There's weird upper case for the first character after block.  I know
some subsystems like this, but in general try to at least be consistent
for the series.

+	/*
+	 * attributes which require some form of locking
+	 * other than q->sysfs_lock

Make that a proper sentence:

	 * Attributes which require some form of locking
	 * other than q->sysfs_lock.

+	/*
+	 * protects elevator switch/update
+	 */

Also make this a full sentence, and mention which fields this protects.

Otherwise looks good.