migrate: Bump migration version number

v1 of the migration stream format, had some flaws: it didn't properly
handle endianness of the MSS field, and it didn't transfer the RFC7323
timestamp.  We've now fixed those bugs, but it requires incompatible
changes to the stream format.

Because of the timestamps in particular, v1 is not really usable, so there
is little point maintaining compatible support for it.  However, v1 is in
released packages, both upstream and downstream (RHEL at least).  Just
updating the stream format without bumping the version would lead to very
cryptic errors if anyone did attempt to migrate between an old and new
passt.

So, bump the migration version to v2, so we'll get a clear error message if
anyone attempts this.  We don't attempt to maintain backwards compatibility
with v1, however: we'll simply fail if given a v1 stream.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/migrate.c b/migrate.c
index 0fca77b..48d63a0 100644
--- a/migrate.c
+++ b/migrate.c
@@ -96,8 +96,8 @@ static int seen_addrs_target_v1(struct ctx *c,
 	return 0;
 }
 
-/* Stages for version 1 */
-static const struct migrate_stage stages_v1[] = {
+/* Stages for version 2 */
+static const struct migrate_stage stages_v2[] = {
 	{
 		.name = "observed addresses",
 		.source = seen_addrs_source_v1,
@@ -118,7 +118,11 @@ static const struct migrate_stage stages_v1[] = {
 
 /* Supported encoding versions, from latest (most preferred) to oldest */
 static const struct migrate_version versions[] = {
-	{ 1,	stages_v1, },
+	{ 2,	stages_v2, },
+	/* v1 was released, but not widely used.  It had bad endianness for the
+	 * MSS and omitted timestamps, which meant it usually wouldn't work.
+	 * Therefore we don't attempt to support compatibility with it.
+	 */
 	{ 0 },
 };