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Commit 908f4fbd authored by NeilBrown's avatar NeilBrown
Browse files

md/raid5: be more thorough in calculating 'degraded' value. 



When an array is being reshaped to change the number of devices,
the two halves can be differently degraded.  e.g. one could be
missing a device and the other not.

So we need to be more careful about calculating the 'degraded'
attribute.

Instead of just inc/dec at appropriate times, perform a full
re-calculation examining both possible cases.  This doesn't happen
often so it not a big cost, and we already have most of the code to
do it.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 2e61ebbc

drivers/md/raid5.c

+33 −30
Original line number Diff line number Diff line
@@ -370,12 +370,10 @@ static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector, 
 * of the two sections, and some non-in_sync devices may

 * be insync in the section most affected by failed devices.

 */

static int has_failed(struct r5conf *conf)

static int calc_degraded(struct r5conf *conf)

{

	int degraded;

	int degraded, degraded2;

	int i;

	if (conf->mddev->reshape_position == MaxSector)

		return conf->mddev->degraded > conf->max_degraded;



	rcu_read_lock();

	degraded = 0;
@@ -399,14 +397,14 @@ static int has_failed(struct r5conf *conf) 
				degraded++;

	}

	rcu_read_unlock();

	if (degraded > conf->max_degraded)

		return 1;

	if (conf->raid_disks == conf->previous_raid_disks)

		return degraded;

	rcu_read_lock();

	degraded = 0;

	degraded2 = 0;

	for (i = 0; i < conf->raid_disks; i++) {

		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);

		if (!rdev || test_bit(Faulty, &rdev->flags))

			degraded++;

			degraded2++;

		else if (test_bit(In_sync, &rdev->flags))

			;

		else
@@ -416,9 +414,22 @@ static int has_failed(struct r5conf *conf) 
			 * almost certainly hasn't.

			 */

			if (conf->raid_disks <= conf->previous_raid_disks)

				degraded++;

				degraded2++;

	}

	rcu_read_unlock();

	if (degraded2 > degraded)

		return degraded2;

	return degraded;

}



static int has_failed(struct r5conf *conf)

{

	int degraded;



	if (conf->mddev->reshape_position == MaxSector)

		return conf->mddev->degraded > conf->max_degraded;



	degraded = calc_degraded(conf);

	if (degraded > conf->max_degraded)

		return 1;

	return 0;
@@ -1724,18 +1735,15 @@ static void error(struct mddev *mddev, struct md_rdev *rdev) 
{

	char b[BDEVNAME_SIZE];

	struct r5conf *conf = mddev->private;

	unsigned long flags;

	pr_debug("raid456: error called\n");



	if (test_and_clear_bit(In_sync, &rdev->flags)) {

		unsigned long flags;

	spin_lock_irqsave(&conf->device_lock, flags);

		mddev->degraded++;

	clear_bit(In_sync, &rdev->flags);

	mddev->degraded = calc_degraded(conf);

	spin_unlock_irqrestore(&conf->device_lock, flags);

		/*

		 * if recovery was running, make sure it aborts.

		 */

	set_bit(MD_RECOVERY_INTR, &mddev->recovery);

	}



	set_bit(Blocked, &rdev->flags);

	set_bit(Faulty, &rdev->flags);

	set_bit(MD_CHANGE_DEVS, &mddev->flags);
@@ -4852,8 +4860,7 @@ static int run(struct mddev *mddev) 
		dirty_parity_disks++;

	}



	mddev->degraded = (max(conf->raid_disks, conf->previous_raid_disks)

			   - working_disks);

	mddev->degraded = calc_degraded(conf);



	if (has_failed(conf)) {

		printk(KERN_ERR "md/raid:%s: not enough operational devices"
@@ -5025,7 +5032,7 @@ static int raid5_spare_active(struct mddev *mddev) 
		}

	}

	spin_lock_irqsave(&conf->device_lock, flags);

	mddev->degraded -= count;

	mddev->degraded = calc_degraded(conf);

	spin_unlock_irqrestore(&conf->device_lock, flags);

	print_raid5_conf(conf);

	return count;
@@ -5286,8 +5293,7 @@ static int raid5_start_reshape(struct mddev *mddev) 
		 * pre and post number of devices.

		 */

		spin_lock_irqsave(&conf->device_lock, flags);

		mddev->degraded += (conf->raid_disks - conf->previous_raid_disks)

			- added_devices;

		mddev->degraded = calc_degraded(conf);

		spin_unlock_irqrestore(&conf->device_lock, flags);

	}

	mddev->raid_disks = conf->raid_disks;
@@ -5356,12 +5362,9 @@ static void raid5_finish_reshape(struct mddev *mddev) 
			revalidate_disk(mddev->gendisk);

		} else {

			int d;

			mddev->degraded = conf->raid_disks;

			for (d = 0; d < conf->raid_disks ; d++)

				if (conf->disks[d].rdev &&

				    test_bit(In_sync,

					     &conf->disks[d].rdev->flags))

					mddev->degraded--;

			spin_lock_irq(&conf->device_lock);

			mddev->degraded = calc_degraded(conf);

			spin_unlock_irq(&conf->device_lock);

			for (d = conf->raid_disks ;

			     d < conf->raid_disks - mddev->delta_disks;

			     d++) {