infra: add compression infrastructure

kernel/Kconfig

@@ -7,6 +7,8 @@ config MARS
 	depends on m
 	depends on BLOCK && PROC_SYSCTL && HIGH_RES_TIMERS
 	default n
+	select LZO_COMPRESS
+	select LZO_DECOMPRESS
 	select CRYPTO_MD5
 	select CRYPTO_CRC32
 	select CRYPTO_CRC32C

kernel/compat.h

@@ -229,4 +229,7 @@ extern int _compat_unlink(
 #define HAS_SHA1
 #endif
 
+/* compression stuff */
+#include <linux/lzo.h>
+
 #endif /* _MARS_COMPAT */

kernel/mars.h

@@ -179,6 +179,8 @@ enum _MREF_FLAGS {
 	_MREF_CHKSUM_CRC32,
 	_MREF_CHKSUM_SHA1,
 	_MREF_CHKSUM_LAST,
+	_MREF_COMPRESS_LZO = 24,
+	_MREF_COMPRESS_LAST,
 };
 
 #define MREF_UPTODATE        (1UL << _MREF_UPTODATE)
@@ -194,12 +196,14 @@ enum _MREF_FLAGS {
 #define MREF_CHKSUM_CRC32    (1UL << _MREF_CHKSUM_CRC32)
 #define MREF_CHKSUM_SHA1     (1UL << _MREF_CHKSUM_SHA1)
 #define MREF_CHKSUM_LAST     (1UL << _MREF_CHKSUM_LAST)
+#define MREF_COMPRESS_LZO    (1UL << _MREF_COMPRESS_LZO)
 #define MREF_CHKSUM_ANY      (MREF_CHKSUM_MD5_OLD |	\
 			      MREF_CHKSUM_MD5 |		\
 			      MREF_CHKSUM_CRC32C |	\
 			      MREF_CHKSUM_CRC32 |	\
 			      MREF_CHKSUM_SHA1 |	\
 			      MREF_CHKSUM_LAST)
+#define MREF_COMPRESS_ANY     (MREF_COMPRESS_LZO)
 
 #define MREF_OBJECT(OBJTYPE)						\
 	CALLBACK_OBJECT(OBJTYPE);					\
@@ -529,6 +533,30 @@ extern __u32 mars_digest(__u32 digest_flags,
 
 extern void mref_checksum(struct mref_object *mref);
 
+/*******************************************************************/
+
+/* compression stuff */
+
+#define MARS_MAX_COMPR_SIZE (PAGE_SIZE * 8)
+
+extern int compress_overhead;
+
+extern __u32 available_compression_mask;
+extern __u32 usable_compression_mask;
+
+extern int mars_compress(void *src_data,
+			 int src_len,
+			 void *dst_data,
+			 int dst_len,
+			 __u32 check_flags,
+			 __u32 *result_flags);
+
+void *mars_decompress(void *src_data,
+		      int src_len,
+		      void *dst_data,
+		      int dst_len,
+		      __u32 check_flags);
+
 /////////////////////////////////////////////////////////////////////////
 
 /* Crash-testing instrumentation.

kernel/mars_generic.c

@@ -632,6 +632,134 @@ void mref_checksum(struct mref_object *mref)
 	memcpy(&mref->ref_checksum, checksum, len);
 }
 
+/*******************************************************************/
+
+/* compression */
+
+int compress_overhead = 0;
+
+__u32 available_compression_mask =
+	0;
+
+__u32 usable_compression_mask = 0;
+
+__u32 used_compression = 0;
+
+int mars_compress(void *src_data,
+		  int src_len,
+		  void *dst_data,
+		  int dst_len,
+		  __u32 check_flags,
+		  __u32 *result_flags)
+{
+	void *tmp_buf = dst_data;
+	int res = 0;
+
+	check_flags &= usable_compression_mask;
+	if (!(check_flags & MREF_COMPRESS_ANY)) {
+		used_compression = 0;
+		return 0;
+	}
+
+	if (unlikely(src_len > MARS_MAX_COMPR_SIZE)) {
+		MARS_ERR("tryping to compress %d, more than %ld bytes\n",
+			 src_len, MARS_MAX_COMPR_SIZE);
+		goto done;
+	}
+
+ done:
+	if (!dst_data)
+		brick_mem_free(tmp_buf);
+	return res;
+}
+
+void *mars_decompress(void *src_data,
+		      int src_len,
+		      void *dst_data,
+		      int dst_len,
+		      __u32 check_flags)
+{
+	void *res_buf = dst_data;
+
+	if (!res_buf)
+		res_buf = brick_mem_alloc(dst_len);
+
+	MARS_ERR("decompression not compiled into kernel module\n");
+
+ err:
+	if (!dst_data)
+		brick_mem_free(res_buf);
+	res_buf = NULL;
+
+ done:
+	return res_buf;
+}
+
+#ifdef CONFIG_MARS_BENCHMARK
+#define MARS_CLEAN_SIZE 256
+
+static
+void make_fake_page(__u32 *testpage)
+{
+	int i;
+
+	/* some fake compression data */
+	for (i = 0; i < PAGE_SIZE / sizeof(__u32); i++)
+		testpage[i] = (__u32)i;
+}
+
+static
+void benchmark_compress(char *name, __u32 flags)
+{
+	void *testpage = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	__u32 result_flags;
+	long long delta;
+	int status;
+	int i;
+
+	usable_compression_mask = MREF_COMPRESS_ANY;
+
+	make_fake_page(testpage);
+	delta = TIME_THIS(
+			  for (i = 0; i < 10000; i++) {
+				  memset(testpage, 0, MARS_CLEAN_SIZE);
+				  result_flags = 0;
+				  status =
+				  mars_compress(testpage, PAGE_SIZE,
+						NULL, PAGE_SIZE + compress_overhead,
+						flags, &result_flags);
+				  if (unlikely(status <= 0) || !(flags & result_flags)) {
+					  MARS_ERR("%s compress failure, status=%d, flags=%x\n",
+						   name, status, result_flags);
+					  goto err;
+				  }
+			  }
+			  );
+	printk("%-8s compress duration = %12lld ns\n", name, delta);
+
+ err:
+	kfree(testpage);
+	usable_compression_mask = 0;
+}
+
+#endif
+
+static
+int init_mars_compress(void)
+{
+	int max_len = 0;
+
+#ifdef CONFIG_MARS_BENCHMARK
+	(void)benchmark_compress;
+#endif
+	return 0;
+}
+
+static
+void exit_mars_compress(void)
+{
+}
+
 /////////////////////////////////////////////////////////////////////
 
 // tracing
@@ -843,6 +971,8 @@ int __init init_mars(void)
 	}
 #endif /* MARS_HAS_NEW_CRYPTO */
 
+	init_mars_compress();
+
 	return 0;
 }
 
@@ -852,6 +982,8 @@ void exit_mars(void)
 
 	put_fake();
 
+	exit_mars_compress();
+
 #ifdef MARS_HAS_NEW_CRYPTO
 	exit_mars_digest();
 #else  /* MARS_HAS_NEW_CRYPTO */

kernel/sy_old/mars_main.c

@@ -88,6 +88,7 @@ static int _tmp_features_version = OPTIONAL_FEATURES_VERSION;
 static int _tmp_strategy_version = OPTIONAL_STRATEGY_VERSION;
 
 static __u32 _tmp_digest_mask    = MREF_CHKSUM_MD5_OLD;
+static __u32 _tmp_compression_mask = MREF_COMPRESS_ANY;
 
 /* Portability: can we use get_random_int() in a module? */
 #include <linux/string_helpers.h>
@@ -2683,13 +2684,14 @@ void _make_alive(void)
 	features = path_make(stringify(OPTIONAL_FEATURES_VERSION)
 			     ","
 			     stringify(OPTIONAL_STRATEGY_VERSION)
-			     ",0x%08x", available_digest_mask);
+			     ",0x%08x",
+			     available_digest_mask | available_compression_mask);
 	__make_alivelink_str("features", features, true);
 	brick_string_free(features);
 	features = path_make("%d,%d,0x%08x",
 			     usable_features_version,
 			     usable_strategy_version,
-			     usable_digest_mask);
+			     usable_digest_mask | usable_compression_mask);
 	__make_alivelink_str("usable", features, true);
 	brick_string_free(features);
 	__make_alivelink_str("buildtag", BUILDTAG "(" BUILDDATE ")", true);
@@ -2936,6 +2938,7 @@ int _make_peer(struct mars_global *global, struct mars_dent *dent)
 	/* at least one digest must remain usable */
 	peer->available_mask |= MREF_CHKSUM_MD5_OLD;
 	_tmp_digest_mask &= peer->available_mask;
+	_tmp_compression_mask &= peer->available_mask;
 	if (peer->features_version < _tmp_features_version)
 		_tmp_features_version = peer->features_version;
 	if (peer->strategy_version < _tmp_strategy_version)
@@ -6436,9 +6439,11 @@ static int _main_thread(void *data)
 		usable_features_version = _tmp_features_version;
 		usable_strategy_version = _tmp_strategy_version;
 		usable_digest_mask = _tmp_digest_mask;
+		usable_compression_mask = (_tmp_compression_mask & available_compression_mask);
 		_tmp_features_version = OPTIONAL_FEATURES_VERSION;
 		_tmp_strategy_version = OPTIONAL_STRATEGY_VERSION;
 		_tmp_digest_mask = available_digest_mask;
+		_tmp_compression_mask = available_compression_mask;
 
 		down_read(&rot_sem);
 		for (tmp = rot_anchor.next; tmp != &rot_anchor; tmp = tmp->next) {