f2fs_reserve_new_blocks
ret = f2fs_reserve_new_blocks(dn, 1);
err = f2fs_reserve_new_blocks(&dn, prealloc);
int f2fs_reserve_new_blocks(struct dnode_of_data *dn, blkcnt_t count);
ret = f2fs_reserve_new_blocks(dn, count);
TRACE_EVENT(f2fs_reserve_new_blocks,