md-cluster: Use a small window for raid10 resync
Suspending the entire device for resync could take
too long. Resync in small chunks.
cluster's resync window is maintained in r10conf as
cluster_sync_low and cluster_sync_high, and processed
in raid10's sync_request(). If the current resync is
outside the cluster resync window:
1. Set the cluster_sync_low to curr_resync_completed.
2. Set cluster_sync_high to cluster_sync_low + stripe
size.
3. Send a message to all nodes so they may add it in
their suspension list.
Note:
We only support "near" raid10 so far, resync a far or
offset raid10 array could have trouble. So raid10_run
checks the layout of clustered raid10, it will refuse
to run if the layout is not correct.
With the "near" layout we process one stripe at a time
progressing monotonically through the address space.
So we can have a sliding window of whole-stripes which
moves through the array suspending IO on other nodes,
and both resync which uses array addresses and recovery
which uses device addresses can stay within this window.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/drivers/md/raid10.h b/drivers/md/raid10.h
index 735ce1a..2bef4e8 100644
--- a/drivers/md/raid10.h
+++ b/drivers/md/raid10.h
@@ -88,6 +88,12 @@ struct r10conf {
* the new thread here until we fully activate the array.
*/
struct md_thread *thread;
+
+ /*
+ * Keep track of cluster resync window to send to other nodes.
+ */
+ sector_t cluster_sync_low;
+ sector_t cluster_sync_high;
};
/*