Re: [PATCH] Fix stray --cluster-confrim crash

[NeilBrown <neilb@suse.de>]

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On Mon, 2 Mar 2015 10:55:49 -0600 Goldwyn Rodrigues <rgoldwyn@suse.de> wrote:

> Hi Neil,
> 
> This fix is againt the md/for-next.
> 
> A --cluster-confirm without an --add (by another node) can
> crash the kernel.
> 
> Fix it by guarding it using a state.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> --- 
> diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
> index 03e521a..96679b2 100644
> --- a/drivers/md/md-cluster.c
> +++ b/drivers/md/md-cluster.c
> @@ -42,6 +42,10 @@ struct resync_info {
>  	__le64 hi;
>  };
>  
> +/* md_cluster_info flags */
> +#define		MD_CLUSTER_WAITING_FOR_NEWDISK		1
> +
> +
>  struct md_cluster_info {
>  	/* dlm lock space and resources for clustered raid. */
>  	dlm_lockspace_t *lockspace;
> @@ -61,6 +65,7 @@ struct md_cluster_info {
>  	struct dlm_lock_resource *no_new_dev_lockres;
>  	struct md_thread *recv_thread;
>  	struct completion newdisk_completion;
> +	unsigned long state;
>  };
>  
>  enum msg_type {
> @@ -380,9 +385,11 @@ static void process_add_new_disk(struct mddev *mddev, struct cluster_msg *cmsg)
>  	snprintf(raid_slot, 16, "RAID_DISK=%d", cmsg->raid_slot);
>  	pr_info("%s:%d Sending kobject change with %s and %s\n", __func__, __LINE__, disk_uuid, raid_slot);
>  	init_completion(&cinfo->newdisk_completion);
> +	set_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state);
>  	kobject_uevent_env(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE, envp);
>  	wait_for_completion_timeout(&cinfo->newdisk_completion,
>  			NEW_DEV_TIMEOUT);
> +	clear_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state);
>  }
>  
>  
> @@ -832,13 +839,19 @@ static int add_new_disk_finish(struct mddev *mddev)
>  	return ret;
>  }
>  
> -static void new_disk_ack(struct mddev *mddev, bool ack)
> +static int new_disk_ack(struct mddev *mddev, bool ack)
>  {
>  	struct md_cluster_info *cinfo = mddev->cluster_info;
>  
> +	if (!test_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state)) {
> +		pr_warn("md-cluster(%s): Spurious cluster confirmation\n", mdname(mddev));
> +		return -EINVAL;
> +	}
> +
>  	if (ack)
>  		dlm_unlock_sync(cinfo->no_new_dev_lockres);
>  	complete(&cinfo->newdisk_completion);
> +	return 0;
>  }
>  
>  static struct md_cluster_operations cluster_ops = {
> diff --git a/drivers/md/md-cluster.h b/drivers/md/md-cluster.h
> index 60d7e58..7417133 100644
> --- a/drivers/md/md-cluster.h
> +++ b/drivers/md/md-cluster.h
> @@ -21,7 +21,7 @@ struct md_cluster_operations {
>  	int (*area_resyncing)(struct mddev *mddev, sector_t lo, sector_t hi);
>  	int (*add_new_disk_start)(struct mddev *mddev, struct md_rdev *rdev);
>  	int (*add_new_disk_finish)(struct mddev *mddev);
> -	void (*new_disk_ack)(struct mddev *mddev, bool ack);
> +	int (*new_disk_ack)(struct mddev *mddev, bool ack);
>  };
>  
>  #endif /* _MD_CLUSTER_H */
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 23784988..461024d 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -5757,7 +5755,7 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
>  
>  	if (mddev_is_clustered(mddev) &&
>  		!(info->state & ((1 << MD_DISK_CLUSTER_ADD) | (1 << MD_DISK_CANDIDATE)))) {
> -		pr_err("%s: Cannot add to clustered mddev. Try --cluster-add\n",
> +		pr_err("%s: Cannot add to clustered mddev.\n",
>  			       mdname(mddev));
>  		return -EINVAL;
>  	}
> @@ -5855,7 +5853,11 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
>  			if (info->state & (1 << MD_DISK_CANDIDATE)) {
>  				/* Through --cluster-confirm */
>  				set_bit(Candidate, &rdev->flags);
> -				md_cluster_ops->new_disk_ack(mddev, true);
> +				err = md_cluster_ops->new_disk_ack(mddev, true);
> +				if (err) {
> +					export_rdev(rdev);
> +					return err;
> +				}
>  			} else if (info->state & (1 << MD_DISK_CLUSTER_ADD)) {
>  				/* --add initiated by this node */
>  				err = md_cluster_ops->add_new_disk_start(mddev, rdev);
> --
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Makes sense.
Applied, thanks.

NeilBrown

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