Re: [PATCH 2/5] btrfs: add flags to give an hint to the chunk allocator

[Josef Bacik <josef@toxicpanda.com>]

On 2/1/21 4:28 PM, Goffredo Baroncelli wrote:
> From: Goffredo Baroncelli <kreijack@inwind.it>
> 
> Add the following flags to give an hint about which chunk should be
> allocated in which a disk.
> The following flags are created:
> 
> - BTRFS_DEV_ALLOCATION_PREFERRED_DATA
>    preferred data chunk, but metadata chunk allowed
> - BTRFS_DEV_ALLOCATION_PREFERRED_METADATA
>    preferred metadata chunk, but data chunk allowed
> - BTRFS_DEV_ALLOCATION_METADATA_ONLY
>    only metadata chunk allowed
> - BTRFS_DEV_ALLOCATION_DATA_ONLY
>    only data chunk allowed
> 
> Signed-off-by: Goffredo Baroncelli <kreijack@inwid.it>
> ---
>   include/uapi/linux/btrfs_tree.h | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
> 
> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> index 58d7cff9afb1..bd3af853df0c 100644
> --- a/include/uapi/linux/btrfs_tree.h
> +++ b/include/uapi/linux/btrfs_tree.h
> @@ -361,6 +361,24 @@ struct btrfs_key {
>   	__u64 offset;
>   } __attribute__ ((__packed__));
>   
> +/* dev_item.type */
> +
> +/* btrfs chunk allocation hints */
> +#define BTRFS_DEV_ALLOCATION_MASK_BIT_COUNT	3
> +#define BTRFS_DEV_ALLOCATION_MASK ((1ULL << \
> +		BTRFS_DEV_ALLOCATION_MASK_BIT_COUNT) -1)
> +#define BTRFS_DEV_ALLOCATION_MASK_COUNT (1ULL << \
> +		BTRFS_DEV_ALLOCATION_MASK_BIT_COUNT)

We just want to define the actual values that are going to disk, helpers can be 
defined elsewhere.  Thanks,

Josef