Re: [PATCH v2 1/8] linux-user: Add support for a group of btrfs ioctls used for subvolumes

[Laurent Vivier]

Le 03/08/2020 à 11:46, Filip Bozuta a écrit :
> This patch implements functionality of following ioctls:
> 
> BTRFS_IOC_SUBVOL_CREATE - Creating a btrfs subvolume
> 
>     Create a btrfs subvolume. The subvolume is created using the ioctl's
>     third argument which represents a pointer to a following structure
>     type:
> 
>     struct btrfs_ioctl_vol_args {
>       __s64 fd;
>       char name[BTRFS_PATH_NAME_MAX + 1];
>     };
> 
>     Before calling this ioctl, the fields of this structure should be filled
>     with aproppriate values. The fd field represents the file descriptor
>     value of the subvolume and the name field represents the subvolume
>     path.
> 
> BTRFS_IOC_SUBVOL_GETFLAGS - Getting subvolume flags
> 
>     Read the flags of the btrfs subvolume. The flags are read using
>     the ioctl's third argument that is a pointer of __u64 (unsigned long).
>     The third argument represents a bit mask that can be composed of following
>     values:
>     BTRFS_SUBVOL_RDONLY           (1ULL << 1)
>     BTRFS_SUBVOL_QGROUP_INHERIT   (1ULL << 2)
>     BTRFS_DEVICE_SPEC_BY_ID       (1ULL << 3)
>     BTRFS_SUBVOL_SPEC_BY_ID       (1ULL << 4)
> 
> BTRFS_IOC_SUBVOL_SETFLAGS - Setting subvolume flags
> 
>     Set the flags of the btrfs subvolume. The flags are set using the
>     ioctl's third argument that is a pointer of __u64 (unsigned long).
>     The third argument represents a bit mask that can be composed of same
>     values as in the case of previous ioctl (BTRFS_IOC_SUBVOL_GETFLAGS).
> 
> BTRFS_IOC_SUBVOL_GETINFO - Getting subvolume information
> 
>     Read information about the subvolume. The subvolume information is
>     returned in the ioctl's third argument which represents a pointer to
>     a following structure type:
> 
>     struct btrfs_ioctl_get_subvol_info_args {
>       /* Id of this subvolume */
>       __u64 treeid;
> 
>       /* Name of this subvolume, used to get the real name at mount point */
>       char name[BTRFS_VOL_NAME_MAX + 1];
> 
>       /*
>        * Id of the subvolume which contains this subvolume.
>        * Zero for top-level subvolume or a deleted subvolume.
>        */
>       __u64 parent_id;
> 
>       /*
>        * Inode number of the directory which contains this subvolume.
>        * Zero for top-level subvolume or a deleted subvolume
>        */
>       __u64 dirid;
> 
>       /* Latest transaction id of this subvolume */
>       __u64 generation;
> 
>       /* Flags of this subvolume */
>       __u64 flags;
> 
>       /* UUID of this subvolume */
>       __u8 uuid[BTRFS_UUID_SIZE];
> 
>       /*
>        * UUID of the subvolume of which this subvolume is a snapshot.
>        * All zero for a non-snapshot subvolume.
>        */
>       __u8 parent_uuid[BTRFS_UUID_SIZE];
> 
>       /*
>        * UUID of the subvolume from which this subvolume was received.
>        * All zero for non-received subvolume.
>        */
>       __u8 received_uuid[BTRFS_UUID_SIZE];
> 
>       /* Transaction id indicating when change/create/send/receive happened */
>       __u64 ctransid;
>       __u64 otransid;
>       __u64 stransid;
>       __u64 rtransid;
>       /* Time corresponding to c/o/s/rtransid */
>       struct btrfs_ioctl_timespec ctime;
>       struct btrfs_ioctl_timespec otime;
>       struct btrfs_ioctl_timespec stime;
>       struct btrfs_ioctl_timespec rtime;
> 
>       /* Must be zero */
>       __u64 reserved[8];
>      };
> 
>      All of the fields of this structure are filled after the ioctl call.
> 
> Implementation notes:
> 
>     Ioctls BTRFS_IOC_SUBVOL_CREATE and BTRFS_IOC_SUBVOL_GETINFO have structure
>     types as third arguments. That is the reason why a corresponding 
> definition
>     are added in file 'linux-user/syscall_types.h'.
> 
>     The line '#include <linux/btrfs.h>' is added in file 
> 'linux-user/syscall.c' to
>     recognise preprocessor definitions for these ioctls. Since the file 
> "linux/btrfs.h"
>     was added in the kernel version 3.9, it is enwrapped in an #ifdef 
> statement
>     with parameter CONFIG_BTRFS which is defined in 'configure' if the
>     header file is present.
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> Reviewed-by: Laurent Vivier <laurent@vivier.eu>
> ---
>  configure                  |  9 +++++++++
>  linux-user/ioctls.h        | 15 +++++++++++++++
>  linux-user/syscall.c       |  3 +++
>  linux-user/syscall_defs.h  |  8 ++++++++
>  linux-user/syscall_types.h | 28 ++++++++++++++++++++++++++++
>  5 files changed, 63 insertions(+)
> 
> diff --git a/configure b/configure
> index b969dee675..8b3b214031 100755
> --- a/configure
> +++ b/configure
> @@ -4945,6 +4945,12 @@ if check_include sys/kcov.h ; then
>      kcov=yes
>  fi
>  
> +# check for btrfs filesystem support (kernel must be 3.9+)
> +btrfs=no
> +if check_include linux/btrfs.h ; then
> +    btrfs=yes
> +fi
> +
>  # If we're making warnings fatal, apply this to Sphinx runs as well
>  sphinx_werror=""
>  if test "$werror" = "yes"; then
> @@ -7057,6 +7063,9 @@ fi
>  if test "$kcov" = "yes" ; then
>    echo "CONFIG_KCOV=y" >> $config_host_mak
>  fi
> +if test "$btrfs" = "yes" ; then
> +  echo "CONFIG_BTRFS=y" >> $config_host_mak
> +fi
>  if test "$inotify" = "yes" ; then
>    echo "CONFIG_INOTIFY=y" >> $config_host_mak
>  fi
> diff --git a/linux-user/ioctls.h b/linux-user/ioctls.h
> index 0defa1d8c1..544184ff95 100644
> --- a/linux-user/ioctls.h
> +++ b/linux-user/ioctls.h
> @@ -174,6 +174,21 @@
>       IOCTL(FS_IOC32_GETVERSION, IOC_R, MK_PTR(TYPE_INT))
>       IOCTL(FS_IOC32_SETVERSION, IOC_W, MK_PTR(TYPE_INT))
>  
> +#ifdef BTRFS_IOC_SUBVOL_CREATE
> +     IOCTL(BTRFS_IOC_SUBVOL_CREATE, IOC_W,
> +           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_vol_args)))
> +#endif
> +#ifdef BTRFS_IOC_SUBVOL_GETFLAGS
> +     IOCTL(BTRFS_IOC_SUBVOL_GETFLAGS, IOC_R, MK_PTR(TYPE_ULONGLONG))
> +#endif
> +#ifdef BTRFS_IOC_SUBVOL_SETFLAGS
> +     IOCTL(BTRFS_IOC_SUBVOL_SETFLAGS, IOC_W, MK_PTR(TYPE_ULONGLONG))
> +#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)))
> +#endif
> +
>  #ifdef CONFIG_USBFS
>    /* USB ioctls */
>    IOCTL(USBDEVFS_CONTROL, IOC_RW,
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 05f03919ff..4a65b28999 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -112,6 +112,9 @@
>  #include <linux/if_alg.h>
>  #include <linux/rtc.h>
>  #include <sound/asound.h>
> +#ifdef CONFIG_BTRFS
> +#include <linux/btrfs.h>
> +#endif
>  #include "linux_loop.h"
>  #include "uname.h"
>  
> diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
> index 152ec637cb..67a3c110b6 100644
> --- a/linux-user/syscall_defs.h
> +++ b/linux-user/syscall_defs.h
> @@ -967,6 +967,14 @@ struct target_rtc_pll_info {
>  #define TARGET_FS_IOC32_GETVERSION TARGET_IOR('v', 1, int)
>  #define TARGET_FS_IOC32_SETVERSION TARGET_IOW('v', 2, int)
>  
> +/* btrfs ioctls */
> +#define TARGET_BTRFS_IOC_SUBVOL_CREATE          
> TARGET_IOWU(BTRFS_IOCTL_MAGIC, 14)
> +#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_GET_SUBVOL_INFO        
> TARGET_IORU(BTRFS_IOCTL_MAGIC, 60)
> +
>  /* usb ioctls */
>  #define TARGET_USBDEVFS_CONTROL TARGET_IOWRU('U', 0)
>  #define TARGET_USBDEVFS_BULK TARGET_IOWRU('U', 2)
> diff --git a/linux-user/syscall_types.h b/linux-user/syscall_types.h
> index 4e12c1661e..75ce6482ea 100644
> --- a/linux-user/syscall_types.h
> +++ b/linux-user/syscall_types.h
> @@ -321,6 +321,34 @@ STRUCT(blkpg_partition,
>         MK_ARRAY(TYPE_CHAR, BLKPG_DEVNAMELTH), /* devname */
>         MK_ARRAY(TYPE_CHAR, BLKPG_VOLNAMELTH)) /* volname */
>  
> +STRUCT(btrfs_ioctl_vol_args,
> +       TYPE_LONGLONG, /* fd */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_PATH_NAME_MAX + 1)) /* name */
> +
> +STRUCT(btrfs_ioctl_timespec,
> +       TYPE_ULONGLONG, /* sec */
> +       TYPE_INT) /* nsec */
> +
> +STRUCT(btrfs_ioctl_get_subvol_info_args,
> +       TYPE_ULONGLONG, /* treeid */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_VOL_NAME_MAX + 1),
> +       TYPE_ULONGLONG, /* parentid */
> +       TYPE_ULONGLONG, /* dirid */
> +       TYPE_ULONGLONG, /* generation */
> +       TYPE_ULONGLONG, /* flags */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_UUID_SIZE), /* uuid */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_UUID_SIZE), /* parent_uuid */
> +       MK_ARRAY(TYPE_CHAR, BTRFS_UUID_SIZE), /* received_uuid */
> +       TYPE_ULONGLONG, /* ctransid */
> +       TYPE_ULONGLONG, /* otransid */
> +       TYPE_ULONGLONG, /* stransid */
> +       TYPE_ULONGLONG, /* rtransid */
> +       MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* ctime */
> +       MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* otime */
> +       MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* stime */
> +       MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* rtime */
> +       MK_ARRAY(TYPE_ULONGLONG, 8)) /* reserved */
> +
>  STRUCT(rtc_time,
>         TYPE_INT, /* tm_sec */
>         TYPE_INT, /* tm_min */
> 

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

Thanks,
Laurent