Re: [PATCH 09/19] btrfs: limit super block locations in HMZONED mode

[Josef Bacik]

On Fri, Jun 07, 2019 at 10:10:15PM +0900, Naohiro Aota wrote:
> When in HMZONED mode, make sure that device super blocks are located in
> randomly writable zones of zoned block devices. That is, do not write super
> blocks in sequential write required zones of host-managed zoned block
> devices as update would not be possible.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
> Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
> ---
>  fs/btrfs/disk-io.c     | 11 +++++++++++
>  fs/btrfs/disk-io.h     |  1 +
>  fs/btrfs/extent-tree.c |  4 ++++
>  fs/btrfs/scrub.c       |  2 ++
>  4 files changed, 18 insertions(+)
> 
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 7c1404c76768..ddbb02906042 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -3466,6 +3466,13 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev)
>  	return latest;
>  }
>  
> +int btrfs_check_super_location(struct btrfs_device *device, u64 pos)
> +{
> +	/* any address is good on a regular (zone_size == 0) device */
> +	/* non-SEQUENTIAL WRITE REQUIRED zones are capable on a zoned device */

This is not how you do multi-line comments in the kernel.  Thanks,

Josef