IORING_REGISTER_DST_REPLACE
if (ctx->buf_table.nr && !(arg->flags & IORING_REGISTER_DST_REPLACE))
if (arg->flags & IORING_REGISTER_DST_REPLACE)
if (buf.flags & ~(IORING_REGISTER_SRC_REGISTERED|IORING_REGISTER_DST_REPLACE))
if (!(buf.flags & IORING_REGISTER_DST_REPLACE) && ctx->buf_table.nr)