Allow to compress on-the-wire data using two algorithms:

- HOLE - it simply turns all-zero blocks into few bytes header;
	it is extremely fast, so it is turned on by default;
	it is mostly intended to speed up initial synchronization
	where we expect many zeros;
- LZF - very fast algorithm by Marc Alexander Lehmann, which shows
	very decent compression ratio and has BSD license.

MFC after:	2 weeks

1 files changed, 6 insertions, 0 deletions

diff --git a/sbin/hastd/hast.h b/sbin/hastd/hast.h
index fe9cf0d..8c64395 100644
--- a/sbin/hastd/hast.h
+++ b/sbin/hastd/hast.h
@@ -117,6 +117,10 @@ struct hastd_config {
 #define	HAST_REPLICATION_MEMSYNC	1
 #define	HAST_REPLICATION_ASYNC		2
 
+#define	HAST_COMPRESSION_NONE	0
+#define	HAST_COMPRESSION_HOLE	1
+#define	HAST_COMPRESSION_LZF	2
+
 #define	HAST_CHECKSUM_NONE	0
 #define	HAST_CHECKSUM_CRC32	1
 #define	HAST_CHECKSUM_SHA256	2
@@ -137,6 +141,8 @@ struct hast_resource {
 	int	hr_keepdirty;
 	/* Path to a program to execute on various events. */
 	char	hr_exec[PATH_MAX];
+	/* Compression algorithm. */
+	int	hr_compression;
 	/* Checksum algorithm. */
 	int	hr_checksum;