BTRFS_FS_STATE_RO
set_bit(BTRFS_FS_STATE_RO, &fs_info->fs_state);
return test_bit(BTRFS_FS_STATE_RO, &fs_info->fs_state) ||
[BTRFS_FS_STATE_RO] = 0,
set_bit(BTRFS_FS_STATE_RO, &btrfs_sb(sb)->fs_state);
clear_bit(BTRFS_FS_STATE_RO, &btrfs_sb(sb)->fs_state);