mdmon: periodically checkpoint recovery

The kernel updates and notifies md/sync_completed when it is time to
take a checkpoint.  When this occurs (at 1/16 array size intervals)
write 'idle' to md/sync_action to have the current recovery position
updated in recovery_start and resync_start.

Requires the metadata handler to reset ->last_checkpoint when it has
determined that recovery has ended.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/mdmon.h b/mdmon.h
index 20a0a013..5c515663 100644
--- a/mdmon.h
+++ b/mdmon.h
@@ -32,6 +32,15 @@ struct active_array {
 	int action_fd;
 	int resync_start_fd;
 	int metadata_fd; /* for monitoring rw/ro status */
+	int sync_completed_fd; /* for checkpoint notification events */
+	unsigned long long last_checkpoint; /* sync_completed fires for many
+					     * reasons this field makes sure the
+					     * kernel has made progress before
+					     * moving the checkpoint.  It is
+					     * cleared by the metadata handler
+					     * when it determines recovery is
+					     * terminated.
+					     */
 
 	enum array_state prev_state, curr_state, next_state;
 	enum sync_action prev_action, curr_action, next_action;