pstore: Use crypto compress API

In the pstore compression part, we use zlib/lzo/lz4/lz4hc/842
compression algorithm API to implement pstore compression backends. But
there are many repeat codes in these implementations. This patch uses
crypto compress API to simplify these codes.

1) rewrite allocate_buf_for_compression, free_buf_for_compression,
pstore_compress, pstore_decompress functions using crypto compress API.
2) drop compress, decompress, allocate, free functions in pstore_zbackend,
and add zbufsize function to get each different compress buffer size.
3) use late_initcall to call ramoops_init later, to make sure the crypto
subsystem has already initialized.
4) use 'unsigned int' type instead of 'size_t' in pstore_compress,
pstore_decompress functions' length arguments.
5) rename 'zlib' to 'deflate' to follow the crypto API's name convention.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
[kees: tweaked error messages on allocation failures and Kconfig help]
Signed-off-by: Kees Cook <keescook@chromium.org>

fs/pstore/Kconfig

@@ -12,51 +12,47 @@ config PSTORE
 	   If you don't have a platform persistent store driver,
 	   say N.
 
-config PSTORE_ZLIB_COMPRESS
-	bool "ZLIB compression"
+config PSTORE_DEFLATE_COMPRESS
+	bool "DEFLATE (ZLIB) compression"
 	default y
 	depends on PSTORE
-	select ZLIB_DEFLATE
-	select ZLIB_INFLATE
+	select CRYPTO_DEFLATE
 	help
-	  This option enables ZLIB compression algorithm support.
+	  This option enables DEFLATE (also known as ZLIB) compression
+	  algorithm support.
 
 config PSTORE_LZO_COMPRESS
 	bool "LZO compression"
 	depends on PSTORE
-	select LZO_COMPRESS
-	select LZO_DECOMPRESS
+	select CRYPTO_LZO
 	help
 	  This option enables LZO compression algorithm support.
 
 config PSTORE_LZ4_COMPRESS
 	bool "LZ4 compression"
 	depends on PSTORE
-	select LZ4_COMPRESS
-	select LZ4_DECOMPRESS
+	select CRYPTO_LZ4
 	help
 	  This option enables LZ4 compression algorithm support.
 
 config PSTORE_LZ4HC_COMPRESS
 	bool "LZ4HC compression"
 	depends on PSTORE
-	select LZ4HC_COMPRESS
-	select LZ4_DECOMPRESS
+	select CRYPTO_LZ4HC
 	help
 	  This option enables LZ4HC (high compression) mode algorithm.
 
 config PSTORE_842_COMPRESS
 	bool "842 compression"
 	depends on PSTORE
-	select 842_COMPRESS
-	select 842_DECOMPRESS
+	select CRYPTO_842
 	help
 	  This option enables 842 compression algorithm support.
 
 config PSTORE_COMPRESS
 	def_bool y
 	depends on PSTORE
-	depends on PSTORE_ZLIB_COMPRESS || PSTORE_LZO_COMPRESS ||	\
+	depends on PSTORE_DEFLATE_COMPRESS || PSTORE_LZO_COMPRESS ||	\
 		   PSTORE_LZ4_COMPRESS || PSTORE_LZ4HC_COMPRESS ||	\
 		   PSTORE_842_COMPRESS
 
@@ -69,12 +65,12 @@ choice
 	  the kernel command line.
 
 	  Currently, pstore has support for 5 compression algorithms:
-	  zlib, lzo, lz4, lz4hc and 842.
+	  deflate, lzo, lz4, lz4hc and 842.
 
-	  The default compression algorithm is zlib.
+	  The default compression algorithm is deflate.
 
-	config PSTORE_ZLIB_COMPRESS_DEFAULT
-		bool "zlib" if PSTORE_ZLIB_COMPRESS=y
+	config PSTORE_DEFLATE_COMPRESS_DEFAULT
+		bool "deflate" if PSTORE_DEFLATE_COMPRESS=y
 
 	config PSTORE_LZO_COMPRESS_DEFAULT
 		bool "lzo" if PSTORE_LZO_COMPRESS=y
@@ -93,7 +89,7 @@ endchoice
 config PSTORE_COMPRESS_DEFAULT
 	string
 	depends on PSTORE_COMPRESS
-	default "zlib" if PSTORE_ZLIB_COMPRESS_DEFAULT
+	default "deflate" if PSTORE_DEFLATE_COMPRESS_DEFAULT
 	default "lzo" if PSTORE_LZO_COMPRESS_DEFAULT
 	default "lz4" if PSTORE_LZ4_COMPRESS_DEFAULT
 	default "lz4hc" if PSTORE_LZ4HC_COMPRESS_DEFAULT