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Commit c04be0aa authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: Improve locking around error handling 



The error handling routines don't use proper locking, and so two concurrent
errors could trigger a problem.

So:
  - use test-and-set and test-and-clear to synchonise
    the In_sync bits with the ->degraded count
  - use the spinlock to protect updates to the
    degraded count (could use an atomic_t but that
    would be a bigger change in code, and isn't
    really justified)
  - remove un-necessary locking in raid5

Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 11ce99e6

drivers/md/raid1.c

+11 −5
Original line number Diff line number Diff line
@@ -959,14 +959,16 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev) 
		 * normal single drive

		 */

		return;

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

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

		unsigned long flags;

		spin_lock_irqsave(&conf->device_lock, flags);

		mddev->degraded++;

		spin_unlock_irqrestore(&conf->device_lock, flags);

		/*

		 * if recovery is running, make sure it aborts.

		 */

		set_bit(MD_RECOVERY_ERR, &mddev->recovery);

	}

	clear_bit(In_sync, &rdev->flags);

	set_bit(Faulty, &rdev->flags);

	set_bit(MD_CHANGE_DEVS, &mddev->flags);

	printk(KERN_ALERT "raid1: Disk failure on %s, disabling device. \n"
@@ -1022,9 +1024,11 @@ static int raid1_spare_active(mddev_t *mddev) 
		mdk_rdev_t *rdev = conf->mirrors[i].rdev;

		if (rdev

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

		    && !test_bit(In_sync, &rdev->flags)) {

		    && !test_and_set_bit(In_sync, &rdev->flags)) {

			unsigned long flags;

			spin_lock_irqsave(&conf->device_lock, flags);

			mddev->degraded--;

			set_bit(In_sync, &rdev->flags);

			spin_unlock_irqrestore(&conf->device_lock, flags);

		}

	}
@@ -2048,7 +2052,7 @@ static int raid1_reshape(mddev_t *mddev) 
	mirror_info_t *newmirrors;

	conf_t *conf = mddev_to_conf(mddev);

	int cnt, raid_disks;



	unsigned long flags;

	int d, d2;



	/* Cannot change chunk_size, layout, or level */
@@ -2107,7 +2111,9 @@ static int raid1_reshape(mddev_t *mddev) 
	kfree(conf->poolinfo);

	conf->poolinfo = newpoolinfo;



	spin_lock_irqsave(&conf->device_lock, flags);

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

	spin_unlock_irqrestore(&conf->device_lock, flags);

	conf->raid_disks = mddev->raid_disks = raid_disks;

	mddev->delta_disks = 0;

drivers/md/raid10.c

+8 −4
Original line number Diff line number Diff line
@@ -950,14 +950,16 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev) 
		 * really dead" tests...

		 */

		return;

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

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

		unsigned long flags;

		spin_lock_irqsave(&conf->device_lock, flags);

		mddev->degraded++;

		spin_unlock_irqrestore(&conf->device_lock, flags);

		/*

		 * if recovery is running, make sure it aborts.

		 */

		set_bit(MD_RECOVERY_ERR, &mddev->recovery);

	}

	clear_bit(In_sync, &rdev->flags);

	set_bit(Faulty, &rdev->flags);

	set_bit(MD_CHANGE_DEVS, &mddev->flags);

	printk(KERN_ALERT "raid10: Disk failure on %s, disabling device. \n"
@@ -1033,9 +1035,11 @@ static int raid10_spare_active(mddev_t *mddev) 
		tmp = conf->mirrors + i;

		if (tmp->rdev

		    && !test_bit(Faulty, &tmp->rdev->flags)

		    && !test_bit(In_sync, &tmp->rdev->flags)) {

		    && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {

			unsigned long flags;

			spin_lock_irqsave(&conf->device_lock, flags);

			mddev->degraded--;

			set_bit(In_sync, &tmp->rdev->flags);

			spin_unlock_irqrestore(&conf->device_lock, flags);

		}

	}

drivers/md/raid5.c

+12 −8
Original line number Diff line number Diff line
@@ -636,7 +636,6 @@ static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done, 
 	struct stripe_head *sh = bi->bi_private;

	raid5_conf_t *conf = sh->raid_conf;

	int disks = sh->disks, i;

	unsigned long flags;

	int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);



	if (bi->bi_size)
@@ -654,7 +653,6 @@ static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done, 
		return 0;

	}



	spin_lock_irqsave(&conf->device_lock, flags);

	if (!uptodate)

		md_error(conf->mddev, conf->disks[i].rdev);
@@ -662,8 +660,7 @@ static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done, 
	

	clear_bit(R5_LOCKED, &sh->dev[i].flags);

	set_bit(STRIPE_HANDLE, &sh->state);

	__release_stripe(conf, sh);

	spin_unlock_irqrestore(&conf->device_lock, flags);

	release_stripe(sh);

	return 0;

}
@@ -697,9 +694,11 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev) 


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

		set_bit(MD_CHANGE_DEVS, &mddev->flags);

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

		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);

			spin_unlock_irqrestore(&conf->device_lock, flags);

			/*

			 * if recovery was running, make sure it aborts.

			 */
@@ -3418,9 +3417,11 @@ static int raid5_spare_active(mddev_t *mddev) 
		tmp = conf->disks + i;

		if (tmp->rdev

		    && !test_bit(Faulty, &tmp->rdev->flags)

		    && !test_bit(In_sync, &tmp->rdev->flags)) {

		    && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {

			unsigned long flags;

			spin_lock_irqsave(&conf->device_lock, flags);

			mddev->degraded--;

			set_bit(In_sync, &tmp->rdev->flags);

			spin_unlock_irqrestore(&conf->device_lock, flags);

		}

	}

	print_raid5_conf(conf);
@@ -3556,6 +3557,7 @@ static int raid5_start_reshape(mddev_t *mddev) 
	struct list_head *rtmp;

	int spares = 0;

	int added_devices = 0;

	unsigned long flags;



	if (mddev->degraded ||

	    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
@@ -3597,7 +3599,9 @@ static int raid5_start_reshape(mddev_t *mddev) 
				break;

		}



	spin_lock_irqsave(&conf->device_lock, flags);

	mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;

	spin_unlock_irqrestore(&conf->device_lock, flags);

	mddev->raid_disks = conf->raid_disks;

	mddev->reshape_position = 0;

	set_bit(MD_CHANGE_DEVS, &mddev->flags);