[PULL 2/8] linux-user: Add support for a group of btrfs ioctls used for snapshots

[Laurent Vivier]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

This patch implements functionality for following ioctls:

BTRFS_IOC_SNAP_CREATE - Creating a subvolume snapshot

    Create a snapshot of a btrfs subvolume. The snapshot is created using the
    ioctl's third argument that is a pointer to a 'struct btrfs_ioctl_vol_args'
    (which was mentioned in the previous patch). Before calling this ioctl,
    the fields of the structure should be filled with aproppriate values for
    the file descriptor and path of the subvolume for which the snapshot is to
    be created.

BTRFS_IOC_SNAP_DESTROY - Removing a subvolume snapshot

    Delete a snapshot of a btrfs subvolume. The snapshot is deleted using the
    ioctl's third argument that is a pointer to a 'struct btrfs_ioctl_vol_args'
    (which was mentioned in the previous patch). Before calling this ioctl,
    the fields of the structure should be filled with aproppriate values for
    the file descriptor and path of the subvolume for which the snapshot is to
    be deleted.

Implementation notes:

    Since the thunk type 'struct btrfs_ioctl_vol_args' is defined in the
    previous patch, the implementation for these ioctls was straightforward.

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Tested-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200823195014.116226-3-Filip.Bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/ioctls.h        | 8 ++++++++
 linux-user/syscall_defs.h  | 2 ++
 linux-user/syscall_types.h | 3 ++-
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/linux-user/ioctls.h b/linux-user/ioctls.h
index bf89b96d27b0..bddeaca9e7ec 100644
--- a/linux-user/ioctls.h
+++ b/linux-user/ioctls.h
@@ -174,10 +174,18 @@
      IOCTL(FS_IOC32_GETVERSION, IOC_R, MK_PTR(TYPE_INT))
      IOCTL(FS_IOC32_SETVERSION, IOC_W, MK_PTR(TYPE_INT))
 
+#ifdef BTRFS_IOC_SNAP_CREATE
+     IOCTL(BTRFS_IOC_SNAP_CREATE, 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)))
 #endif
+#ifdef BTRFS_IOC_SNAP_DESTROY
+     IOCTL(BTRFS_IOC_SNAP_DESTROY, 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
diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
index cae79f8492e1..1519de7a5565 100644
--- a/linux-user/syscall_defs.h
+++ b/linux-user/syscall_defs.h
@@ -1006,7 +1006,9 @@ struct target_rtc_pll_info {
 #define TARGET_FS_IOC32_SETVERSION TARGET_IOW('v', 2, int)
 
 /* btrfs ioctls */
+#define TARGET_BTRFS_IOC_SNAP_CREATE            TARGET_IOWU(BTRFS_IOCTL_MAGIC, 
1)
 #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,\
diff --git a/linux-user/syscall_types.h b/linux-user/syscall_types.h
index 0ce58d77727c..853b91d21275 100644
--- a/linux-user/syscall_types.h
+++ b/linux-user/syscall_types.h
@@ -358,7 +358,8 @@ STRUCT(blkpg_partition,
        MK_ARRAY(TYPE_CHAR, BLKPG_DEVNAMELTH), /* devname */
        MK_ARRAY(TYPE_CHAR, BLKPG_VOLNAMELTH)) /* volname */
 
-#ifdef BTRFS_IOC_SUBVOL_CREATE
+#if defined(BTRFS_IOC_SUBVOL_CREATE) || defined(BTRFS_IOC_SNAP_CREATE) || \
+    defined(BTRFS_IOC_SNAP_DESTROY)
 STRUCT(btrfs_ioctl_vol_args,
        TYPE_LONGLONG, /* fd */
        MK_ARRAY(TYPE_CHAR, BTRFS_PATH_NAME_MAX + 1)) /* name */
-- 
2.26.2