>
 #include <linux/string.h>
 #include <linux/timer.h>
@@ -192,6 +195,13 @@ static int zbufsize_842(size_t size)
 }
 #endif
 
+#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
+static int zbufsize_zstd(size_t size)
+{
+	return ZSTD_compressBound(size);
+}
+#endif
+
 static const struct pstore_zbackend *zbackend __ro_after_init;
 
 static const struct pstore_zbackend zbackends[] = {
@@ -224,6 +234,12 @@ static const struct pstore_zbackend zbackends[] = {
 		.zbufsize	= zbufsize_842,
 		.name		= "842",
 	},
+#endif
+#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
+	{
+		.zbufsize	= zbufsize_zstd,
+		.name		= "zstd",
+	},
 #endif
 	{ }
 };