Re: [PATCH v2 4/8] linux-user: Add support for btrfs ioctls used to get/set features

[Laurent Vivier]

Le 03/08/2020 à 11:46, Filip Bozuta a écrit :
> This patch implements functionality for following ioctls:
> 
> BTRFS_IOC_GET_FEATURES - Getting feature flags
> 
>     Read feature flags for a btrfs filesystem. The feature flags
>     are returned inside the ioctl's third argument which represents
>     a pointer to a following structure type:
> 
>     struct btrfs_ioctl_feature_flags {
>       __u64 compat_flags;
>       __u64 compat_ro_flags;
>       __u64 incompat_flags;
>     };
> 
>     All of the structure field represent bit masks that can be composed
>     of values which can be found on:
>     https://elixir.bootlin.com/linux/latest/source/fs/btrfs/ctree.h#L282
> 
> BTRFS_IOC_SET_FEATURES - Setting feature flags
> 
>     Set and clear feature flags for a btrfs filesystem. The feature flags
>     are set using the ioctl's third argument which represents a
>     'struct btrfs_ioctl_feature_flags[2]' array. The first element of the
>     array represent flags which are to be cleared and the second element of
>     the array represent flags which are to be set. The second element has the
>     priority over the first, which means that if there are matching flags
>     in the elements, they will be set in the filesystem. If the flag values
>     in the third argument aren't correctly set to be composed of the available
>     predefined flag values, errno ENOPERM ("Operation not permitted") is 
> returned.
> 
> BTRFS_IOC_GET_SUPPORTED_FEATURES - Getting supported feature flags
> 
>     Read supported feature flags for a btrfs filesystem. The supported
>     feature flags are read using the ioctl's third argument which represents
>     a 'struct btrfs_ioctl_feature_flags[3]' array. The first element of this
>     array represents all of the supported flags in the btrfs filesystem.
>     The second element represents flags that can be safely set and third 
> element
>     represent flags that can be safely clearead.
> 
> Implementation notes:
> 
>     All of the implemented ioctls use 'struct btrfs_ioctl_feature_flags' as
>     third argument. That is the reason why a corresponding defintion was added
>     in file 'linux-user/syscall_types.h'.
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> Reviewed-by: Laurent Vivier <laurent@vivier.eu>
> ---
>  linux-user/ioctls.h        | 12 ++++++++++++
>  linux-user/syscall_defs.h  |  3 +++
>  linux-user/syscall_types.h |  5 +++++
>  3 files changed, 20 insertions(+)
> 
> diff --git a/linux-user/ioctls.h b/linux-user/ioctls.h
> index c20bd97736..c6303a0406 100644
> --- a/linux-user/ioctls.h
> +++ b/linux-user/ioctls.h
> @@ -216,6 +216,18 @@
>       IOCTL(BTRFS_IOC_GET_DEV_STATS, IOC_RW,
>             MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_get_dev_stats)))
>  #endif
> +#ifdef BTRFS_IOC_GET_FEATURES
> +     IOCTL(BTRFS_IOC_GET_FEATURES, IOC_R,
> +           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_feature_flags)))
> +#endif
> +#ifdef BTRFS_IOC_SET_FEATURES
> +     IOCTL(BTRFS_IOC_SET_FEATURES, IOC_W,
> +           MK_PTR(MK_ARRAY(MK_STRUCT(STRUCT_btrfs_ioctl_feature_flags), 2)))
> +#endif
> +#ifdef BTRFS_IOC_GET_SUPPORTED_FEATURES
> +     IOCTL(BTRFS_IOC_GET_SUPPORTED_FEATURES, IOC_R,
> +           MK_PTR(MK_ARRAY(MK_STRUCT(STRUCT_btrfs_ioctl_feature_flags), 3)))
> +#endif
>  #ifdef BTRFS_IOC_GET_SUBVOL_INFO
>       IOCTL(BTRFS_IOC_GET_SUBVOL_INFO, IOC_R,
>             MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_get_subvol_info_args)))
> diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
> index 23f966d552..13a444356b 100644
> --- a/linux-user/syscall_defs.h
> +++ b/linux-user/syscall_defs.h
> @@ -981,6 +981,9 @@ struct target_rtc_pll_info {
>                                                             abi_ullong)
>  #define TARGET_BTRFS_IOC_DEV_INFO               
> TARGET_IOWRU(BTRFS_IOCTL_MAGIC, 30)
>  #define TARGET_BTRFS_IOC_GET_DEV_STATS          
> TARGET_IOWRU(BTRFS_IOCTL_MAGIC, 52)
> +#define TARGET_BTRFS_IOC_GET_FEATURES           
> TARGET_IORU(BTRFS_IOCTL_MAGIC, 57)
> +#define TARGET_BTRFS_IOC_SET_FEATURES           
> TARGET_IOWU(BTRFS_IOCTL_MAGIC, 57)
> +#define TARGET_BTRFS_IOC_GET_SUPPORTED_FEATURES 
> TARGET_IORU(BTRFS_IOCTL_MAGIC, 57)
>  #define TARGET_BTRFS_IOC_GET_SUBVOL_INFO        
> TARGET_IORU(BTRFS_IOCTL_MAGIC, 60)
>  
>  /* usb ioctls */
> diff --git a/linux-user/syscall_types.h b/linux-user/syscall_types.h
> index b5718231e5..e26ab01e8f 100644
> --- a/linux-user/syscall_types.h
> +++ b/linux-user/syscall_types.h
> @@ -365,6 +365,11 @@ STRUCT(btrfs_ioctl_get_dev_stats,
>         MK_ARRAY(TYPE_ULONGLONG,
>                  128 - 2 - BTRFS_DEV_STAT_VALUES_MAX)) /* unused */
>  
> +STRUCT(btrfs_ioctl_feature_flags,
> +       TYPE_ULONGLONG, /* compat_flags */
> +       TYPE_ULONGLONG, /* compat_ro_flags */
> +       TYPE_ULONGLONG) /* incompat_flags */
> +
>  STRUCT(rtc_time,
>         TYPE_INT, /* tm_sec */
>         TYPE_INT, /* tm_min */
> 

Applied to my linux-user-for-5.2 branch.

Thanks,
Laurent