btrfs: re-instantiate the removed BTRFS_SUBVOL_CREATE_ASYNC definition

The commit 9c1036fdb1d1ff1b ("btrfs: Remove BTRFS_SUBVOL_CREATE_ASYNC
support") breaks strace build with the kernel headers from git:

    btrfs.c: In function "btrfs_test_subvol_ioctls":
    btrfs.c:531:23: error: "BTRFS_SUBVOL_CREATE_ASYNC" undeclared (first use
    in this function)
       vol_args_v2.flags = BTRFS_SUBVOL_CREATE_ASYNC;

Moreover, it is improper to break UAPI, strace uses the definitions to
decode ioctls that are considered part of public API.

Restore the macro definition and put it under "#ifndef __KERNEL__"
in order to prevent inadvertent in-kernel usage.

Fixes: 9c1036fdb1d1ff1b ("btrfs: Remove BTRFS_SUBVOL_CREATE_ASYNC support")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 8134924..e6b6cb0 100644 (file)
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -36,12 +36,10 @@ struct btrfs_ioctl_vol_args {
 #define BTRFS_DEVICE_PATH_NAME_MAX     1024
 #define BTRFS_SUBVOL_NAME_MAX          4039
 
-/*
- * Deprecated since 5.7:
- *
- * BTRFS_SUBVOL_CREATE_ASYNC   (1ULL << 0)
- */
-
+#ifndef __KERNEL__
+/* Deprecated since 5.7 */
+# define BTRFS_SUBVOL_CREATE_ASYNC     (1ULL << 0)
+#endif
 #define BTRFS_SUBVOL_RDONLY            (1ULL << 1)
 #define BTRFS_SUBVOL_QGROUP_INHERIT    (1ULL << 2)