block: document the blk_eh_timer_return values

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/blkdev.h

@@ -326,8 +326,8 @@ typedef int (init_rq_fn)(struct request_queue *, struct request *, gfp_t);
 typedef void (exit_rq_fn)(struct request_queue *, struct request *);
 
 enum blk_eh_timer_return {
-	BLK_EH_DONE,
-	BLK_EH_RESET_TIMER,
+	BLK_EH_DONE,		/* drivers has completed the command */
+	BLK_EH_RESET_TIMER,	/* reset timer and try again */
 };
 
 typedef enum blk_eh_timer_return (rq_timed_out_fn)(struct request *);