Re: [PATCH] block: check disk exist before trying to add partition

[Jan Kara <jack@suse.cz>]

On Tue 08-06-21 17:27:07, Yufen Yu wrote:
> If disk have been deleted, we should return fail for ioctl
> BLKPG_DEL_PARTITION. Otherwise, the directory /sys/class/block
> may remain invalid symlinks file. The race as following:
> 
> blkdev_open
> 				del_gendisk
> 				    disk->flags &= ~GENHD_FL_UP;
> 				    blk_drop_partitions
> blkpg_ioctl
>     bdev_add_partition
>     add_partition
>         device_add
> 	    device_add_class_symlinks
> 
> ioctl may add_partition after del_gendisk() have tried to delete
> partitions. Then, symlinks file will be created.
> 
> Signed-off-by: Yufen Yu <yuyufen@huawei.com>

Looks good to me. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  block/partitions/core.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/block/partitions/core.c b/block/partitions/core.c
> index dc60ecf46fe6..58662a0f48e4 100644
> --- a/block/partitions/core.c
> +++ b/block/partitions/core.c
> @@ -449,17 +449,26 @@ int bdev_add_partition(struct block_device *bdev, int partno,
>  		sector_t start, sector_t length)
>  {
>  	struct block_device *part;
> +	struct gendisk *disk = bdev->bd_disk;
> +	int ret;
>  
>  	mutex_lock(&bdev->bd_mutex);
> -	if (partition_overlaps(bdev->bd_disk, start, length, -1)) {
> -		mutex_unlock(&bdev->bd_mutex);
> -		return -EBUSY;
> +	if (!(disk->flags & GENHD_FL_UP)) {
> +		ret = -ENXIO;
> +		goto out;
>  	}
>  
> -	part = add_partition(bdev->bd_disk, partno, start, length,
> +	if (partition_overlaps(disk, start, length, -1)) {
> +		ret = -EBUSY;
> +		goto out;
> +	}
> +
> +	part = add_partition(disk, partno, start, length,
>  			ADDPART_FLAG_NONE, NULL);
> +	ret = PTR_ERR_OR_ZERO(part);
> +out:
>  	mutex_unlock(&bdev->bd_mutex);
> -	return PTR_ERR_OR_ZERO(part);
> +	return ret;
>  }
>  
>  int bdev_del_partition(struct block_device *bdev, int partno)
> -- 
> 2.25.4
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR