[v3,2/8] linux-user: Add support for a group of btrfs ioctls used for snapshots

Commit Message

Filip Bozuta Aug. 23, 2020, 7:50 p.m. UTC

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 <[e-mail]>
---
 linux-user/ioctls.h        | 8 ++++++++
 linux-user/syscall_defs.h  | 2 ++
 linux-user/syscall_types.h | 3 ++-
 3 files changed, 12 insertions(+), 1 deletion(-)

Patch

diff --git a/linux-user/ioctls.h b/linux-user/ioctls.h
index 12d1444224..f33a99f8b6 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 2757956dfa..a945e12547 100644
--- a/linux-user/syscall_defs.h
+++ b/linux-user/syscall_defs.h
@@ -968,7 +968,9 @@  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 db61dbc1b3..038cd7869b 100644
--- a/linux-user/syscall_types.h
+++ b/linux-user/syscall_types.h
@@ -354,7 +354,8 @@  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 */