[dm-devel] [PATCH 1/4] block: add a hard-readonly flag to struct gendisk

[Martin K. Petersen]

Hi Christoph!

>  - If BLKROSET is used to set a whole-disk device read-only, any
>    partitions will end up in a read-only state until the user
>    explicitly clears the flag.

This no longer appears to be the case with your tweak.

It's very common for database folks to twiddle the read-only state of
block devices and partitions. I know that our users will find it very
counter-intuitive that setting /dev/sda read-only won't prevent writes
to /dev/sda1.

>  int bdev_read_only(struct block_device *bdev)
>  {
>  	if (!bdev)
>  		return 0;
> -	return bdev->bd_read_only;
> +	return bdev->bd_read_only ||
> +		test_bit(GD_READ_ONLY, &bdev->bd_disk->state);
>  }

I suggest doing bd->bd_read_only || get_disk_ro(...) here. That does
take part0 into account.

>  static inline int get_disk_ro(struct gendisk *disk)
>  {
> -	return disk->part0->bd_read_only;
> +	return disk->part0->bd_read_only ||
> +		test_bit(GD_READ_ONLY, &disk->state);
>  }
>  
>  extern void disk_block_events(struct gendisk *disk);

-- 
Martin K. Petersen	Oracle Linux Engineering