Re: [PATCH v2 1/4] linux-user: Add support for a group of btrfs inode ioctls

[Laurent Vivier <laurent@vivier.eu>]

Le 17/07/2020 à 16:44, Filip Bozuta a écrit :
> This patch implements functionality of following ioctls:
> 
> BTRFS_IOC_INO_LOOKUP - Reading tree root id and path
> 
>     Read tree root id and path for a given file or directory.
>     The name and tree root id are returned in an ioctl's third
>     argument that represents a pointer to a following type:
> 
>     struct btrfs_ioctl_ino_lookup_args {
> 	__u64 treeid;
> 	__u64 objectid;
> 	char name[BTRFS_INO_LOOKUP_PATH_MAX];
>     };
> 
>     Before calling this ioctl, field 'objectid' should be filled
>     with the object id value for which the tree id and path are
>     to be read. Value 'BTRFS_FIRST_FREE_OBJECTID' represents the
>     object id for the first available btrfs object (directory or
>     file).
> 
> BTRFS_IOC_INO_PATHS - Reading paths to all files
> 
>     Read path to all files with a certain inode number. The paths
>     are returned in the ioctl's third argument which represents
>     a pointer to a following type:
> 
>     struct btrfs_ioctl_ino_path_args {
> 	__u64				inum;		/* in */
> 	__u64				size;		/* in */
> 	__u64				reserved[4];
> 	/* struct btrfs_data_container	*fspath;	   out */
> 	__u64				fspath;		/* out */
>      };
> 
>      Before calling this ioctl, the 'inum' and 'size' field should
>      be filled with the aproppriate inode number and size of the
>      directory where file paths should be looked for. For now, the
>      paths are returned in an '__u64' (unsigned long long) value
>      'fspath'.
> 
> BTRFS_IOC_LOGICAL_INO - Reading inode numbers
> 
>      Read inode numbers for files on a certain logical adress. The
>      inode numbers are returned in the ioctl's third argument which
>      represents a pointer to a following type:
> 
>      struct btrfs_ioctl_logical_ino_args {
> 	__u64				logical;	/* in */
> 	__u64				size;		/* in */
> 	__u64				reserved[3];	/* must be 0 for now */
> 	__u64				flags;		/* in, v2 only */
> 	/* struct btrfs_data_container	*inodes;	out   */
> 	__u64				inodes;
>      };
> 
>      Before calling this ioctl, the 'logical' and 'size' field should
>      be filled with the aproppriate logical adress and size of where
>      the inode numbers of files should be looked for. For now, the
>      inode numbers are returned in an '__u64' (unsigned long long)
>      value 'inodes'.
> 
> BTRFS_IOC_LOGICAL_INO_V2 - Reading inode numbers
> 
>      Same as the above mentioned ioctl except that it allows passing
>      a flags 'BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET'.
> 
> BTRFS_IOC_INO_LOOKUP_USER - Reading subvolume name and path
> 
>      Read name and path of a subvolume. The tree root id and
>      path are read in an ioctl's third argument which represents a
>      pointer to a following type:
> 
>      struct btrfs_ioctl_ino_lookup_user_args {
> 	/* in, inode number containing the subvolume of 'subvolid' */
> 	__u64 dirid;
> 	/* in */
> 	__u64 treeid;
> 	/* out, name of the subvolume of 'treeid' */
> 	char name[BTRFS_VOL_NAME_MAX + 1];
> 	/*
> 	 * out, constructed path from the directory with which the ioctl is
> 	 * called to dirid
> 	 */
> 	char path[BTRFS_INO_LOOKUP_USER_PATH_MAX];
>      };
> 
>      Before calling this ioctl, the 'dirid' and 'treeid' field should
>      be filled with aproppriate values which represent the inode number
>      of the directory that contains the subvolume and treeid of the
>      subvolume.
> 
> Implementation notes:
> 
>      All of the ioctls in this patch use structure types as third arguments.
>      That is the reason why aproppriate thunk definitions were added in file
>      'syscall_types.h'.
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> ---
>  linux-user/ioctls.h        | 20 ++++++++++++++++++++
>  linux-user/syscall_defs.h  | 10 ++++++++++
>  linux-user/syscall_types.h | 24 ++++++++++++++++++++++++
>  3 files changed, 54 insertions(+)
> 
...

> diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
> index 9db6f46cba..7bb105428b 100644
> --- a/linux-user/syscall_defs.h
> +++ b/linux-user/syscall_defs.h
> @@ -982,12 +982,18 @@ struct target_rtc_pll_info {
>                                                 14, struct btrfs_ioctl_vol_args)
>  #define TARGET_BTRFS_IOC_SNAP_DESTROY           TARGET_IOW(BTRFS_IOCTL_MAGIC, \
>                                                 15, struct btrfs_ioctl_vol_args)
> +#define TARGET_BTRFS_IOC_INO_LOOKUP             TARGET_IOWR(BTRFS_IOCTL_MAGIC,\
> +                                        18, struct btrfs_ioctl_ino_lookup_args)
>  #define TARGET_BTRFS_IOC_SUBVOL_GETFLAGS        TARGET_IOR(BTRFS_IOCTL_MAGIC, \
>                                                             25, abi_ullong)
>  #define TARGET_BTRFS_IOC_SUBVOL_SETFLAGS        TARGET_IOW(BTRFS_IOCTL_MAGIC, \
>                                                             26, abi_ullong)
>  #define TARGET_BTRFS_IOC_DEV_INFO               TARGET_IOWR(BTRFS_IOCTL_MAGIC,\
>                                            30, struct btrfs_ioctl_dev_info_args)
> +#define TARGET_BTRFS_IOC_INO_PATHS              TARGET_IOWR(BTRFS_IOCTL_MAGIC,\
> +                                          35, struct btrfs_ioctl_ino_path_args)
> +#define TARGET_BTRFS_IOC_LOGICAL_INO            TARGET_IOWR(BTRFS_IOCTL_MAGIC,\
> +                                       36, struct btrfs_ioctl_logical_ino_args)
>  #define TARGET_BTRFS_IOC_GET_DEV_STATS          TARGET_IOWR(BTRFS_IOCTL_MAGIC,\
>                                            52, struct btrfs_ioctl_get_dev_stats)
>  #define TARGET_BTRFS_IOC_GET_FEATURES           TARGET_IOR(BTRFS_IOCTL_MAGIC, \
> @@ -996,8 +1002,12 @@ struct target_rtc_pll_info {
>                                         57, struct btrfs_ioctl_feature_flags[2])
>  #define TARGET_BTRFS_IOC_GET_SUPPORTED_FEATURES TARGET_IOR(BTRFS_IOCTL_MAGIC, \
>                                         57, struct btrfs_ioctl_feature_flags[3])
> +#define TARGET_BTRFS_IOC_LOGICAL_INO_V2         TARGET_IOWR(BTRFS_IOCTL_MAGIC,\
> +                                       59, struct btrfs_ioctl_logical_ino_args)
>  #define TARGET_BTRFS_IOC_GET_SUBVOL_INFO        TARGET_IOR(BTRFS_IOCTL_MAGIC, \
>                                     60, struct btrfs_ioctl_get_subvol_info_args)
> +#define TARGET_BTRFS_IOC_INO_LOOKUP_USER        TARGET_IOWR(BTRFS_IOCTL_MAGIC,\
> +                                   62, struct btrfs_ioctl_ino_lookup_user_args)

Use the 'U' variant.

>  
>  /* usb ioctls */
>  #define TARGET_USBDEVFS_CONTROL TARGET_IOWRU('U', 0)
> diff --git a/linux-user/syscall_types.h b/linux-user/syscall_types.h
> index e26ab01e8f..980c29000a 100644
> --- a/linux-user/syscall_types.h
> +++ b/linux-user/syscall_types.h
> @@ -349,6 +349,30 @@ STRUCT(btrfs_ioctl_get_subvol_info_args,
>         MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* rtime */
>         MK_ARRAY(TYPE_ULONGLONG, 8)) /* reserved */
>  
> +STRUCT(btrfs_ioctl_ino_lookup_args,
> +       TYPE_ULONGLONG, /* treeid */
> +       TYPE_ULONGLONG, /* objectid */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_INO_LOOKUP_PATH_MAX)) /* name */
> +
> +STRUCT(btrfs_ioctl_ino_path_args,
> +       TYPE_ULONGLONG, /* inum */
> +       TYPE_ULONGLONG, /* size */
> +       TYPE_ULONGLONG, /* reserved */

This is reserved[4], use MK_ARRAY() here

> +       TYPE_ULONGLONG) /* fspath */
> +
> +STRUCT(btrfs_ioctl_logical_ino_args,
> +       TYPE_ULONGLONG, /* logical */
> +       TYPE_ULONGLONG, /* size */
> +       TYPE_ULONGLONG, /* reserved */

reserved[3]

> +       TYPE_ULONGLONG, /* flags */
> +       TYPE_ULONGLONG) /* inodes */
> +
> +STRUCT(btrfs_ioctl_ino_lookup_user_args,
> +       TYPE_ULONGLONG, /* dirid */
> +       TYPE_ULONGLONG, /* treeid */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_VOL_NAME_MAX + 1), /* name */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_INO_LOOKUP_USER_PATH_MAX)) /* path */
> +
>  STRUCT(btrfs_ioctl_dev_info_args,
>         TYPE_ULONGLONG, /* devid */
>         MK_ARRAY(TYPE_CHAR, BTRFS_UUID_SIZE), /* uuid */
> 

Thanks,
Laurent