Block live migration

This patch introduces block migration called during live migration. Block
are being copied to the destination in an async way. First the code will
transfer the whole disk and then transfer all dirty blocks accumulted during
the migration.
Still need to improve transition from the iterative phase of migration to the
end phase. For now transition will take place when all blocks transfered once,
all the dirty blocks will be transfered during the end phase (guest is
suspended).

Changes from v4:
- Global variabels moved to a global state structure allocated dynamically.
- Minor coding style issues.
- Poll block.c for tracking of dirty blocks instead of manage it here.

Signed-off-by: Liran Schour <lirans@il.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

migration.h

@@ -30,6 +30,8 @@ struct MigrationState
     void (*cancel)(MigrationState *s);
     int (*get_status)(MigrationState *s);
     void (*release)(MigrationState *s);
+    int blk;
+    int shared;
 };
 
 typedef struct FdMigrationState FdMigrationState;
@@ -65,27 +67,35 @@ void do_info_migrate(Monitor *mon);
 int exec_start_incoming_migration(const char *host_port);
 
 MigrationState *exec_start_outgoing_migration(const char *host_port,
-					     int64_t bandwidth_limit,
-					     int detach);
+					      int64_t bandwidth_limit,
+					      int detach,
+					      int blk,
+					      int inc);
 
 int tcp_start_incoming_migration(const char *host_port);
 
 MigrationState *tcp_start_outgoing_migration(const char *host_port,
 					     int64_t bandwidth_limit,
-					     int detach);
+					     int detach,
+					     int blk,
+					     int inc);
 
 int unix_start_incoming_migration(const char *path);
 
 MigrationState *unix_start_outgoing_migration(const char *path,
 					      int64_t bandwidth_limit,
-					      int detach);
+					      int detach,
+					      int blk,
+					      int inc);
 
 int fd_start_incoming_migration(const char *path);
 
 MigrationState *fd_start_outgoing_migration(Monitor *mon,
 					    const char *fdname,
 					    int64_t bandwidth_limit,
-					    int detach);
+					    int detach,
+					    int blk,
+					    int inc);
 
 void migrate_fd_monitor_suspend(FdMigrationState *s);