add resync speed control for dm-raid1

index 9bfd057..43e428a 100644
@@ -13,6 +13,7 @@
 #include <linux/pagemap.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
+#include <linux/ratelimit.h>
 #include <linux/device-mapper.h>
 #include <linux/dm-io.h>
 #include <linux/dm-dirty-log.h>

@@ -26,6 +27,11 @@
 #define DM_RAID1_HANDLE_ERRORS 0x01
 #define errors_handled(p)	((p)->features & DM_RAID1_HANDLE_ERRORS)
 
+/* Default resync interval*/
+#define RESYNC_JIFFIES	HZ
+/* Default max resync speed in KB/s */
+#define DEFAULT_RESYNC_SPEED		(0xFFFFFFF)
+
 static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped);
 
 /*-----------------------------------------------------------------

@@ -69,6 +75,9 @@ struct mirror_set {
 	int log_failure;
 	int leg_failure;
 	atomic_t suspend;
+	/* recovery speed control */
+	struct ratelimit_state ms_rlimit;
+	struct delayed_work resync_waker;
 
 	atomic_t default_mirror;	/* Default mirror */
 

@@ -383,12 +392,18 @@ static void do_recovery(struct mirror_set *ms)
 	/*
 	 * Copy any already quiesced regions.
 	 */
-	while ((reg = dm_rh_recovery_start(ms->rh))) {
+	while (__ratelimit(&ms->ms_rlimit) &&
+			(reg = dm_rh_recovery_start(ms->rh))) {
 		r = recover(ms, reg);
 		if (r)
 			dm_rh_recovery_end(reg, 0);
 	}
 
+	/* Broke off the resync process, so wake up kmirrord later on */
+	if (!ms->in_sync)
+		schedule_delayed_work(&ms->resync_waker,
+				      ms->ms_rlimit.interval);
+
 	/*
 	 * Update the in sync flag.
 	 */

@@ -842,6 +857,14 @@ static void do_mirror(struct work_struct *work)
 	do_failures(ms, &failures);
 }
 
+static void do_resync_wake(struct work_struct *work)
+{
+	struct mirror_set *ms =
+		container_of(work, struct mirror_set, resync_waker.work);
+
+	wakeup_mirrord(ms);
+}
+
 /*-----------------------------------------------------------------
  * Target functions
  *---------------------------------------------------------------*/

@@ -852,6 +875,7 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
 {
 	size_t len;
 	struct mirror_set *ms = NULL;
+	int burst;
 
 	len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
 

@@ -875,6 +899,10 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
 	ms->leg_failure = 0;
 	atomic_set(&ms->suspend, 0);
 	atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
+	burst = (DEFAULT_RESYNC_SPEED * (RESYNC_JIFFIES / HZ)) << 1;
+	burst = DIV_ROUND_UP(burst, region_size);
+	ratelimit_state_init(&ms->ms_rlimit, RESYNC_JIFFIES, burst);
+	INIT_DELAYED_WORK(&ms->resync_waker, do_resync_wake);
 
 	ms->read_record_pool = mempool_create_slab_pool(MIN_READ_RECORDS,
 						_dm_raid1_read_record_cache);

index 43e428a..3cdad37 100644
@@ -1361,6 +1361,49 @@ static void mirror_resume(struct dm_target *ti)
 }
 
 /*
+ * convert speed into members of ratelimit_state
+ */
+static void speed_to_rlimit(struct mirror_set *ms, struct ratelimit_state *rl,
+			    unsigned int speed)
+{
+	sector_t region_size = dm_rh_get_region_size(ms->rh);
+
+	rl->interval = RESYNC_JIFFIES;
+	rl->burst = (speed * (RESYNC_JIFFIES / HZ)) << 1;
+	rl->burst = DIV_ROUND_UP(rl->burst, region_size);
+}
+
+/*
+ * Message interface
+ *	set-max-resync-speed $speed(KB/s)
+ */
+static int mirror_message(struct dm_target *ti, unsigned argc, char **argv)
+{
+	struct mirror_set *ms = ti->private;
+	unsigned int speed;
+	int ret = 0;
+
+	if (!strcasecmp(argv[0], "set-max-resync-speed")) {
+		if (sscanf(argv[1], "%u", &speed) != 1) {
+			DMWARN("invalid speed parameter %s", argv[1]);
+			ret = -EINVAL;
+			goto error;
+		}
+
+		speed_to_rlimit(ms, &ms->ms_rlimit, speed);
+		goto out;
+	} else {
+		ret = -EINVAL;
+		goto error;
+	}
+
+error:
+	DMWARN("unrecognised message received.");
+out:
+	return ret;
+}
+
+/*
  * device_status_char
  * @m: mirror device/leg we want the status of
  *

@@ -1450,6 +1493,7 @@ static struct target_type mirror_target = {
 	.presuspend = mirror_presuspend,
 	.postsuspend = mirror_postsuspend,
 	.resume	 = mirror_resume,
+	.message = mirror_message,
 	.status	 = mirror_status,
 	.iterate_devices = mirror_iterate_devices,
 };

index 3cdad37..68081ff 100644
@@ -1427,6 +1427,20 @@ static char device_status_char(struct mirror *m)
 		(test_bit(DM_RAID1_READ_ERROR, &(m->error_type))) ? 'R' : 'U';
 }
 
+/*
+ * get speed from ratelimit_state
+ */
+static unsigned int rlimit_to_speed(struct mirror_set *ms,
+				    struct ratelimit_state *rl)
+{
+	sector_t region_size = dm_rh_get_region_size(ms->rh);
+	unsigned int time, burst;
+
+	time = rl->interval / HZ;
+	burst = (rl->burst * region_size) >> 1;
+
+	return burst / time;
+}
 
 static int mirror_status(struct dm_target *ti, status_type_t type,
 			 char *result, unsigned int maxlen)

@@ -1445,9 +1459,10 @@ static int mirror_status(struct dm_target *ti, status_type_t type,
 		}
 		buffer[m] = '\0';
 
-		DMEMIT("%llu/%llu 1 %s ",
+		DMEMIT("%llu/%llu 1 %u 1 %s ",
 		      (unsigned long long)log->type->get_sync_count(log),
-		      (unsigned long long)ms->nr_regions, buffer);
+		      (unsigned long long)ms->nr_regions,
+		      rlimit_to_speed(ms, &ms->ms_rlimit), buffer);
 
 		sz += log->type->status(log, type, result+sz, maxlen-sz);