PM / Hibernate: Improve performance of LZO/plain hibernation, checksum image

Use threads for LZO compression/decompression on hibernate/thaw.
Improve buffering on hibernate/thaw.
Calculate/verify CRC32 of the image pages on hibernate/thaw.

In my testing, this improved write/read speed by a factor of about two.
Signed-off-by: Bojan Smojver <bojan@rexursive.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

kernel/power/Kconfig

@@ -27,6 +27,7 @@ config HIBERNATION
 	select HIBERNATE_CALLBACKS
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
+	select CRC32
 	---help---
 	  Enable the suspend to disk (STD) functionality, which is usually
 	  called "hibernation" in user interfaces.  STD checkpoints the

kernel/power/hibernate.c

@@ -657,6 +657,9 @@ int hibernate(void)
 			flags |= SF_PLATFORM_MODE;
 		if (nocompress)
 			flags |= SF_NOCOMPRESS_MODE;
+		else
+		        flags |= SF_CRC32_MODE;
+
 		pr_debug("PM: writing image.\n");
 		error = swsusp_write(flags);
 		swsusp_free();

kernel/power/power.h

@@ -146,6 +146,7 @@ extern int swsusp_swap_in_use(void);
  */
 #define SF_PLATFORM_MODE	1
 #define SF_NOCOMPRESS_MODE	2
+#define SF_CRC32_MODE	        4
 
 /* kernel/power/hibernate.c */
 extern int swsusp_check(void);