Re: [PATCH v2] t_snapshot_deleted_subvolume: add check for BTRFS_IOC_SNAP_DESTROY_V2

[David Sterba <dsterba@suse.cz>]

On Wed, Jan 31, 2024 at 11:23:48PM -0500, Yang Xu wrote:
> On some platform, struct btrfs_ioctl_vol_args_v2 is defined, but the
> macros BTRFS_IOC_SNAP_DESTROY_V2 is not defined. This will cause
> compile error. Add check for BTRFS_IOC_SNAP_DESTROY_V2 to solve this
> problem.
> 
> BTRFS_IOC_SNAP_CREATE_V2 and BTRFS_IOC_SUBVOL_CREATE_V2 were
> introduced together with struct btrfs_ioctl_vol_args_v2 by the
> commit 55e301fd57a6 ("Btrfs: move fs/btrfs/ioctl.h to
> include/uapi/linux/btrfs.h"). So there is no need to check them.
> 
> Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
> ---
>  configure.ac                       |  1 +
>  src/t_snapshot_deleted_subvolume.c | 10 +++++-----
>  2 files changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/configure.ac b/configure.ac
> index b22fc52b..b14b1ab8 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -109,6 +109,7 @@ AC_CHECK_MEMBERS([struct btrfs_ioctl_vol_args_v2.subvolid], [], [], [[
>  #include <stddef.h>
>  #include <linux/btrfs.h>
>  ]])
> +AC_CHECK_DECLS([BTRFS_IOC_SNAP_DESTROY_V2],,,[#include <linux/btrfs.h>])
>  
>  AC_CONFIG_HEADERS([include/config.h])
>  AC_CONFIG_FILES([include/builddefs])
> diff --git a/src/t_snapshot_deleted_subvolume.c b/src/t_snapshot_deleted_subvolume.c
> index c3adb1c4..402c0515 100644
> --- a/src/t_snapshot_deleted_subvolume.c
> +++ b/src/t_snapshot_deleted_subvolume.c
> @@ -20,11 +20,6 @@
>  #define BTRFS_IOCTL_MAGIC 0x94
>  #endif
>  
> -#ifndef BTRFS_IOC_SNAP_DESTROY_V2
> -#define BTRFS_IOC_SNAP_DESTROY_V2 \
> -	_IOW(BTRFS_IOCTL_MAGIC, 63, struct btrfs_ioctl_vol_args_v2)
> -#endif
> -
>  #ifndef BTRFS_IOC_SNAP_CREATE_V2
>  #define BTRFS_IOC_SNAP_CREATE_V2 \
>  	_IOW(BTRFS_IOCTL_MAGIC, 23, struct btrfs_ioctl_vol_args_v2)
> @@ -58,6 +53,11 @@ struct btrfs_ioctl_vol_args_v2 {
>  };
>  #endif
>  
> +#if !HAVE_DECL_BTRFS_IOC_SNAP_DESTROY_V2

This is right for AC_CHECK_DECLS. Other macros like AC_CHECK_HEADERS do
not define the HAVE_... in case it's not found so the #if !HAVE_...
would be wrong. Slightly confusing.

> +#define BTRFS_IOC_SNAP_DESTROY_V2 \
> +	_IOW(BTRFS_IOCTL_MAGIC, 63, struct btrfs_ioctl_vol_args_v2)
> +#endif
> +
>  int main(int argc, char **argv)
>  {
>  	if (argc != 2) {
> -- 
> 2.39.3
>