Re: [PATCH v2 3/8] linux-user: Add support for btrfs ioctls used to manipulate with devices

[Laurent Vivier]

Le 03/08/2020 à 11:46, Filip Bozuta a écrit :
> This patch implements functionality for following ioctls:
> 
> BTRFS_IOC_SCAN_DEV - Scanning device for a btrfs filesystem
> 
>     Scan a device for a btrfs filesystem. The device that is to
>     be scanned is passed in the ioctl's third argument which
>     represents a pointer to a 'struct ioc_vol_args' (which was
>     mentioned in a previous patch). Before calling this ioctl,
>     the name field of this structure should be filled with the
>     aproppriate name value which represents a path for the device.
>     If the device contains a btrfs filesystem, the ioctl returns 0,
>     otherwise a negative value is returned.
> 
> BTRFS_IOC_ADD_DEV - Adding a device to a btrfs filesystem
> 
>     Add a device to a btrfs filesystem. The device that is to be
>     added is passed in the ioctl's third argument which represents
>     a pointer to a 'struct ioc_vol_args' (which was mentioned in
>     a previous patch). Before calling this ioctl, the name field of
>     this structure should be filled with the aproppriate name value
>     which represents a path for the device.
> 
> BTRFS_IOC_RM_DEV - Removing a device from a btrfs filesystem
> 
>     Remove a device from a btrfs filesystem. The device that is to be
>     removed is passed in the ioctl's third argument which represents
>     a pointer to a 'struct ioc_vol_args' (which was mentioned in
>     a previous patch). Before calling this ioctl, the name field of
>     this structure should be filled with the aproppriate name value
>     which represents a path for the device.
> 
> BTRFS_IOC_DEV_INFO - Getting information about a device
> 
>     Obtain information for device in a btrfs filesystem. The information
>     is gathered in the ioctl's third argument which represents a pointer
>     to a following structure type:
> 
>     struct btrfs_ioctl_dev_info_args {
>       __u64 devid;                            /* in/out */
>       __u8 uuid[BTRFS_UUID_SIZE];             /* in/out */
>       __u64 bytes_used;                       /* out */
>       __u64 total_bytes;                      /* out */
>       __u64 unused[379];                      /* pad to 4k */
>       __u8 path[BTRFS_DEVICE_PATH_NAME_MAX];  /* out */
>     };
> 
>     Before calling this ioctl, field "devid" should be set with the id value
>     for the device for which the information is to be obtained. If this field
>     is not aproppriately set, the errno ENODEV ("No such device") is returned.
> 
> BTRFS_IOC_GET_DEV_STATS - Getting device statistics
> 
>     Obtain stats informatin for device in a btrfs filesystem. The information
>     is gathered in the ioctl's third argument which represents a pointer to
>     a following structure type:
> 
>     struct btrfs_ioctl_get_dev_stats {
>       __u64 devid;                            /* in */
>       __u64 nr_items;                         /* in/out */
>       __u64 flags;                            /* in/out */
> 
>       /* out values: */
>       __u64 values[BTRFS_DEV_STAT_VALUES_MAX];
> 
>       /*
>        * This pads the struct to 1032 bytes. It was originally meant to pad to
>        * 1024 bytes, but when adding the flags field, the padding calculation
>        * was not adjusted.
>        */
>       __u64 unused[128 - 2 - BTRFS_DEV_STAT_VALUES_MAX];
>     };
> 
>     Before calling this ioctl, field "devid" should be set with the id value
>     for the device for which the information is to be obtained. If this field
>     is not aproppriately set, the errno ENODEV ("No such device") is returned.
> 
> BTRFS_IOC_FORGET_DEV - Remove unmounted devices
> 
>     Search and remove all stale devices (devices which are not mounted).
>     The third ioctl argument is a pointer to a 'struct btrfs_ioctl_vol_args'.
>     The ioctl call will release all unmounted devices which match the path
>     which is specified in the "name" field of the structure. If an empty
>     path ("") is specified, all unmounted devices will be released.
> 
> Implementation notes:
> 
>     Ioctls BTRFS_IOC_DEV_INFO and BTRFS_IOC_GET_DEV_STATS use types
>     'struct btrfs_ioctl_dev_info_args' and ' struct btrfs_ioctl_get_dev_stats'
>     as third argument types. That is the reason why corresponding structure
>     definitions were added in file 'linux-user/syscall_types.h'.
>     Since the thunk type for 'struct ioc_vol_args' was already added in a
>     previous patch, the rest of the implementation was straightforward.
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> Reviewed-by: Laurent Vivier <laurent@vivier.eu>
> ---
>  linux-user/ioctls.h        | 24 ++++++++++++++++++++++++
>  linux-user/syscall_defs.h  |  6 ++++++
>  linux-user/syscall_types.h | 16 ++++++++++++++++
>  3 files changed, 46 insertions(+)
> 
> diff --git a/linux-user/ioctls.h b/linux-user/ioctls.h
> index 2422675dd0..c20bd97736 100644
> --- a/linux-user/ioctls.h
> +++ b/linux-user/ioctls.h
> @@ -178,6 +178,22 @@
>       IOCTL(BTRFS_IOC_SNAP_CREATE, IOC_W,
>             MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_vol_args)))
>  #endif
> +#ifdef BTRFS_IOC_SCAN_DEV
> +     IOCTL(BTRFS_IOC_SCAN_DEV, IOC_W,
> +           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_vol_args)))
> +#endif
> +#ifdef BTRFS_IOC_FORGET_DEV
> +     IOCTL(BTRFS_IOC_FORGET_DEV, IOC_W,
> +           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_vol_args)))
> +#endif
> +#ifdef BTRFS_IOC_ADD_DEV
> +     IOCTL(BTRFS_IOC_ADD_DEV, IOC_W,
> +           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_vol_args)))
> +#endif
> +#ifdef BTRFS_IOC_RM_DEV
> +     IOCTL(BTRFS_IOC_RM_DEV, IOC_W,
> +           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_vol_args)))
> +#endif
>  #ifdef BTRFS_IOC_SUBVOL_CREATE
>       IOCTL(BTRFS_IOC_SUBVOL_CREATE, IOC_W,
>             MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_vol_args)))
> @@ -192,6 +208,14 @@
>  #ifdef BTRFS_IOC_SUBVOL_SETFLAGS
>       IOCTL(BTRFS_IOC_SUBVOL_SETFLAGS, IOC_W, MK_PTR(TYPE_ULONGLONG))
>  #endif
> +#ifdef BTRFS_IOC_DEV_INFO
> +     IOCTL(BTRFS_IOC_DEV_INFO, IOC_RW,
> +           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_dev_info_args)))
> +#endif
> +#ifdef BTRFS_IOC_GET_DEV_STATS
> +     IOCTL(BTRFS_IOC_GET_DEV_STATS, IOC_RW,
> +           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_get_dev_stats)))
> +#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 16966c323f..23f966d552 100644
> --- a/linux-user/syscall_defs.h
> +++ b/linux-user/syscall_defs.h
> @@ -969,12 +969,18 @@ struct target_rtc_pll_info {
>  
>  /* btrfs ioctls */
>  #define TARGET_BTRFS_IOC_SNAP_CREATE            
> TARGET_IOWU(BTRFS_IOCTL_MAGIC, 1)
> +#define TARGET_BTRFS_IOC_SCAN_DEV               
> TARGET_IOWU(BTRFS_IOCTL_MAGIC, 4)
> +#define TARGET_BTRFS_IOC_FORGET_DEV             
> TARGET_IOWU(BTRFS_IOCTL_MAGIC, 5)
> +#define TARGET_BTRFS_IOC_ADD_DEV                
> TARGET_IOWU(BTRFS_IOCTL_MAGIC, 10)
> +#define TARGET_BTRFS_IOC_RM_DEV                 
> TARGET_IOWU(BTRFS_IOCTL_MAGIC, 11)
>  #define TARGET_BTRFS_IOC_SUBVOL_CREATE          
> TARGET_IOWU(BTRFS_IOCTL_MAGIC, 14)
>  #define TARGET_BTRFS_IOC_SNAP_DESTROY           
> TARGET_IOWU(BTRFS_IOCTL_MAGIC, 15)
>  #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_IOWRU(BTRFS_IOCTL_MAGIC, 30)
> +#define TARGET_BTRFS_IOC_GET_DEV_STATS          
> TARGET_IOWRU(BTRFS_IOCTL_MAGIC, 52)
>  #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 75ce6482ea..b5718231e5 100644
> --- a/linux-user/syscall_types.h
> +++ b/linux-user/syscall_types.h
> @@ -349,6 +349,22 @@ STRUCT(btrfs_ioctl_get_subvol_info_args,
>         MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* rtime */
>         MK_ARRAY(TYPE_ULONGLONG, 8)) /* reserved */
>  
> +STRUCT(btrfs_ioctl_dev_info_args,
> +       TYPE_ULONGLONG, /* devid */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_UUID_SIZE), /* uuid */
> +       TYPE_ULONGLONG, /* bytes_used */
> +       TYPE_ULONGLONG, /* total_bytes */
> +       MK_ARRAY(TYPE_ULONGLONG, 379), /* unused */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_DEVICE_PATH_NAME_MAX)) /* path */
> +
> +STRUCT(btrfs_ioctl_get_dev_stats,
> +       TYPE_ULONGLONG, /* devid */
> +       TYPE_ULONGLONG, /* nr_items */
> +       TYPE_ULONGLONG, /* flags */
> +       MK_ARRAY(TYPE_ULONGLONG, BTRFS_DEV_STAT_VALUES_MAX), /* values */
> +       MK_ARRAY(TYPE_ULONGLONG,
> +                128 - 2 - BTRFS_DEV_STAT_VALUES_MAX)) /* unused */
> +
>  STRUCT(rtc_time,
>         TYPE_INT, /* tm_sec */
>         TYPE_INT, /* tm_min */
> 

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

Thanks,
Laurent