Re: [PATCH v2 2/4] btrfs: add filesystem generation to fsinfo ioctl

[Nikolay Borisov <nborisov@suse.com>]

On 13.07.20 г. 15:28 ч., Johannes Thumshirn wrote:
> Add retrieval of the filesystem's generation to the fsinfo ioctl. This is
> driven by setting the BTRFS_FS_INFO_FLAG_GENERATION flag in
> btrfs_ioctl_fs_info_args::flags.
> 
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> ---
>  fs/btrfs/ioctl.c           | 5 +++++
>  include/uapi/linux/btrfs.h | 6 +++++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 3a566cf71fc6..f1b433ec09e8 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3247,6 +3247,11 @@ static long btrfs_ioctl_fs_info(struct btrfs_fs_info *fs_info,
>  		fi_args->flags |= BTRFS_FS_INFO_FLAG_CSUM_INFO;
>  	}
>  
> +	if (flags_in & BTRFS_FS_INFO_FLAG_GENERATION) {
> +		fi_args->generation = fs_info->generation;
> +		fi_args->flags |= BTRFS_FS_INFO_FLAG_GENERATION;
> +	}
> +
>  	if (copy_to_user(arg, fi_args, sizeof(*fi_args)))
>  		ret = -EFAULT;
>  
> diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
> index b3e0af77642f..b8373723eb4a 100644
> --- a/include/uapi/linux/btrfs.h
> +++ b/include/uapi/linux/btrfs.h
> @@ -250,6 +250,9 @@ struct btrfs_ioctl_dev_info_args {
>  /* Request information about checksum type and size */
>  #define BTRFS_FS_INFO_FLAG_CSUM_INFO			(1 << 0)
>  
> +/* Request information about filesystem generation */
> +#define BTRFS_FS_INFO_FLAG_GENERATION			(1 << 1)
> +
>  struct btrfs_ioctl_fs_info_args {
>  	__u64 max_id;				/* out */
>  	__u64 num_devices;			/* out */
> @@ -261,7 +264,8 @@ struct btrfs_ioctl_fs_info_args {
>  	__u16 csum_type;			/* out */
>  	__u16 csum_size;			/* out */
>  	__u64 flags;				/* in/out */
> -	__u8 reserved[968];			/* pad to 1k */
> +	__u64 generation;			/* out */
> +	__u8 reserved[960];			/* pad to 1k */
>  };
>  
>  
>