md: use sysfs_notify_dirent to notify changes to md/array_state

Now that we have sysfs_notify_dirent, use it to notify changes
to md/array_state.
As sysfs_notify_dirent can be called in atomic context, we can
remove the delayed notify and the MD_NOTIFY_ARRAY_STATE flag.

Signed-off-by: NeilBrown <[e-mail]>

drivers/md/md.c

···
 		list_del(&mddev->all_mddevs);
 		spin_unlock(&all_mddevs_lock);
 		blk_cleanup_queue(mddev->queue);
+		if (mddev->sysfs_state)
+			sysfs_put(mddev->sysfs_state);
+		mddev->sysfs_state = NULL;
 		kobject_put(&mddev->kobj);
 	} else
 		spin_unlock(&all_mddevs_lock);
···
 	if (err)
 		return err;
 	else {
-		sysfs_notify(&mddev->kobj, NULL, "array_state");
+		sysfs_notify_dirent(mddev->sysfs_state);
 		return len;
 	}
 }
···
 	if (error)
 		printk(KERN_WARNING "md: cannot register %s/md - name in use\n",
 		       disk->disk_name);
-	else
+	else {
 		kobject_uevent(&mddev->kobj, KOBJ_ADD);
+		mddev->sysfs_state = sysfs_get_dirent(mddev->kobj.sd, "array_state");
+	}
 	return NULL;
 }
 
···
 	if (!atomic_read(&mddev->writes_pending)) {
 		mddev->safemode = 1;
 		if (mddev->external)
-			set_bit(MD_NOTIFY_ARRAY_STATE, &mddev->flags);
+			sysfs_notify_dirent(mddev->sysfs_state);
 	}
 	md_wakeup_thread(mddev->thread);
 }
···
 
 	mddev->changed = 1;
 	md_new_event(mddev);
-	sysfs_notify(&mddev->kobj, NULL, "array_state");
+	sysfs_notify_dirent(mddev->sysfs_state);
 	sysfs_notify(&mddev->kobj, NULL, "sync_action");
 	sysfs_notify(&mddev->kobj, NULL, "degraded");
 	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
···
 	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 	md_wakeup_thread(mddev->thread);
 	md_wakeup_thread(mddev->sync_thread);
-	sysfs_notify(&mddev->kobj, NULL, "array_state");
+	sysfs_notify_dirent(mddev->sysfs_state);
 	return 0;
 }
 
···
 			module_put(mddev->pers->owner);
 			mddev->pers = NULL;
 			/* tell userspace to handle 'inactive' */
-			sysfs_notify(&mddev->kobj, NULL, "array_state");
+			sysfs_notify_dirent(mddev->sysfs_state);
 
 			set_capacity(disk, 0);
 			mddev->changed = 1;
···
 			mdname(mddev));
 	err = 0;
 	md_new_event(mddev);
-	sysfs_notify(&mddev->kobj, NULL, "array_state");
+	sysfs_notify_dirent(mddev->sysfs_state);
 out:
 	return err;
 }
···
 	if (_IOC_TYPE(cmd) == MD_MAJOR && mddev->ro && mddev->pers) {
 		if (mddev->ro == 2) {
 			mddev->ro = 0;
-			sysfs_notify(&mddev->kobj, NULL, "array_state");
+			sysfs_notify_dirent(mddev->sysfs_state);
 			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 			md_wakeup_thread(mddev->thread);
 		} else {
···
 		spin_unlock_irq(&mddev->write_lock);
 	}
 	if (did_change)
-		sysfs_notify(&mddev->kobj, NULL, "array_state");
+		sysfs_notify_dirent(mddev->sysfs_state);
 	wait_event(mddev->sb_wait,
 		   !test_bit(MD_CHANGE_CLEAN, &mddev->flags) &&
 		   !test_bit(MD_CHANGE_PENDING, &mddev->flags));
···
 			mddev->safemode = 1;
 		spin_unlock_irq(&mddev->write_lock);
 		md_update_sb(mddev, 0);
-		sysfs_notify(&mddev->kobj, NULL, "array_state");
+		sysfs_notify_dirent(mddev->sysfs_state);
 	} else
 		spin_unlock_irq(&mddev->write_lock);
 
···
 	if (mddev->bitmap)
 		bitmap_daemon_work(mddev->bitmap);
 
-	if (test_and_clear_bit(MD_NOTIFY_ARRAY_STATE, &mddev->flags))
-		sysfs_notify(&mddev->kobj, NULL, "array_state");
-
 	if (mddev->ro)
 		return;
 
···
 				mddev->safemode = 0;
 			spin_unlock_irq(&mddev->write_lock);
 			if (did_change)
-				sysfs_notify(&mddev->kobj, NULL, "array_state");
+				sysfs_notify_dirent(mddev->sysfs_state);
 		}
 
 		if (mddev->flags)

include/linux/raid/md_k.h

···
 #define MD_CHANGE_DEVS	0	/* Some device status has changed */
 #define MD_CHANGE_CLEAN 1	/* transition to or from 'clean' */
 #define MD_CHANGE_PENDING 2	/* superblock update in progress */
-#define MD_NOTIFY_ARRAY_STATE 3	/* atomic context wants to notify userspace */
 
 	int				ro;
 
···
 							 * starts here */
 	sector_t			resync_max;	/* resync should pause
 							 * when it gets here */
+
+	struct sysfs_dirent		*sysfs_state;	/* handle for 'array_state'
+							 * file in sysfs.
+							 */
 
 	spinlock_t			write_lock;
 	wait_queue_head_t		sb_wait;	/* for waiting on superblock updates */